WEBVTT 1 00:00:00.000 --> 00:00:01.020 Welcome, ladies and gentlemen. 2 00:00:02.140 --> 00:00:06.140 I'm here to chair the session and to introduce Mary White. 3 00:00:06.740 --> 00:00:10.420 I'm Norman Harville, and I'm professorial fellow at Flinders University, 4 00:00:10.660 --> 00:00:12.540 and you don't need to know any more than that. 5 00:00:12.600 --> 00:00:13.580 You need to know about Mary. 6 00:00:14.900 --> 00:00:19.960 Mary grew up in southern Rhodesia and got her master's degree 7 00:00:21.220 --> 00:00:24.320 at Cape Town University in paleobotany, 8 00:00:24.480 --> 00:00:28.340 which is something that I am learning more and more about as I listen to her. 9 00:00:29.040 --> 00:00:35.940 She came to Australia with her family in 1955 and has been here and was since that time. 10 00:00:36.400 --> 00:00:40.900 In the 1980s onwards, she was consultant to the Bureau of Mineral Resources 11 00:00:40.900 --> 00:00:43.440 and consultant to many mining companies as well. 12 00:00:44.100 --> 00:00:49.360 She has done a lot of research into the whole field of paleobotany, 13 00:00:49.460 --> 00:00:54.780 and some of her books you will find, and examples of which are two recent ones, 14 00:00:54.800 --> 00:00:58.320 Running Down, Water in a Changing Land, Listen, Our Land is Crying, 15 00:00:58.340 --> 00:01:00.620 Australia's Environment, Problems and Solutions. 16 00:01:01.480 --> 00:01:05.860 There's a whole list of books which she has written, all of which are in this field, 17 00:01:05.960 --> 00:01:09.320 as well as some children's books, which I'd love to find out about more later. 18 00:01:11.040 --> 00:01:15.160 Macquarie University granted her a Doctor of Science degree for her books 19 00:01:15.160 --> 00:01:19.240 and her research in those fields, and the Queensland University of Technology 20 00:01:19.240 --> 00:01:25.940 also granted her Doctor's degree in 1999, and she received the Riversley Medal for Excellence 21 00:01:25.940 --> 00:01:28.320 in Promoting Understanding of Australian Pre-Education. 22 00:01:28.340 --> 00:01:31.840 You see, we are talking about the life of our nation, 23 00:01:31.840 --> 00:01:36.220 and we are talking about life of our nation, and we are talking about life of our nation, 24 00:01:36.360 --> 00:01:37.300 and we are talking about life of our nation, 25 00:01:37.380 --> 00:01:37.660 and we are talking about life of our nation, 26 00:01:37.660 --> 00:01:37.700 and we are talking about life of our nation, 27 00:01:37.700 --> 00:01:39.660 life of our nation, life of our nation, 28 00:01:39.660 --> 00:01:39.740 life of our nation, life of our nation, 29 00:01:39.740 --> 00:01:40.660 life of our nation, life of our nation, 30 00:01:40.680 --> 00:01:43.980 life of our nation, life of our nation, 31 00:01:44.100 --> 00:01:45.600 life of our nation, life of our nation, 32 00:01:45.620 --> 00:01:48.020 life of our nation, life of our nation, 33 00:01:49.720 --> 00:01:58.220 life of our nation, life of our nation, life of our nation, 34 00:02:02.180 --> 00:02:06.640 Well, I'll say good evening, shall I, because it's nice and dark. 35 00:02:08.600 --> 00:02:15.260 I'm delighted to be here with you and to talk about something that is so close to my heart. 36 00:02:16.920 --> 00:02:25.260 I use river red gums lining ephemeral rivers into the arid interior of the continent as symbols of adaptation. 37 00:02:25.260 --> 00:02:32.200 Because my message is that for sustainability we must adapt our practices and expectations 38 00:02:32.200 --> 00:02:36.240 and work within the parameters set by the continent itself. 39 00:02:37.260 --> 00:02:41.540 The geological history of Australia has created a unique land mass. 40 00:02:42.740 --> 00:02:53.320 We need to understand that history in order that we might know how to manage its resources of soil and water sustainably. 41 00:02:53.520 --> 00:02:55.240 In addition, we must have... 42 00:02:55.260 --> 00:02:58.760 We need to have information on how things were at the time of European settlement 43 00:02:58.760 --> 00:03:02.260 so that we can see what changes we have made. 44 00:03:02.900 --> 00:03:09.180 We can go to the archives and we can read the accounts of early explorers and travellers 45 00:03:09.180 --> 00:03:13.060 and early settlers to find out those sort of things. 46 00:03:13.720 --> 00:03:18.540 People came from northern hemisphere lands and thought Australia would respond to land use practices 47 00:03:18.540 --> 00:03:24.940 in the same way that they were used to in the lands that they came from. 48 00:03:26.780 --> 00:03:34.760 This sort of Eurocentric thinking still plagues our management and in particular our water management. 49 00:03:35.760 --> 00:03:42.440 A river, according to what rivers ought to do if you read normal geography books 50 00:03:42.440 --> 00:03:49.140 and if you come from the northern hemisphere, it should rise on high ground and should run briskly to the sea. 51 00:03:50.640 --> 00:03:53.740 And you would know that... 52 00:03:54.560 --> 00:03:55.240 Australia is a very strong land. 53 00:03:55.240 --> 00:03:57.180 Australia doesn't exactly fit that pattern. 54 00:03:57.560 --> 00:04:00.360 And when early explorers crossed the great divide 55 00:04:00.360 --> 00:04:04.740 and started to explore the internal parts of our continent, 56 00:04:05.100 --> 00:04:08.660 they came on huge rivers flowing westwards. 57 00:04:09.500 --> 00:04:13.900 And so, quite logically, they set off to find the inland sea. 58 00:04:14.960 --> 00:04:15.880 And it was simply... 59 00:04:15.880 --> 00:04:18.720 I mean, we look now and wonder why they did it, 60 00:04:18.780 --> 00:04:21.820 but in the context of the times, it was what you would do. 61 00:04:22.740 --> 00:04:25.080 They simply had no idea... 62 00:04:25.240 --> 00:04:26.840 They just had no idea of what Australia was like. 63 00:04:27.000 --> 00:04:30.740 And in fact, how much of Australia is inward draining. 64 00:04:31.860 --> 00:04:34.020 I was supposed to be given a pointer. 65 00:04:34.220 --> 00:04:35.620 Where is the young man who's... 66 00:04:37.420 --> 00:04:40.240 Anyway, you can see the map without a pointer. 67 00:04:40.520 --> 00:04:44.620 The whole blue area is virtually inward draining. 68 00:04:44.760 --> 00:04:51.480 The Northern Territory, South Australia and all this half of it draining towards Lake Eyre. 69 00:04:51.640 --> 00:04:54.300 Excuse me, Mary. The pointer is on your feed. 70 00:04:54.520 --> 00:04:55.120 No. 71 00:04:55.160 --> 00:04:55.220 It's on the... 72 00:04:55.220 --> 00:04:55.880 No. 73 00:04:55.880 --> 00:04:57.000 It's the bridge line. 74 00:04:59.320 --> 00:05:00.800 Not on this one. 75 00:05:01.260 --> 00:05:02.600 Not on this one. 76 00:05:03.640 --> 00:05:04.280 Sorry. 77 00:05:05.000 --> 00:05:08.840 The West Australian section is an ancient crater, 78 00:05:08.840 --> 00:05:10.800 an ancient building block of the continent. 79 00:05:11.040 --> 00:05:16.000 And those black dots are chains of salt lakes lying in ancient river valleys. 80 00:05:16.260 --> 00:05:19.340 And those river valleys that you walk in today 81 00:05:19.340 --> 00:05:23.000 and in which the salt lakes or some of the modern rivers 82 00:05:23.000 --> 00:05:25.040 were carved into the landscape, 83 00:05:25.040 --> 00:05:27.460 300 million years ago. 84 00:05:28.100 --> 00:05:32.500 Australia has some of the oldest landscapes preserved anywhere on Earth. 85 00:05:35.040 --> 00:05:38.940 Then you see also that we have only one really major river system. 86 00:05:39.160 --> 00:05:40.280 This is the Murray-Darling. 87 00:05:40.760 --> 00:05:45.760 And the Murray-Darling River System is itself essentially inward draining 88 00:05:45.760 --> 00:05:50.480 because its tributaries rise on the edge of the Great Divide 89 00:05:51.040 --> 00:05:53.740 and flow mainly westwards 90 00:05:53.740 --> 00:05:57.660 to join to form the two major rivers. 91 00:05:58.680 --> 00:06:01.300 And the thing about the Murray-Darling System 92 00:06:01.300 --> 00:06:06.640 is that it has only one exit for all that huge catchment, 93 00:06:06.660 --> 00:06:11.360 only one exit to the sea at Murray-Math down there. 94 00:06:11.540 --> 00:06:14.860 So you've got a huge drainage area, 95 00:06:14.980 --> 00:06:16.440 a huge catchment area, 96 00:06:16.580 --> 00:06:18.320 and one exit to the sea. 97 00:06:18.960 --> 00:06:22.580 You'll also notice just how few rivers there are 98 00:06:22.580 --> 00:06:26.040 that run like rivers should and run to the sea. 99 00:06:26.600 --> 00:06:30.900 And in other words, very, very different. 100 00:06:31.360 --> 00:06:34.380 And because rivers mainly run inwards 101 00:06:34.380 --> 00:06:36.940 and not doing what rivers should, 102 00:06:38.120 --> 00:06:42.020 a river and even the ones that eventually reach the sea 103 00:06:42.020 --> 00:06:44.160 have a long way to go in the Murray System 104 00:06:44.160 --> 00:06:46.340 and Murray-Darling System, for instance. 105 00:06:46.500 --> 00:06:50.380 You get a great accumulation of sediment on the landscape 106 00:06:50.380 --> 00:06:54.360 because rivers should carry away the products of weathering 107 00:06:54.360 --> 00:06:56.880 and take them back to the ocean. 108 00:06:57.260 --> 00:06:58.440 And this doesn't happen. 109 00:06:58.580 --> 00:07:02.460 As a result, Australia is a land of vast floodplains 110 00:07:02.460 --> 00:07:05.420 and because salt also accumulates on lands, 111 00:07:06.240 --> 00:07:09.780 it also accumulates and isn't carried back to the sea 112 00:07:09.780 --> 00:07:13.940 and a salt water table today underlies much of the land. 113 00:07:14.620 --> 00:07:17.660 The early explorers in the highlands, 114 00:07:17.800 --> 00:07:19.500 as they crossed the Great Divide, 115 00:07:19.500 --> 00:07:22.360 they saw the headwaters of our major rivers. 116 00:07:22.940 --> 00:07:24.800 And in the early days, 117 00:07:24.840 --> 00:07:26.740 the headwaters of our major streams 118 00:07:26.740 --> 00:07:30.980 were mostly what have been described as chains of ponds. 119 00:07:31.060 --> 00:07:33.700 You still have rare examples like this 120 00:07:33.700 --> 00:07:35.760 where you have deep black swamp soil 121 00:07:36.400 --> 00:07:38.640 with a few deep pools in it 122 00:07:38.640 --> 00:07:42.380 and the river really doesn't start as a river. 123 00:07:42.480 --> 00:07:45.220 It starts as a swamp with deep pools. 124 00:07:45.380 --> 00:07:47.920 They sort of then begin to trickle 125 00:07:47.920 --> 00:07:49.480 and you get the beginnings of streams 126 00:07:49.500 --> 00:07:54.720 but the headwaters are in valleys that are filled like this. 127 00:07:56.520 --> 00:07:58.760 The actual chains of ponds, 128 00:07:58.780 --> 00:08:00.560 such ones as our left, 129 00:08:00.720 --> 00:08:02.860 are endangered and protected these days 130 00:08:02.860 --> 00:08:07.660 because the early settlers turned their cattle into these areas. 131 00:08:08.200 --> 00:08:09.820 Where there were reed beds, 132 00:08:09.960 --> 00:08:12.680 they destroyed the reeds so that the cattle could get to water 133 00:08:12.680 --> 00:08:16.400 and of course the cattle made paths that connected the water 134 00:08:16.400 --> 00:08:19.480 and started the beginning of the water. 135 00:08:19.500 --> 00:08:22.760 And this is the beginning of erosion in the headwater swamps. 136 00:08:23.280 --> 00:08:26.060 And in fact, a great deal of erosion 137 00:08:26.060 --> 00:08:29.940 resulted from only a couple of decades of grazing 138 00:08:30.500 --> 00:08:32.560 in the top country. 139 00:08:33.460 --> 00:08:35.940 Another thing about the early rivers was 140 00:08:36.500 --> 00:08:38.000 that a lot of the rivers... 141 00:08:38.000 --> 00:08:40.160 This is just to show you 142 00:08:40.160 --> 00:08:45.180 the actual scooping out of the headwater swamps, 143 00:08:45.340 --> 00:08:49.300 eroding and then the sediment getting carried down 144 00:08:49.500 --> 00:08:50.900 further down the rivers. 145 00:08:51.220 --> 00:08:53.880 And very shortly, as I mentioned, 146 00:08:54.000 --> 00:08:55.160 within a couple of decades, 147 00:08:55.480 --> 00:08:57.480 you had great slugs of sand 148 00:08:57.480 --> 00:09:00.820 being taken out of these headwater swamps 149 00:09:00.820 --> 00:09:02.460 and sent down the river. 150 00:09:02.820 --> 00:09:05.160 And a river, a healthy river, 151 00:09:05.400 --> 00:09:08.420 ought to have a great deal of difference in its bed. 152 00:09:08.540 --> 00:09:12.200 It has places where the water runs over stones, riffles. 153 00:09:12.520 --> 00:09:15.380 It has deep pools and a great deal of variety 154 00:09:15.380 --> 00:09:16.800 for the different... 155 00:09:17.500 --> 00:09:18.900 and different sort of ecosystems 156 00:09:19.500 --> 00:09:20.320 for its biota. 157 00:09:20.600 --> 00:09:23.340 But when you get a great deal of sand coming down rivers, 158 00:09:23.640 --> 00:09:25.560 you get a great deal of uniformity 159 00:09:25.560 --> 00:09:27.080 and you lose a lot of biodiversity. 160 00:09:28.740 --> 00:09:30.080 And the early rivers, 161 00:09:30.240 --> 00:09:34.020 a lot of them simply petered out into reed beds 162 00:09:34.020 --> 00:09:35.580 or into billabongs. 163 00:09:36.480 --> 00:09:39.500 And the river systems as such, 164 00:09:39.680 --> 00:09:41.680 the Murray-Darling River system, for instance, 165 00:09:42.500 --> 00:09:44.860 wasn't as connected as it is today. 166 00:09:45.160 --> 00:09:47.560 When you read the early archival records 167 00:09:47.560 --> 00:09:49.480 of early explorers, 168 00:09:49.500 --> 00:09:52.360 you constantly come upon the sort of statements, 169 00:09:52.620 --> 00:09:55.540 we followed the river into swamps or billabongs. 170 00:09:55.960 --> 00:09:58.160 And then after that, 171 00:09:58.220 --> 00:10:00.180 there were a number of small channels 172 00:10:00.180 --> 00:10:04.180 and we couldn't decide where it was, 173 00:10:04.420 --> 00:10:05.280 where it went, 174 00:10:05.420 --> 00:10:07.400 or in fact, what was the river. 175 00:10:07.560 --> 00:10:09.800 And it was only at times of flood, 176 00:10:10.040 --> 00:10:13.200 because you know this is a land of drought and flood, 177 00:10:13.400 --> 00:10:15.520 it was only at times of flood 178 00:10:15.520 --> 00:10:18.880 that you had the actual connecting of the river system. 179 00:10:18.880 --> 00:10:22.340 And the river would get beyond its hold up in swamps and whatnot 180 00:10:22.880 --> 00:10:25.720 and run down and eventually connect to the river 181 00:10:25.720 --> 00:10:27.260 that it was supposed to connect to. 182 00:10:28.220 --> 00:10:32.520 The Loughlin today still runs into that huge Kumbungi swamp 183 00:10:32.520 --> 00:10:36.720 and its exit today is much more well defined. 184 00:10:36.980 --> 00:10:37.940 It goes on and joins, 185 00:10:38.240 --> 00:10:43.300 but it used to be a very ill-defined number of sort of channels 186 00:10:43.300 --> 00:10:45.860 that filled at times of flood. 187 00:10:46.440 --> 00:10:48.860 The Paroo River is one of our amazing, 188 00:10:48.860 --> 00:10:51.000 entertaining rivers that is virtually untouched. 189 00:10:51.200 --> 00:10:53.000 I hope it can stay like that. 190 00:10:53.240 --> 00:10:55.860 It has absolutely vast floodplains. 191 00:10:55.880 --> 00:10:58.340 There are hundreds of kilometres of floodplain. 192 00:10:58.660 --> 00:11:01.680 And this picture with all its water holes 193 00:11:01.680 --> 00:11:03.800 in the swampy country and whatnot 194 00:11:04.860 --> 00:11:08.080 gives you an idea of what the termination 195 00:11:08.080 --> 00:11:10.120 of a lot of our rivers were like 196 00:11:10.860 --> 00:11:13.020 before they became deeply incised 197 00:11:13.020 --> 00:11:16.260 and did what I've called in that book of mine, 198 00:11:16.360 --> 00:11:18.660 what happened was that the rivers 199 00:11:18.860 --> 00:11:22.800 changed from being rivers to being essentially drains. 200 00:11:22.920 --> 00:11:24.320 They drained the landscape, 201 00:11:24.440 --> 00:11:26.920 but they didn't behave like the river ought to behave 202 00:11:28.480 --> 00:11:31.840 in a very different and Australian sort of way. 203 00:11:32.540 --> 00:11:35.540 And another consequence of our land management 204 00:11:35.540 --> 00:11:37.780 has been the deep incision of the rivers. 205 00:11:38.000 --> 00:11:40.620 They've become this change 206 00:11:40.620 --> 00:11:43.820 from being a wonderful wandering thing 207 00:11:43.820 --> 00:11:46.740 that went into swamps and billabongs and so on 208 00:11:46.740 --> 00:11:48.580 to becoming deeply incised. 209 00:11:48.580 --> 00:11:52.640 And the actual channels have been eroded out 210 00:11:52.640 --> 00:11:54.600 and all the sediment and whatnot 211 00:11:54.600 --> 00:11:56.480 has gone on further downstream. 212 00:11:57.020 --> 00:11:59.040 And at times of flood, of course, 213 00:11:59.060 --> 00:12:00.460 it's carried on to the floodplains 214 00:12:00.460 --> 00:12:03.760 and completely alters the floodplains as well. 215 00:12:04.000 --> 00:12:07.760 So we've made huge changes in only 200 years. 216 00:12:07.820 --> 00:12:10.820 In most cases, it's in 150 or even less 217 00:12:10.820 --> 00:12:13.920 that land management surrounding the rivers 218 00:12:13.920 --> 00:12:16.540 and what we have actually done to the rivers themselves, 219 00:12:16.680 --> 00:12:18.460 clearing their banks and so on, 220 00:12:18.580 --> 00:12:20.500 has resulted in huge change. 221 00:12:21.580 --> 00:12:23.700 And of course, in a dry continent like this, 222 00:12:23.780 --> 00:12:25.400 most of our rivers are ephemeral. 223 00:12:25.480 --> 00:12:26.700 This is a river bed. 224 00:12:27.380 --> 00:12:30.880 And the interesting thing about the ephemeral rivers 225 00:12:30.880 --> 00:12:33.960 is the enormous power of the river 226 00:12:33.960 --> 00:12:36.660 when it does flow at a time of flood. 227 00:12:36.980 --> 00:12:39.160 And you'll see there in front of the gum trees 228 00:12:39.160 --> 00:12:41.880 the enormous stack of tree trunks, 229 00:12:41.940 --> 00:12:43.460 and they're sizeable tree trunks, 230 00:12:43.460 --> 00:12:45.280 stacked to about six foot high. 231 00:12:45.620 --> 00:12:47.520 So ephemeral rivers, 232 00:12:47.520 --> 00:12:49.960 when you're travelling in the outback 233 00:12:49.960 --> 00:12:52.480 on treks and things the way I do, 234 00:12:52.600 --> 00:12:54.160 you walk down these places, 235 00:12:54.280 --> 00:12:55.600 but please don't be in them 236 00:12:55.600 --> 00:12:58.340 when there's a flood coming down 237 00:12:58.340 --> 00:13:01.160 because they are amazingly powerful 238 00:13:01.160 --> 00:13:03.060 when they actually flow. 239 00:13:04.760 --> 00:13:06.400 This is the Darling Full, 240 00:13:06.640 --> 00:13:08.080 or reasonably full. 241 00:13:08.720 --> 00:13:10.560 And this is near Bourke. 242 00:13:10.660 --> 00:13:13.380 You'll see the river red gums, 243 00:13:13.400 --> 00:13:14.300 their roots exposed, 244 00:13:14.680 --> 00:13:16.740 because water has been extracted 245 00:13:17.520 --> 00:13:20.960 rapidly, and when the banks are saturated, 246 00:13:21.340 --> 00:13:22.280 the mud is saturated, 247 00:13:22.700 --> 00:13:25.780 you get a great deal of slumping 248 00:13:25.780 --> 00:13:28.700 of the bank structure into the river. 249 00:13:28.820 --> 00:13:32.500 You see how turbid the river is too as a result. 250 00:13:32.840 --> 00:13:35.560 Our rivers have the most variable flow patterns 251 00:13:35.560 --> 00:13:37.020 of any in the world. 252 00:13:40.420 --> 00:13:41.540 And originally, 253 00:13:41.640 --> 00:13:43.240 before we started interfering, 254 00:13:43.500 --> 00:13:45.400 it was quite normal for the Darling 255 00:13:45.400 --> 00:13:46.800 often to look like this. 256 00:13:46.800 --> 00:13:49.080 This actually is almost at the same place 257 00:13:49.080 --> 00:13:49.880 as that last, 258 00:13:50.000 --> 00:13:51.920 the same stretch of river 259 00:13:51.920 --> 00:13:53.980 as the last photograph was taken. 260 00:13:55.560 --> 00:13:58.940 And in times of very severe drought, 261 00:13:59.040 --> 00:14:00.340 a great deal of the Darling 262 00:14:00.340 --> 00:14:02.820 would have been reduced to dry patches like this 263 00:14:02.820 --> 00:14:04.040 and few deep pools. 264 00:14:04.220 --> 00:14:06.160 Of course these days they aren't the deep pools, 265 00:14:06.440 --> 00:14:08.240 they've been filled with silt and whatnot. 266 00:14:08.620 --> 00:14:11.680 And downstream of some of the major dams, 267 00:14:11.680 --> 00:14:13.200 any of the places where you extract 268 00:14:13.200 --> 00:14:15.080 massive water for cotton and so on, 269 00:14:15.080 --> 00:14:17.360 the Darling often looks like this. 270 00:14:18.280 --> 00:14:20.100 And just to show you one more 271 00:14:20.100 --> 00:14:21.460 of what happens to the Darling, 272 00:14:21.580 --> 00:14:23.320 this is the Darling in 1991. 273 00:14:26.640 --> 00:14:29.840 Green and toxic with cyanobacteria. 274 00:14:29.840 --> 00:14:33.240 Now it's not just unpleasant algae, 275 00:14:33.440 --> 00:14:35.000 it is toxic things. 276 00:14:35.100 --> 00:14:36.500 If anything drinks that water, 277 00:14:36.600 --> 00:14:39.140 it gets extremely sick and possibly dies. 278 00:14:40.080 --> 00:14:43.440 And the Darling has a Guinness Book of Records record 279 00:14:43.440 --> 00:14:44.960 for the longest stretch 280 00:14:45.080 --> 00:14:49.120 of river ever to be simultaneously toxic 281 00:14:49.120 --> 00:14:50.600 with cyanobacteria. 282 00:14:50.660 --> 00:14:54.240 In 1991, a thousand kilometres of the Darling 283 00:14:54.240 --> 00:14:56.100 were poisonous like this. 284 00:14:57.280 --> 00:14:59.420 This is not, actually I was incorrect, 285 00:14:59.600 --> 00:15:01.220 this is not photographed in 1991, 286 00:15:01.320 --> 00:15:03.200 this is just one of these dry times, 287 00:15:03.260 --> 00:15:06.660 this is a local infestation with these things. 288 00:15:08.340 --> 00:15:11.560 The fact is that the river doesn't get flushed out regularly 289 00:15:11.560 --> 00:15:13.660 because it doesn't have the major floods 290 00:15:13.660 --> 00:15:15.360 that clean it out, 291 00:15:15.500 --> 00:15:17.860 and you've got a great deal of nutrient 292 00:15:17.860 --> 00:15:19.300 being brought into the rivers 293 00:15:19.300 --> 00:15:23.400 from farming operations on its tributaries mainly 294 00:15:24.820 --> 00:15:26.620 that bring the water in, 295 00:15:26.700 --> 00:15:29.280 because the Darling has very little local runoff. 296 00:15:29.320 --> 00:15:31.460 It depends almost entirely on the water 297 00:15:31.460 --> 00:15:33.740 that comes from the better watered parts of the world. 298 00:15:34.440 --> 00:15:37.400 And because of this great variability of flow, 299 00:15:37.600 --> 00:15:40.200 of course we've altered our rivers, our major ones. 300 00:15:40.500 --> 00:15:42.520 We've put in weirs like this, 301 00:15:42.520 --> 00:15:44.020 and modified the flow. 302 00:15:44.260 --> 00:15:46.800 It allows continuity of supply, 303 00:15:47.020 --> 00:15:49.300 which is what we need for the sort of farming 304 00:15:49.300 --> 00:15:50.380 and things that we do, 305 00:15:50.520 --> 00:15:53.480 but we have found that it's not what the river needs at all. 306 00:15:53.800 --> 00:15:55.520 And we've also, of course, built dams, 307 00:15:56.040 --> 00:15:59.100 massive dams for things like the Snowy Scheme. 308 00:15:59.420 --> 00:16:02.800 And I think it's becoming generally recognised 309 00:16:02.800 --> 00:16:04.720 that although the Snowy Scheme, 310 00:16:04.780 --> 00:16:07.500 when I arrived in Australia in the 50s, 311 00:16:07.520 --> 00:16:09.800 that was still being made, 312 00:16:09.880 --> 00:16:11.460 and it was a wonderful nation builder, 313 00:16:11.580 --> 00:16:12.440 and it was an amazing, 314 00:16:12.520 --> 00:16:15.200 an amazing feat, an engineering feat, 315 00:16:16.320 --> 00:16:19.300 causing, I mean, pulling Australia together 316 00:16:19.300 --> 00:16:21.800 and a source of great pride and all the rest of it. 317 00:16:21.940 --> 00:16:23.020 But environmentally, 318 00:16:23.400 --> 00:16:25.760 the Snowy Scheme has been a total disaster, 319 00:16:26.100 --> 00:16:27.860 because it's brought water to places 320 00:16:27.860 --> 00:16:30.100 that shouldn't have had it in quantity, 321 00:16:30.200 --> 00:16:34.100 and we are beginning to see all the problems that are emerging, 322 00:16:34.200 --> 00:16:35.620 or they're pretty far advanced. 323 00:16:36.420 --> 00:16:39.040 I'm going to give you a brief sort of geological history 324 00:16:39.040 --> 00:16:41.120 so that you can understand a little of this. 325 00:16:41.120 --> 00:16:42.540 I really need my pointer. 326 00:16:43.020 --> 00:16:45.680 But you'll see the South Pole. 327 00:16:45.960 --> 00:16:48.840 This is, I can't even focus on this one. 328 00:16:50.000 --> 00:16:54.120 The South Pole is at Bourke in western New South Wales. 329 00:16:54.280 --> 00:16:57.700 Now, you all know that Australia was part of Gondwana 330 00:16:57.700 --> 00:17:00.460 for a great deal of geological time. 331 00:17:00.720 --> 00:17:01.860 And I always say, 332 00:17:01.940 --> 00:17:03.980 can you think of a better place for the South Pole 333 00:17:03.980 --> 00:17:05.740 than Bourke in western New South Wales? 334 00:17:08.120 --> 00:17:10.460 So unlikely, but it was a warm world 335 00:17:10.460 --> 00:17:11.580 without polar ice, 336 00:17:11.840 --> 00:17:13.980 and at that time, there was actually, 337 00:17:14.100 --> 00:17:17.560 we were still connected to the northern supercontinent of La Roesia, 338 00:17:17.760 --> 00:17:20.880 and you had land virtually from the North Pole 339 00:17:20.880 --> 00:17:23.200 to the South Pole down one side of the globe. 340 00:17:23.440 --> 00:17:27.420 If you'd been an early dinosaur just emerging in the Triassic, 341 00:17:27.500 --> 00:17:30.020 you could have walked from the North Pole to the South Pole 342 00:17:30.020 --> 00:17:32.080 without crossing anything approaching an ocean. 343 00:17:33.180 --> 00:17:34.880 So a very different world, 344 00:17:34.940 --> 00:17:37.720 and Australia is an ancient stable land mass. 345 00:17:38.420 --> 00:17:40.440 It had been a very, 346 00:17:40.460 --> 00:17:44.340 it had been weathering and eroding under the elements 347 00:17:44.340 --> 00:17:46.320 for hundreds of millions of years, 348 00:17:46.400 --> 00:17:47.420 even at this stage. 349 00:17:47.820 --> 00:17:52.180 No renewal of soils by passage of ice sheets across it 350 00:17:52.180 --> 00:17:54.560 for 300 million years up to the present. 351 00:17:55.680 --> 00:17:58.360 And very little volcanic activity, 352 00:17:58.640 --> 00:18:00.120 and of course it's volcanic activity 353 00:18:00.120 --> 00:18:02.300 that makes better quality soil. 354 00:18:02.560 --> 00:18:05.680 When you've got soil that is made from ancient weathered rocks, 355 00:18:05.920 --> 00:18:08.460 it's already lost a lot of the nutrients 356 00:18:08.460 --> 00:18:09.840 that are needed for agriculture. 357 00:18:10.460 --> 00:18:14.680 And in fact, only about 6% of Australia's soil 358 00:18:14.680 --> 00:18:16.480 is of arable quality. 359 00:18:18.660 --> 00:18:20.420 This is in the Jurassic, 360 00:18:20.640 --> 00:18:21.880 this is the age of dinosaurs. 361 00:18:23.280 --> 00:18:26.180 Just to show you what was happening in eastern Gondwana, 362 00:18:26.340 --> 00:18:28.940 we were, the continents were beginning to split apart. 363 00:18:29.100 --> 00:18:34.300 India was opening its connection to the West Australian margin, 364 00:18:34.500 --> 00:18:36.380 and was about to set off. 365 00:18:36.480 --> 00:18:38.540 It was the first to leave Gondwana. 366 00:18:38.780 --> 00:18:40.340 There was sort of a rift 367 00:18:40.460 --> 00:18:41.400 between the valley system developing 368 00:18:41.400 --> 00:18:43.060 between Australia and Antarctica, 369 00:18:43.440 --> 00:18:44.860 but we were still firmly attached. 370 00:18:45.420 --> 00:18:48.420 And the important thing there is the light-coloured part 371 00:18:48.420 --> 00:18:50.020 in what is now eastern Australia, 372 00:18:50.240 --> 00:18:52.940 because that was fresh water sedimentation 373 00:18:52.940 --> 00:18:55.040 in a sinking geological basin. 374 00:18:55.360 --> 00:18:57.760 And those sedimentary layers 375 00:18:57.760 --> 00:19:01.480 are major aquifers of the great Artesian basin. 376 00:19:04.460 --> 00:19:09.340 In the Cretaceous, we're coming to slightly further along, 377 00:19:09.440 --> 00:19:10.440 100, 100, 378 00:19:10.460 --> 00:19:12.380 around about 120 million years ago, 379 00:19:12.460 --> 00:19:14.700 a great deal of the surface of Australia 380 00:19:14.700 --> 00:19:16.920 was covered by epicontinental seas. 381 00:19:17.260 --> 00:19:20.760 Sea levels were high because of the volcanic activity 382 00:19:20.760 --> 00:19:23.900 and stuff that was going on with the general separation 383 00:19:23.900 --> 00:19:25.720 of the supercontinent. 384 00:19:25.980 --> 00:19:29.360 But also we now know there's information to the effect 385 00:19:29.360 --> 00:19:32.300 that Australia at this time was sinking generally 386 00:19:32.300 --> 00:19:33.860 in relation to sea level. 387 00:19:33.940 --> 00:19:35.640 It was later to pop up again. 388 00:19:36.060 --> 00:19:37.200 Continents do that. 389 00:19:37.200 --> 00:19:39.260 It's now we have much better ways 390 00:19:39.260 --> 00:19:41.120 of finding out all these things. 391 00:19:41.220 --> 00:19:43.260 And no sooner have you written a book 392 00:19:43.260 --> 00:19:44.680 and been convinced of something 393 00:19:45.200 --> 00:19:47.920 than they find that that was yesterday's news 394 00:19:47.920 --> 00:19:49.680 and you've got to think completely differently. 395 00:19:50.520 --> 00:19:52.060 I know all about that. 396 00:19:52.940 --> 00:19:56.360 So in the area that is the great Artesian basin, 397 00:19:56.580 --> 00:19:58.840 which is the eastern part of our continent, 398 00:19:59.460 --> 00:20:01.580 marine rocks were then put in, 399 00:20:01.640 --> 00:20:04.500 capping the water-bearing ones, 400 00:20:04.640 --> 00:20:07.180 and some of them water-bearing later themselves. 401 00:20:08.240 --> 00:20:10.340 Completing the great Artesian basin. 402 00:20:10.660 --> 00:20:12.540 And the great Artesian basin 403 00:20:12.540 --> 00:20:14.920 is enormously important in Australia today 404 00:20:14.920 --> 00:20:17.540 because in the driest vegetated continent, 405 00:20:17.740 --> 00:20:21.620 groundwater on a scale like that is very, very important. 406 00:20:22.160 --> 00:20:25.200 That red area is along the flank, 407 00:20:25.900 --> 00:20:27.540 the western flank of the Great Divide, 408 00:20:27.720 --> 00:20:30.760 where nearly all the recharge takes place. 409 00:20:31.000 --> 00:20:33.960 And most of it in the Queensland section there. 410 00:20:34.820 --> 00:20:37.180 And the water travels in the north, 411 00:20:37.200 --> 00:20:39.500 mostly in the south-westerly direction, 412 00:20:39.840 --> 00:20:43.140 heading in the general direction of Lake Eyre. 413 00:20:43.400 --> 00:20:46.400 And water in an underground aquifer like that 414 00:20:46.400 --> 00:20:48.820 is not a river that flows freely. 415 00:20:49.200 --> 00:20:52.340 It's simply water moving inside the rock 416 00:20:52.340 --> 00:20:55.420 in the pores between the incompletely cemented 417 00:20:55.420 --> 00:20:57.300 sand grains in a sandstone. 418 00:20:58.200 --> 00:21:00.260 And it moves at a metre a year. 419 00:21:00.580 --> 00:21:02.620 So if you've got water that's fallen 420 00:21:02.620 --> 00:21:04.340 in the sort of long-reach area 421 00:21:04.340 --> 00:21:06.300 somewhere up there in Queensland, 422 00:21:06.300 --> 00:21:08.740 that's travelling down towards Lake Eyre, 423 00:21:08.820 --> 00:21:11.960 and it emerges at Lake Eyre in a moundspring, 424 00:21:12.620 --> 00:21:17.040 that water is something like 2 million years old. 425 00:21:18.340 --> 00:21:21.300 And I hope when you go to the Moundspring National Park, 426 00:21:21.400 --> 00:21:23.440 you will treat it with considerable reverence. 427 00:21:23.480 --> 00:21:26.380 I've just been talking a thing about holy water, 428 00:21:26.540 --> 00:21:28.320 and if that sort of water isn't holy, 429 00:21:28.480 --> 00:21:30.140 I don't know what is. 430 00:21:31.300 --> 00:21:33.800 And these lines of moundsprings, of course, 431 00:21:33.800 --> 00:21:36.160 mark the edge of that great Artesian basin. 432 00:21:36.300 --> 00:21:38.420 It's where the aquifer bends up 433 00:21:38.420 --> 00:21:41.060 against other more ancient rocks. 434 00:21:41.660 --> 00:21:46.980 And, of course, Aboriginals used these routes 435 00:21:46.980 --> 00:21:50.280 where they could sort of depend on water 436 00:21:50.280 --> 00:21:52.920 from moundsprings in their travels across the desert. 437 00:21:53.060 --> 00:21:54.920 And in the early days, of course, 438 00:21:54.920 --> 00:21:57.580 when the telegraph line was being established 439 00:21:57.580 --> 00:21:58.860 across our continent, 440 00:21:59.100 --> 00:22:02.060 it also followed the lines of moundsprings. 441 00:22:03.040 --> 00:22:05.520 Now the great Artesian basin has been, 442 00:22:05.520 --> 00:22:08.040 um, exploited since 1880, 443 00:22:08.260 --> 00:22:10.840 when they put down, I think it was 1881 perhaps, 444 00:22:10.980 --> 00:22:13.380 when they put down the first Artesian bore. 445 00:22:13.660 --> 00:22:16.860 And the water used to come spurting to the surface, 446 00:22:17.520 --> 00:22:20.340 shooting as high as this roof and from many of the things, 447 00:22:20.520 --> 00:22:22.980 and it simply was allowed to run away 448 00:22:23.520 --> 00:22:25.700 along bore drains into the countryside. 449 00:22:26.300 --> 00:22:31.900 And the awful thing is that in all the use of Artesian water 450 00:22:31.900 --> 00:22:33.760 since the 1880s, 451 00:22:33.760 --> 00:22:38.420 something like 95 or 96% of the water 452 00:22:38.420 --> 00:22:42.380 has simply been lost to seepage and evaporation. 453 00:22:42.880 --> 00:22:45.420 There's been this absolutely shocking waste 454 00:22:45.420 --> 00:22:49.020 because it was an unseen source of water, 455 00:22:49.120 --> 00:22:50.720 apparently endless, 456 00:22:51.000 --> 00:22:52.560 and what we now find, of course, 457 00:22:52.640 --> 00:22:55.100 is because of the very heavy tapping of the basin 458 00:22:55.100 --> 00:22:55.860 that has gone on, 459 00:22:55.960 --> 00:22:57.580 the pressure has disappeared 460 00:22:57.580 --> 00:23:00.940 and mostly these days you have to pipe, 461 00:23:01.180 --> 00:23:03.580 you have to pump water to the surface. 462 00:23:03.580 --> 00:23:06.040 There are remedying things, 463 00:23:06.320 --> 00:23:08.340 a lot of the bores are being piped 464 00:23:08.340 --> 00:23:11.120 and there's a general move these days 465 00:23:11.120 --> 00:23:13.600 to do something about this shocking sort of waste 466 00:23:13.600 --> 00:23:15.920 because in a dry continent, of course, 467 00:23:15.980 --> 00:23:18.480 all water is extremely important. 468 00:23:19.800 --> 00:23:23.880 What I have found is that as a result 469 00:23:23.880 --> 00:23:26.900 of taking water into arid landscapes, 470 00:23:27.320 --> 00:23:29.520 you would think that that was a good thing to do. 471 00:23:29.620 --> 00:23:31.560 I mean, how nice if you can bring water 472 00:23:31.560 --> 00:23:33.080 to places that have never had it. 473 00:23:33.080 --> 00:23:35.080 But in fact, what has happened 474 00:23:35.080 --> 00:23:37.900 as a result of taking water into the dry lands 475 00:23:37.900 --> 00:23:39.420 of the great Artesian basin 476 00:23:40.080 --> 00:23:42.780 has been virtually to desertify, 477 00:23:42.840 --> 00:23:45.920 to damage and to create anything 478 00:23:45.920 --> 00:23:47.300 but what you would have expected. 479 00:23:47.780 --> 00:23:51.580 It simply is because when you have got open bore drains 480 00:23:51.580 --> 00:23:52.600 which bring water, 481 00:23:52.720 --> 00:23:54.380 when you've got watering points, 482 00:23:54.760 --> 00:23:57.740 you have a situation where there's no area 483 00:23:57.740 --> 00:24:02.600 that is too far from water for grazing animals to graze. 484 00:24:03.080 --> 00:24:05.760 And because these are fragile lands 485 00:24:05.760 --> 00:24:08.640 where drought is always just around the corner, 486 00:24:08.800 --> 00:24:11.140 it simply means that you've got overgrazing 487 00:24:11.140 --> 00:24:12.360 and you've got damage. 488 00:24:12.800 --> 00:24:15.100 So, and another thing, of course, 489 00:24:15.140 --> 00:24:18.800 is that when you've got readily available water like that, 490 00:24:18.840 --> 00:24:21.840 there is just no way that you can control feral populations, 491 00:24:22.480 --> 00:24:25.360 whether they be of the sort of animals 492 00:24:25.360 --> 00:24:28.000 that you've introduced, the goats and the cattle and whatnot, 493 00:24:28.220 --> 00:24:30.920 or whether it's simply a huge buildup 494 00:24:30.920 --> 00:24:32.720 of kangaroo numbers, for instance. 495 00:24:33.080 --> 00:24:36.060 So you are adding enormous grazing pressures 496 00:24:36.060 --> 00:24:39.840 to those even of the ones that you have controlled. 497 00:24:41.040 --> 00:24:43.420 Just another mention of groundwater, 498 00:24:43.720 --> 00:24:46.920 the irrigated cotton in the Namoy Valley, for instance. 499 00:24:47.000 --> 00:24:49.180 I'm sure you would have read in newspapers recently 500 00:24:49.880 --> 00:24:54.300 the fact that all the irrigation in the Namoy 501 00:24:54.300 --> 00:24:57.340 is on, or just about all of it is on groundwater. 502 00:24:57.800 --> 00:25:00.900 And to produce the cotton that they produce, 503 00:25:00.980 --> 00:25:03.060 they are extracting twice a year 504 00:25:03.080 --> 00:25:05.620 just as much water from the groundwater 505 00:25:05.620 --> 00:25:08.740 as is replenished annually. 506 00:25:09.220 --> 00:25:11.820 So the thing is completely unsustainable. 507 00:25:12.160 --> 00:25:14.220 And Australia has this amazing 508 00:25:14.220 --> 00:25:18.260 and absolutely terrifying socioeconomic problem, really. 509 00:25:18.460 --> 00:25:21.200 The fact is we produce the best cotton, 510 00:25:21.400 --> 00:25:22.880 we produce the best rice, 511 00:25:22.980 --> 00:25:24.940 we're marvellous in the things we do, 512 00:25:25.000 --> 00:25:27.280 you're blown away by the technology that's used 513 00:25:27.280 --> 00:25:30.620 in the sort of massive farming enterprises 514 00:25:30.620 --> 00:25:33.060 that are producing things like cotton, 515 00:25:33.080 --> 00:25:36.080 but at what cost? 516 00:25:36.460 --> 00:25:38.980 And that is something that ultimately 517 00:25:38.980 --> 00:25:41.460 is going to have to be addressed. 518 00:25:41.920 --> 00:25:45.520 So just to go back to a bit more geological history, 519 00:25:45.840 --> 00:25:48.400 84 million, India's gone, 520 00:25:48.580 --> 00:25:52.260 we've already got a seaway between Australia and Antarctica, 521 00:25:52.660 --> 00:25:55.820 but we are still connected through Tasmania 522 00:25:55.820 --> 00:25:57.420 and the South Tasman Rise, 523 00:25:58.080 --> 00:26:00.840 and along the eastern margin of the continent, 524 00:26:00.900 --> 00:26:02.720 the Tasman Sea is opening, 525 00:26:03.080 --> 00:26:04.540 or beginning to open, 526 00:26:04.760 --> 00:26:07.240 and the New Zealand subcontinent, 527 00:26:07.320 --> 00:26:11.160 a fairly large landmass that was adjacent on that side, 528 00:26:11.760 --> 00:26:14.440 moves away and incidentally sinks. 529 00:26:14.780 --> 00:26:16.600 And next year, I hope, 530 00:26:16.640 --> 00:26:19.400 if I've finished the book I'm working on at the moment, 531 00:26:19.480 --> 00:26:23.420 I intend to write a book on sinking the New Zealand subcontinent. 532 00:26:23.640 --> 00:26:27.260 I thought it would do a lot of good for trans-Tasman relations. 533 00:26:29.160 --> 00:26:31.340 Because almost everything sank. 534 00:26:31.440 --> 00:26:33.060 The only parts of it that are above us, 535 00:26:33.060 --> 00:26:34.240 above the sea today, 536 00:26:34.380 --> 00:26:36.220 are New Zealand and New Caledonia, 537 00:26:36.440 --> 00:26:38.800 and the rest is the Lord Howe Rise, 538 00:26:39.000 --> 00:26:39.780 the Norfolk Rise, 539 00:26:39.960 --> 00:26:42.200 the big plateaus and things around New Zealand. 540 00:26:43.700 --> 00:26:45.620 So, Australia being freed, 541 00:26:45.940 --> 00:26:49.020 the eastern margin of the continent 542 00:26:49.020 --> 00:26:50.500 then started to tilt, 543 00:26:50.680 --> 00:26:53.380 and to create the high ground 544 00:26:53.380 --> 00:26:55.180 which was going to be defined later 545 00:26:55.180 --> 00:26:59.340 to become the Great Divide along the edge. 546 00:26:59.540 --> 00:27:02.080 And at the same time as the edge was tilting, 547 00:27:02.080 --> 00:27:04.960 the centre of the continent started to sink. 548 00:27:05.120 --> 00:27:08.120 So you can see why the inward draining map 549 00:27:08.120 --> 00:27:10.800 that I showed you originated. 550 00:27:12.120 --> 00:27:14.060 At 60 million years ago, 551 00:27:14.140 --> 00:27:16.000 and this is getting pretty close, 552 00:27:16.720 --> 00:27:18.680 we're still connected. 553 00:27:19.760 --> 00:27:21.460 There's a lot of granite and stuff 554 00:27:21.460 --> 00:27:24.420 put in underneath that edge of the continent 555 00:27:24.420 --> 00:27:27.700 underlying the Great Divide all the way down. 556 00:27:27.800 --> 00:27:29.100 And the Murray Basin, 557 00:27:29.100 --> 00:27:30.860 you can see there the light patch, 558 00:27:30.860 --> 00:27:32.980 the Murray Basin started to sink. 559 00:27:33.220 --> 00:27:36.360 And the Murray Basin is a sinking geological basin 560 00:27:36.360 --> 00:27:38.380 that is accumulating sediment. 561 00:27:38.820 --> 00:27:41.440 And a great deal of the hydrological problems 562 00:27:41.440 --> 00:27:42.520 we have there today 563 00:27:42.520 --> 00:27:45.740 are the fact that it is a basin-shaped structure 564 00:27:45.740 --> 00:27:49.260 and it's got that one very small exit to the sea. 565 00:27:49.480 --> 00:27:52.180 So when you add too much water to it 566 00:27:52.180 --> 00:27:54.660 or do things that upsets its hydrology, 567 00:27:55.260 --> 00:27:59.560 you very soon have exactly like a wash basin 568 00:27:59.560 --> 00:28:00.840 with a tap there. 569 00:28:00.840 --> 00:28:01.720 And that's the only thing that keeps on running 570 00:28:01.720 --> 00:28:03.420 and only one small plug. 571 00:28:05.080 --> 00:28:06.880 So at 45 million, 572 00:28:07.380 --> 00:28:11.040 we finally break loose and set off as an island continent. 573 00:28:11.240 --> 00:28:13.200 This final severance takes place 574 00:28:13.840 --> 00:28:16.480 and Tasmania, lucky to come along with us, 575 00:28:16.620 --> 00:28:17.780 it had many options. 576 00:28:21.740 --> 00:28:24.280 They always grumble when I go to Tasmania 577 00:28:24.280 --> 00:28:26.460 and say, you know, you people on the mainland 578 00:28:26.460 --> 00:28:28.200 treat us as though we're not important, 579 00:28:28.260 --> 00:28:29.700 we're just a little appendage. 580 00:28:29.740 --> 00:28:30.760 And I say, well, you know, 581 00:28:30.840 --> 00:28:32.820 you'd better shut up because you had options. 582 00:28:32.900 --> 00:28:35.120 You could have stuck onto Antarctica and frozen. 583 00:28:35.640 --> 00:28:37.160 You could have drifted out 584 00:28:37.160 --> 00:28:39.880 with the New Zealand subcontinent and sunk. 585 00:28:40.240 --> 00:28:42.640 And so even if you're a bit neglected, 586 00:28:42.640 --> 00:28:45.000 at least you're above water and following us. 587 00:28:47.360 --> 00:28:50.080 So there you've got the centre of the continent 588 00:28:50.080 --> 00:28:52.940 still sinking, fresh water sediment where it's yellow, 589 00:28:53.240 --> 00:28:55.200 the Murray Basin still sinking 590 00:28:55.200 --> 00:28:56.480 and being filled with sediment, 591 00:28:56.620 --> 00:29:00.780 and Australia setting off and moving north. 592 00:29:00.840 --> 00:29:01.500 We're moving northwards steadily 593 00:29:01.500 --> 00:29:03.840 and we're still moving northwards, as you know. 594 00:29:04.320 --> 00:29:07.300 And at the time that we set off and moved northwards, 595 00:29:07.500 --> 00:29:13.780 ours was a green, largely forested and well-watered land, 596 00:29:14.840 --> 00:29:19.080 in spite of the fact that we were in such high latitudes, 597 00:29:19.080 --> 00:29:21.460 the southern margin at 85 degrees south. 598 00:29:23.040 --> 00:29:25.580 It was a warm world, as I mentioned before, 599 00:29:25.740 --> 00:29:27.880 without polar ice caps, 600 00:29:27.880 --> 00:29:30.540 because you only have the ice age conditions 601 00:29:30.540 --> 00:29:33.420 interrupting about once every 300 million years. 602 00:29:34.300 --> 00:29:38.400 And there was no sort of selection in this... 603 00:29:38.400 --> 00:29:42.040 This is the mixed Gondwanan forest, we call it. 604 00:29:42.900 --> 00:29:46.860 It contained all the things that have now sorted themselves out 605 00:29:46.860 --> 00:29:50.580 according to their preference for areas that are perhumid, 606 00:29:50.620 --> 00:29:51.920 which are very few in Australia, 607 00:29:52.220 --> 00:29:55.780 or increasingly for the dry areas 608 00:29:55.780 --> 00:29:57.680 as Australia moved northwards 609 00:29:57.880 --> 00:29:59.100 and became much drier. 610 00:29:59.500 --> 00:30:01.920 Well, I wanted, when I wrote that book called 611 00:30:01.920 --> 00:30:04.020 After the Greening, The Browning of Australia, 612 00:30:04.360 --> 00:30:06.680 I wanted to know what was in Australia 613 00:30:06.680 --> 00:30:11.020 at the time of separation, at 45 million years ago. 614 00:30:11.600 --> 00:30:15.200 And so I went with the South Australian Geological Survey 615 00:30:15.880 --> 00:30:16.860 into Lake Eyre. 616 00:30:17.420 --> 00:30:20.880 Stewart Creek is one of the creeks that runs into Lake Eyre, 617 00:30:20.960 --> 00:30:24.300 one of the dry salt creeks in the centre. 618 00:30:24.680 --> 00:30:27.140 And there we collected 619 00:30:27.140 --> 00:30:29.960 the most amazing plant fossils. 620 00:30:30.520 --> 00:30:31.960 They're wonderfully preserved 621 00:30:31.960 --> 00:30:33.640 because they're silcrete, 622 00:30:33.740 --> 00:30:35.540 they've become hardened with silica, 623 00:30:36.140 --> 00:30:38.420 and they get this wonderful desert varnish. 624 00:30:38.680 --> 00:30:40.020 And some of you might recognise, 625 00:30:40.440 --> 00:30:42.080 anybody from roundabout Sydney 626 00:30:42.080 --> 00:30:44.820 would certainly recognise that big leaf. 627 00:30:45.200 --> 00:30:47.480 It's a leaf of the Illawarra flame tree, 628 00:30:47.600 --> 00:30:50.040 or very close to it, a brachychiton. 629 00:30:50.400 --> 00:30:52.920 And in those forests in the centre, 630 00:30:53.000 --> 00:30:54.260 which is now the Dead Heart, 631 00:30:54.400 --> 00:30:55.960 where there's just nothing, 632 00:30:57.140 --> 00:30:59.200 there were all the sort of things 633 00:30:59.200 --> 00:31:02.020 that you've got in the Queensland rainforests. 634 00:31:02.020 --> 00:31:04.360 And there were eucalypts, 635 00:31:04.440 --> 00:31:05.820 the genus Eucalyptus, 636 00:31:05.820 --> 00:31:07.940 with its gum nuts and all the rest of it. 637 00:31:08.040 --> 00:31:09.300 There were casuarinas, 638 00:31:09.500 --> 00:31:10.840 and there were all the things 639 00:31:10.840 --> 00:31:14.680 that are the sclerophyll element today. 640 00:31:14.980 --> 00:31:18.460 They were still in a good mixture there, 641 00:31:18.560 --> 00:31:20.700 at least in heavy riverine forest, 642 00:31:20.780 --> 00:31:21.600 if nothing else, 643 00:31:21.740 --> 00:31:23.540 at 45 million years ago. 644 00:31:24.720 --> 00:31:25.980 And in fact, 645 00:31:25.980 --> 00:31:27.500 as I said, 646 00:31:27.580 --> 00:31:30.600 most of the continent was forested at that time, 647 00:31:30.740 --> 00:31:34.620 though with a land mass as large as ours is, 648 00:31:34.840 --> 00:31:36.860 you never had completely uniform, 649 00:31:37.200 --> 00:31:40.220 you had rain shadow areas and things like that. 650 00:31:40.420 --> 00:31:42.240 And because of poor soils, 651 00:31:42.280 --> 00:31:45.220 a great deal of the sclerophyll element anyway, 652 00:31:45.480 --> 00:31:47.900 but largely sort of mixed 653 00:31:47.900 --> 00:31:49.760 because there wasn't the separation out 654 00:31:49.760 --> 00:31:53.500 according to what could stand drier conditions. 655 00:31:54.600 --> 00:31:56.440 The Great Divide is interesting 656 00:31:56.440 --> 00:32:00.000 because you can actually trace 657 00:32:00.000 --> 00:32:02.300 the northward movement of the Australian continent 658 00:32:02.300 --> 00:32:04.020 by looking at the Great Divide. 659 00:32:04.140 --> 00:32:06.200 The red dotted line is the actual divide. 660 00:32:06.580 --> 00:32:08.840 Rivers run to the sea 661 00:32:08.840 --> 00:32:11.520 if they rise to the right of it, 662 00:32:11.600 --> 00:32:13.020 and they run inwards 663 00:32:13.680 --> 00:32:15.760 if they rise on the other side. 664 00:32:16.020 --> 00:32:16.960 The dark dots, 665 00:32:17.300 --> 00:32:20.600 the green line is the edge of the escarpment. 666 00:32:21.060 --> 00:32:23.480 That tilted edge was then eroded 667 00:32:23.500 --> 00:32:26.520 back to form the ranges of the Great Escarpment. 668 00:32:26.640 --> 00:32:28.240 Not a true mountain range 669 00:32:28.240 --> 00:32:30.880 like you get in areas where you've had collision 670 00:32:30.880 --> 00:32:32.960 of tectonic plates and huge mountains, 671 00:32:33.260 --> 00:32:36.420 but the best we have in terms of high ground 672 00:32:36.420 --> 00:32:37.540 in Australia, of course. 673 00:32:37.740 --> 00:32:41.360 And those grey spots are all areas of volcanic soil. 674 00:32:41.820 --> 00:32:45.280 And what's been happening is that as we move northwards, 675 00:32:45.460 --> 00:32:48.820 the continent passed over a point of weakness 676 00:32:48.820 --> 00:32:50.500 in the Earth's crust 677 00:32:50.500 --> 00:32:52.900 through which you had the, 678 00:32:52.900 --> 00:32:57.380 the volcanoes erupting at different times. 679 00:32:58.400 --> 00:33:00.140 And if you look at the, 680 00:33:00.900 --> 00:33:04.700 the volcanic point up near Cairns, 681 00:33:04.800 --> 00:33:06.900 these days we can date basalts 682 00:33:06.900 --> 00:33:08.640 and find out how old they are. 683 00:33:08.880 --> 00:33:11.100 And the basalts up there are something like 684 00:33:11.100 --> 00:33:12.860 40 million years old. 685 00:33:13.180 --> 00:33:15.420 And the basalts down near Melbourne 686 00:33:15.420 --> 00:33:18.280 on this hotspot volcanic chain 687 00:33:18.900 --> 00:33:21.860 are something like 5 million years old. 688 00:33:22.380 --> 00:33:26.080 And then if you, you've got two groups of ones 689 00:33:26.080 --> 00:33:28.720 like those two big ones up at the top, 690 00:33:29.620 --> 00:33:31.720 you measure the distance between them, 691 00:33:31.740 --> 00:33:33.680 you can actually calculate the rate 692 00:33:33.680 --> 00:33:37.140 at which the continent has passed over the hotspot 693 00:33:37.140 --> 00:33:40.400 with these volcanoes erupting through it. 694 00:33:40.520 --> 00:33:42.820 And it's from that that we get the, 695 00:33:42.840 --> 00:33:47.340 the business of 6.7 centimetres a year. 696 00:33:48.160 --> 00:33:51.280 And incidentally, just to give you some sort of idea, 697 00:33:52.080 --> 00:33:55.840 Townsville, which is, is now just in the tropics, 698 00:33:55.960 --> 00:33:59.000 it was at 30 degrees south, 699 00:33:59.160 --> 00:34:01.200 which is Sydney's level, 700 00:34:01.380 --> 00:34:04.500 Sydney's latitude 20 million years ago. 701 00:34:04.960 --> 00:34:07.820 And the Tropic of Capricorn that delimits the, 702 00:34:07.860 --> 00:34:10.880 the tropics of course lies at 23 and a half degrees south. 703 00:34:11.180 --> 00:34:15.100 So Townsville has only been in the tropics 704 00:34:15.100 --> 00:34:19.480 for about a short period. 705 00:34:19.480 --> 00:34:24.360 Cape York reached the Tropic of Capricorn 16 million years ago. 706 00:34:24.420 --> 00:34:27.200 I think the Townsville one is about 3 million years 707 00:34:27.200 --> 00:34:28.600 since it was in the tropics. 708 00:34:28.800 --> 00:34:32.820 Cape York reached the Tropic of Capricorn 16 million years ago. 709 00:34:33.020 --> 00:34:36.680 So that means we've only had anything of tropical nature 710 00:34:36.680 --> 00:34:39.640 in Australia in the last 15 million years. 711 00:34:40.720 --> 00:34:43.700 These volcanic eruptions of course are very important 712 00:34:43.700 --> 00:34:45.480 from the agricultural point of view 713 00:34:45.480 --> 00:34:47.340 because where you've got volcanoes, 714 00:34:47.380 --> 00:34:49.460 you've got good volcanoes. 715 00:34:49.480 --> 00:34:50.000 You've got volcanic soil. 716 00:34:50.500 --> 00:34:55.340 And like the soil that we've got on the Darling Downs. 717 00:34:55.740 --> 00:34:59.520 The Darling Downs of course is a major food production area, 718 00:34:59.840 --> 00:35:01.740 very best practice farming. 719 00:35:01.940 --> 00:35:03.900 You'll notice the major contours. 720 00:35:04.080 --> 00:35:06.100 All the contours are grassed. 721 00:35:06.100 --> 00:35:07.740 It's all done highly scientifically. 722 00:35:08.180 --> 00:35:12.320 You get heavy torrential sort of subtropical to tropical rain 723 00:35:12.320 --> 00:35:14.920 and look at the erosion that is happening 724 00:35:15.480 --> 00:35:17.840 between those very carefully constructed, 725 00:35:18.020 --> 00:35:18.940 uh, 726 00:35:18.940 --> 00:35:21.280 contours that are supposed to stop erosion. 727 00:35:21.680 --> 00:35:25.760 For as long as you have bare soil and tropical rain, 728 00:35:25.980 --> 00:35:27.540 you are going to lose soil. 729 00:35:27.840 --> 00:35:29.020 And the most, um, 730 00:35:29.640 --> 00:35:33.680 the most sort of optimistic people who know what's happening 731 00:35:33.680 --> 00:35:35.000 in terms of soil loss, 732 00:35:35.940 --> 00:35:38.020 think that maybe in 50 years 733 00:35:38.020 --> 00:35:40.220 all the good soil on the Darling Downs 734 00:35:40.220 --> 00:35:43.080 will have gone off, eroded away and disappeared. 735 00:35:43.920 --> 00:35:48.440 Um, a lot of us think that maybe it's more like 20 than 50. 736 00:35:48.940 --> 00:35:52.900 Because unless they return to covering the ground 737 00:35:52.900 --> 00:35:56.420 with deep-rooted perennial type vegetation, 738 00:35:57.220 --> 00:36:01.080 and for as long as Australia thinks of itself as an agricultural nation, 739 00:36:01.260 --> 00:36:02.400 it's not going to do that. 740 00:36:02.980 --> 00:36:08.120 So we have major problems even with the good agricultural soil, 741 00:36:08.320 --> 00:36:10.880 which is of very, very limited extent, 742 00:36:10.960 --> 00:36:12.280 as I told you before, 743 00:36:12.400 --> 00:36:16.160 most of our soils are from ancient, uh, well-weathered rocks. 744 00:36:17.460 --> 00:36:18.100 Now, 745 00:36:18.100 --> 00:36:20.140 while Australia was moving northwards, 746 00:36:21.920 --> 00:36:23.800 it was isolating, um, 747 00:36:23.920 --> 00:36:27.000 Antarctica was becoming increasingly isolated. 748 00:36:28.100 --> 00:36:32.680 And as a result of having a passageway between Antarctica 749 00:36:32.680 --> 00:36:35.480 and the other lands that were moving away from it, 750 00:36:35.580 --> 00:36:38.140 you had the development of a circumpolar current. 751 00:36:38.460 --> 00:36:41.180 You've got a spinning earth, so you get a spinning current, 752 00:36:41.500 --> 00:36:44.680 which cuts off Antarctica from any warm water 753 00:36:44.680 --> 00:36:46.680 that is going, coming south 754 00:36:46.680 --> 00:36:48.260 from the equator. 755 00:36:48.880 --> 00:36:51.300 And that middle figure there, it's nought, 756 00:36:51.340 --> 00:36:54.200 that middle figure should be 10 degrees and then 20 degrees. 757 00:36:54.360 --> 00:36:57.600 That just gives you some idea of the cooling of the ocean water 758 00:36:57.600 --> 00:36:58.440 around Antarctica. 759 00:36:59.200 --> 00:37:00.660 Before we split off, 760 00:37:00.880 --> 00:37:02.640 that's at about 55 million, 761 00:37:02.760 --> 00:37:05.920 the sea temperature around Antarctica 762 00:37:05.920 --> 00:37:08.340 was 20 degrees centigrade. 763 00:37:08.660 --> 00:37:11.740 And that is the temperature of summer water 764 00:37:11.740 --> 00:37:14.600 in Sydney Harbour, where I bathe every morning 765 00:37:14.600 --> 00:37:16.660 at 5 o'clock in the summer. 766 00:37:16.680 --> 00:37:18.840 And then you've got the, 767 00:37:18.840 --> 00:37:21.780 the general trend is a cooling trend, 768 00:37:22.060 --> 00:37:24.540 but with sort of flat bits and increased, 769 00:37:24.860 --> 00:37:27.740 uh, times of, uh, cooling. 770 00:37:27.960 --> 00:37:31.120 And a major cooling event at about 6 degrees. 771 00:37:31.540 --> 00:37:34.260 And then, again, a slight warming. 772 00:37:34.460 --> 00:37:37.420 And then, by 2.6 million, 773 00:37:37.580 --> 00:37:39.820 the start of the Pleistocene Ice Age, 774 00:37:40.040 --> 00:37:43.420 the Antarctic, which had been driving the cooling of the earth 775 00:37:43.420 --> 00:37:45.120 alone up to this point, 776 00:37:45.120 --> 00:37:48.960 it had so cooled things that the northern ice cap started to form. 777 00:37:49.280 --> 00:37:51.340 And those wiggles at the top 778 00:37:51.340 --> 00:37:55.780 are the repeated swings from glacial stages 779 00:37:55.780 --> 00:37:58.360 to interglacials in the northern hemisphere. 780 00:37:58.480 --> 00:38:02.920 And they record something like, uh, 14 or 15 of them. 781 00:38:03.100 --> 00:38:06.120 And we are at the very top of that wriggly bit 782 00:38:06.120 --> 00:38:10.640 living in the final, um, interglacial. 783 00:38:12.060 --> 00:38:13.680 Just to, um, 784 00:38:13.680 --> 00:38:17.360 to show you what that cooling sequence, 785 00:38:17.640 --> 00:38:19.740 we can trace it in the fossil record, 786 00:38:19.840 --> 00:38:21.040 the plant fossil record, 787 00:38:21.320 --> 00:38:23.640 at about 35 million years ago 788 00:38:23.640 --> 00:38:26.120 when the first glaciers formed on Antarctica. 789 00:38:26.660 --> 00:38:29.880 Our forests were full of, of the southern beach, 790 00:38:30.120 --> 00:38:32.680 uh, that's, that's the Antarctic beach. 791 00:38:33.260 --> 00:38:36.440 And as we move further northwards, 792 00:38:36.620 --> 00:38:39.360 though the original Gondwanan forest 793 00:38:39.360 --> 00:38:41.760 became very much restricted to areas 794 00:38:41.760 --> 00:38:43.300 that were still suitably wet, 795 00:38:43.680 --> 00:38:44.740 and pleasant for it. 796 00:38:44.880 --> 00:38:47.900 And the sclerophyll element in the vegetation 797 00:38:47.900 --> 00:38:49.080 was sifted out, 798 00:38:49.280 --> 00:38:52.360 and we had increasing areas and, uh, 799 00:38:52.540 --> 00:38:55.640 with, uh, very Australian type vegetation. 800 00:38:56.960 --> 00:38:58.820 At 20 million years ago, 801 00:38:58.900 --> 00:39:00.940 when we were halfway between, uh, 802 00:39:01.080 --> 00:39:04.040 where we are, where we had been attached to Antarctica 803 00:39:04.040 --> 00:39:05.200 and where we are today, 804 00:39:05.420 --> 00:39:08.000 this is a reconstruction from Lake Palankaruna, 805 00:39:08.140 --> 00:39:10.520 which is a dry salt lake next to Lake Eyre. 806 00:39:10.780 --> 00:39:13.660 And a massive, marvelous marsupial lake, 807 00:39:13.680 --> 00:39:15.860 hills of all sorts, great big running birds, 808 00:39:16.060 --> 00:39:17.500 still a great deal of forest, 809 00:39:17.700 --> 00:39:19.440 and there were even freshwater dolphins 810 00:39:19.440 --> 00:39:22.220 in our rivers at that stage. 811 00:39:22.400 --> 00:39:23.700 And we had flamingos. 812 00:39:23.700 --> 00:39:26.000 In fact, we still had flamingos here 813 00:39:26.000 --> 00:39:28.860 until 400,000 years ago, 814 00:39:28.880 --> 00:39:31.400 some stage of the present ice age 815 00:39:31.400 --> 00:39:32.320 when they disappeared. 816 00:39:32.680 --> 00:39:37.560 So, still a well-vegetated, uh, continent at that stage. 817 00:39:38.140 --> 00:39:40.560 But with the drier type of vegetation, 818 00:39:40.960 --> 00:39:43.540 the general drier conditions of the world, 819 00:39:43.540 --> 00:39:46.380 because more water of the world's budget 820 00:39:46.380 --> 00:39:48.500 was being used up in ice, 821 00:39:48.960 --> 00:39:52.060 it meant that we had increasing fire, 822 00:39:52.260 --> 00:39:53.260 natural fire. 823 00:39:53.740 --> 00:39:57.040 And, um, fire has actually been 824 00:39:57.040 --> 00:40:00.120 a very important, uh, thing in Australia 825 00:40:00.120 --> 00:40:02.120 for the last 15 million years. 826 00:40:02.680 --> 00:40:05.560 And then with the opening of the center of the continent, 827 00:40:05.680 --> 00:40:07.900 as the center really began to dry, 828 00:40:08.140 --> 00:40:10.620 you had the open grasslands, 829 00:40:10.840 --> 00:40:12.020 the Kenepod shrublands, 830 00:40:12.020 --> 00:40:13.920 the saltbush plains, and so on. 831 00:40:14.160 --> 00:40:18.200 And, uh, co-evolution of the hopping stride of kangaroos, 832 00:40:18.260 --> 00:40:20.960 because it's no good hopping like a kangaroo 833 00:40:20.960 --> 00:40:24.380 if you're living in a heavily vegetated, uh, environment. 834 00:40:25.940 --> 00:40:28.080 Just to go back to the six, 835 00:40:28.200 --> 00:40:30.040 the last six million to show, 836 00:40:30.220 --> 00:40:33.560 um, it's interesting that it's this, this period, 837 00:40:33.720 --> 00:40:35.440 the last six million years, 838 00:40:35.580 --> 00:40:38.260 that have made Australia the driest vegetated continent. 839 00:40:38.580 --> 00:40:41.280 But even more significant is what happened in Africa, 840 00:40:41.280 --> 00:40:43.120 because it was a general trend. 841 00:40:43.820 --> 00:40:46.160 You had this big cooling event 842 00:40:46.160 --> 00:40:48.360 between six and five million years ago. 843 00:40:48.680 --> 00:40:50.880 And as a result of that in Africa, 844 00:40:51.020 --> 00:40:53.040 the tropical forests contracted, 845 00:40:54.280 --> 00:40:56.480 and the ape men, or whatever you like to call them, 846 00:40:56.540 --> 00:40:57.860 the ancestral apes, 847 00:40:57.920 --> 00:41:00.180 couldn't go on swinging about in the trees, 848 00:41:00.280 --> 00:41:03.220 and they came down and walked upright on the savanna. 849 00:41:03.780 --> 00:41:05.740 And then at 2.6 million, 850 00:41:05.840 --> 00:41:09.440 where you get the beginning of the northern ice cap, 851 00:41:09.600 --> 00:41:11.260 uh, a major cooling event, 852 00:41:11.280 --> 00:41:13.300 when we're really into Pleistocene ice age, 853 00:41:13.480 --> 00:41:15.900 you suddenly see in the, uh, 854 00:41:16.140 --> 00:41:21.540 the sort of, um, evolutionary sequence of man in Africa, 855 00:41:21.720 --> 00:41:24.880 the branching off of the Homo line 856 00:41:24.880 --> 00:41:26.820 from the Australopithecines. 857 00:41:27.220 --> 00:41:31.200 And it is that section there that you see 858 00:41:31.200 --> 00:41:36.780 with the 14, um, um, swings from glacial to interglacial 859 00:41:36.780 --> 00:41:37.940 in the northern hemisphere, 860 00:41:37.940 --> 00:41:40.940 we only have, uh, sort of three, 861 00:41:40.960 --> 00:41:44.360 or perhaps four, uh, sort of events like that 862 00:41:44.360 --> 00:41:47.320 that we can detect in, in Australia. 863 00:41:48.260 --> 00:41:52.740 So this is the rundown to the actual Pleistocene ice age, 864 00:41:52.860 --> 00:41:56.560 and the last 2.6 million are in the Pleistocene ice age 865 00:41:56.560 --> 00:42:00.320 with its glaciations and its interglacial periods. 866 00:42:01.940 --> 00:42:05.740 Uh, Gondwanan Forest had contracted by then in Australia 867 00:42:05.740 --> 00:42:07.320 two very small remnants 868 00:42:07.320 --> 00:42:09.720 in topographically suitable areas, 869 00:42:10.280 --> 00:42:14.360 and you had the cooler sort with the North of Phagos, 870 00:42:14.520 --> 00:42:17.140 uh, in the more southerly part of the continent, 871 00:42:17.400 --> 00:42:21.220 and the northern, uh, Gondwanan Forest, 872 00:42:21.460 --> 00:42:24.300 uh, in the odd pockets that were left, 873 00:42:24.440 --> 00:42:26.060 uh, to the north. 874 00:42:27.360 --> 00:42:29.760 When you realize just what it was like 875 00:42:29.760 --> 00:42:31.540 to have ice age in Australia, 876 00:42:31.860 --> 00:42:35.000 uh, you understand a great deal of the problems 877 00:42:35.000 --> 00:42:35.920 that we have today. 878 00:42:36.160 --> 00:42:37.280 Uh, ice age, 879 00:42:37.320 --> 00:42:39.420 didn't mean ice and snow for Australia. 880 00:42:39.680 --> 00:42:43.560 It meant extraordinary dryness and extraordinary windiness. 881 00:42:43.860 --> 00:42:46.400 Half the rainfall over all the continent, 882 00:42:47.320 --> 00:42:48.720 considerably cooler temperatures, 883 00:42:48.800 --> 00:42:51.160 between seven and nine degrees overall, 884 00:42:51.360 --> 00:42:53.100 is, uh, they think at the moment, 885 00:42:54.320 --> 00:42:56.320 and extraordinary windiness. 886 00:42:56.460 --> 00:42:58.260 It was windy and dry, 887 00:42:58.400 --> 00:43:01.540 and all these, the continental shelves 888 00:43:01.540 --> 00:43:04.160 of all the continents were exposed, 889 00:43:05.320 --> 00:43:07.300 so you had vegetation growing up, 890 00:43:07.300 --> 00:43:07.440 and you had to be very careful 891 00:43:07.440 --> 00:43:08.840 about the wind blowing out onto them where possible. 892 00:43:09.440 --> 00:43:12.700 All that dark area, about 80% of the continent, 893 00:43:12.880 --> 00:43:14.620 under wind-blown sand, 894 00:43:14.900 --> 00:43:17.700 and it's the time when the major deserts in Australia 895 00:43:17.700 --> 00:43:21.300 were made as a result of the extreme windiness and dryness. 896 00:43:21.560 --> 00:43:24.120 The white area would have been very scrappy stuff, 897 00:43:24.320 --> 00:43:26.140 rather like the Mulga lands today, 898 00:43:26.880 --> 00:43:28.360 and the gray part, 899 00:43:28.520 --> 00:43:30.600 the only part in which there was woodland, 900 00:43:30.860 --> 00:43:32.140 and hidden in that, 901 00:43:32.200 --> 00:43:34.560 the remaining pockets of Gondwanan Forest. 902 00:43:34.940 --> 00:43:36.940 This spotted part in the eastern, 903 00:43:36.940 --> 00:43:37.680 eastern highlands, 904 00:43:37.900 --> 00:43:41.740 would have been a sort of special, 905 00:43:42.920 --> 00:43:44.200 rather sparse, 906 00:43:44.240 --> 00:43:45.980 alpine sort of grassland. 907 00:43:46.940 --> 00:43:48.660 And round Mount Kosciusko, 908 00:43:48.840 --> 00:43:49.860 if you're being generous, 909 00:43:50.080 --> 00:43:53.880 perhaps 50 square kilometers were glaciated. 910 00:43:54.000 --> 00:43:55.040 Only 50. 911 00:43:55.260 --> 00:43:57.880 Most of us think it was probably more like 25. 912 00:43:58.540 --> 00:44:00.860 A small ice cap, the black thing, 913 00:44:00.920 --> 00:44:03.540 on the central plateau in Tasmania, 914 00:44:03.580 --> 00:44:04.280 further south. 915 00:44:04.640 --> 00:44:06.000 And for the rest, 916 00:44:06.000 --> 00:44:07.780 it wasn't ice and snow, 917 00:44:07.960 --> 00:44:10.440 it was just extremely windy, 918 00:44:10.660 --> 00:44:12.100 and extremely dry. 919 00:44:12.380 --> 00:44:14.840 And if you doubt just how windy and dry, 920 00:44:15.060 --> 00:44:18.160 have a look at a satellite image of the Simpson Desert today. 921 00:44:18.340 --> 00:44:20.880 The parallel lines are the dunes, 922 00:44:20.900 --> 00:44:26.800 and some of those dunes stream 300 kilometers downwind, 923 00:44:26.980 --> 00:44:29.980 and there are plenty of them that are almost as high 924 00:44:29.980 --> 00:44:33.020 as this ceiling here above me. 925 00:44:33.020 --> 00:44:35.820 And that tells you something of dryness, 926 00:44:35.860 --> 00:44:36.820 lack of vegetation, 927 00:44:37.120 --> 00:44:40.640 and general misery with wind and so on. 928 00:44:41.040 --> 00:44:42.120 In contrast, 929 00:44:42.240 --> 00:44:43.360 the northern hemisphere, 930 00:44:44.140 --> 00:44:47.320 because of land being very close to the North Pole, 931 00:44:47.540 --> 00:44:50.060 huge ice sheets up to a mile thick, 932 00:44:50.100 --> 00:44:51.620 the way they are in ice ages, 933 00:44:51.800 --> 00:44:53.640 were able to travel across land, 934 00:44:53.920 --> 00:44:56.980 and go far further under their own weight 935 00:44:56.980 --> 00:45:00.720 and forward movement than the climate alone would have determined. 936 00:45:00.900 --> 00:45:01.460 And in fact, 937 00:45:01.460 --> 00:45:03.540 they reached the Ohio River in the States, 938 00:45:03.800 --> 00:45:05.580 came down right over Great Britain, 939 00:45:05.700 --> 00:45:07.220 and heading for the Mediterranean. 940 00:45:08.180 --> 00:45:12.380 And when you've got great big ice sheets grinding across landscapes, 941 00:45:12.780 --> 00:45:14.420 they grind up fresh, 942 00:45:14.720 --> 00:45:16.020 new rock, 943 00:45:16.220 --> 00:45:17.940 and they create fresh, 944 00:45:18.160 --> 00:45:18.500 new, 945 00:45:18.640 --> 00:45:19.200 deep, 946 00:45:19.200 --> 00:45:20.440 fertile soils. 947 00:45:21.460 --> 00:45:23.140 And when the ice retreated finally, 948 00:45:23.900 --> 00:45:25.960 good climates were established, 949 00:45:26.220 --> 00:45:28.000 climate reliable with spring, 950 00:45:28.160 --> 00:45:28.700 summer, 951 00:45:28.840 --> 00:45:29.820 autumn and winter, 952 00:45:29.820 --> 00:45:31.240 and reliable rainfall. 953 00:45:31.660 --> 00:45:33.620 So, you knew when to plant, 954 00:45:33.840 --> 00:45:35.320 you knew when things would grow, 955 00:45:35.440 --> 00:45:36.440 you knew when to harvest, 956 00:45:36.680 --> 00:45:40.580 and it was safe enough in the winter to leave things fallow. 957 00:45:40.700 --> 00:45:43.780 And the agricultural and land use practices 958 00:45:43.780 --> 00:45:48.600 of the times were developed in lands that had had this sort of renewal. 959 00:45:48.880 --> 00:45:50.840 And when settlers came to Australia, 960 00:45:51.180 --> 00:45:54.420 they simply brought those practices here 961 00:45:54.420 --> 00:45:58.600 and imposed them on a land which had a completely different, 962 00:45:58.600 --> 00:46:01.440 it couldn't have been more different in terms of its history, 963 00:46:01.560 --> 00:46:04.460 particularly its Ice Age history. 964 00:46:04.780 --> 00:46:10.380 And it's been this business of completely misunderstanding the capacity of the land 965 00:46:10.380 --> 00:46:12.680 and thinking it would respond like Europe 966 00:46:12.680 --> 00:46:18.760 that has been at the bottom of most of our major environmental problems. 967 00:46:19.140 --> 00:46:20.100 And of course, 968 00:46:20.100 --> 00:46:21.600 we didn't get a reliable climate, 969 00:46:22.320 --> 00:46:23.440 we got ENSO, 970 00:46:23.600 --> 00:46:25.980 the El Niño Southern Oscillation business, 971 00:46:26.280 --> 00:46:28.440 the peaks of all the droughts are the red ones, 972 00:46:28.440 --> 00:46:29.120 the blue ones at the bottom. 973 00:46:29.460 --> 00:46:31.360 These enormous swings, 974 00:46:32.260 --> 00:46:36.120 which makes Australia a land of drought and flood 975 00:46:36.120 --> 00:46:39.260 and totally unpredictable weather patterns over most of it. 976 00:46:39.380 --> 00:46:42.060 So, it is extraordinarily difficult to manage. 977 00:46:43.440 --> 00:46:43.880 And of course, 978 00:46:43.940 --> 00:46:47.020 sea level was grossly affected by the amount of ice. 979 00:46:47.360 --> 00:46:49.640 You'll see at 20,000, 980 00:46:50.380 --> 00:46:53.080 this is the sort of last interglacial, 981 00:46:53.340 --> 00:46:54.680 and at 20,000, 982 00:46:54.680 --> 00:46:56.720 very low sea levels. 983 00:46:56.940 --> 00:46:57.960 And then, in fact, 984 00:46:58.440 --> 00:46:59.160 the sea level rose, 985 00:46:59.360 --> 00:47:01.020 it's not marked at the end of this, 986 00:47:01.220 --> 00:47:02.360 but you see at the beginning, 987 00:47:02.560 --> 00:47:05.100 sea level higher than it is today. 988 00:47:05.720 --> 00:47:09.120 And the same thing happened in our present interglacial. 989 00:47:09.420 --> 00:47:13.400 At about 9,000 years ago in particular, 990 00:47:13.740 --> 00:47:16.820 sea levels were considerably higher than they are now. 991 00:47:17.980 --> 00:47:19.380 And of course, 992 00:47:19.380 --> 00:47:20.600 when sea levels were low, 993 00:47:20.820 --> 00:47:23.080 rivers had to cut down very deep 994 00:47:23.080 --> 00:47:24.160 to make, 995 00:47:25.220 --> 00:47:27.360 to run into the sea. 996 00:47:27.360 --> 00:47:30.300 And so, we've got the most wonderful sculpturing 997 00:47:30.300 --> 00:47:31.480 of our coastlines 998 00:47:31.480 --> 00:47:33.400 and all the deep estuaries 999 00:47:33.400 --> 00:47:34.860 and things like Sydney Harbour. 1000 00:47:35.220 --> 00:47:37.180 These sort of estuaries all round 1001 00:47:37.180 --> 00:47:39.180 as a result of the low sea levels. 1002 00:47:39.340 --> 00:47:39.820 And of course, 1003 00:47:39.840 --> 00:47:40.640 these days, 1004 00:47:40.660 --> 00:47:42.260 you can see by the amount of sand 1005 00:47:42.260 --> 00:47:43.340 and all in that one, 1006 00:47:43.480 --> 00:47:45.660 our estuary is in a pretty sad state 1007 00:47:45.660 --> 00:47:47.520 because of the land management 1008 00:47:47.520 --> 00:47:51.080 that has resulted in the enormous production of sediment 1009 00:47:51.080 --> 00:47:51.840 and so on. 1010 00:47:52.880 --> 00:47:55.380 So, we've got these estuaries all round the coast. 1011 00:47:55.880 --> 00:47:57.340 At times of low sea levels, 1012 00:47:57.340 --> 00:47:59.500 we were joined to New Guinea. 1013 00:48:00.160 --> 00:48:01.320 And of course, 1014 00:48:01.340 --> 00:48:04.260 Tasmania was joined on again at that stage too. 1015 00:48:04.480 --> 00:48:05.840 We'd be pleased about that. 1016 00:48:05.900 --> 00:48:06.800 We didn't leave it behind. 1017 00:48:07.320 --> 00:48:11.940 And the whole part to our north, 1018 00:48:11.980 --> 00:48:14.480 the Indonesia and all of that part, 1019 00:48:14.620 --> 00:48:15.840 a great deal of land 1020 00:48:15.840 --> 00:48:18.740 because of the exposure of continental shelves, 1021 00:48:18.960 --> 00:48:21.880 making it easy for people to migrate. 1022 00:48:21.940 --> 00:48:24.180 Very short distances between islands 1023 00:48:24.180 --> 00:48:25.700 for people with boats. 1024 00:48:26.000 --> 00:48:27.320 So, a very different, 1025 00:48:27.340 --> 00:48:27.860 very different world. 1026 00:48:28.980 --> 00:48:32.440 And then with the higher sea levels later, 1027 00:48:32.620 --> 00:48:34.060 when they were extra high, 1028 00:48:34.300 --> 00:48:35.240 of course, 1029 00:48:35.960 --> 00:48:37.340 a great deal of flooding 1030 00:48:37.860 --> 00:48:41.180 of the very flat northern margin of our continent. 1031 00:48:41.340 --> 00:48:43.520 The flood plains of the north of our continent 1032 00:48:43.520 --> 00:48:46.660 had the sea coming right into them. 1033 00:48:46.760 --> 00:48:49.160 You had mangrove swamps far inland. 1034 00:48:49.740 --> 00:48:51.700 And where you've got mangroves 1035 00:48:51.700 --> 00:48:54.160 and the sort of anaerobic conditions 1036 00:48:54.160 --> 00:48:55.880 that you get in mangrove swamps, 1037 00:48:55.880 --> 00:48:58.120 you have a great deal of sulphur produced. 1038 00:48:58.740 --> 00:49:02.600 And the potential acid sulphate soils 1039 00:49:02.600 --> 00:49:03.880 result from that. 1040 00:49:04.080 --> 00:49:05.940 The same thing happened with the sea 1041 00:49:05.940 --> 00:49:08.180 penetrating into our estuaries 1042 00:49:08.180 --> 00:49:09.600 far up our rivers 1043 00:49:09.600 --> 00:49:13.160 so that we've got acid sulphate soil problems 1044 00:49:13.160 --> 00:49:16.080 in our major river valleys 1045 00:49:16.080 --> 00:49:17.460 and all along, 1046 00:49:17.580 --> 00:49:19.520 particularly in the tropics, of course, 1047 00:49:19.640 --> 00:49:23.080 but along a great deal of the east coast of the continent 1048 00:49:23.080 --> 00:49:24.160 as well as the north. 1049 00:49:24.160 --> 00:49:26.000 And one has to wonder 1050 00:49:26.000 --> 00:49:30.180 at the wisdom of growing sugarcane, 1051 00:49:30.260 --> 00:49:31.920 for instance, in these areas, 1052 00:49:31.980 --> 00:49:34.260 because the moment you open them up to the air, 1053 00:49:34.380 --> 00:49:37.840 you get the enormous production of sulphuric acid. 1054 00:49:38.160 --> 00:49:40.980 And the amount of acid and sediment and stuff 1055 00:49:40.980 --> 00:49:43.140 that's leaking into the ocean, 1056 00:49:43.340 --> 00:49:45.220 into the sort of lagoon or part 1057 00:49:45.220 --> 00:49:48.040 behind the Great Barrier Reef, for instance, 1058 00:49:48.280 --> 00:49:51.160 is a source of enormous worry to all of us. 1059 00:49:52.120 --> 00:49:54.140 Australia is the flattest of all the continents. 1060 00:49:54.140 --> 00:49:55.840 That is a satellite image 1061 00:49:55.840 --> 00:49:58.420 with every wrinkle much exaggerated. 1062 00:49:58.560 --> 00:50:00.400 You can see the major basin structures 1063 00:50:00.400 --> 00:50:01.620 in it rather nicely. 1064 00:50:02.640 --> 00:50:04.140 And as I said before, 1065 00:50:04.400 --> 00:50:05.880 it's a land of floodplains 1066 00:50:05.880 --> 00:50:08.400 and because of the sediment retention 1067 00:50:08.400 --> 00:50:11.340 that results from being extremely flat. 1068 00:50:11.620 --> 00:50:15.400 And if you want to see the greatest sort of expression 1069 00:50:15.400 --> 00:50:17.240 of that flatness and sediment, 1070 00:50:17.440 --> 00:50:19.380 this is the Kupo River system. 1071 00:50:20.060 --> 00:50:22.120 The wonderful anabranching, 1072 00:50:22.220 --> 00:50:24.120 the rivers can't cut down deep enough 1073 00:50:24.140 --> 00:50:25.900 because they're not running to the sea or anything. 1074 00:50:26.040 --> 00:50:27.460 So when you've got masses of water, 1075 00:50:27.600 --> 00:50:29.500 you've got great overland flooding 1076 00:50:30.140 --> 00:50:35.200 and then it forms these multiple structures. 1077 00:50:35.760 --> 00:50:37.320 It's called anabranching. 1078 00:50:37.560 --> 00:50:40.140 And the Diamantina is the other one. 1079 00:50:40.480 --> 00:50:43.660 And what other continent has got river systems 1080 00:50:43.660 --> 00:50:44.680 that look like this? 1081 00:50:44.760 --> 00:50:47.180 I mean, it's bloody marvellous. 1082 00:50:49.260 --> 00:50:52.620 And when you get the massive overland floods, 1083 00:50:52.620 --> 00:50:56.440 then some of the water manages to get down towards Lake Eyre. 1084 00:50:56.580 --> 00:50:58.780 And every now and then, as you know, 1085 00:50:58.880 --> 00:51:02.200 the lake fills and stays with plenty of water in it 1086 00:51:02.200 --> 00:51:03.900 for quite a considerable time. 1087 00:51:04.180 --> 00:51:06.800 But it's very important that we don't do anything 1088 00:51:06.800 --> 00:51:10.400 to stop these floods by damming the headwaters, 1089 00:51:10.420 --> 00:51:12.760 for instance, to grow cotton on the Kupa 1090 00:51:12.760 --> 00:51:14.700 as they keep on proposing to do, 1091 00:51:14.840 --> 00:51:18.440 simply because it will kill the centre of the continent. 1092 00:51:18.880 --> 00:51:21.620 Because this is a land of floodplains, 1093 00:51:21.620 --> 00:51:24.800 not lovely dramatic ones like this, 1094 00:51:24.920 --> 00:51:27.320 but for instance, this is a floodplain of the Gwada. 1095 00:51:27.920 --> 00:51:29.980 And originally, as I said, 1096 00:51:30.100 --> 00:51:34.400 it was necessary for the floods to come across these landscapes 1097 00:51:34.400 --> 00:51:37.080 to refill the shallow aquifers. 1098 00:51:37.220 --> 00:51:39.320 And the early explorers used to say 1099 00:51:39.320 --> 00:51:41.140 that no matter where they were, 1100 00:51:41.340 --> 00:51:44.240 even sort of 20 miles from the nearest river, 1101 00:51:44.520 --> 00:51:45.740 official river, 1102 00:51:46.260 --> 00:51:48.280 the Aboriginals who went with them 1103 00:51:48.280 --> 00:51:50.520 could dig down only about a metre 1104 00:51:50.520 --> 00:51:51.600 and obtain water. 1105 00:51:51.620 --> 00:51:52.520 And they could obtain fresh water. 1106 00:51:53.460 --> 00:51:55.520 Simply because every now and then 1107 00:51:55.520 --> 00:51:57.440 there was a flood across these floodplains, 1108 00:51:57.640 --> 00:51:59.720 the aquifers were refilled. 1109 00:51:59.820 --> 00:52:01.640 And we, with our management, 1110 00:52:01.900 --> 00:52:05.100 have to a large extent eliminated this natural process. 1111 00:52:05.640 --> 00:52:08.400 That gives you some idea of the Condamine River at the top. 1112 00:52:08.440 --> 00:52:09.840 These are the rivers south of it, 1113 00:52:09.880 --> 00:52:12.680 down to the border with New South Wales. 1114 00:52:13.060 --> 00:52:16.280 That is the normal sort of extent of flooding 1115 00:52:16.280 --> 00:52:17.740 in good flood years. 1116 00:52:17.900 --> 00:52:20.960 And some of that flooding happens every year. 1117 00:52:20.960 --> 00:52:22.920 And of course it's very inconvenient 1118 00:52:22.920 --> 00:52:24.820 if you're farming on the floodplains 1119 00:52:24.820 --> 00:52:26.620 or if you've built your town on the river. 1120 00:52:27.400 --> 00:52:29.940 And what you've simply got to realise is 1121 00:52:29.940 --> 00:52:33.720 that it is very important for the natural way of things 1122 00:52:33.720 --> 00:52:35.760 if you want things to be sustainable. 1123 00:52:36.520 --> 00:52:38.460 We have another major problem. 1124 00:52:38.980 --> 00:52:41.560 This is the Barwon Darling system. 1125 00:52:42.700 --> 00:52:45.120 And rather small print, I'm afraid. 1126 00:52:45.180 --> 00:52:47.320 The red dots are all dams. 1127 00:52:47.320 --> 00:52:49.780 And you'll see they're close to the headwaters 1128 00:52:49.780 --> 00:52:52.080 because the edge of the white there 1129 00:52:52.080 --> 00:52:55.420 is the edge of the Great Divide where the rivers arise. 1130 00:52:56.320 --> 00:52:59.000 And when you dam the headwaters 1131 00:52:59.000 --> 00:53:01.580 and when rainfall decreases greatly 1132 00:53:01.580 --> 00:53:03.280 the further west you go, 1133 00:53:04.100 --> 00:53:07.500 you have a really difficult sort of situation 1134 00:53:07.500 --> 00:53:10.040 because you are robbing the river downstream. 1135 00:53:10.600 --> 00:53:13.260 And you can see how much alteration we've made 1136 00:53:13.260 --> 00:53:14.880 in weirs to the Darling. 1137 00:53:15.000 --> 00:53:16.980 And the Darling has no local runoff. 1138 00:53:17.120 --> 00:53:19.400 It depends entirely on the water 1139 00:53:19.400 --> 00:53:22.520 that comes from its tributaries. 1140 00:53:22.780 --> 00:53:25.280 So river management, very difficult. 1141 00:53:25.800 --> 00:53:27.440 And it's not only salt. 1142 00:53:27.520 --> 00:53:30.360 A sand that is accumulated on the floodplains 1143 00:53:30.360 --> 00:53:32.500 but the salt, as I mentioned before, 1144 00:53:32.620 --> 00:53:34.060 that accumulates on the land 1145 00:53:34.060 --> 00:53:36.360 goes down to the water table. 1146 00:53:36.600 --> 00:53:38.680 And when the water table is at depth 1147 00:53:38.680 --> 00:53:39.700 it's not much problem. 1148 00:53:39.900 --> 00:53:42.760 This is at Kerrang in north-western Victoria. 1149 00:53:43.620 --> 00:53:47.120 That is a window into the saline water table. 1150 00:53:47.260 --> 00:53:48.960 That's commercial extraction 1151 00:53:49.400 --> 00:53:49.540 and it's not much salt. 1152 00:53:49.720 --> 00:53:53.300 There's a little gantry between the two major dumps 1153 00:53:53.300 --> 00:53:55.180 and it's about six foot high. 1154 00:53:55.320 --> 00:53:57.600 So you've got some idea of the size 1155 00:53:57.600 --> 00:53:59.720 of these sort of elongated pyramid things. 1156 00:54:00.000 --> 00:54:02.420 They stretch for about a third of a kilometre. 1157 00:54:03.280 --> 00:54:05.160 And when you've got that sort of salt 1158 00:54:05.160 --> 00:54:06.800 lurking just below the surface, 1159 00:54:06.980 --> 00:54:10.860 the horizon to the left there is green. 1160 00:54:10.960 --> 00:54:12.120 That is a wheat field. 1161 00:54:12.380 --> 00:54:14.920 I was standing on a road here to photograph this 1162 00:54:14.920 --> 00:54:17.760 with a wheat field newly planted behind me. 1163 00:54:18.720 --> 00:54:19.200 And... 1164 00:54:19.400 --> 00:54:22.380 when you've got salt in that sort of quantity 1165 00:54:22.380 --> 00:54:26.000 just below and you've got a rising water table, 1166 00:54:26.200 --> 00:54:28.560 there's no need to tell you what that means 1167 00:54:28.560 --> 00:54:29.920 in terms of salinisation. 1168 00:54:30.620 --> 00:54:33.700 And you've got vast areas of the Murray Basin 1169 00:54:33.700 --> 00:54:35.400 and the West Australian wheat belt 1170 00:54:35.400 --> 00:54:38.340 and increasingly other areas suffering from salinity. 1171 00:54:38.960 --> 00:54:42.060 They also just suffer from plain water logging like that, 1172 00:54:42.100 --> 00:54:44.480 salt water, so all that will grow is 1173 00:54:44.480 --> 00:54:46.080 is samphires and things. 1174 00:54:46.380 --> 00:54:47.760 And it's the... 1175 00:54:47.760 --> 00:54:49.380 has been so easy to get 1176 00:54:49.400 --> 00:54:51.080 to upset the hydrology because, 1177 00:54:51.180 --> 00:54:52.120 as I told you before, 1178 00:54:52.440 --> 00:54:55.820 a basin structure with only one exit to the sea 1179 00:54:56.400 --> 00:54:57.600 is very easily affected. 1180 00:55:00.200 --> 00:55:02.240 Another thing is that when once you've upset 1181 00:55:02.240 --> 00:55:05.000 the hydrology in something like the Murray Basin, 1182 00:55:05.000 --> 00:55:06.380 or in the Murray Basin in particular, 1183 00:55:07.300 --> 00:55:10.600 what the alterations that we have made to the hydrology 1184 00:55:10.600 --> 00:55:12.460 have got to work their way through the system. 1185 00:55:12.720 --> 00:55:16.080 And so even if we do best practice farming 1186 00:55:16.080 --> 00:55:18.100 on the surface and everything that we can, 1187 00:55:18.100 --> 00:55:20.500 we're still going to have a deterioration 1188 00:55:20.500 --> 00:55:23.620 in terms of salt in the river, salt in the land, 1189 00:55:24.420 --> 00:55:26.880 for 50 years if you're an optimist, 1190 00:55:26.940 --> 00:55:29.060 for 100 years if you're a pessimist, 1191 00:55:29.080 --> 00:55:30.060 so take your pick. 1192 00:55:30.980 --> 00:55:33.780 And even the Murray, which is our icon river, 1193 00:55:35.700 --> 00:55:37.840 recently it was suggested that it, 1194 00:55:37.880 --> 00:55:39.340 the Tumut and the Murrumbidgee, 1195 00:55:39.360 --> 00:55:41.080 should be put on an endangered list. 1196 00:55:41.320 --> 00:55:44.000 And you people in Adelaide don't need to be told 1197 00:55:44.000 --> 00:55:46.740 what it's like to be on the tail end of a river 1198 00:55:46.740 --> 00:55:48.080 when Queensland's climate change 1199 00:55:48.100 --> 00:55:48.900 has taken what it wants, 1200 00:55:49.240 --> 00:55:51.400 New South Wales has taken what it wants, 1201 00:55:51.740 --> 00:55:54.500 and everybody has added the fertilizer, 1202 00:55:55.040 --> 00:55:59.180 the toxins, the pesticides, you name it, 1203 00:55:59.320 --> 00:56:02.080 and your drinking water so often 1204 00:56:03.280 --> 00:56:05.560 is also on the endangered list. 1205 00:56:06.840 --> 00:56:09.460 It's been by altering the hydrology 1206 00:56:09.460 --> 00:56:11.600 that we have done all these things. 1207 00:56:12.020 --> 00:56:14.700 Tree clearing, a major thing. 1208 00:56:15.100 --> 00:56:17.380 Trees anyway only sort of grew up 1209 00:56:17.380 --> 00:56:20.480 in any profusion up in those sort of areas. 1210 00:56:21.000 --> 00:56:22.700 Massive clearing where it's red, 1211 00:56:22.900 --> 00:56:25.120 a moderate in the yellow, 1212 00:56:25.260 --> 00:56:27.740 and there's still bits where there's minimal clearing. 1213 00:56:28.140 --> 00:56:30.760 But the moment you take away the deep-rooted vegetation 1214 00:56:31.380 --> 00:56:33.480 which keeps the water table down at depth 1215 00:56:33.480 --> 00:56:35.080 because of evapotranspiration, 1216 00:56:35.280 --> 00:56:38.480 you have rising water tables and you have problems. 1217 00:56:38.960 --> 00:56:41.580 And of course the Brigalow clearing in Queensland, 1218 00:56:41.900 --> 00:56:44.280 an absolute shocking disgrace. 1219 00:56:45.380 --> 00:56:47.360 They are clearing land there more than 1220 00:56:47.380 --> 00:56:50.700 it is being cleared in the Brazilian rainforest. 1221 00:56:51.040 --> 00:56:53.480 We all get up and shout about people removing 1222 00:56:53.480 --> 00:56:57.660 the tropical forests, but this goes on in our backyard. 1223 00:56:58.060 --> 00:57:01.620 And the soil under the Brigalow is fertile only 1224 00:57:01.620 --> 00:57:03.800 because the Brigalow is a legume, 1225 00:57:03.920 --> 00:57:05.240 therefore it fixes nitrogen. 1226 00:57:05.660 --> 00:57:08.560 So you mine that nitrogen by planting things 1227 00:57:08.560 --> 00:57:11.800 for a couple of years, then you're back to poor soils, 1228 00:57:12.080 --> 00:57:16.360 easily erodible, and no way back. 1229 00:57:16.360 --> 00:57:20.980 So not very impressive one way or another. 1230 00:57:21.360 --> 00:57:23.240 New South Wales can't be too smug 1231 00:57:23.240 --> 00:57:27.220 because we clear 30,000 hectares a year. 1232 00:57:27.500 --> 00:57:30.100 I don't think you've ever had that sort of stuff 1233 00:57:30.100 --> 00:57:32.940 to clear in South Australia, 1234 00:57:33.140 --> 00:57:35.160 but you suffer the consequences 1235 00:57:35.160 --> 00:57:37.280 because you're on the end of the river systems. 1236 00:57:38.460 --> 00:57:41.080 We've had an enormous impact on the continent. 1237 00:57:41.160 --> 00:57:46.060 This is virtually sort of the greatest change to land cover. 1238 00:57:46.360 --> 00:57:50.100 In spite of the fact that this is a sparsely populated land 1239 00:57:50.100 --> 00:57:53.040 and huge areas and whatnot. 1240 00:57:53.960 --> 00:57:57.080 Australia today is the driest vegetated continent. 1241 00:57:57.440 --> 00:58:01.900 70% acutely arid, in fact 40% is considered desert. 1242 00:58:02.280 --> 00:58:05.520 15% is semi-arid around that 1243 00:58:05.520 --> 00:58:08.360 and suffers from pretty regular droughts 1244 00:58:08.940 --> 00:58:10.540 and more arid times. 1245 00:58:10.820 --> 00:58:14.360 And that means that 15% of the continent 1246 00:58:14.360 --> 00:58:16.340 is reasonably well watered. 1247 00:58:17.400 --> 00:58:19.420 And over most of the continent 1248 00:58:19.420 --> 00:58:22.100 evaporation is an order of magnitude 1249 00:58:22.100 --> 00:58:24.400 higher than precipitation. 1250 00:58:26.120 --> 00:58:29.800 And the United Nations has been saying for ages 1251 00:58:30.360 --> 00:58:32.140 that the arid lands of the world 1252 00:58:32.140 --> 00:58:33.820 are desertifying very rapidly 1253 00:58:34.360 --> 00:58:37.280 and that biodiversity loss in them is extremely serious. 1254 00:58:37.540 --> 00:58:39.000 We are the driest continent. 1255 00:58:39.140 --> 00:58:42.140 We have a miserable record in biodiversity loss. 1256 00:58:42.540 --> 00:58:46.340 And we are the only people who can save our biodiversity 1257 00:58:46.360 --> 00:58:49.180 because our biota is unique 1258 00:58:49.780 --> 00:58:52.060 and nobody else can save it for us. 1259 00:58:52.840 --> 00:58:56.660 So Australia has only very limited food bowl areas. 1260 00:58:56.840 --> 00:58:58.520 They're shown rather nicely in that. 1261 00:58:58.840 --> 00:59:00.380 Largely the Murray Basin, 1262 00:59:00.420 --> 00:59:02.220 a bit of sugar cane and stuff at the top. 1263 00:59:02.240 --> 00:59:04.140 But the food bowl is that with the arrow 1264 00:59:04.140 --> 00:59:06.040 and the West Australian wheat belt. 1265 00:59:06.260 --> 00:59:09.220 Already about a third of that land 1266 00:59:09.220 --> 00:59:10.860 has gone to salinity 1267 00:59:10.860 --> 00:59:14.120 and at least half of it is in extreme danger. 1268 00:59:15.300 --> 00:59:16.340 But there's a lot of diversity. 1269 00:59:16.360 --> 00:59:18.220 There's still this sort of madness that goes on. 1270 00:59:18.280 --> 00:59:24.140 We consider ourselves an agricultural nation. 1271 00:59:24.700 --> 00:59:29.100 And we feed by what we produce in this country 1272 00:59:29.100 --> 00:59:31.960 because of wanting to be part of the global economy. 1273 00:59:32.080 --> 00:59:34.500 We feed 80 million people. 1274 00:59:35.360 --> 00:59:37.300 20 million are resident in Australia. 1275 00:59:37.720 --> 00:59:41.100 And we're doing it at the cost of our basic resources 1276 00:59:41.100 --> 00:59:42.220 of soil and water. 1277 00:59:43.540 --> 00:59:46.340 We've got massive socioeconomic development. 1278 00:59:46.360 --> 00:59:46.760 We've got huge dilemmas 1279 00:59:46.760 --> 00:59:49.060 and things that simply have to be addressed. 1280 00:59:49.520 --> 00:59:51.580 And although Australia looks like a large, 1281 00:59:51.680 --> 00:59:54.400 empty continent just waiting to be filled with people, 1282 00:59:54.580 --> 00:59:58.540 and some people in power obviously still see it that way, 1283 00:59:58.720 --> 01:00:00.920 it's only small in terms of usability. 1284 01:00:02.380 --> 01:00:04.400 Water is our most precious resource. 1285 01:00:05.280 --> 01:00:06.920 See, that river doesn't look... 1286 01:00:06.920 --> 01:00:08.280 That's part of the Darling, actually. 1287 01:00:09.960 --> 01:00:11.700 And it is the limiting factor. 1288 01:00:11.900 --> 01:00:14.980 Many lands of the world are running out of fresh water 1289 01:00:14.980 --> 01:00:17.300 and many have it so badly polluted 1290 01:00:17.300 --> 01:00:19.340 that it's just about useless anyway. 1291 01:00:20.080 --> 01:00:21.780 There's an ecological footprint, 1292 01:00:22.180 --> 01:00:24.380 the amount of land that is needed, 1293 01:00:24.660 --> 01:00:28.560 productive land to sustain each one of us 1294 01:00:28.560 --> 01:00:31.560 in the lifestyle which we like to keep. 1295 01:00:32.020 --> 01:00:35.380 And already, if you work out the ecological footprint 1296 01:00:35.380 --> 01:00:38.660 for Australia, our population should have stopped 1297 01:00:38.660 --> 01:00:40.080 at about 13 million. 1298 01:00:40.180 --> 01:00:41.260 And I'm an optimist. 1299 01:00:41.260 --> 01:00:43.100 I think Tim Flannery says about eight. 1300 01:00:44.040 --> 01:00:44.960 And so... 1301 01:00:44.980 --> 01:00:47.580 So considering that our water resources are fully committed, 1302 01:00:47.840 --> 01:00:50.440 we are already thoroughly overpopulated. 1303 01:00:52.860 --> 01:00:56.880 So once again, I return to my river red gums 1304 01:00:56.880 --> 01:01:00.760 and say again that we've got to adapt to the continent 1305 01:01:00.760 --> 01:01:04.080 in our expectations and in our usage. 1306 01:01:04.340 --> 01:01:05.700 It has set the parameters 1307 01:01:05.700 --> 01:01:09.120 and we are destroying it by imposing our will upon it. 1308 01:01:09.260 --> 01:01:09.860 Thank you. 1309 01:01:27.600 --> 01:01:28.040 APPLAUSE 1310 01:01:28.040 --> 01:01:29.700 Sounds really nice. 1311 01:01:30.160 --> 01:01:30.920 Have a drink. 1312 01:01:32.300 --> 01:01:33.720 Thank you very much, Mary. 1313 01:01:34.680 --> 01:01:36.440 I realise that our time is up, 1314 01:01:36.500 --> 01:01:38.740 but I think since this is the last session, 1315 01:01:38.900 --> 01:01:39.860 some people might... 1316 01:01:39.860 --> 01:01:42.640 We might take a few questions if people really have some... 1317 01:01:42.640 --> 01:01:44.400 And I'm happy to stay and talk to people. 1318 01:01:44.400 --> 01:01:45.960 And we can talk afterwards as well. 1319 01:01:46.100 --> 01:01:48.960 But any urgent questions that people would like to pose to Mary? 1320 01:01:49.140 --> 01:01:50.560 I know some people have to go. 1321 01:01:50.940 --> 01:01:51.380 Yes? 1322 01:01:52.700 --> 01:01:53.560 There's a mic here. 1323 01:01:53.700 --> 01:01:54.980 I just need to get another microphone. 1324 01:01:55.340 --> 01:01:55.600 OK. 1325 01:01:56.140 --> 01:01:56.940 That's very cool. 1326 01:01:58.500 --> 01:02:00.140 I was just going to ask... 1327 01:02:00.140 --> 01:02:01.800 I'm a secondary school teacher 1328 01:02:02.400 --> 01:02:03.060 and I was just wondering, 1329 01:02:03.200 --> 01:02:06.420 have you written anything in regards to 1330 01:02:07.600 --> 01:02:10.420 that particular level of education or... 1331 01:02:10.420 --> 01:02:11.860 For secondary schools? 1332 01:02:12.120 --> 01:02:12.340 Yes. 1333 01:02:12.340 --> 01:02:13.520 Well, I would think that, listen, 1334 01:02:13.520 --> 01:02:17.020 our land is crying on land use and running down. 1335 01:02:17.360 --> 01:02:19.340 It's intended exactly for that. 1336 01:02:19.440 --> 01:02:20.900 And I've just been talking at Canasta, 1337 01:02:21.080 --> 01:02:24.640 which is your science teacher education thing, you know? 1338 01:02:24.740 --> 01:02:28.720 And most of them are using these books. 1339 01:02:28.840 --> 01:02:32.840 And because I really try to write science for general readers. 1340 01:02:33.100 --> 01:02:34.620 There's no need for jargon. 1341 01:02:34.720 --> 01:02:36.980 And if you do have to use a scientific word, 1342 01:02:37.020 --> 01:02:39.020 you can put its meaning in brackets and whatnot. 1343 01:02:39.240 --> 01:02:40.380 Kids can read this. 1344 01:02:41.400 --> 01:02:43.500 A bright child at the end of... 1345 01:02:43.520 --> 01:02:43.920 I'm sorry. 1346 01:02:43.920 --> 01:02:44.260 A bright child at the end of primary school 1347 01:02:44.260 --> 01:02:46.160 as well as all the secondary ones. 1348 01:02:46.280 --> 01:02:46.920 So no problem. 1349 01:02:47.340 --> 01:02:48.340 I hope you do. 1350 01:02:50.220 --> 01:02:50.740 OK. 1351 01:02:50.860 --> 01:02:51.580 One more back there. 1352 01:02:51.680 --> 01:02:53.540 Can we call out? 1353 01:02:53.900 --> 01:02:55.080 I just want to ask... 1354 01:03:00.760 --> 01:03:05.000 Large trees evaporate large quantities of water into the atmosphere. 1355 01:03:05.320 --> 01:03:06.920 When you clear those trees away, 1356 01:03:07.100 --> 01:03:08.520 that evaporation disappears. 1357 01:03:09.140 --> 01:03:11.960 I wonder if you'd care to comment on the climate change effects 1358 01:03:11.960 --> 01:03:13.340 of land clearance. 1359 01:03:13.600 --> 01:03:14.000 Thank you. 1360 01:03:14.180 --> 01:03:14.660 Yes. 1361 01:03:14.680 --> 01:03:15.440 Well, enormous. 1362 01:03:15.740 --> 01:03:18.000 And I think much, much underestimated. 1363 01:03:18.320 --> 01:03:21.620 And all you have to do is remove all the tropical forests 1364 01:03:21.620 --> 01:03:23.780 to completely alter world climate. 1365 01:03:23.860 --> 01:03:26.040 You don't have to worry about greenhouse or anything else. 1366 01:03:26.220 --> 01:03:27.860 I mean, it's going to happen anyway. 1367 01:03:28.160 --> 01:03:32.260 And where you have land that is degraded, 1368 01:03:32.960 --> 01:03:34.680 you have great up currents and whatnot. 1369 01:03:35.020 --> 01:03:37.700 And you can have one of our wonderful fences 1370 01:03:37.700 --> 01:03:39.340 that stops the rabbits and whatnot. 1371 01:03:39.520 --> 01:03:41.940 And so you've got vegetation on one side, 1372 01:03:41.940 --> 01:03:43.900 and you've got degraded land on the other. 1373 01:03:44.120 --> 01:03:45.360 And believe it or not, 1374 01:03:45.520 --> 01:03:49.520 a great deal more rain falls in the well-vegetated part, 1375 01:03:49.660 --> 01:03:52.160 and it misses the part that most needs it, 1376 01:03:52.200 --> 01:03:53.800 or probably doesn't most need it, 1377 01:03:53.820 --> 01:03:54.660 because it would erode it. 1378 01:03:54.740 --> 01:03:59.980 But a huge effect from changes in vegetation, 1379 01:04:00.320 --> 01:04:02.680 something very much underestimated. 1380 01:04:04.640 --> 01:04:07.120 So I don't know what we do about all this. 1381 01:04:07.200 --> 01:04:11.120 We revegetate to lower water tables, 1382 01:04:11.120 --> 01:04:14.220 and ultimately we can do a little locally. 1383 01:04:14.760 --> 01:04:16.860 You mentioned at one point the United Nations. 1384 01:04:17.000 --> 01:04:19.020 You know, obviously, about the Earth Charter 1385 01:04:19.020 --> 01:04:19.780 and that whole proposal. 1386 01:04:20.200 --> 01:04:22.340 You support that, I assume, 1387 01:04:22.440 --> 01:04:24.200 and its whole proposal for sustainability? 1388 01:04:24.780 --> 01:04:27.300 Well, I think anything that is proposed 1389 01:04:27.300 --> 01:04:29.980 that hopefully makes things more sustainable, 1390 01:04:30.040 --> 01:04:31.280 we've got to go along with. 1391 01:04:31.560 --> 01:04:34.200 But knowing the way government and people work, 1392 01:04:34.440 --> 01:04:36.120 you've got to fall over the precipice 1393 01:04:36.120 --> 01:04:38.600 before you admit that it's there. 1394 01:04:38.960 --> 01:04:40.840 And a lot of the things 1395 01:04:41.120 --> 01:04:41.660 that need to be done, 1396 01:04:41.700 --> 01:04:44.380 we've got a very brief window of opportunity in Australia. 1397 01:04:44.560 --> 01:04:46.800 If we don't turn things around in the next 10 years, 1398 01:04:47.380 --> 01:04:48.160 it's too late. 1399 01:04:48.600 --> 01:04:50.260 We can't wait for the kids, 1400 01:04:50.340 --> 01:04:52.960 who are all well and truly versed in these things 1401 01:04:52.960 --> 01:04:54.000 and worried about them. 1402 01:04:54.060 --> 01:04:56.300 They're much better at it than their parents. 1403 01:04:56.800 --> 01:04:58.400 We can't wait for them to do it. 1404 01:04:58.460 --> 01:04:59.900 We have got to make decisions. 1405 01:05:01.020 --> 01:05:02.620 Well, I think we probably need to call it. 1406 01:05:02.760 --> 01:05:04.480 Those who want to talk with Mary afterwards 1407 01:05:04.480 --> 01:05:05.380 are welcome to do so. 1408 01:05:05.440 --> 01:05:06.740 Once again, thank you very much. 1409 01:05:11.120 --> 01:05:12.240 .