WEBVTT 1 00:00:00.000 --> 00:00:03.960 Welcome, everyone, to this afternoon session of the Festival of Ideas, 2 00:00:03.980 --> 00:00:09.240 which is entitled Salt of the Earth, Water, Salinity and the Limits of Growth. 3 00:00:09.960 --> 00:00:13.960 My name is Mark Cully, and I'm going to be chairing the session today. 4 00:00:14.380 --> 00:00:18.680 I'm the Deputy Director of the National Institute of Labor Studies 5 00:00:18.680 --> 00:00:20.420 at Flinders University. 6 00:00:21.720 --> 00:00:26.320 And what, you might well ask, does a labor economist know 7 00:00:26.320 --> 00:00:28.740 about the topic under consideration today? 8 00:00:29.520 --> 00:00:33.380 The answer, and I suspect it's the same for a good many of you, 9 00:00:34.140 --> 00:00:34.980 is bugger all. 10 00:00:36.440 --> 00:00:39.520 So I'm going to be very much a non-participating chair. 11 00:00:40.660 --> 00:00:44.840 That's why we have today four very distinguished scientists 12 00:00:45.460 --> 00:00:49.340 who are going to outline a vision of the future of Adelaide, 13 00:00:49.380 --> 00:00:53.260 of the Murray-Darling Basin and its downstream of Australia. 14 00:00:53.620 --> 00:00:56.660 In non-technical terms, I think they're going to tell us 15 00:00:56.660 --> 00:00:58.280 that technically, 16 00:00:59.420 --> 00:01:02.320 we're stuffed if we don't alter our ways. 17 00:01:04.020 --> 00:01:06.900 Some of you might recall a book which had the title 18 00:01:06.900 --> 00:01:09.700 The Limits to Growth, which is part of our subtitle today, 19 00:01:09.860 --> 00:01:11.580 that appeared in 1972. 20 00:01:12.080 --> 00:01:15.920 It was commissioned by an enigmatically titled body 21 00:01:15.920 --> 00:01:16.960 called the Club of Rome. 22 00:01:17.580 --> 00:01:21.700 And a group of scientists from the Massachusetts Institute of Technology 23 00:01:22.400 --> 00:01:24.340 developed the first ever computer model 24 00:01:24.340 --> 00:01:28.680 which forecast population growth, natural resource consumption, 25 00:01:28.740 --> 00:01:29.920 pollution and so on. 26 00:01:30.280 --> 00:01:32.540 Their conclusions were shattering. 27 00:01:33.040 --> 00:01:34.960 Taking the then trajectories of growth, 28 00:01:35.780 --> 00:01:38.860 the planet would reach full capacity within 100 years 29 00:01:38.860 --> 00:01:41.020 and in effect burst, 30 00:01:41.960 --> 00:01:44.540 leading to a sudden and uncontrollable decline 31 00:01:44.540 --> 00:01:47.000 in both population and economic activity. 32 00:01:47.580 --> 00:01:49.480 And this was 1972, remember. 33 00:01:49.700 --> 00:01:53.640 This was before people really started talking seriously about global warming, 34 00:01:53.720 --> 00:01:57.500 before we had become really fully aware of the dangers of salinity. 35 00:01:57.840 --> 00:01:58.720 Now, a lot of people, 36 00:01:58.720 --> 00:02:00.200 of course, rejected this scenario. 37 00:02:01.420 --> 00:02:03.860 If I can adopt a biblical metaphor, 38 00:02:04.120 --> 00:02:05.880 which is in keeping with the title of this session, 39 00:02:06.080 --> 00:02:08.220 it seems to me they are rather like Lot's wife, 40 00:02:08.360 --> 00:02:11.940 who was unwilling to forsake the pleasures of Sodom and Gomorrah 41 00:02:11.940 --> 00:02:15.840 and was then, as a result, turned into a pillar of salt. 42 00:02:17.900 --> 00:02:19.520 This isn't a doom-laden scenario. 43 00:02:19.700 --> 00:02:21.780 We're not talking about a preordained future, 44 00:02:21.900 --> 00:02:22.700 but about a choice. 45 00:02:23.500 --> 00:02:24.700 So let us have the debate. 46 00:02:24.860 --> 00:02:27.000 Let us hear the choices outlined starkly 47 00:02:27.000 --> 00:02:28.060 and then let us consider, 48 00:02:28.060 --> 00:02:29.320 let us consider our options. 49 00:02:31.380 --> 00:02:32.660 When we think about the options, 50 00:02:32.800 --> 00:02:35.220 we need to have regard to political structures 51 00:02:35.220 --> 00:02:38.120 and the forums in which we can take action. 52 00:02:38.480 --> 00:02:41.140 We've just been reminded in the session just before this 53 00:02:41.140 --> 00:02:41.820 by John Williams 54 00:02:41.820 --> 00:02:43.920 that one of the legacies of Federation 55 00:02:44.660 --> 00:02:47.840 is the division of powers between the state and the Commonwealth, 56 00:02:48.120 --> 00:02:49.220 the states and the Commonwealth. 57 00:02:50.640 --> 00:02:52.480 That could give rise to a situation 58 00:02:53.460 --> 00:02:54.800 where farmers in Queensland can, 59 00:02:55.700 --> 00:02:57.800 with the apparent consent of their government, 60 00:02:58.060 --> 00:02:59.900 continue to rid the land of trees 61 00:02:59.900 --> 00:03:02.220 without regard to the environmental damage 62 00:03:02.220 --> 00:03:04.160 that does to other states 63 00:03:04.660 --> 00:03:07.200 and the consequences that has on things like 64 00:03:07.200 --> 00:03:08.940 the near undrinkability of our water. 65 00:03:09.780 --> 00:03:11.140 But before we talk about the options, 66 00:03:11.240 --> 00:03:14.140 I think we have to do the hard bit, 67 00:03:14.160 --> 00:03:14.820 do the science, 68 00:03:15.480 --> 00:03:17.160 and hopefully in a way we can understand. 69 00:03:17.480 --> 00:03:19.180 So let me now introduce our four speakers. 70 00:03:19.640 --> 00:03:20.940 We have two locals, 71 00:03:21.200 --> 00:03:23.100 one roving internationalist, 72 00:03:23.120 --> 00:03:25.020 and a visitor from the United States. 73 00:03:25.580 --> 00:03:28.040 Each of them will talk for about a minute, 74 00:03:28.040 --> 00:03:28.580 about 10 minutes, 75 00:03:30.120 --> 00:03:31.560 after which time they'll get a bell, 76 00:03:31.720 --> 00:03:34.580 and that will leave around about half an hour 77 00:03:34.580 --> 00:03:36.620 for you to ask questions of them. 78 00:03:37.480 --> 00:03:39.580 So taking them in the order in which they will speak, 79 00:03:39.760 --> 00:03:43.040 and closest to me is Dr Peter Jell 80 00:03:43.040 --> 00:03:46.380 of the Department of Geographical Environmental Studies 81 00:03:46.380 --> 00:03:47.660 at the University of Adelaide. 82 00:03:48.520 --> 00:03:50.640 Peter is presently writing a book on biodiversity, 83 00:03:50.760 --> 00:03:52.520 which is due to be published next year, 84 00:03:52.640 --> 00:03:54.980 and he recently convened a conference 85 00:03:54.980 --> 00:03:57.040 on the future of the Murray-Darling Basin, 86 00:03:57.940 --> 00:03:58.820 Lessons from History. 87 00:03:59.920 --> 00:04:03.240 He's going to outline the physical history of the world 88 00:04:03.240 --> 00:04:05.080 over the past 50,000 years for us, 89 00:04:06.220 --> 00:04:08.700 and then tell us what the next 100 years might look like. 90 00:04:10.200 --> 00:04:13.140 We will then hear next to him Dr Warren Wood, 91 00:04:13.300 --> 00:04:15.720 who is a research hydrologist from the United States, 92 00:04:15.960 --> 00:04:18.440 a visiting lecturer in the Department of Geography 93 00:04:18.440 --> 00:04:20.300 and Climate Change at Oxford University, 94 00:04:20.580 --> 00:04:22.920 and the editor of the journal Groundwater. 95 00:04:23.280 --> 00:04:26.120 He also holds some type of meritorious service award 96 00:04:26.120 --> 00:04:27.000 from the United States, 97 00:04:27.140 --> 00:04:29.520 which I guess is the US equivalent to a knighthood. 98 00:04:33.520 --> 00:04:36.180 He's going to be followed by David Chittleborough, 99 00:04:36.280 --> 00:04:39.400 who is the associate professor in the Department of Soil and Water 100 00:04:39.400 --> 00:04:41.020 at the University of Adelaide. 101 00:04:41.300 --> 00:04:43.540 David is an expert in catchment processes, 102 00:04:44.700 --> 00:04:46.740 contaminant transport, and salinity. 103 00:04:47.160 --> 00:04:50.240 He's going to talk about the different types of salinity, 104 00:04:50.460 --> 00:04:53.960 and I've already learnt that there is, in fact, more than one type. 105 00:04:54.680 --> 00:04:57.360 And last of all, we will hear John Leake, 106 00:04:57.480 --> 00:05:00.260 who is the head of the Institute for International Development 107 00:05:00.260 --> 00:05:03.340 and an adviser to governments here and abroad 108 00:05:03.340 --> 00:05:05.080 about natural resource use. 109 00:05:05.380 --> 00:05:06.960 He's recently reviewed Australia's 110 00:05:07.820 --> 00:05:10.780 National Dry Land Salinity Program for the Federal Government. 111 00:05:11.020 --> 00:05:12.780 So please make them welcome. 112 00:05:20.000 --> 00:05:22.340 Thanks, Mark. 113 00:05:22.420 --> 00:05:23.940 Yes, well, my temporal perspective is that, 114 00:05:23.960 --> 00:05:28.980 as Mark suggested, I'll try and contain my geographic perspective to Australia. 115 00:05:30.740 --> 00:05:33.100 And as a prelude to this presentation, 116 00:05:33.300 --> 00:05:37.040 I'd like to acknowledge the traditional owners of the Willandra Lakes region, 117 00:05:37.580 --> 00:05:40.900 and also given the themes, one of the themes of the festival, 118 00:05:40.920 --> 00:05:44.360 I suppose the traditional owners of the rest of the country as well. 119 00:05:47.520 --> 00:05:50.720 Well after an elderly man was buried in a ceremony 120 00:05:50.720 --> 00:05:53.360 amongst the dunes to the south of Lake Mungo, 121 00:05:53.980 --> 00:05:58.200 a population of indigenous Australians were reaping a harvest. 122 00:05:59.260 --> 00:06:03.560 For them, they were in the lucky part of what we now call the lucky country. 123 00:06:04.780 --> 00:06:09.140 A dramatic change in the climate had delivered them a feast of Roman proportions. 124 00:06:11.040 --> 00:06:14.360 Their lake was drying out, it was desiccating in the late summer sun, 125 00:06:14.520 --> 00:06:18.000 and the dorsal fins of golden perch and Murray Cod 126 00:06:18.000 --> 00:06:20.900 could be seen above the surface of the increasingly salty waters, 127 00:06:21.160 --> 00:06:23.900 much as those of European carp. 128 00:06:23.900 --> 00:06:25.760 And the carp can be seen in billabongs today. 129 00:06:27.280 --> 00:06:28.920 They were swimming sluggishly, 130 00:06:28.940 --> 00:06:31.900 stunned by the osmotic pressures brought by the briny waters. 131 00:06:32.920 --> 00:06:34.840 This was not a product of El Niño, 132 00:06:34.940 --> 00:06:38.200 for the El Niño sudden oscillation was yet in place, in fact. 133 00:06:39.260 --> 00:06:41.760 It was a consequence of global climate change 134 00:06:41.760 --> 00:06:44.700 driven by the eccentricity of the Earth's orbit around the sun. 135 00:06:45.600 --> 00:06:50.860 And it was ultimately to drive the Earth into arguably its coldest snap since the K-T boundary. 136 00:06:52.320 --> 00:06:53.880 Mean temperatures would become more and more frequent, 137 00:06:53.900 --> 00:06:55.260 as much as 10 degrees cooler. 138 00:06:55.960 --> 00:07:00.220 But critically, the climate would become as much as 50% drier. 139 00:07:01.860 --> 00:07:05.380 For these people, the hundred year drought, as it might have been known, 140 00:07:05.540 --> 00:07:07.800 meant fish for dinner every night. 141 00:07:08.960 --> 00:07:10.480 In the end, though, drought, 142 00:07:10.480 --> 00:07:13.520 and the satanic mockery of snow, as it's been called, 143 00:07:13.700 --> 00:07:16.640 salt claimed their fish and their fresh waters 144 00:07:16.640 --> 00:07:19.540 and turned their feast into a 2,000 year famine. 145 00:07:23.900 --> 00:07:27.800 30,000 years later, but still 4,000 BC, 146 00:07:28.720 --> 00:07:30.600 the Earth's orbit was again at play. 147 00:07:31.900 --> 00:07:34.440 The balance had shifted and the giant rain gauge lakes 148 00:07:34.440 --> 00:07:38.160 of western Victoria, giant volcanic craters, 149 00:07:38.900 --> 00:07:41.680 were spilling over under the new regime of warmth and wetness. 150 00:07:42.620 --> 00:07:45.940 Forests expanded and drainage lines swamped up. 151 00:07:46.520 --> 00:07:48.380 The fresh waters had returned 152 00:07:48.380 --> 00:07:51.100 and with them came bountiful resources for the inhabitants. 153 00:07:51.100 --> 00:07:54.480 It must have been an incredibly wet place indeed, 154 00:07:54.640 --> 00:07:56.420 only 6,000 years ago. 155 00:07:58.520 --> 00:08:00.980 Yet again, about 3,000 years later, 156 00:08:01.020 --> 00:08:03.460 but still about 500 years BC, 157 00:08:04.680 --> 00:08:05.640 desiccation returned. 158 00:08:06.580 --> 00:08:08.260 The rain gauge lakes dropped 159 00:08:08.260 --> 00:08:12.120 and some Murray River billabongs lost contact with the river. 160 00:08:12.880 --> 00:08:15.880 On Kangaroo Island, the fresh waters of Lashmars Lagoon 161 00:08:15.880 --> 00:08:18.040 abruptly turned to salt, 162 00:08:18.160 --> 00:08:20.460 being starved of flushing rains. 163 00:08:22.540 --> 00:08:24.960 Salinisation, driven by climate change, 164 00:08:25.320 --> 00:08:27.320 appears to have been a key factor 165 00:08:27.320 --> 00:08:29.480 in forcing the indigenous islanders 166 00:08:29.480 --> 00:08:31.840 to abandon their part of the lucky country, 167 00:08:32.240 --> 00:08:35.440 to return only sporadically before Europeans were to arrive. 168 00:08:38.800 --> 00:08:40.600 About 2,000 years later, 169 00:08:40.660 --> 00:08:42.740 and maybe as much as 100 years before 170 00:08:42.740 --> 00:08:44.700 flinders sailed around the southern coast, 171 00:08:45.420 --> 00:08:49.000 the climate-sensitive rain gauge lakes started to change again. 172 00:08:50.100 --> 00:08:51.080 A sensitive climate, 173 00:08:51.080 --> 00:08:53.280 a century or more before carbon emissions 174 00:08:53.280 --> 00:08:55.740 enhanced the greenhouse blanket that we know of, 175 00:08:55.920 --> 00:08:58.980 the water level at Lake Keelanbeet began to fall. 176 00:08:59.960 --> 00:09:01.700 From a depth of 28 metres, 177 00:09:02.020 --> 00:09:06.040 the level of the lake's waters fell and fell and fell, 178 00:09:06.180 --> 00:09:08.920 and it became saltier and saltier. 179 00:09:11.000 --> 00:09:14.240 Today, I'm reported it is 21 metres lower 180 00:09:14.240 --> 00:09:15.580 and it's still falling. 181 00:09:16.220 --> 00:09:18.000 So in less than three centuries, 182 00:09:18.200 --> 00:09:20.860 this rain gauge in western Victoria 183 00:09:21.080 --> 00:09:23.380 has lost 75% of its volume, 184 00:09:24.120 --> 00:09:28.060 become twice the salinity of Bass Strait in that time. 185 00:09:30.340 --> 00:09:32.920 Around the margins of this impressive volcanic lake 186 00:09:32.920 --> 00:09:35.180 are carbonate slabs, which are precipitating out 187 00:09:35.180 --> 00:09:37.720 at a rate which would impress even Mr Grollo. 188 00:09:40.220 --> 00:09:42.060 CSIRO's Roger Jones states that 189 00:09:42.060 --> 00:09:43.580 in a recent journal of hydrology, 190 00:09:43.620 --> 00:09:47.140 the pre-European climate certainly would have been wetter, 191 00:09:47.140 --> 00:09:50.100 probably cloudier, and perhaps cooler 192 00:09:50.100 --> 00:09:51.940 than the present phase of desiccation. 193 00:09:54.540 --> 00:09:55.920 So what are the messages here? 194 00:09:56.860 --> 00:09:58.620 Clearly to me, one is that no matter 195 00:09:58.620 --> 00:10:01.300 what engineering solutions we might devise, 196 00:10:01.800 --> 00:10:04.320 humanity is a subject to the reign of climate change. 197 00:10:05.300 --> 00:10:07.280 It has changed and it is changing. 198 00:10:08.480 --> 00:10:11.020 These changes can be the order of the decadal variations 199 00:10:11.020 --> 00:10:13.200 of the type that defeated the Great Wheat Drive 200 00:10:13.200 --> 00:10:15.200 in South Australia in the late 1800s, 201 00:10:15.200 --> 00:10:18.020 or of cycles over much longer return times. 202 00:10:20.100 --> 00:10:22.140 The instrumental record shows that the climates 203 00:10:22.140 --> 00:10:23.920 of the first half of the 20th century 204 00:10:24.500 --> 00:10:26.340 was distinct from that of the second. 205 00:10:26.520 --> 00:10:28.920 The instrumental record shows climate change. 206 00:10:30.520 --> 00:10:34.320 Yet, to my mind, scientists are using that 20th century data 207 00:10:34.320 --> 00:10:38.100 to model catchments that are about to come under 21st century climates. 208 00:10:40.340 --> 00:10:43.020 Other models, climate models, suggest 209 00:10:43.020 --> 00:10:44.720 the mean temperature of the latter might be 210 00:10:44.720 --> 00:10:47.900 1 to 3.5 degrees higher than the mean of the former. 211 00:10:49.240 --> 00:10:50.080 What does that mean? 212 00:10:50.080 --> 00:10:52.900 We get that sort of range of variation on a day-to-day basis. 213 00:10:55.400 --> 00:10:58.200 While collectively the ancestors of some of the audience 214 00:10:58.200 --> 00:11:01.380 may have experienced falls of that sort of magnitude, 215 00:11:01.860 --> 00:11:04.820 the upper temperature estimates exceed the highs experienced 216 00:11:04.820 --> 00:11:07.560 by the planet since the last time sea levels 217 00:11:07.560 --> 00:11:09.900 were anywhere near present 120,000 years ago. 218 00:11:11.460 --> 00:11:14.460 In fact, Jim Bowler, the man who stumbled across that burial 219 00:11:14.460 --> 00:11:17.080 on the shores of Lake Mungo in the early 1970s, 220 00:11:18.260 --> 00:11:20.060 observed at a greenhouse meeting in May, 221 00:11:20.080 --> 00:11:23.720 in Melbourne in 1993, after CSIRO's Peter Whetton 222 00:11:23.720 --> 00:11:26.000 announced the possibility of a four degree warming, 223 00:11:27.080 --> 00:11:29.420 that such an increase would represent possibly 224 00:11:29.420 --> 00:11:31.120 the highest mean temperatures experienced 225 00:11:31.120 --> 00:11:32.540 for the entire Pleistocene. 226 00:11:34.780 --> 00:11:37.580 That means we might have to go back as far as Australopithecus 227 00:11:37.580 --> 00:11:40.800 to find a hominid that has experienced such high temperatures. 228 00:11:42.440 --> 00:11:45.580 It is not only the magnitude of the change that is of concern, 229 00:11:45.660 --> 00:11:48.420 it is the rate of change which is forecast. 230 00:11:48.980 --> 00:11:50.060 And that could see a change in the climate. 231 00:11:50.080 --> 00:11:54.300 And that can exceed any documented in the area of mammals and flowering plants. 232 00:11:55.820 --> 00:12:00.220 If forecasts come true, we are in for one serious scientific 233 00:12:01.080 --> 00:12:02.840 and social science experiment. 234 00:12:04.020 --> 00:12:06.520 My message here is that Southern Australia has experienced 235 00:12:06.520 --> 00:12:10.060 substantial hydrological changes in response to climate oscillations 236 00:12:10.060 --> 00:12:13.340 over the last glacial, interglacial cycles and longer. 237 00:12:14.800 --> 00:12:19.840 Also, we are in the midst of a drying phase whose origins extend back to 238 00:12:20.080 --> 00:12:21.780 before the Industrial Revolution. 239 00:12:23.340 --> 00:12:26.720 Yet over the same time it took to deforest the Murray-Darling Basin 240 00:12:26.720 --> 00:12:29.380 and set water tables rising by 25cm a year, 241 00:12:29.580 --> 00:12:33.400 we are anticipating an additional anthropogenic warm phase 242 00:12:33.400 --> 00:12:35.360 beyond the experience of the species. 243 00:12:37.940 --> 00:12:39.040 What does this mean? 244 00:12:39.200 --> 00:12:42.380 Well, the forecasters are doing their best to come to terms with this 245 00:12:42.380 --> 00:12:44.200 in terms of regional differences. 246 00:12:45.280 --> 00:12:49.440 Roger Jones again, modelling the future Macquarie River flows, 247 00:12:49.440 --> 00:12:54.020 under a range of climate scenarios, provides some disturbing predictions. 248 00:12:55.280 --> 00:12:58.680 In summary, winter-spring rainfall could decrease by 20% 249 00:12:59.400 --> 00:13:03.460 and a reduction in water allocation to irrigators would therefore be necessary. 250 00:13:04.880 --> 00:13:07.680 Commitments to environmental flows will come under increasing pressure, 251 00:13:07.840 --> 00:13:09.600 further threatening the Macquarie marshes. 252 00:13:10.700 --> 00:13:13.420 Rates of sanitisation might be moderated in fact, 253 00:13:13.540 --> 00:13:18.040 because reduced rainfall would buffer rising groundwaters. 254 00:13:19.440 --> 00:13:23.200 However, reductions in streamflow would increase river salt concentrations. 255 00:13:24.760 --> 00:13:29.780 Tree planting, interestingly, may exacerbate runoff and flow reductions, 256 00:13:29.920 --> 00:13:32.200 so we need to be careful where we plant our trees 257 00:13:32.200 --> 00:13:37.400 because they may actually lead towards increasing salt concentrations in rivers, 258 00:13:37.560 --> 00:13:44.140 despite their yielding benefits for salinity, biodiversity and carbon sequestration. 259 00:13:46.380 --> 00:13:48.520 Salinity and water resource issues 260 00:13:48.520 --> 00:13:51.060 will be critical even if we limit growth 261 00:13:51.060 --> 00:13:53.760 and turn the clock back towards pre-regulation. 262 00:13:54.540 --> 00:13:57.700 Climate change dictates that we will need to do even more. 263 00:13:58.740 --> 00:14:01.900 This may come from resource use efficiencies and innovations. 264 00:14:03.220 --> 00:14:06.200 At a local scale, there are some encouraging results. 265 00:14:07.240 --> 00:14:12.540 On the Tregao Plain, one of the first sores of the Murray Basin, salt sores, 266 00:14:12.580 --> 00:14:16.720 groundwater pumping has lowered the water table from the capillary zone 267 00:14:16.720 --> 00:14:18.360 to a depth of five metres. 268 00:14:19.260 --> 00:14:22.640 The saline water is pondered, cleaned by algae, 269 00:14:22.800 --> 00:14:27.460 and the purified product is available under the market name Pyramid Salt. 270 00:14:27.680 --> 00:14:30.460 Yes, we now have boutique salt on the market. 271 00:14:32.100 --> 00:14:35.180 These algae-eating brine shrimp are sold to the aquarium trade, 272 00:14:35.820 --> 00:14:39.540 and there are even thoughts of running a snapper aquaculture industry 273 00:14:39.540 --> 00:14:43.960 400 kilometres from the sea, adjacent to a rejuvenated dairy industry. 274 00:14:45.820 --> 00:14:49.520 In conclusion, the experiences of Easter Island 275 00:14:49.520 --> 00:14:51.880 and the Indus, Tigris and Euphrates valleys 276 00:14:51.880 --> 00:14:55.760 all tell us that humans can suffer at the hands of their own mismanagement. 277 00:14:56.520 --> 00:15:00.000 Lake Mungo and Lashmar's Lagoon tell us that they may also suffer 278 00:15:00.000 --> 00:15:04.780 at the whim of climate change, driven by forces related to the planet's orbit. 279 00:15:05.820 --> 00:15:10.900 Something engineers and politicians, as far as I know, are unable to control. 280 00:15:13.500 --> 00:15:15.560 So, getting back to the limits of growth. 281 00:15:17.000 --> 00:15:19.820 I'd suggest that economists can only claim we're in growth 282 00:15:20.440 --> 00:15:22.960 because they cannot quantify environmental decline. 283 00:15:24.780 --> 00:15:29.240 I'd suggest that the $1.5 billion is a very small drop 284 00:15:29.240 --> 00:15:31.060 in what's to become a very salty bucket. 285 00:15:32.640 --> 00:15:36.160 Perhaps the last time Australia had so little control over its fate 286 00:15:36.160 --> 00:15:37.580 was in 1939-40. 287 00:15:38.960 --> 00:15:40.800 If we were able to budget to include 288 00:15:40.900 --> 00:15:43.520 the environment, I think we'd see that we may require 289 00:15:44.120 --> 00:15:47.300 measures akin to the war effort, sustained over decades, 290 00:15:48.120 --> 00:15:50.840 to deal with the dual adversaries of environmental mismanagement 291 00:15:50.840 --> 00:15:51.980 and global warming. 292 00:15:52.300 --> 00:15:53.060 Thanks very much. 293 00:16:05.900 --> 00:16:07.260 It's a tough act to follow. 294 00:16:08.300 --> 00:16:10.700 I wish to thank the organisers of the 295 00:16:10.900 --> 00:16:12.340 National Satellite Festival of Ideas 296 00:16:12.340 --> 00:16:15.020 for inviting me to participate in this year's events. 297 00:16:15.680 --> 00:16:19.140 As a hydrologist, I would like to confine my remarks 298 00:16:19.140 --> 00:16:22.900 to the salinity part of the problem in this topic, 299 00:16:23.740 --> 00:16:27.580 as my expertise does not include population growth 300 00:16:27.580 --> 00:16:30.740 or the role of its control. 301 00:16:32.280 --> 00:16:35.100 Let me define the problem as I see it, though. 302 00:16:35.720 --> 00:16:38.460 In spite of two nasty world wars, 303 00:16:38.460 --> 00:16:42.260 a lot of regional conflicts, as they're euphemistically called, 304 00:16:42.440 --> 00:16:46.420 and epidemics like the flu, influenza of 1918, 305 00:16:46.660 --> 00:16:47.820 and the current AIDS, 306 00:16:48.000 --> 00:16:51.860 we have quadrupled our population 307 00:16:52.460 --> 00:16:56.120 in the last 100 years to about 6 billion people. 308 00:16:56.440 --> 00:16:59.360 It is projected that in the next 100 years, 309 00:16:59.580 --> 00:17:01.360 it'll be 12 billion people. 310 00:17:04.240 --> 00:17:06.340 Now, how do we feed this population? 311 00:17:07.020 --> 00:17:11.760 We require increased production from agricultural land, 312 00:17:12.520 --> 00:17:15.980 and as most of the arable land on the Earth 313 00:17:15.980 --> 00:17:18.700 is already under cultivation, 314 00:17:19.140 --> 00:17:23.420 where are we going to get this additional production from? 315 00:17:24.060 --> 00:17:26.140 Yet we have this white cancer, 316 00:17:26.240 --> 00:17:27.920 as I refer to it as salinity, 317 00:17:27.960 --> 00:17:31.180 because of its slow, insidious death of land. 318 00:17:31.420 --> 00:17:34.640 It has claimed tens of millions of hectares worldwide, 319 00:17:34.900 --> 00:17:36.320 over three billion years, 320 00:17:36.320 --> 00:17:38.840 three million hectares in Australia alone, 321 00:17:39.280 --> 00:17:44.040 and is set to poise to claim even more. 322 00:17:44.900 --> 00:17:47.700 So not only do we have an increasing population, 323 00:17:48.200 --> 00:17:50.640 we have a diminished land resource 324 00:17:51.320 --> 00:17:52.720 capable of feeding this population. 325 00:17:54.220 --> 00:17:57.580 Let's review the simple concepts 326 00:17:58.320 --> 00:18:01.580 involved behind the cause of this white cancer. 327 00:18:04.400 --> 00:18:05.620 Consider a base, 328 00:18:05.620 --> 00:18:06.440 a typical basin. 329 00:18:06.940 --> 00:18:09.280 All of the water comes from rainfall, 330 00:18:09.440 --> 00:18:11.760 and most of the salts are derived from the rain. 331 00:18:12.820 --> 00:18:14.700 There's a small component of salt 332 00:18:14.700 --> 00:18:16.520 that's added to the weathering of rocks, 333 00:18:16.680 --> 00:18:19.920 and some from rocks deposited in ancient seas, 334 00:18:20.240 --> 00:18:22.660 but the vast majority is from rain. 335 00:18:23.580 --> 00:18:25.560 This is not intuitively obvious, 336 00:18:25.640 --> 00:18:28.780 as most people consider rain and snow to be pure. 337 00:18:28.960 --> 00:18:30.040 In fact, the expression, 338 00:18:30.260 --> 00:18:31.640 pure as the driven snow, 339 00:18:31.880 --> 00:18:34.580 is a phrase that we all use. 340 00:18:35.620 --> 00:18:37.760 But if we look at a simple calculation, 341 00:18:38.620 --> 00:18:40.660 we can see if we only have two milligrams 342 00:18:41.620 --> 00:18:44.900 per liter of salt in rainwater, 343 00:18:45.620 --> 00:18:49.740 and if we receive 500 millimeters a year of rainfall, 344 00:18:51.140 --> 00:18:53.660 that each year we're going to have 345 00:18:53.660 --> 00:18:57.580 about 500 liters of water per square meter. 346 00:18:58.360 --> 00:19:01.880 Now this gives us about one gram of salt per year. 347 00:19:02.240 --> 00:19:03.940 If we have a million years, 348 00:19:03.940 --> 00:19:07.120 this gives us a thousand kilograms of salt 349 00:19:07.120 --> 00:19:08.440 for every square meter. 350 00:19:08.640 --> 00:19:11.080 This has just come from our pure rain. 351 00:19:15.400 --> 00:19:18.580 Clearly we do not have all of this kind of salt generated, 352 00:19:18.800 --> 00:19:21.000 and there is a natural flushing process. 353 00:19:21.760 --> 00:19:23.240 Water and salt, however, 354 00:19:23.400 --> 00:19:26.140 are removed from the land by different processes. 355 00:19:26.640 --> 00:19:28.940 Some water leaves by river flow, 356 00:19:29.080 --> 00:19:31.400 but the majority is transpired by plants. 357 00:19:31.620 --> 00:19:33.920 That is, as the plants use the liquid water, 358 00:19:33.940 --> 00:19:36.220 they discharge it as a vapor. 359 00:19:36.860 --> 00:19:40.140 Salt is, however, only removed by the river flow. 360 00:19:40.620 --> 00:19:42.260 Thus you have different processes 361 00:19:42.260 --> 00:19:44.840 for the removal of salt and water from a basin, 362 00:19:45.020 --> 00:19:46.680 and this is important in understanding 363 00:19:47.300 --> 00:19:51.380 the salinity interactions and ramifications. 364 00:19:52.340 --> 00:19:56.000 In natural systems that are unchanging with time, 365 00:19:56.120 --> 00:19:58.240 an equilibrium is reached 366 00:19:58.240 --> 00:19:59.920 where the salt entering a basin 367 00:19:59.920 --> 00:20:02.300 is equal to the salt leaving the basin 368 00:20:02.300 --> 00:20:03.280 by the stream flow. 369 00:20:03.280 --> 00:20:06.400 The equilibrium concentration of salt 370 00:20:06.400 --> 00:20:08.500 remaining in the slowly moving groundwater 371 00:20:08.500 --> 00:20:10.700 is controlled by two factors, 372 00:20:10.940 --> 00:20:12.760 the slope of the water table 373 00:20:12.760 --> 00:20:15.800 and the permeability of the rocks, 374 00:20:15.860 --> 00:20:18.560 or the ease in which water can flow through the rocks. 375 00:20:19.480 --> 00:20:24.000 Some basins have naturally higher concentrations of salt 376 00:20:24.000 --> 00:20:27.380 because of this variation in processes. 377 00:20:28.340 --> 00:20:29.960 In much of Australia, 378 00:20:30.060 --> 00:20:31.280 the low topography means 379 00:20:31.860 --> 00:20:33.260 that the slope of the water 380 00:20:33.280 --> 00:20:34.980 table is low 381 00:20:34.980 --> 00:20:37.900 and the natural flushing is very slow. 382 00:20:38.620 --> 00:20:41.920 Thus while the equilibrium concentrations of salts 383 00:20:41.920 --> 00:20:44.020 tend to be very high in Australia, 384 00:20:44.340 --> 00:20:47.180 the low slope also means 385 00:20:47.180 --> 00:20:49.320 that the top of the groundwater table 386 00:20:49.320 --> 00:20:51.800 is very close to the land surface. 387 00:20:52.540 --> 00:20:54.700 In natural undisturbed systems, 388 00:20:54.800 --> 00:20:58.600 vegetation develops that uses this shallow water 389 00:20:58.600 --> 00:21:01.060 and which keeps the top of the water table deeper 390 00:21:01.060 --> 00:21:03.100 than otherwise would be 391 00:21:03.280 --> 00:21:03.980 the case. 392 00:21:04.100 --> 00:21:05.360 Now along come man 393 00:21:05.360 --> 00:21:07.300 cutting the natural vegetation, 394 00:21:07.660 --> 00:21:10.360 replacing with crops that use less water. 395 00:21:10.520 --> 00:21:13.880 The result is an increase in recharge of the groundwater 396 00:21:14.600 --> 00:21:17.340 and is accompanied by a consequent rise 397 00:21:17.340 --> 00:21:18.580 in the groundwater table. 398 00:21:19.080 --> 00:21:22.040 If the water table rises to within a meter 399 00:21:22.040 --> 00:21:24.940 or two meters of the surface in the capillary zone, 400 00:21:25.960 --> 00:21:30.100 the water will evaporate directly from the water table 401 00:21:30.100 --> 00:21:31.500