From New Scientist, 16/5:
Land clearances turned up the heat on Australian climate
Deforestation by European settlers may be to blame for making Australia’s drought longer, hotter and dryer than it would be otherwise.
The “big dry”, Australia’s 11-year drought, has been blamed on greenhouse gases and natural variability. To see if deforestation played a part, Clive McAlpine of the University of Queensland in Brisbane and colleagues used a climate model to simulate Australian conditions from the 1950s to 2003. They then compared the impact of today’s fragmented vegetation, obtained from satellite images, with that of 1788, prior to European settlement.
Over much of south-east Australia, where the drought has hit hardest, less that 10 per cent of the original vegetation remains. The team’s model showed that this land clearance has increased the length of droughts in the area by one to two weeks per year. In years of extreme drought, the loss of vegetation caused the number of days above 35°C to increase by six to 18 days, and the number of dry days to increase by five to 15 days (Geophysical Research Letters, in press).
“Land clearing may be having a similar impact on the drought as greenhouse gases,” says McAlpine. Reforestation could minimise future droughts, he adds.
“It’s a nice piece of work,” says Andy Pitman of the University of New South Wales in Sydney, but he adds that the modelling needs to be confirmed.
Trees and vegetation attract and retain moisture, so it is not surprising to attribute one cause of the ongoing drought in south-eastern Australia to continued land clearance. Population expansion is accelerating this, with former open grasslands being smothered under the continued assault of housing developments (“More loss than gain in encroaching urban sprawl on threatened open plains”, The Age, 31/5/2008).
“David Attenborough: Our planet is overcrowded”, New Scientist, 15/5. An interview, where David Attenborough gives his views on the problem. He is somewhat restrained in his opinions, perhaps because he does not want to alienate.
The latest venture for this veteran of wildlife documentaries is as controversial as anything he has done in his long career. He has become a patron of the Optimum Population Trust, a think tank on population growth and environment with a scary website showing the global population as it grows. “For the past 20 years I’ve never had any doubt that the source of the Earth’s ills is overpopulation. I can’t go on saying this sort of thing and then fail to put my head above the parapet.”
There are nearly three times as many people on the planet as when Attenborough started making television programmes in the 1950s – a fact that has convinced him that if we don’t find a solution to our population problems, nature will. “Other horrible factors will come along and fix it, like mass starvation.”
Trying to pin him down about the specifics of what to do, however, proves tricky. He says it involves persuading people that their lives and the lives of their children would be better if they didn’t exceed a certain number of births per family. And that dramatic drop in birth rate rests on providing universal suffrage, education – particularly for women – and decent standards of living for all. It’s a daunting task, but the first step, he argues, is to acknowledge that population is a problem.
But isn’t the problem solving itself, as people have fewer children and population growth rates slow? Yes, he says, if you discount immigration, the UK’s population is more or less static, but it is not so elsewhere. This troubles Attenborough: sounding off about high population and fertility rates in other countries can sound patronising – or worse.
The world at the start of Attenborough’s career half a century ago was clearly a very different place. His passion about population seems to connect to a feeling that part of the joy of living rests in the natural world – a world without too many people, where seeking out wildlife means hard days canoeing rather than watching tourist boats arrive twice daily.
Two dumb letters (for obvious reasons) from the Herald-Sun this week:
Future needs population plan
The Budget speech and responses to it seem to have missed the most important issue. Australia is not producing enough children. If a society has a shrinking population, it will automatically have a shrinking economy. The most important issue for the Australian Government to grapple with is not the economy, but the shrinking population.
Where are the measures to ensure men at family-forming age (16-30) are able to earn an income that will support women at their prime age of fertility (16-30)? Women will not have babies if they cannot see reliable support into the future.
– Jeremy Hearn, Carnegie, 14/5
Jeremy Hearn (“Future needs population plan”, May 14): Babies are the solution to our problems. More babies, more workers, growing nation and more money.
– Brian Harris, Glenroy, 18/5.
Incidentally, Brian Harris has been writing anti-abortion letters to the H-S for years; he seems obsessed with the issue.
I sent in a letter, but it might be too late to get it published:
Jeremy Hearn (“Future needs population plan”, May 14) evidently hasn’t noticed that Australia’s population is already at an unsustainable level – with water supplies dwindling and infrastructure unable to cope with the increasing numbers – so the last thing we need are more babies.
