Climate: the peril we face

The Australian
April 07, 2007
Leigh Dayton, Science writer

NEARLY a third of the world's plants and animals face extinction, billions of people will be affected by water shortages, and countries across Asia and Africa will be racked by disease and starvation under alarming global warming forecasts made last night by the world's leading climate experts.

The assessment, made by the 2500 scientists who comprise the UN's Intergovernmental Panel on Climate Change, paints the most disturbing picture yet of the damage the world can expect from global warming. Depending on how quickly the planet heats up, vulnerable species could begin disappearing as early as 2030. Australian biodiversity is projected to decline by 2020 at sites such as the Great Barrier Reef, Kakadu National Park and sub-Antarctic regions including Macquarie Island.

Draft versions of the summary of the IPCC report, which contains the dire predictions, were fiercely disputed during a week of tense negotiations, ending with a marathon 24-hour session. Publication was delayed after the US, China and Saudi Arabia objected to the toughly worded text, delegates said.

The Impacts, Adaptation and Vulnerability report, released last night in Brussels, sets out scientists' predictions for the impact on the planet, its plants and animals if the IPCC's earlier forecast of a 1.1C-6.4C rise in global temperatures by 2100 proves correct.

It predicts that millions of people -- mostly in the poorest regions of the world -- would suffer malnutrition, disease, and increased untimely death rates because of heat waves, floods, storms, fires and droughts. The productivity of the world's oceans is likely to plunge, as seas become acidic, with today's coastlines vanishing as sea levels rise and increasingly fierce storms lash the shores.

Agricultural systems are expected to change dramatically, as parts of the planet become too hot or too cold for traditional crops. And glaciers providing fresh drinking water to people in the most populated parts of the world, such as Bangladesh, would disappear, leaving nothing but thirst.

"Roughly 20-30 per cent. .. of species assessed so far are likely to be at increasingly high risk of extinction if global mean temperatures exceed 2-3C above pre-industrial levels," a draft of the report says. "By 2080, it is likely that 1.1 (billion) to 3.2 billion people will be experiencing water scarcity."

The push to extinction -- caused if global average temperatures rise as little as 1.5C above 1990 levels -- would come in response to the reduction or loss of habitat critical to species which can survive only in specific environments.

In Australia, highly adaptable species such as cane toads, cockroaches and some kangaroo species would probably cope, said Andy Pitman, a climate scientist with the University of New South Wales. "But species that lack tolerance to climate like some small possums and koalas -- the cute ones -- would not (survive)." By 2050, flows into the Murray-Darling Basin could fall by 10 per cent to 25 per cent and coastal sea levels could rise by 18-59cm. Even the Australian ski season would be shortened.

However, it is the poorer tropical countries -- the least to blame for the fossil-fuel pollution that scientists say drives global warming -- that will be worst hit. The report is the second of four volumes that comprise the panel's fourth assessment of global warming. Its review of the science of climate change was released in February, with a report on mitigation options and a synthesis report due in coming months.

More than 2500 scientists contributed to the fourth assessment, among them 15 Australian lead authors of the new report. This week, as a working group meeting in Brussels thrashed out the final wording of the summary for policy-makers, extinction became a topic of heated debate between government officials and scientists such as Australian David Karoly, now with the University of Oklahoma.

Dr Karoly -- who will move to University of Melbourne later this year -- and other lead authors claimed diplomats attempted to water down their warnings. They said officials, presumably from the US, forced last-minute changes. US officials were reported to have argued to reduce "quantification", while the Europeans sought to send a strong message about the impacts of climate change.

A final draft, obtained by The Australian, showed the phrase stating that 20-30 per cent of species "will be committed to extinction" had been softened by inserting a reference to species "assessed so far". Retired scientist Ian Burton -- attending the meeting on behalf of the Stockholm Environment Institute -- said the section had been "diluted".

But Australian lead author CSIRO scientist Kevin Hennessy disagreed with Dr Burton's claim. "In any process there will be differing opinions," he said. "(US officials) simply wanted to ensure the report conveyed the most robust science, if it needed to be defensible." Dr Hennessy added that comments from officials regarding the section on Australia and New Zealand toughened, rather than softened, the final wording.

Differences between the final draft and the official document support Dr Hennessy's view. Warnings regarding the loss of regional biodiversity by 2030 were strengthened, for instance, by bringing forward the date to 2020. However, it is clear delegates from China and Saudi Arabia pushed strongly to tone down the degree of certainty of sections covering global natural systems.

They pushed to have statements made with "very high confidence" pulled back to "high confidence", which means more than 80 per cent accuracy as opposed to 90 per cent or near certainty.

Link: www.ipcc.ch