2500 scientists, 1200 pages, and one quibble

Age
February 3, 2007

AFTER years of research and a marathon week of intense secret debate, scientists from around the world last night signed off on a bleak assessment of a devastated planet: Earth.

A turbulent future of violent storms, devastating drought, increasing temperatures and rising sea levels is inevitable, according to a United Nations report released in Paris last night. The report, the work of 2500 scientists over six years, is considered the most authoritative evaluation of climate change ever produced.

It anticipates temperatures will rise by at least 1.1 degrees by the end of the century, with the high-end estimate at 6.4 degrees.

While scientific dissent continues to divide experts on some core questions — like the rate at which seas will rise, and the ferocity of cyclones fed by warmer waters — the Paris statement is most notable for its consensus on the issue of what, or who, is to blame. Humanity.

The final text of the report says it is "very likely" that human activities led by burning fossil fuels account for most of the warming in the past 50 years. This represents a significant ramping up of the language of the last report of the Intergovernmental Panel on Climate Change, in 2001, which said the link was "likely".

Scientists going into the final four-day workshop to craft a summary of the fourth assessment of the IPCC said this was the most important paragraph of the 1200-page report. Many were seeking an emphatic, unequivocal assessment of the severity and cause of climate change to help draw a line under scientific debate about what was occurring, and shift political momentum to the issue of what to do.

Their efforts nearly faltered with a last-ditch bid to water down the statement from two nations — Saudi Arabia and one other unnamed country (not the United States or Australia) among the 130 countries represented at the Paris plenary.

The statement eventually passed intact after the meeting accepted a suggestion — initiated by Australia — to deal with the dissenting country's concerns in a footnote. It states that there are remaining uncertainties over climate change "based on current methodologies".

Debate on this issue bogged down talks for many hours. Other key areas of disagreement were over sea levels and cyclones, said Dr Geoff Love, the head of the Australian Bureau of Meteorology and a member of the Australian team at the talks.

En route from Paris to Melbourne yesterday, Dr Love said the debate was not so much about the science as about the semantics in the summary, which will provide a framework for policymakers around the world.

As the forum broke up, The Guardian broke a story claiming that scientists and economists had been offered $10,000 each by a lobby group funded by one of the world's largest oil companies — ExxonMobil — to undermine efforts to gain a consensus on the report.

Dr Love said the atmosphere inside the closed talks was intense and exhausting,"but generally a co-operative one, with the scientists often having the deciding say in issues of nuance".

It had been anticipated that debate over the rate and extent of sea-level rises predicted in the report might have been particularly fierce. Scientists going into the discussions wanted the language sharpened, citing concerns that the figures — which retreated on the gloomier 2001 predictions to put the rise at a maximum 59 centimetres by the end of this century — did not take into account recent melting of ice sheets in Antarctica and Greenland. Another report published in Science this month puts the upper range at 140 centimetres.

Dr Love, a former secretary of the IPCC, said debate on sea levels was anti-climactic. It appeared many scientists were satisfied that the statement recognised that uncertainties about ice-sheet melt could add another 25 per cent to those figures.

He said discussion over cyclones was intense, coloured by US sensitivities in the wake of hurricane Katrina and a finding that increased cyclone activity in the North Atlantic since 1970 correlated with global warming. The statement has huge implications for insurance. "America was very particular about the words (on cyclones) but I think the words are very consistent with the science," Dr Love said.

The line-by-line editing of the final summary had been a long-winded and difficult process, Dr Love said. Final submissions from policymakers and governments had resulted in the draft report being substantially rewritten even as it was going before the Paris conference.

Dr Graeme Pearman, one of Australia's leading experts on climate change, said the IPCC report represented a monumental effort to find consensus that would allow the world to respond to climate change. "It really is a social process which is designed to bring together the science and to present it in a way that policymakers think they need to know," Dr Pearman said. "It is an enormous human experiment, and thank goodness we are doing it."