Human link to climate change stronger than ever: draft report

Nina Chestney and Alister Doyle PlanetArk 17 Dec 12;

International climate scientists are more certain than ever that humans are responsible for global warming, rising sea levels and extreme weather events, according to a leaked draft report by an influential panel of experts.

The early draft, which is still subject to change before a final version is released in late 2013, showed that a rise in global average temperatures since pre-industrial times was set to exceed 2 degrees Celsius by 2100, and may reach 4.8 Celsius.

"It is extremely likely that human activities have caused more than half of the observed increase in global average surface temperatures since the 1950s," the Intergovernmental Panel on Climate Change (IPCC) draft report said.

"Extremely likely" in the IPCC's language means a level of certainty of at least 95 percent. The next level is "virtually certain", or 99 percent, the greatest possible certainty for the scientists.

The IPCC's previous report, in 2007, said it was at least 90 percent certain that human activities, led by burning fossil fuels, were the cause of rising temperatures.

The draft was shown on a climate change skeptic blog.

The IPCC said the unauthorized, premature posting of the draft may lead to confusion because the report was still work in progress and was likely to change before it is released.

A United Nations conference last week aimed at curbing emissions of greenhouse gases blamed for global warning yielded no progress and three countries - Canada, Russia and Japan - have abandoned the Kyoto Protocol limiting the emissions.

The United States never ratified it in the first place, and it excludes developing countries where emissions are growing most quickly.

Countries agreed to extend Kyoto to 2020, but only those covering less than 15 percent of world greenhouse gas emissions signed up. Developing nations said they would push next year for a radical U.N. mechanism to compensate them for the impact of climate change.

The IPCC said it had "high confidence" that human activity had caused large-scale changes in oceans, in ice sheets or mountain glaciers, and in sea levels in the second half of the twentieth century, according to the draft.

It said some extreme weather events had also changed due to human influences.

THREAT TO CITIES

The draft's scenarios forecast a rise in temperatures of between 0.2 and 4.8 Celsius this century - a narrower band than in 2007. But in almost all of the scenarios, the rise would exceed 2 degrees Celsius.

Governments pledged in 2010 to try to stop global temperatures rising by more than 2 degrees, a threshold seen by scientists as the maximum to avoid more extreme weather, droughts, floods, and other climate change impacts.

Carbon dioxide concentrations in the atmosphere were the highest in 800,000 years, according to the draft report.

The draft also said that sea levels were likely to rise by between 29 and 82 centimeters by the end of the century - compared to 18-59 centimeters projected in the 2007 report.

Rising sea levels are a threat to people living in low-lying areas, from Bangladesh to the cities of New York, London and Buenos Aires. They open up the risk of storm surges, coastal erosion and, in the worst case scenario, the complete swamping of large areas of land.

The IPCC carries weight because it brings together all scientific research on climate change and informs policymakers.

Many countries want to study the final IPCC report before signing up to a new global pact to cut greenhouse gas emissions.

The draft included a possible future acceleration of ice loss from Antarctica and Greenland, which was omitted in 2007. It stopped short of including some research carried out since 2007 that suggested seas may rise by up to 2 meters by 2100.

(Editing by Tom Pfeiffer)

IPCC critical of climate change report leak
David Shukman BBC News 14 Dec 12;

The UN climate science panel has criticised a blogger who has published a draft version of its next report.

The Intergovernmental Panel on Climate Change (IPCC) is preparing what is known as its Fifth Assessment Report for publication next year.

The work looks to draw together research to provide a statement on global warming and its future effects.

The drafting of the reports is open to reviewers but on the condition that no details are published.

In a statement, the IPCC says it "regrets this unauthorized posting which interferes with the process of assessment and review".

The draft posted online is of what's called Working Group 1 (WGI), the first stage of the next report.

This covers the physical aspects of climate science, including observations of temperature and computer models of possible scenarios for future warming.

The IPCC statement read: "The unauthorized and premature posting of the drafts of the WGI AR5, which are works in progress, may lead to confusion because the text will necessarily change in some respects once all the review comments have been addressed.

"It is regrettable that one out of many hundreds of reviewers broke the terms of the review."

The draft was posted by US climate sceptic Alec Rawls, who runs a blog called Stop Green Suicide.

It is reported that he highlighted one particular sentence in the draft - about the possible effect of cosmic rays on the climate - claiming it undermined the case that most recent warming has been driven by man-made greenhouse gases.

However, when the BBC attempted to access the blogger's site it was not available but a number of other sites were providing links to places where the report could be viewed or downloaded online.

'Cherry picking'

Climate scientists, reacting to the leak, have condemned the "cherry picking" of this one point in a long report and have said that other sections reinforce the central argument about the cause of climate change.

In any event, the text faces several further stages of possible revision before publication late next year.

A meeting of lead authors in Tasmania next month will be the next chance to review all the latest comments.

One lead author, Richard Betts of the Met Office, tweeted that further alterations were likely.

"Worth pointing out that the wording in the leaked IPCC WG1 draft chapters may still change in the final versions, following review comments," he wrote.

The leak highlights a fundamental question about the way the IPCC is managed in the age of the internet.

While it aims to be open to all contributions, the system of conducting the drafting and discussions in private has long been under pressure.

Prof Piers Forster of Leeds University, UK, said the rationale behind the IPCC process was "to iron out all the errors and inconsistencies which might be inadvertently included.

"Personally, I would be happy if the IPCC process were even more open and public, and I think we as scientists need to explore how we can best match the development of measured critical arguments with those of the Twitter generation."

This comes as the IPCC is under intense pressure following the discovery of errors in its last assessment, released in 2007.

An inquiry by the Inter Academy Council concluded in 2010 that the IPCC needed better management to handle the growing complexity of climate science and the scrutiny of the outside world.

The panel's reports are designed to provide a consensus statement on the latest climate science to help governments decide how to respond.