U.N. Report Describes Risks of Inaction on Climate Change

VALENCIA, Spain, Nov. 17 — Secretary General Ban Ki-moon, describing climate change as “the defining challenge of our age,” released the final report of a United Nations panel on climate change here today and called on the United States and China to play “a more constructive role.”

His challenge to the world’s two greatest greenhouse gas emitters came just two weeks before the world’s energy ministers meet in Bali , Indonesia , to begin talks on creating a global climate treaty to replace the Kyoto Protocol, which expires in 2012.

Neither the United States nor China is a signatory to Kyoto , which seeks to limit the growth of greenhouse gas emissions.

“Today the world’s scientists have spoken, clearly and in one voice,” Mr. Ban said of the report, the Synthesis Report of the United Nations Intergovernmental Panel on Climate Change. “In Bali , I expect the world’s policymakers to do the same.”

He added: “The breakthrough needed in Bali is for a comprehensive climate change deal that all nations can embrace.”

Members of the panel said their review of the data led them to conclude as a group and individually that reductions in greenhouse gasses had to start immediately to avert a global climate disaster that could leave island states submerged and abandoned, African crop yields decreased by 50 percent, and cause over a 5 percent decrease in global gross domestic product.

The panel, which was awarded the Nobel Peace Prize last month, said the world would have to reverse the growth of greenhouse gas emissions by 2015 to avert major problems.

“If there’s no action before 2012, that’s too late,” said Rajendra Pachauri, a scientist and economist who heads the Intergovernmental Panel on Climate Change. “What we do in the next two to three years will determine our future. This is the defining moment.”

He said that since the panel began its work five years ago, scientists have recorded “much stronger trends in climate change,” like a recent melting of polar ice that had not been predicted. “That means you better start with intervention much earlier.”

The panel’s fourth, and final, report culls its conclusions by combining thousands of pages of scientific data that accompanied the previous three individually reports — which had not previously been reviewed as a whole by the panel — creating new emphasis and alarm, scientists said. The first report covered climate trends; the second, the world’s ability to adapt to a warming planet; the third, strategies for reducing carbon emissions. With their mission now concluded, the hundreds of scientists on the panel were more free in speaking out than previously.

Martin Parry, a British climate expert who was co-chairman of the delegation that wrote the second report, said many scientists now believed that warming by 2 degrees Celsius, or 3.6 degrees Fahrenheit, above pre-industrial levels by the end of this century was inevitable because of a lag effect, even if current rising emissions trends could be reversed immediately.

"The sense of urgency when you put these pieces together is new and striking," Mr. Parry said. "I’ve come out of this process more pessimistic about the possibilities than I thought I would do."

Reaction was muted from the United States , whose policies were the object of criticism in the halls here this week. A United States delegation approved of the final product though it had insisted on some changes.

The latest report is mostly a compendium with easy-to-use charts and tables, intended to be a “pocket guide for policy makers.” For example, a chart predicts at 2 degrees of global temperature rise up to 30 percent of species are at risk of extinction, and the world will be at higher risk of mortality from heat waves, floods and droughts.

Above 2 degrees and particularly if 3 degrees of warming is reached, the report says, millions more people will experience flooding each year, about 30 percent of wetlands would be lost, global health services would be burdened, and there would be massive deaths of corals. Warming is associated with sea level rise, ocean warming and an increased frequency of extreme weather events — such as heat waves and storms, the report says.

“It’s extremely clear and is very explicit that the cost of inaction will be huge compared to the cost of action,” said Jeff Sachs, head of Columbia University’s Earth Institute. “We can’t afford to wait for some perfect accord to replace Kyoto , for some grand agreement. We can afford to spend year bickering about it. We need to start acting now.”

He said that delegates to Bali should take action immediately where they do agree, for example starting immediate publicly financed demonstration projects on new technologies like “carbon capture,” a “promising but not proved” system that pumps emission underground instead of releasing them into the sky. He said the energy ministers should immediately start a Global Fund to help poor countries avoid deforestation; deforestation also causes emission to increase because growing plants absorb carbon in the atmosphere.

Again, this fourth synthesis report had to be reviewed and approved by the delegates 130 nations gather here this week. But this time both the scientists and environmental groups said there had been no major dilution of the important messages, and several new important points were made.

For example, this summary was the first to acknowledge that the melting of the Greenland ice sheet from rising temperature could result in sea-level rise over centuries rather than millennia. “Many of my colleagues would consider that kind of melt a catastrophe” so rapid that mankind would not be able to adapt, said Michael Oppenheimer, a climate scientist at Princeton University who contributed to the panel.

At a news conference last night after the synthesis report was approved, James L. Connaughton, the chairman of the president’s council on environmental quality, said President Bush had agreed with leaders of the other major industrialized nations that “the issue warrants urgent action and we need to bring forward in a more accelerated way the technologies that will make a lasting solution possible.”

But he declined to say how much warming the administration considered acceptable, saying, “We don’t have a view on that.”

But he quickly added that while acknowledging that the United States had tried to make some changes in the draft, Dr. Sharon Hays, leader of the American delegation here said the goal was not political but “to make sure the final report matches the science.”

But Sthepanie Tunmore, a campaigner with Greenpeace International, who had observer status as the countries debated the text, questioned that explanation.

She said, for example, that the United States had tried to remove a section of the report titled “Reasons for Concern,” a section which clearly lists a litany of consequences of climate change, that are either likely or possible. One is the melting of ice sheets, which the panel for the first time explicitly said in a summary document could occur over centuries.

The United States argued there was no reason to include the section, because all of it was contained somewhere in the previous technical documents. These documents run into thousands of pages. But “Reasons for Concern” remained in the end.

“We think it’s the strongest document so far from the panel,” Ms. Tunmore said.

United Nations officials also pointed out that disaster could be averted but only with strong policies, like increasing energy efficiency of cars and setting up carbon markets, a market-based system that effectively forces companies and countries to pay in one way or another for the cost of the greenhouse gasses they emit.

The European Union already has such a carbon-trading system in place for many industries, and is fighting to bring airlines into the scheme.

“Stabilization of emissions can be achieved by deployment of a portfolio of technologies that exist or are already under development,” Achim Steiner, head of the United Nations Environment Program, said here.

But he noted that developed countries would have to help poorer ones in implementing such schemes, which are often expensive.

He emphasized that the report sent a message to individuals as well as world leaders: “What we need is a new ethic in which every person — changes life style, attitude and behavior.”

Others said politicians should focus more on how man will adapts to the changes that will almost certainly occur. “We can’t mitigate our way out to this at this point, so we’re going to have to put more emphasis on that,’ Dr. Parry said. “The Bali process treats adaptation as a poor sister, and we’ve lost 10 years by doing that.

By ELISABETH ROSENTHAL