Panel: Global warming 'extremely likely' man-made-A A +A
Friday, September 27, 2013
STOCKHOLM -- Human activity is the dominant cause of the global warming observed since the 1950s, a new report by an international scientific group said Friday.
Calling man-made warming "extremely likely," the Intergovernmental Panel on Climate Change (IPCC) used the strongest words yet on the issue as it adopted its assessment on the state of the climate system.
In its previous assessment last 2007, the UN-sponsored panel said it was "very likely" that global warming was man-made.
According to the report, the evidence has grown a clearer understanding of the climate system and improved models to analyze the impact of rising temperatures.
"Our assessment of the science finds that the atmosphere and ocean have warmed, the amount of snow and ice has diminished, the global mean sea level has risen and the concentrations of greenhouse gases have increased," said Qin Dahe, co-chair of the working group that wrote the report.
The full 2,000-page report will not be released until Monday, but a summary for policymakers with the key findings was published Friday.
From the predicted rise of seven to 23 inches (18-59 centimeter) in the sea levels of its previous report, the IPCC raised the projections to ten to 32 inches (26-82 centimeters) by the end of the century.
The IPCC assessments form the scientific basis of UN negotiations on a new climate deal.
Governments are expected to finish the agreement in 2015, but it is still unclear whether they will commit to the emission cuts which scientists say will be necessary to keep the temperature below a limit at which the worst effects of climate change can be avoided.
Using four scenarios with different emissions controls, the report projected that global average temperatures would rise by 0.3 to 4.8 degrees C by the end of the century, which is 0.5-8.6 F.
Only the two lower scenarios based on significant cuts in CO2 emissions came in below the 2-degree C (3.6 F) limit that countries have set as their target in the climate talks to avoid the worst impacts of warming.
At this point, emissions keep rising mainly due to rapid growth in China and other emerging economies. They said rich countries should take the lead on emissions cuts because they've pumped carbon into the atmosphere for longer.
Climate activists said the report should spur governments to action.
"There are few surprises in this report but the increase in the confidence around many observations just validates what we are seeing happening around us," said Samantha Smith, of the World Wildlife Fund.
One of the most controversial subjects in the report was how to deal with a purported slowdown in warming in the past 15 years. Climate skeptics say this "hiatus" casts doubt on the scientific consensus on climate change.
Many governments had objections over how the issue was treated in earlier drafts and some had called for it to be deleted altogether.
In the end, the IPCC made only a brief mention of the issue in the summary for policymakers, stressing that short-term records are sensitive to natural variability and don't in general reflect long-term trends. (AP)