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U.S. and European Union envoys are seeking more clarity from the United Nations on a slowdown in global warming that climate skeptics have cited as a reason not to "panic" about environmental changes, leaked documents show.
They're requesting that more details on the so-called "hiatus" be included in a key document set to be debated at a UN conference next month that will summarize the latest scientific conclusions on climate change.
Including more information on the hiatus will help officials counter arguments that the slowing pace of global warming in recent years is a sign that the long-term trend may be discounted, according to Bob Ward, policy director at the Grantham Research Institute on Climate Change and the Environment at the London School of Economics.
"In the public debate, there are people who are using the slowdown to say global warming is less of a problem than thought," Ward said in an interview yesterday. "It has to be fully explained in the summary."
A draft of the summary and the underlying 2,200-page report from the UN Intergovernmental Panel on Climate Change were obtained by Bloomberg from a person with official access to the documents who declined to be further identified because it hasn't been published.
Government envoys from around the world will debate the final wording of the summary at an IPCC meeting that starts in Stockholm on Sept. 23. That document, formally the Summary for Policymakers, is designed to be used by ministers working to devise by 2015 a global treaty to curb climate change.
'Key Issue'
The current version of the summary needs more information about the hiatus, according to the EU and the U.S.
"The recent slowing of the temperature trend is currently a key issue, yet it has not been adequately addressed in the SPM," the EU said, according to an official paper that includes all governmental comments on the draft report. The U.S. comment suggested "adding information on recent hiatus in global mean air temperature trend."
Isaac Valero-Ladron, a spokesman for EU Climate Action Commissioner Connie Hedegaard, declined to comment, citing a confidentiality agreement with the IPCC and the lack of a finalized text.
Jonathan Lynn, a spokesman for the UN panel, and Nayyera Haq, a U.S. State Department spokeswoman, both declined to comment.
Addressing the hiatus is important because skeptics of man's influence on warming the planet have seized on the slowing pace temperature increase as evidence that scientists have exaggerated the impact of manmade greenhouse gases. That supports their assertion that there's less need for expensive policies to curb carbon emissions from factories, vehicles and deforestation.
Climate Sensitivity
"Some people have suggested that the slowdown means that climate sensitivity is lower," said Ward from the Grantham Institute.
Climate sensitivity is the increase in temperatures resulting from a doubling of carbon dioxide in the atmosphere. In the latest draft, sensitivity is estimated at 1.5 degrees Celsius (2.7 degrees Fahrenheit) to 4.5 degrees Celsius. That compares with the estimate of 2 degrees to 4.5 degrees from the UN's last major climate assessment in 2007.
The summary document notes that the rate of warming over the past 15 years "is smaller than the trend since 1951," citing a rate of about 0.05 degrees Celsius per decade in the years 1998 through 2012. The rate was about 0.12 degrees per decade from 1951 through 2012.
Carbon Emissions
The slowdown came as emissions grew, with the concentration of carbon dioxide in the atmosphere this year exceeding 400 parts per million for the first time on record.
The draft report includes possible reasons for the slowing rate, including natural variability, volcanic eruptions and a drop in solar energy reaching the Earth.
"Much of the information is present but it requires a lot of effort on the part of the reader to piece it all together," the 28-nation EU said in the comments document.
The U.S. requested clarity on the implications of the data, commenting "this is an example of providing a bunch of numbers, then leave them up in the air without a concrete conclusion."
Norway, Denmark and China requested information on the role oceans have played in the slowdown. China cited three scientific papers, including a study in the journal Geophysical Research Letters in May that found deep ocean waters below 700 meters (2,300 feet) have absorbed more heat since 1999.
Ocean Temperatures
A separate study in the journal Nature Aug. 28 linked the hiatus to a cooling of surface waters in the eastern Pacific. The cut-off date for papers to be considered in the UN report was March 15.
The UN World Meteorological Organization defines climate as the average weather over a 30-year period, and scientists say the 15-year slowdown isn't long enough to mark a trend. Hungary and Germany, both EU members, cited this as a reason to delete any reference to the hiatus in the summary, while Japan questioned the purpose of using a 15-year average.
"A 15-years period of observation is not sufficient to give a qualified analysis of the global mean surface temperature trend in an assessment of climate change," Germany said. It also said the use of the word "hiatus" is "strongly misleading" because "there is not a pause or interruption, but a decrease in the warming trend."
"We never comment on the internal procedures of the IPCC," Nikolai Fichtner, a spokesman for the German environment ministry, said in an e-mail.
Slowdown Acknowledged
The slowdown in warming has been acknowledged by the U.K. Met Office, which produces one of the world's three main series of global temperature data, and James Hansen, the former NASA scientist who first brought climate change to the attention of Congress in the 1980s. They say the data is still compatible with humans being the main cause of warming.
Even with the slowdown, the decade of 2001 to 2010 was the warmest for both hemispheres and for land and sea, the WMO said July 3 in a report. The World Bank says the planet is on course to warm by 4 degrees Celsius by 2100 because of rising emissions.
That hasn't stopped skeptics, from scientists to lawmakers and bloggers from seizing on the issue.
The Global Warming Policy Foundation, a U.K.-based research group that describes itself as "deeply concerned about the costs" of climate change policies, said in a report in March that "we are on the threshold of global observations becoming incompatible with the consensus theory of climate change."
Don't 'Panic'
The Wall Street Journal published in January 2012 an opinion piece signed by 16 scientists that cited "the lack of global warming for well over 10 years now" as a reason not to "panic" about climate change. They included professors at Princeton and Cambridge universities, Massachusetts Institute of Technology, and former U.S. Senator and Apollo 17 astronaut Harrison Schmitt.
The comments on the slowdown are among 1,855 from governments around the world detailed in the document. The comments range from requests to spell out what acronyms stand for and eliminate scientific jargon to clarifying the likelihood of predictions and shuffling bits of text about.
