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9/19/13, "Climate report struggles with temperature quirks," AP, via St. Louis Post Dispatch
"Scientists working on a landmark U.N. report on climate change are
struggling over how to address a wrinkle in the meteorological data that
has given ammunition to global-warming skeptics: The heating of Earth's
surface appears to have slowed in the past 15 years even though
greenhouse gas emissions keep rising.
For years, skeptics have
touted what looks like a slowdown in surface warming since 1998 to cast
doubt on the scientific consensus that humans are cooking the planet by
burning coal, oil and natural gas.
Scientists and statisticians
have dismissed the purported slowdown as a statistical mirage, arguing
among other things that it reflects random climate fluctuations and an
unusually hot year picked as the starting point for charting
temperatures. They also say the data suggests the "missing" heat is
simply settling temporarily in the ocean.
But as scientists
study the issue, the notion of a slowdown has gained more mainstream
attention, putting pressure on the authors of the new U.N. report to
deal with it....
Leaked documents obtained by The Associated Press show there are deep
concerns among governments over how to address the purported slowdown
ahead of next week's meeting of the IPCC.
"I think to not address
it would be a problem because then you basically have the denialists
saying, `Look, the IPCC is silent on this issue,'" said Alden Meyer of
the Washington-based advocacy group Union of Concerned Scientists.
In
a leaked June draft of the report's summary for policymakers, the IPCC
said that while the rate of warming between 1998 and 2012 was about half
the average rate since 1951, the globe is still heating up. As for the
apparent slowdown, it cited natural variability in the climate system,
as well as cooling effects from volcanic eruptions and a downward phase
in solar activity.
But in comments to the IPCC obtained by the AP,
several governments that reviewed the draft objected to how the issue
was tackled.
Germany called for the reference to the slowdown to
be deleted, saying a time span of 10 to 15 years was misleading in the
context of climate change, which is measured over decades and centuries.
The
U.S. also urged the authors to include the "leading hypothesis" that
the reduction in warming is linked to more heat being transferred to the
deep ocean.
Belgium
objected to using 1998 as a starting year for any statistics. That year
was exceptionally warm, so any graph showing global temperatures
starting with 1998 looks flat. Using 1999 or 2000 as a starting year
would yield a more upward-pointing curve. In fact, every year after 2000
has been warmer than the year 2000.
Hungary worried the report would provide ammunition for skeptics....
Many
researchers say the slowdown in warming is related to the natural ocean
warming and cooling cycles known as El Nino and La Nina. Also, a 2013
study by Kevin Trenberth at the National Center for Atmospheric Research
found dramatic recent warming in the deeper oceans, between 2,300 and
6,500 feet.
"The heat is not missing," said University of Victoria
climate scientist Andrew Weaver, who is also a Green Party member of
the British Columbia parliament. "The heat is there. The heat is in the
ocean."
The idea is that the energy trapped by carbon dioxide and
greenhouse gases has to go somewhere on Earth, said Princeton University
climate scientist Michael Oppenheimer. But that heat energy will
eventually make its way to the ocean surface and the air, putting
surface warming back on the increasing track, he said.
"Energy will hide out in the ocean for a while before it pops out into the atmosphere," Oppenheimer said.
For
scientists studying the last 10 years, what's been happening "is a cool
question," said U.S. National Oceanic and Atmospheric Administration
scientist Gabriel Vecchi. But "anybody who tries to use the past 10
years to argue about the reality of global warming _ which is based upon
century-scale data _ is just being distracting."
Jonathan Lynn, a
spokesman for the IPCC, declined to comment on the content of the
report because it hasn't been made final, but said it would provide "a
comprehensive picture of all the science relevant to climate change."...
A final version will be presented at the end of the panel's meeting in Stockholm next week.
The
IPCC's conclusions are important because they serve as the scientific
basis for U.N. negotiations on curbing emissions of CO2 and other
greenhouse gases. A global climate treaty is supposed to be adopted in
2015." via Free Republic
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