It's been 25 years since the nations of the world formed the Intergovernmental Panel on Climate Change to assess the state of climate science. And, like many 25-year-olds, the panel is now facing questions of its identity and its future.
Some are calling for the panel to change its scope, moving from the "mega-reports" released every six years to more targeted reports, such as the 2012 special report the panel released on extreme weather events.
"My view is that the cost to science and scientists of carrying out the IPCC work has become out of balance with the value of the mega-reports," said Michael Oppenheimer, the Princeton University scientist who served as a lead author of the Nobel Prize-winning fourth assessment report, released in 2007.
"Now we're getting to the point where a lot of what is reported is incremental progress."
This lack of big, breaking-news science updates may have played a role in the scant media attention the panel received, at least in the United States, when it released its "Summary for Policymakers," which highlighted major findings from its fifth science report, on Sept. 27.
"I think the fifth assessment is not surprising, and there is nothing earthshakingly new," said David Hunter, who directs American University's program on international and comparative environmental law.
The call for changing the IPCC is not new, either; in 2010 a number of scientists editorialized in Nature calling for a variety of changes.
Now, with the recent publication of the physical science draft -- the first in a series of three reports that make up the fifth assessment report -- such calls have been renewed.
Yet as Hunter points out, the panel's reports are not meant to target the mass media.
"It's meant to inform policymakers with a statement about where we are."
Just painstaking, or essential?
And in that role, said Alden Meyer, who directs policy and strategy at the Union of Concerned Scientists and who has decades of experience in international climate negotiations, the IPCC reports are fulfilling their mission.
"I think it would be a mistake to say we don't need these kind of periodic, systemic overviews of the state of the science, reporting what we know," Meyer said.
What some see as the painstaking, exhausting process of volunteer scientists working for three years on a report whose summary is then approved, line by line, by participating governments, others see as key to the report's credibility and validity.
In the past, Meyer noted, the report has proved a strong science platform for international negotiations over emissions reduction targets.
The first report, in 1990, catalyzed the 1992 United Nations Framework Convention on Climate Change, which now has 195 participating countries, Meyer said. And the strong science it provided in 1995 led to the Kyoto Protocol, in 1997.
Following that, the science in the third assessment report, released in 2001, led to many countries ratifying the Kyoto Protocol and committing to reducing greenhouse gas emissions.
Princeton's Oppenheimer agreed that the reports have played a key role in forcing policymakers to focus on climate change.
"I think it's safe to say without the IPCC reports, there would not be the sort of continual ongoing governmental focus and the search, although not always fruitfully, to reduce emissions," he said.
And in Europe, said Robert Watson, who chaired the IPCC from 1997 to 2002, the IPCC reports provided a foundation for individual countries' policies on reducing emissions.
"The United Kingdom, Germany and France have justified their strong domestic actions on climate change on the IPCC reports," he said.
The recently released IPCC summary for policymakers characterized the science of humans' role in warming the climate as "virtually certain" and laid out an emissions budget to keep global warming under 2 degrees Celsius.
Would smaller, targeted reports be better?
The science is clear, but it may not be enough to get a strong international agreement to curb emissions, said American University's Hunter and others.
"I think we can look at this and say: Science is not the problem," Hunter said. "The political reality, particularly here in the U.S., but also in China ... is that it is not clear that there is a political formula for a global instrument [to reduce emissions enough]."
Now that the big science questions are more or less settled, Oppenheimer and some others have called for a new approach.
The suggestion: Create smaller, more targeted reports focusing on an issue of interest to policymakers. The 2012 severe weather assessment is an example.
Changing the structure in this way has the effect of putting less of a burden on volunteer scientists, because the turnaround time is shorter and fewer scientists are involved. It also provides relevant science for policymakers on issues they care about.
"It's important for IPCC to be providing more timely, more pointed information," Oppenheimer said.
Watson, the former IPCC chairman, agrees that a new process for assessments ought to be put in place and that targeted reports might prove more useful for policymakers.
"The mega-reports, they really are making the scientific community fatigued, let's be honest," Watson said.
More news that countries can use?
In a meeting prior to the release of the most recent IPCC summary for policymakers, Jerry Meehl, a climate scientist at the National Center for Atmospheric Research who has served as a lead author for the IPCC reports, called the assessment process "long, complicated and arduous."
Watson's suggestion is to move much of the process online, to a system where new science papers are filed in various chapters as they are released. Then, every year or 18 months, scientists assess these updates to see whether they significantly change the science.
"Are the greenhouse gases still going up, what's happened to temperature, precipitation, sea level, glaciers, et cetera," Watson said.
He also sees additional value in the parts of the IPCC that deal more with policy options and mitigation and adaptation measures.
Countries are interested, he said, in understanding how their water supply is going to change or what the impact of climate change will be on their agricultural systems, and how they can adapt to that.
Scientists plan to discuss proposed changes at the upcoming meeting of the American Geophysical Union, in San Francisco. But the power to change the IPCC lies with its governing body.
This group will be examining potential changes in its upcoming meetings, IPCC spokesman Jonathan Lynn told the Guardian newspaper.
"It will be an interesting question, are the governments willing to find another process?" Watson said.
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