When the United Nations' last major climate change report was released in April, it omitted some country-specific emissions data for political reasons, a trio of new papers argue, sounding a warning bell about the global politicization of climate science.

Written by thousands of science, policy, and economics experts from around the world, the UN International Panel on Climate Change (IPCC) reports represent a synthesis of existing climate research knowledge, focusing on the evidence of a warming climate ("virtually certain"), the global impacts, and the ways we might avert its most catastrophic effects. The Summary for Policy-makers draws on the detailed technical report and offers recommendations on cutting carbon emissions and preparing for climate change.

Although the underlying technical material in the IPCC's fifth major report was widely agreed upon and published intact, "heated negotiations among scientific authors and diplomats led to substantial deletion of figures and text from the influential 'Summary for Policy-makers,'" writes Brad Wible, an editor at the journal Science, in the introduction to three papers published Thursday. (See "Battle Plan for Climate Change: How to Cut Greenhouse Gases.")

Wible notes there is "some fear that this redaction of content marks an overstepping of political interests, raising questions about division of labor between scientists and policy-makers and the need for new strategies in assessing complex science."

On the other hand, some observers have suggested that the policy summaries be even more explicitly co-produced with national governments, says Wible.

This discussion was sparked just days after the publication of the IPCC report in April, when report co-author and Harvard environmental economics professor Robert Stavins released a controversial open letter to the IPCC leadership. Stavins criticized the last-minute intervention by several governments in the approval process of the IPCC report in Berlin and called the resulting policy summary document "a summary by policy-makers, not a summary for them."

"Over the course of the two hours of the contact group deliberations, it became clear that the only way the assembled government representatives would approve text for SPM.5.2 [the Summary for Policy-makers] was essentially to remove all 'controversial' text (that is, text that was uncomfortable for any one individual government), which meant deleting almost 75 percent of the text," Stavins wrote on his blog on April 25.

Scientists vs. Diplomats

Wible points out that the stated intention of the IPCC since it was founded in 1988 has always been to "balance governmental and scientific input."

That mandate is unlikely to change, says David Victor, one of the lead authors of the policy discussion in the April IPCC report and the head writer of one of the papers published Thursday in Science, called "Getting Serious About Categorizing Countries."

"I think in an ideal world there would be a firmer separation between the diplomats and the scientists" when it comes to the IPCC process, says Victor, who is a professor of international relations at the University of California, San Diego.

However, Victor adds that he "can't imagine" the national governments from around the world that participate in the IPCC process agreeing to any substantial reforms in that area.

The best that can be hoped for are small changes that streamline the report process, says Victor. "Intergovernmental bodies that require consensus are very bad at handling politically difficult topics," he says. "I don't see a way to fix that problem."

Instead, the public should look more to individual governments and organizations and national climate assessments (such as the one released by the Obama administration May 6) for more concrete action on controversial topics like emissions caps and geoengineering. (See "Climate Report Provides Opportunity for Bridging Political Divide.")

But the second paper in the Science series, "Political Implications of Data Presentation," disagrees. Written by other authors of the last IPCC report, led by Navroz Dubash of the Centre for Policy Research in New Delhi, the paper suggests that what is needed are more and earlier discussions between scientists and policymakers in development of future reports.

"Claiming government overreach and calling for greater insulation of the process come from a misleadingly simple interpretation" that would hinder the effectiveness of IPCC reports in actually influencing policy, Dubash and co-authors write. The fact that governments must approve the policy summary gives it more weight than other technical reports, which is a "process worth preserving."

Victor calls that argument "overly optimistic" and says he doubts earlier conversations between scientists and diplomats would have made a difference. In the 38,000 comments received and evaluated over the IPCC report's development, almost none hinted at the battle over individual country data that erupted in Berlin just days before the document was released, he says.

When governments hold the power to approve the policy document, "they are going to use that power to avoid having anything in the summaries that is politically inconvenient," says Victor.

IPCC co-author Charles Kolstad, a Stanford economist who was not involved with any of the papers released in Science, tells National Geographic that there is a "perception that the main product was the summary for policymakers and that it appeared to be a censored version of what we wrote." Kolstad says it would be better if the public had a clearer distinction of the two sides of the report and says "it would be a mistake to move the policymakers away from the process."

Kolstad adds that it was gratifying "how much the diplomats seemed to care about what was in the IPCC product" and says "remaining relevant is of paramount importance."

Value of Individual Country Data

When the IPCC met in Berlin in April to approve the latest report, representatives from several countries objected to a section in the summary that listed emissions by nation and classified countries according to their economies, says Victor. Those objecting countries included Brazil, China, Malaysia, and Saudi Arabia, he says.

Victor and colleagues wrote in Science that growth in a country's income was the strongest correlating factor with emissions. Developed countries continue to produce the highest emissions on a per capita basis, but most of the growth in global emissions over the past few decades has occurred in developing countries.

A chart removed from the IPCC summary but published in Science shows that much of the growth in recent greenhouse gas emissions comes from Asia, with smaller contributions from the Middle East, Africa, and Latin America. Emissions in developed countries have continued to rise, but at a much slower rate.

To Victor, the logical conclusion of this trend is that "developed countries should be doing more to address climate change, but it is also the case that it is not mathematically possible to stabilize the world's climate unless developing countries are involved."

If the IPCC were to classify countries by their economies, it would "set the stage for political discussions" about what each country's responsibility might be, he says.

However, some governments worried that classification "could be disadvantageous in upcoming negotiations for a new international climate regime," IPCC authors Ottmar Edenhofer and Jan Minx write in the third policy paper in Science, called "Mapmakers and Navigators, Facts and Values."

Still, when all country data was stripped out of the policy summary, other useful information was lost, Victor and colleagues argue. For example, without that data it is harder to understand the impact of trade on emissions.

Reaching Consensus?

Although Dubash and colleagues suggest that the IPCC process can be improved with more collaboration between scientists and policymakers, Victor argues that the fundamental international nature of the group makes it unlikely to be able to reach consensus on controversial topics. "The IPCC is an inherently conservative body," says Victor.

Edenhofer and Minx write that "the real challenge is how the IPCC conducts assessments and deals with entanglement of facts and values at the science-policy interface." They suggest that future reports attempt to allow for different perspectives on policy questions and introduce analysis of how past climate policies have worked.

The IPCC has a choice, say Edenhofer and Minx. It can produce more sanitized reports that are even less relevant to policy or attempt to take on policy questions more directly, with a rational approach that acknowledges different viewpoints.

Stanford's Kolstad says he prefers the latter, although he acknowledges that it can be challenging because "any diplomat can veto any sentence." He adds that colleagues at Stanford and Harvard and their European counterparts are planning a workshop in February on how the IPCC might work better, in preparation for the next round of work.

Despite the most recent report's shortcomings, "when the IPCC says something declarative, such as that humans are responsible for most of the changes to the climate we are seeing, that means there is tremendous consensus around that," says Victor.