When a United Nations panel of experts released a report last week affirming that man-made climate change is a scientific certainty, skeptics of global warming were noisily trying to discredit the panel. In the process, they drowned out the critiques of a far different group.
A broad array of leading climate scientists and policy specialists were also criticizing the panel for the exact opposite reason: They believe the main conclusions of the Intergovernmental Panel on Climate Change (IPCC) may be too general and too conservative to convey a clear message about the grave threat of warming and to inform policies to address local climate change issues. They say that after 25 years it might be time to overhaul the organization and refocus its research priorities.
"The state of the science and the questions to be answered have changed," said Kevin Trenberth, a climate scientist with the National Center for Atmospheric Research who has worked with the IPCC since the early 1990s.
Trenberth and several other scientists who are, or have been, in the IPCC told InsideClimate News that because the panel has already established that global warming is real, rapidly occurring and driven by human activity, it is time to focus less on defending this basic science and focus more on what is less understood. Examples of less certain science include understanding the effects of climate change on extreme weather in different regions, the role the deep ocean plays in the climate cycle and the rate at which sea level will rise over the next century.
The scientists said the IPCC needs to make a number of structural changes, including producing more frequent and focused reports, increasing transparency and shifting some of its attention to hyper-local projections that would provide communities and their leaders a clearer picture of what their futures look like.
"The IPCC reports are very comprehensive and very good," said Michael Oppenheimer, an environmental policy expert at Princeton University and longtime IPCC author. "But 98 percent of the information in them represents incremental advances over the last few years. What the governments need is something that evaluates the science in a very timely fashion … [and produces] reports that are sharp and deep and very, very useful to policymakers."
'How Much Higher Can We Really Go?'
The IPCC was chartered in 1988 under the United Nations to provide governments with an assessment of climate science every six or seven years to inform policy decisions about the climate threats facing the world. At the time it was founded, evidence was piling up that the world was warming and a consensus was forming within the scientific community that human activity—in particular, the burning of fossil fuels—was responsible.
Since then, thousands of scientists have volunteered their time to research, write and review the group's assessments. The process involves years of analyzing tens of thousands of scientific journal articles on topics ranging from sea level rise and glacial melt to past climate shifts. In 2007, the panel shared the Nobel Peace Prize with former Vice President Al Gore.
With every assessment the group publishes four technical reports, each thousands of pages long—one on the basic science, and others on climate impacts and how to adapt to them, ways to curb emissions, and a synthesis of all the findings—as well as a 20-page summary for policymakers that covers the material most relevant to world leaders and the public. Thanks to a growing body of scientific evidence and improved computer models that can project climate changes more accurately and in much finer detail, each report has proclaimed with greater and greater certainty that human activity is the main cause of global warming.
In its third assessment 12 years ago, the IPCC asserted with 66 percent certainty that man-made greenhouse gas emissions were the main driver of global warming since the early 1950s.
In 2007, the group's certainty rose to 90 percent. The panel's just-released fifth assessment, created with the collaboration of more than 800 experts who reviewed more than 9,000 scientific studies, ups its confidence to 95 percent.
"How much higher can we really go?" said Andrew Weaver, a Canadian climate scientist and lead author of the IPCC's section on climate projections, who was elected in May to British Columbia's provincial legislature as a Green Party member.
"You can always appeal to wait for more science, but the reality is we know enough science to know what needs to be done."
How to Make It Better
In interviews, scientists and policy experts suggested five strategies to improve the IPCC: