New Blockbuster IPCC Climate Report: Comprehensive, Authoritative, Conservative

Published: 11:31 AM GMT on September 26, 2013

Comprehensive. Authoritative. Conservative.
Those words summarize the world's most rigorous and important scientific report in history: the 2013 Intergovernmental Panel on Climate Change (IPCC) climate assessment, due to be released at 4am EDT Friday in Stockholm, Sweden. The Nobel Prize-winning IPCC has put together an amazingly authoritative and comprehensive report on a subject crucial to the future of civilization, a report that will guide policymakers worldwide as they struggle to cope with the growing chaos generated by the Great Climate Disruption that is already upon us. The first 31 pages of the report, called the "Summary For Policymakers", is what will be released Friday, and this summary will lay out a powerful scientific case that significant climate change with severe impacts is already occurring, humans are mostly responsible, the pace of climate change is expected to accelerate, and we can make choices to cut emissions of carbon dioxide and other heat-trapping gases to limit the damage.

Q: What is the IPCC?
A: In 1988, 300 scientists and high-ranking government officials at an international conference convened by the United Nations Environmental Programme (UNEP) and the World Meteorological Organization (WMO) concluded that changes in the atmosphere due to human pollution “represent a major threat to international security and are already having harmful consequences over many parts of the globe.” Immediate action was needed, they said, to negotiate a set of strict, specific targets for reducing greenhouse gas emissions. But who should coordinate such an effort? The conservative Reagan Administration and some other governments were wary of control by any group that was part of the United Nations structure. These governments proposed formation of a new, fully independent group under the direct control of representatives appointed by each government—that is, an intergovernmental panel. Responding to this pressure, the WMO and UNEP collaborated in creating the Intergovernmental Panel on Climate Change (IPCC) in 1988. The IPCC was neither a strictly scientific nor a strictly political body, but a unique hybrid. It could issue reports only with the firm agreement of a great majority of the world’s leading climate scientists, plus the unanimous consensus of all participating governments. Importantly, it would put policy options on the table, but would not make explicit policy recommendations. Given these requirements, the IPCC reports tend to be quite conservative, but have unimpeachable authority.

Q: What is an IPCC report?
A: Every 5 - 6 years, the IPCC issues a massive 3,000+ page report summarizing the current state of knowledge on climate change. These "assessment reports" have been issued in 1990, 1995, 2001, 2007, and now, 2013. The latest assessment will be released in four parts:

"The Physical Science Basis" (September 2013) will describe the observed and predicted changes to Earth's climate.

"Impacts, Adaptation and Vulnerability" (March 2014) will document the dire consequences associated with the path that we’re on.

"Mitigation of Climate Change" (April 2014) will outline what it will take to get us back on track to avoid the worst impacts of climate change.

The "Synthesis Report" (October 2014) will summarize all of the other reports.

The scientists who prepare the 3,000+ page report cite over 9,200 peer-reviewed scientific articles, but present no original research of their own. At least 259 authors from 39 countries drafted the part of the report being released this week, and the report was subjected to two rounds of review by 1089 experts in 55 countries beginning in December 2011. None of the scientists were paid for their work. The report was also reviewed by government representatives from 38 nations, and the final report that is being debated in Stockholm this week was revised based on the over 54,000 review comments received. The most important part of the report is the "Summary for Policy Makers", a 31-page document that summarizes the key scientific findings, used by governments to make policy decisions on how to respond to climate change. The "Summary for Policy Makers" for "The Physical Science Basis" portion of the 2013 IPCC report is being released on September 27. The actual 1,000+ page scientific report that the "Summary for Policy Makers" summarizes is being released the following Monday (September 30.) While the "Summary for Policy Makers" is drafted by the scientists who serve as the lead authors for the IPCC report, the summary is subject to approval by the governments of the 195 member nations of the IPCC. During the final week of the approval process, politicians can weigh in and demand changes to the summary drafted by the scientists, since the final "Summary for Policy Makers" requires unanimous approval by all of the IPCC nations. The IPCC reports have the most elaborate review and approval process for any scientific report in the world. In 2007, the IPCC won the Nobel Peace Prize. In short, three words summarize the IPCC reports:


FIgure 1. IPCC lead authors gather for a group photo at the four most recent meetings for drafting of the 2013 IPCC assessment report. Image credit: IPCC.

Q: Do errors in the IPCC reports undermine confidence in the science?
A: No. Two small errors have been found in the 3000+ pages of the 2007 IPCC report. Neither has anything to do with the basic conclusions that the globe is unequivocally warming and that human activity is the primary cause (one error was simply a typo.) The mistakes have been acknowledged and corrected and review procedures are being strengthened to avoid future errors. In a report of over 3,000 pages by hundreds of authors, it is not unusual that there would be a few minor errors. Contrarians seeking to discredit climate science, and some in the media, have blown these errors out of proportion, claiming the errors invalidate the entire IPCC report. It's like saying we need to throw out an entire phone book because two misspellings were found in it.

Q: What are some of the weaknesses of the IPCC report?
1) The report is already out-of-date, since papers had to be submitted for publication by July 2012 and published by March 2013 in order to be cited.

2) The report is tedious, complex, and difficult to read, making this vital science difficult to access. Little regard was given by the IPCC to communicating the results of the report. Science has little value if it is not understandably communicated to those who need the information. Where are the accompanying explanatory videos? Why was the report issued on a Friday, the worst day of the work week to get attention? The IPCC has devoted a very small portion of its budget to communication and outreach, leaving the interpretation of the report to others. I can understand the reluctance of the IPCC to provide a more slick and showy interpretation of the report, since they might be accused of "spinning" the science, and one of the great strengths of the IPCC report is its great science and the impartiality of the content. But the assumption that the science will speak for itself is wrong. The most powerful and richest corporations in world history--the oil companies--are waging very well-funded PR campaigns to deny the science, play up the uncertainties, and question the character of the scientists who write the report. The world's most rigorous and important scientific report in history is being kicked apart by powerful special interests whose profits are threatened by the findings.

3) Since the "Summary for Policymakers" is subject to unanimous approval by politicians, the science is potentially compromised, and the conclusions will tend to be conservative. Naomi Oreskes, in Chapter Six of her book, "Merchants of Doubt", recounts the haggling that led up to the approval of the 1995 Summary for Policy Makers. Government delegates for Saudi Arabia, Kuwait, and other major oil exporting nations demanded a change to the statement the scientists had drafted, "The balance of evidence suggests an appreciable human influence on climate." For two whole days, the scientists haggled with the Saudi delegate over the single word "appreciable". Nearly 30 different alternatives were discussed before IPCC chair Bert Bolin finally found a word that both sides could accept: "The balance of evidence suggests a discernible human influence on climate." The term "discernible" established a middle ground by suggesting that human-caused climate change was detectable, but the level of that influence was subject to debate. This sentence would go on to become one the most famous scientific statements ever made about climate change, but it was more conservative than what the scientists wanted.

4) The lower-end emissions scenario, called RCP2.6, which assumes that CO2 concentrations will reach 421 ppm by the year 2100, is highly unlikely. Earth reached 400 ppm of CO2 earlier this year, and CO2 has increased by over 2 ppm per year during the past decade. CO2 emissions are accelerating, and CO2 levels will surpass 421 ppm by the year 2023 at the current rate of acceleration. RCP2.6 requires that we slash emissions of CO2 by 50%, relative to 1990 levels, by 2050. We are currently on a pace to match or exceed the worst-case scenario considered by the IPCC (RCP8.5), where CO2 levels reach 936 ppm by the year 2100.

The two higher-end emission scenarios of the four considered by the IPCC will very likely warm the planet more than 2°C (3.6°F) over pre-industrial levels. Two degrees Centigrade represents a "dangerous" level of warming for civilization that we must avoid, according to the 2009 Copenhagen Accord, signed by world leaders including President Obama. We will have to work very hard, and very soon, to keep warming below this 2°C "danger" level. As climate writer Elizabeth Kolbert says, holding the global temperature increase to “only” two degrees Celsius, though, is like limiting yourself to “only” a few rounds of Russian roulette: unless you’re uncommonly lucky, the result is not likely be happy. The 0.9°C warming we've experienced since 1900 has already caused a destabilization of global weather patterns, resulting in unprecedented extreme weather events and accelerating melting of polar ice caps. As a group of climate scientists wrote in 2009 at,

"Even a “moderate” warming of 2°C stands a strong chance of provoking drought and storm responses that could challenge civilized society, leading potentially to the conflict and suffering that go with failed states and mass migrations. Global warming of 2°C would leave the Earth warmer than it has been in millions of years, a disruption of climate conditions that have been stable for longer than the history of human agriculture."

I'll have a full analysis of the new IPCC report Friday morning, and will be offering expert commentary live on The Weather Channel beginning at 7:10 am EDT on Friday. The 2013 Summary For Policymakers will be available on the IPCC website beginning at 4 am EDT Friday.

Video 1. I did a live interview with Thursday morning during their 8am - 9am EDT news hour, discussing the upcoming IPCC report.

Jeff Masters

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Cat 6 lead authors: WU cofounder Dr. Jeff Masters (right), who flew w/NOAA Hurricane Hunters 1986-1990, & WU meteorologist Bob Henson, @bhensonweather

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New Blockbuster IPCC Climate Report: Comprehensive, Authoritative, Conservative

Comprehensive. Authoritative. Conservative.
Those words summarize the world's most rigorous and important scientific report in history: the 2013 Intergovernmental Panel on Climate Change (IPCC) climate assessment, due to be released at 4am EDT Friday in Stockholm, Sweden. The Nobel Prize-winning IPCC has put together an amazingly authoritative and comprehensive report on a subject crucial to the future of civilization, a report that will guide policymakers worl...

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