Research Highlight: The State of Climate 2007

Results of one of the most highly anticipated reports on climate change in several years were released to the public last week.

The new Intergovernmental Panel on Climate Change (IPCC) assessment report, “Climate Change 2007,” a synthesis of global climate change studies conducted by the world’s leading climate scientists, provides the most authoritative and sobering depiction of the state of the planet in regards to global warming and its implications for the future. Four researchers from Scripps Institution of Oceanography at UC San Diego took part in drafting the assessment.

A summary of the report written for policymakers was released at a press conference in Paris on Feb. 2. Scripps held a corresponding press conference at Birch Aquarium at Scripps in La Jolla, Calif., on the same day.

The summary concluded that most of the observed increase in globally averaged temperatures since the middle of the 20^th century is very likely due to the rise in human-produced greenhouse gas concentrations. The scientists estimated that air temperatures will rise by the end of the century by between 3.2 and 7.2 degrees Fahrenheit.

“Warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global mean sea level,” said the summary’s authors, among them Scripps climate scientist Richard Somerville. “Continued greenhouse gas emissions at or above current rates would cause further warming and induce many changes in the global climate system during the 21^st century that would very likely be larger than those observed during the 20^th century.”

News coverage of the release of the summary report reached around the world. European cities displayed their concern of climate change and its impacts with public displays at the Eiffel Tower in Paris, the Colosseum in Rome, and the Greek parliament in Athens.

“Feb. 2, 2007 may go down in history as the day the question mark was removed from the question of whether climate change has anything to do with human activities,” said Achim Steiner, head of the U.N. Environment Programme.

The new assessment report, described as a “comprehensive and rigorous picture of the global present state of knowledge of climate change,” is the first volume of the fourth installment of IPCC studies. Six years in the making, the assessment involved thousands of scientists from more than 130 countries. The first phase of “Climate Change 2007” assesses the current scientific knowledge of the natural and human drivers of climate change, observed changes in climate, the ability of science to attribute changes to different causes, and projections for future climate change.

“The significance of the IPCC report is that it will be the definitive assessment of the science of climate change, designed to be policy-relevant but not policy-driven or policy-prescriptive,” said Somerville, a distinguished professor at Scripps Oceanography. “These IPCC reports come out at five- to six-year intervals. This one, like the 2001 report, will doubtless be regarded as the gold standard.”

Somerville is a coordinating lead author of the fourth IPCC report. Other Scripps involvement includes Professor Lynne Talley, who was a lead author of the chapter “Observations: Oceanic Climate Change and Sea Level,” and Professor V. Ramanathan, who served as a review editor. Nobel Laureate and Scripps and UC San Diego Professor Mario Molina also contributed to the report. Many others at Scripps served in various capacities during the report’s development.

At the Scripps conference, Ramanathan and Talley joined Scripps Director Tony Haymet and climate researchers Dan Cayan, Ralph Keeling, and Tim Barnett in relating the IPCC summary’s findings to work taking place at Scripps. Cayan said the international panel’s conclusions confirm aspects of his own work studying climate impacts on California.

“The alarming thing is this is just a taste of things to come,” Cayan said. “Snowpack in the Sierra Nevada, which has been part of our water management strategy, is going to take a hit.”

The World Meteorological Organization and the United Nations Environment Programme launched the IPCC in 1988 in recognition of the looming environmental problems that are associated with global climate change.

Like the new assessment, the preceding three reports, released in 1990, 1995, and 2001, evaluated the state of climate change research and most recent discoveries. The second IPCC assessment report, for example, provided a new framework for understanding humanity’s influence on climate when it concluded “the balance of evidence suggests a discernable human influence on global climate.” A sterner statement emerged from the 2001 report: “There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities.”

The new assessment is expected to have an even larger impact due to a recent rise in attention to global warming studies and their implications. The new awareness has been augmented by recent record-setting annual temperatures, evidence of warming through glacial melting and rising ocean temperatures, and through increased attention via the news media and outlets such as former Vice President Al Gore’s 2006 documentary “An Inconvenient Truth.”

The new report is being released in three phases, with the Feb. 2 installment covering the “Physical Science Basis” from Working Group I.  Working Group II will cover “Impacts, Adaptation, and Vulnerability” and Working Group III’s results cover the “Mitigation of Climate Change.” The full report, including 11 chapters and a technical summary, is expected to be available by November.

— Mario C. Aguilera