The Foreign Service Journal, February 2008

F E B R U A R Y 2 0 0 8 / F O R E I G N S E R V I C E J O U R N A L 27 arth’s temperature is now rising at a rate unprecedented in the experience of modern human society. While some historical changes in climate have resulted from natural causes and variations, the strength of the trends and the patterns of change that have emerged in recent decades indicate that human influences (primarily from increased emissions of carbon dioxide and other greenhouse gases) have now become the dominant factor. More specifically, 11 of the last 12 years (1995-2006) rank among the warmest years in the instrumental record of global surface temperature (kept since 1850). These in- creases are widespread over the globe, with greater in- creases at higher northern latitudes and with land regions warming faster than oceans. The continued increase in oceanic temperatures is significant, however: the oceans absorb over 90 percent of all warming (only 3.3 percent goes to heat the atmosphere and 6.2 percent to melt sea ice and glaciers), and their rising temperatures cannot be explained solely by natural or internal processes, climate variability or solar and volcanic forcing. The measured increases do, however, correlate well with global climate models suggesting that the warming is of human origin. Further, analyses suggest that Earth is now absorbing more energy from the sun than it is emitting back into space, and this has a profoundly important implication: an additional global increase in temperature of almost 1° Celsius is already stored in the oceans, even without any further increase of greenhouse gases. An Arctic Heat Wave As a result of the work of the Nobel Prize–winning Intergovernmental Panel on Climate Change — its “Syn- thesis Report of the IPCC Fourth Assessment Report” was released in November 2007 — there is now higher confidence than in all prior assessments in the projected patterns of warming, including changes in wind patterns, precipitation, extreme weather and sea ice extent. As the IPCC report notes, the most dramatic current and projected changes are centered in the Arctic, where the average temperature has risen at twice the rate of the rest of the world in the past few decades. Some regions (e.g., Alaska) have experienced mean surface tempera- ture increases three to five times the global average. F O C U S O N C L I M AT E C H A N G E T HE A RCTIC B ELLWETHER T HE WORLD WOULD DO WELL TO FOCUS ON THE A RCTIC , WHERE THE AVERAGE TEMPERATURE HAS BEEN RISING AT TWICE THE RATE OF ANYWHERE ELSE . B Y R OBERT W. C ORELL E Robert W. Corell is the global change program director for the H. John Heinz III Center for Science, Economics and the Environment, a nonprofit institution dedicated to improving the scientific and economic foundation for environmental policy through multisectoral collabora- tion among industry, government, academia and envi- ronmental organizations.