Global warming experiences temporary slowdown

Science : “Despite the continued increase in atmospheric greenhouse gas concentrations, the annual-mean global temperature has not risen in the twenty-first century,” according to a recent study by Yu Kosaka and Shang-Ping Xie of the Scripps Institution of Oceanography in San Diego, California, which appears online in Nature. Many natural causes for the temporary global-warming hiatus have been proposed, including a buildup of aerosols in the atmosphere, volcanic eruptions, a lull in solar activity, and heat absorption by Earth’s oceans. To find out how much ocean surface temperatures in the eastern equatorial Pacific affect global atmospheric temperatures, Kosaka and Xie ran a series of experiments called POGA (Pacific Ocean–Global Atmosphere). They found that recent cooling in the Pacific lowered global mean temperatures by 0.15 °C relative to the 1990s. Nevertheless, they say, the effect is only temporary—the climate is going to continue to warm due to increasing greenhouse gas concentrations.