2014-07-23. A pause in global warming? Studies try to better explain what's happened.

posted Aug 15, 2014, 9:22 AM by Alan Gould
For GSS Climate Change chapter 7. Excerpt: Any pause in global warming, such as it may have been during the first decade of the 21st century, might seem to be on its way out. Global average temperatures for May and June 2014 reached record levels of warmth. Last year ranked as somewhere between the second and sixth warmest on record globally, depending on the temperature records you pick. But if history is any guide, expect more pauses in the thermometer's climb toward a warmer world, thanks to the climate's natural variability. That's one implication of two recent studies exploring the pause with an eye toward testing the notions that global warming has ended, as some skeptics have asserted, and that fundamental problems with climate models prevented them from projecting the sudden slowdown in the rate of warming. ...For the skeptic community, "this is proof that global warming stopped and it's no longer a problem, so we don't need to worry about it," ...For scientists seeking to better understand how the climate system works, "it's a really compelling science problem,"  ...Modeling studies over the past several years have converged on natural variability as the most likely explanation for the hiatus in warming, with a decades-long cycle of warming and cooling of surface waters in the Pacific as the prime mover. ...Shaun Lovejoy, a physicist at McGill University in Montreal, looked at the question model-free by conducting a statistical analysis of measured temperatures going back to the 1880s as well as records reconstructed from natural stand-ins for thermometers going back as far as the 1500s. The goal was to answer a basic question: How unexpected are such hiatuses? Modelers were concluding that a hiatus "doesn't look that unlikely; it looks totally possible that it's natural," Dr. Lovejoy says. "But I actually tried to put a number on it, and the number in the end is that we expect such an event every 20 to 50 years."....  http://www.csmonitor.com/Environment/2014/0723/A-pause-in-global-warming-Studies-try-to-better-explain-what-s-happened. By Pete Spotts, The Christian Science Monitor.