Global Science Report is a feature from the Center for the Study of Science, where we highlight one or two important new items in the scientific literature or the popular media. For broader and more technical perspectives, consult our monthly “Current Wisdom.”
Poof, it was gone.
Just like that, the human fingerprints on a century-long warming trend in Northwestern United States were erased and replaced instead by the telltale signs of natural variability.
That is the conclusion of new research published last week by a pair of scientists from the University of Washington. James Johnstone and Nathan Mantua published their paper titled “Atmospheric controls on northeast Pacific temperature variability and change 1900-2012” in the Proceeding of the National Academy of Sciences (PNAS).
So as not to be accused of putting words in their mouth, here, in full, are the contents of a box labeled “Significance” from their paper:
Northeast Pacific coastal warming since 1900 is often ascribed to anthropogenic greenhouse forcing, whereas multidecadal temperature changes are widely interpreted in the framework of the Pacific Decadal Oscillation (PDO), which responds to regional atmospheric dynamics. This study uses several independent data sources to demonstrate that century-long warming around the northeast Pacific margins, like multidecadal variability, can be primarily attributed to changes in atmospheric circulation. It presents a significant reinterpretation of the region’s recent climate change origins, showing that atmospheric conditions have changed substantially over the last century, that these changes are not likely related to historical anthropogenic and natural radiative forcing, and that dynamical mechanisms of interannual and multidecadal temperature variability can also apply to observed century-long trends.
Translation: Natural variability in the atmosphere/ocean dynamics of the northern Pacific Ocean rather than human-caused global warming can largely explain the century-long rise in temperature in the Pacific Northwest.
And the authors have the figures to prove it.