Looming Warming Spurt Could Reshape Climate Debate

Humanity is about to experience a historically unprecedented spike in temperatures.

That’s the ominous conclusion of a vast and growing body of research that links sweeping Pacific Ocean cycles with rates of warming at the planet’s surface — warming rates that could affect how communities and nations respond to threats posed by climate change.

Papers in two leading journals this week reaffirmed that the warming effects of a substantial chunk of our greenhouse gas pollution have been avoided on land for the last 15 to 20 years because of a phase in a decades-long cycle of ocean winds and currents.  With Pacific trade winds expected to slacken in the years ahead, the studies warn that seas will begin absorbing less of global warming’s energy, and that some of the heat they’ve been holding onto will rise to the surface.

“Their results make sense to me, and are consistent with other evidence,” National Center for Atmospheric Research scientist Kevin Trenberth, who has published research dealing with the relationship between Pacific Decadal Oscillation (PDO) phases and surface warming, but who was not involved with either of the new studies, said.  “The PDO clearly plays a key role — and very high PDO values in recent months appear to signal a change.”

The growing body of research helps explain why ocean temperatures have been rising faster than anticipated, and, perhaps more compellingly, why land temperatures rose less than models had projected after the turn of the century — a mystery, sometimes dubbed the warming “hiatus,” “pause” or “faux pause,” that confounded science until just the last couple of years.
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Along with rising tides caused by rising temperatures, intense heat and heat waves are the clearest signs so far that human activity is altering the climate.  A suite of modeling studies have independently concluded that heat waves that ravaged Australia in 2013 would have been almost impossible without the warming effects of our greenhouse gas pollution. Scientists have also directly linked record-breaking heat in Europe with global warming.

Meanwhile, California’s record-breaking heat last year, which some research links more closely with ocean cycles than with global warming, substantially worsened the drought-inducing effects of low rainfall and snowfall rates.  That’s a problem that will continue to worsen fire risks throughout the American West, and much of the rest of the world, as temperatures start to really spike.  That could threaten the survival of entire ecosystems, including the spectacular high-altitude forests of the American Southwest.

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