17 September 2014

This New Era of Climate Instability

In our race to overheat the planet, hot spots have developed. Unless you reside on a yacht, you probably live atop one.

A fireplace is merely a mini hot spot. As warm air rises, cooler air comes rushing in to replace it (the “draw”). With hotter spots, you get a stronger breeze. 

The planet’s new hot spots are, naturally enough, busy rearranging when the winds blow and where the rain falls. Climate change, in other words. (Climate is what you expect. Weather is what you get.)

Since 1977, the continents have been warming twice as fast as the ocean surface. 

Global mean temperature rise (AKA global warming) is just the weighted sum of land and sea surface temperature averages; there is twice as much ocean surface as land. So the difference between land and sea continued to increase. And thus the temperature contrast across coastlines.

That can strengthen the moisture-laden winds coming off the ocean. But a stronger wind need not follow the customary path and may well deliver its moisture somewhere else.

Result? Some places will get unexpected rain, others will lack enough. Flood here, drought there, and who knows when?

This generality tells us quite a lot about what’s ahead. Even minor rearrangements in wind can produce trouble. Change the month when the rains arrive and fields that supported two crops each year may only support one, cutting food yield in half.

Note that no change in the annual rainfall is required for trouble—nor does it take extreme weather, as when prolonged heat waves suck all of the water out of the topsoil so that plants collapse.

Were a new pattern of moisture delivery to stick around for decades, we might slowly adapt. But no. That’s because the laggard in the global warming race just keeps falling further behind with the years, thanks to all of that evaporative cooling of the ocean surface and its greater heat capacity.

As long as “Hot-Spot Temperature” keeps increasing its lead over “Sea Surface Temperature” in this horse race to Hell, the strengthening temperature contrast over coastlines will keep producing newer and newer patterns of moisture delivery. Tracking a staggering target is far more difficult than slow adaptation to a new arrangement.

Welcome to climate instability, where all bets are off because history doesn’t help anymore.

There will be many more bad years for regional agriculture. And that increases the chance of a global bad year, as when Russia and the U.S. both got hit in 2010.

You would think that governments would return to stockpiling grain, and on a far grander scale than the pharaoh’s seven-year plan. Consider what can happen to governments relying on just-in-time supply lines.

The record heat of summer 2010 led to food shortages the following winter—and the world turned out to be surprisingly vulnerable, with lethal food riots in many countries. By the spring of 2011, a number of improvident governments started falling.

Projecting ahead, enough repetition of extreme weather—hurricanes and windstorms, deluge and drought, heat wave and Arctic outbreak—can seriously disorganize our civilization. They can lead to instant slums, a failing economy, climate refugees, resource wars, and a great difficulty in getting anything done—even crucial climate repairs.

Before collapse threatens in the emergency room, physicians institute a number of measures to “stabilize the patient.” You have to start them early to avoid the slippery slope to shock. For climate, we now need that crisis-manager way of thinking, but there is not much of it to be seen in those voluminous climate reports.

Prevention measures such as emissions reduction no longer suffice, however important they remain for the long run. To get there, however, we now need climate repairs, such as cleaning up the 43% excess of carbon dioxide that has accumulated in the air, in order to back us out of the danger zone.

The standard “take” on climate’s future by most well-informed people currently rests on predicted climate at mid-century, a gradual approach to it, and preventing worse through reduced emissions. That won’t do anymore.

In this new era of climate instability, don’t make the mistake of thinking things will change gradually. Or predictably. Or that prevention is still the obvious answer. Think repair and restoration.

William H. Calvin is a professor emeritus at the University of Washington’s medical school in Seattle and the author of Global Fever: How to Treat Climate Change  (University of Chicago Press, 2008). The latest version of the CO2 cleanup was a finalist in MIT's 2013 climate contest.

September 2014    WCalvin@UW.edu      faculty.washington.edu/wcalvin
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