Stop burning fossil fuels now to warm Earth later?
One facet of the earth's climate doesn't often make it into discussions over human-induced climate change. And that is: Before people ever began burning fossil fuels, climate changed, so there's no reason to think that it won't change again. Unless, of course, Homo sapiens — or something else — somehow prevents that change from occurring.Skip to next paragraph
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(Quick note: Obviously, a vociferous contingent does cite the fact that climate has changed in the past, usually as evidence that humans can't be changing climate now, that it's out of our control. Absent a plausible explanation for how the former observation supports the latter conclusion, we're leaving those arguments aside.)
For about 2.58 million years before present, Earth's climate has swung back and forth between cold and warm states. Scientists call this period the Pleistocene — the age of woolly mammoths, woolly rhinos, and, during the past 200,000 years or so, a big-brained, tool-wielding hominid called Homo sapiens. (If 2.58 million years seems longer than you remember the Pleistocene being, that's because scientists recently revised its length, extending it more than 1 million years.)
Scientists think that variations in Earth's orbit are responsible for these cold periods interspersed with warmer ones. Earth's orbit is not a perfect circle, and the angle at which it spins relative to its orbital plane changes as well.
Together, these (and other) shifts alter how much sun hits different regions of the earth during different seasons. If the poles cool — especially the North Pole — and enough ice accumulates, it can trigger an ice age. During the Pleistocene, ice ages occurred roughly on a 100,000 year cycle.
A study reported in the journal Science in September concluded that, as one might predict, the planet was due for another Ice Age sometimes soon. In fact, the arctic had been cooling for the past 2,000 years. But this cooling trend was reversed in the 20th century by anthropogenic greenhouse gases.
In other words, we'd inadvertently saved ourselves from advancing glaciers by burning fossil fuels.
A study published in Geophysical Research Letters this past February made this point explicitly. Gary Shaffer of the Niels Bohr Institute, University of Copenhagen, argued that fossil fuels were so valuable as a tool to modify future climate — to ward off future ice ages — that we should stop burning them now and keep them in reserve for that purpose.