The other global warming

The other global warming
Even if we contain the greenhouse effect, says a Tufts astrophysicist, we'll have another heat problem on our hands
By Bina Venkataraman
January 25, 2009

Human civilization will heat up the planet; the glaciers will melt and the seas will rise. It's a familiar refrain by now, with a familiar solution: stop pumping out the greenhouse gases that trap the sun's heat. But even if we bring the greenhouse effect under control, says a Tufts astrophysicist, the earth will warm up anyway, thanks to a completely different source of heat that we create ourselves.

Over the next 250 years, calculates Eric J. Chaisson in a recent paper, the earth's population will start generating so much of its own heat - chiefly wasted from energy use - that it will warm the earth even without a rise in greenhouse gases. The only way to avoid it, he says, is to rethink how we generate energy.

His paper examines the planet's growing pool of waste heat, a widespread phenomenon that nonetheless has been little studied as a cause of climate change. Nearly everything that uses or generates energy - chiefly power plants, but also cars, snowblowers, computers, and light bulbs - squanders some energy as wasted heat. And the larger and more energy-hungry the human population grows, the more waste heat remains in our atmosphere. "What this means for humans is that this is the ultimate limit to growth," said Dennis Bushnell, the chief scientist at NASA's Langley Research Center, who urged Chaisson to publish his idea. "As we produce more kilowatts, we have to produce more waste heat."

Chaisson's prediction suggests we need to change our energy policy - not just by keeping emissions low, but by shifting toward power sources that don't add new heat to the earth's system. The culprits in the waste-heat problem are not only dirty fossil fuels like coal and oil, but also some "clean" power sources like nuclear and geothermal energy, which still add to the problem by pumping new heat into the atmosphere. The only way to stop waste heat-induced global warming, in Chaisson's view, is to rely on energy that already reaches the earth's surface: sunlight, and the wind and the waves that it powers.

Critics say Chaisson's paper describes a scenario so far in the future, and so dependent on projections, that there's simply no way to know if it will come to pass. They also say it could distract us from the far more urgent problem of greenhouse gases. But the idea has piqued the interest of several scientists from around the world who see an opportunity to avert a crisis before future generations have to face it. And in a broader sense…

http://www.boston.com/bostonglobe/ideas/articles/2009/01/25/the_other_global_warming/

EOS, TRANSACTIONS AMERICAN GEOPHYSICAL UNION, VOL. 89, NO. 28, PG 253
doi:10.1029/2008EO280001, 2008
Long-Term Global Heating From Energy Usage
Eric J. Chaisson
Wright Center, Tufts University, Medford, Mass., USA
Harvard College Observatory, Cambridge, Mass., USA

Abstract
Even if civilization on Earth stops polluting the biosphere with greenhouse gases, humanity could eventually be awash in too much heat, namely, the dissipated heat by-product generated by any nonrenewable energy source. Apart from the Sun's natural aging—which causes an approximately 1% luminosity rise for each 108 years and thus about 1°C increase in Earth's surface temperature—well within 1000 years our technological society could find itself up against a fundamental limit to growth: an unavoidable global heating of roughly 3°C dictated solely by the second law of thermodynamics, a biogeophysical effect often ignored when estimating future planetary warming scenarios.