Common Sense on Climate Change

Appeared in the Ft. Collins Coloradoan on December 24, 2009

Media coverage of the climate change negotiations in Copenhagen often includes some basic misconceptions. We’d like to point out some facts that are not in dispute, and try to cool tempers a little.  We’re both climate scientists with decades of experience: Scott is a Professor of Atmospheric Science at CSU and Todd is a scientist at the Los Alamos National Laboratory. 

One common misconception often repeated in the media is that concern about global warming is based on recent warming trends. We hear endlessly repeated arguments about how much (or how little) the weather has warmed in recent years. Television pundits and politicians sometimes talk themselves blue about whether recent warming is caused by people or natural cycles. But the reason we expect climate to warm with increasing levels of CO2 is not based on past trends. It’s based on simple measurements of heat radiation from the gas itself.

The Earth’s temperature is set by a balance between incoming heat from the Sun and the radiation of that heat back to space. Molecules of carbon dioxide and water vapor in the air absorb some of the outgoing heat and radiate it back down to the surface, like tiny heat lamps in the sky. The heat radiation from CO2 molecules was first discovered nearly 150 years ago. The properties of the gas are not in the slightest dispute, and can be measured by any laboratory with exactly the same results. The basic science was done before the Civil War and does not depend on complicated computer models.

When scientists predict global warming due to continued reliance on fossil fuels, we are simply saying that if you add heat to the surface of the Earth, it will warm up. Another undisputed fact is that since 1800, the amount of CO2 in the air has increased by about 35%. If it were to double from preindustrial levels, 4 watts of heat would shine down on every square meter of the planet: that’s the equivalent of a tiny night-light bulb that burns 24 hours a day, 365 days a year. Simple common sense suggests this will warm the climate.  

You’d think pundits who predict this will not cause climate change would have some kind of explanation for why this extra heat will not warm the planet, but they don’t. They seem to think that because there are natural climate cycles, or because the climate has not yet warmed catastrophically, or because of hacked emails in England the laws of physics have somehow been repealed. Sorry: adding heat to something changes its temperature, unless something else takes the heat away.

Media pundits also seem to think the sky will fall if we burn less fossil fuel. This view betrays a very dim view of human history. If the naysayers had their way, we’d still be driving buggies!  Some argue that our entire modern economy rests on the subsidy of cheap fossil fuel. If they are right, our children’s future is dark indeed because industrialization in China and India will soon outstrip world supplies. We take the more optimistic view that human ingenuity and creativity can and will lead to a bright future in which billions of people can live well without burning coal, oil, or gas.

Scott Denning and Todd Ringler are science advisors to the Fort Collins Sustainability Group.  They can be reached at


Author: Rick Casey

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