Global Warming : Fiction or fact? |

Global Warming : Fiction or fact?

Hal Sundin
Post Independent
Glenwood Springs, CO Colorado
As I See It

Deniers claim either that there is no global warming, or that it is not due to human activities.

First, is global warming real? Some point at this year’s cold snowy winter in the U.S., and say “Global warming? Ha!”. But they are confusing weather and climate. Weather is local, and is made up of events timed in days, months, or even years. Climate is world-wide, and measured in decades, centuries, or millennia. Although this has been a cold and snowy winter in the U.S., globally it has been the fifth warmest on record. Grasping at straws, deniers were quick to hop onto e-mail leaks indicating that a few researchers had tinkered with data and exaggerating how soon earth’s climate would be seriously altered. George Will, and other deniers, love to ridicule scientists, who in the 1970s predicted a cooling trend based on variations in the earth’s orbit, and claim they are now wrong again. What they have failed to recognize is that something more powerful is taking place that has reversed the predicted cooling. The vast majority of both data and climate scientists are in agreement that global warming is real. The irrefutable evidence is the steady warming of the earth’s oceans and rising sea level from melting ice caps, over the past 150 years, two-thirds of which has taken place since 1950. So what is the explanation for this rapid warming trend? Information derived from fossil records indicates that the earth is warmer today than it has been for at least a million years. Coupled with this fact is the virtually lock-step correlation over the past 400,000 years between the amount of carbon dioxide in the atmosphere (as determined from air bubbles trapped in ice core samples), and the temperature of the earth. Since the late 18th Century, atmospheric CO2 has increased from 280 to over 390 parts per million – an astounding 40 percent increase in less than 250 years. It is no accident that this unprecedented rise started with the Industrial Revolution, since which humans have burned ever increasing amounts of fossil fuels: coal, natural gas and petroleum.

Three scientific facts confirm that the burning of fossil fuels is the major cause of that increase in CO2 in the atmosphere. First, we know pretty well how many tons of coal, barrels of oil, and therms of natural gas have been burned since the start of the Industrial Revolution, and can calculate how much CO2 that would produce. The estimated cumulative effect of that amount of CO2 very closely matches the actual buildup of CO2 in the atmosphere since the Industrial Revolution. Second, the oxygen content of the atmosphere has decreased by an amount almost exactly equal to what would be consumed by the burning of that amount of fossil fuels. The third confirming fact is a little more complicated. It involves the ratio between a radioactive isotope of carbon, C14, and the principle isotope, C12, in the atmosphere. All living things that absorb carbon dioxide from the atmosphere into their cells contain those two isotopes in that same ratio. But since C14 is unstable, it decomposes with time and the C14 to C12 ratio decreases. The half-life of C14 is a little over 5,000 years, which enables that ratio to be used to date the age of organic objects pretty accurately up to about three half-lives, or 20,000 years. Obviously, fossil fuels millions of years old no longer contain any measurable amount of C14. And that provides the third proof that burning of fossil fuels is the source of the increase in atmospheric CO2 over the past two centuries. The decrease in the C14/C12 ratio in atmospheric CO2 from its historic value precisely matches that calculated from the amount of fossil fuels burned during that time.

My final comment is on the denier’s argument that the effect of so-called greenhouse gases (primarily CO2) is insignificant compared with the much more massive amount of water vapor that forms clouds. Clouds have always acted as an insulating blanket, but the greenhouse gas effect is quite different. It is caused by a molecular excitation of those gases by solar radiation, which generates large amounts of heat. It is similar to an electric blanket, which like clouds provides insulation when it is not turned on, but turn on the electricity and you create heat.

Is any more proof needed that global warming is real, that we are the cause, and that prompt action is critical if we are to pass on a livable planet for future generations?

– Glenwood Springs resident Hal Sundin’s column runs every other Thursday in the Post Independent.

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