October 9, 2003
by Dennis T. Avery
The global warming theory says that an increase of carbon dioxide (CO2) in the atmosphere will trap more of the sun’s heat and “overcook” the planet. The global climate computer models are programmed to assess how much overcooking we’ll suffer.
But, in the past, have changes in CO2 levels raised—or lowered—real-world temperatures? Recently, both the earth’s temperatures and the CO2 levels in the atmosphere have been rising. But the temperature increase could be just the earth’s recovery from the Little Ice Age, which lasted until about 1850. (Most of the recent warming occurred between 1880 and 1940)
The fact that humanity’s industrial CO2 emissions are rising strongly during the recovery from the Little Ice Age could be just happenstance. Linking cause (a CO2 increase) with effect (higher temperatures) calls for more than a coincidence of timing.
The world has had lots of warmings and coolings through its history, including massive Ice Ages. What can science tell us about the relationship of CO2 and temperature?
A team of ice-core researchers, led by Hubertus Fischer of the Scripps Institute of Oceanography in California, analyzed an Antarctic ice core that gives real-world records of atmospheric CO2 and air temperatures back to 240,000 years ago. The ice core record includes three massive Ice Ages, and the warming periods that followed them.
When the Ice Ages ended, the Scripps researchers found that air temperatures warmed long before there was any increase in atmospheric CO2. In fact, they said, the increases in CO2 lagged the warming by 400 to 1,000 years! That’s just the opposite of the greenhouse theory that CO2 increases lead to warming. (The Fischer team’s analysis was published in the March 12, 1999 issue of Science.)
Eric Steig of the Earth and Environmental Science Department at the University of Pennsylvania argues that CO2 rises during cold periods because they are drier. (Less moisture is evaporated into the air from the oceans, and thus there is less moisture to fall as rain or snow). The drier climate supports less plant life, and carbon is eventually released into the atmosphere from dying trees and then from the soil itself.
In addition, the Fischer team found a 15,000 year period following the second Ice Age when the air’s CO2 content stayed constant while the air temperatures dropped back to near-glacial levels. That doesn’t follow the greenhouse theory either.
Recently, another Scripps team, led by French expert Dr. Nicholas Caillon, also tested Antarctic ice cores, but used a more-accurate argon proxy to measure the CO2 lag more precisely. The Caillon team says their work confirms the Fischer findings (that CO2 increases lagged behind the Antarctic warming) but say argon gives them a more precise estimate of the lag—800 to 200 years.
“This confirms that CO2 is not the forcing that initially drives the climatic system during a deglaciation,” they wrote in Science, March 14, 2003
So real-world Antarctic history shows several cases of CO2 lagging behind, not leading, when the earth warms. It shows another case of CO2 holding constant when the earth is getting cooler. These events do not conform to the greenhouse theory.
The greenhouse theory and all that expensive computer modeling depend on a strong correlation between CO2 and temperature. If CO2 lags warming, or is independent of it, then the computer models are useless.
There is no question that the earth is getting warmer, but a recent study of iceberg debris on the floor of the North Atlantic shows this happens naturally every 1500 years or so, in a cycle that coincides with a known cycle in the magnetic activity of the sun. (That study was led by Dr. Gerard Bond, of the Lamont-Doherty Earth Observatory in Palisades, NY, and published in Science on Nov. 16, 2001.)
If the warming is natural, we won’t be able to stop it no matter how heavily we tax energy, nor how many lives we sacrifice to (1) heat stroke (no summer air conditioning), (2) cold stress due to the high cost of furnace fuel, and (3) food shortages (restricting natural gas for fertilizer production). Nor how many lives we sacrifice to continuing poverty in a Third World that won’t be able to afford any energy except wood from its shrinking forests. The economic shocks of the Kyoto Protocol would be felt most severely by the very young, the very old, the very poor—and the forest wildlife.
Do we owe them something more than a titillating theory that isn’t borne out by the real history of the real world?
Dennis T. Avery is based in Churchville, VA, and is director of the Hudson Institute's Center for Global Food Issues.
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