By DR. DON J. EASTERBROOK
Dr. Don J. Easterbrook, a professor of geology, is a resident of Hailey.
The recent talk by Al Gore and the editorial in the Friday issue of the Idaho Mountain Express underscore the seriousness of global warming. However, both miss some very important points:
The debate is not about whether or not global warming is real. It's about what is causing global warming. Almost no scientists deny that global warming is occurring or that atmospheric CO2 is higher now than ever before, but the latter does not prove the former. Many scientists have presented solid geologic evidence that CO2 is not the cause of global warming.
The Gore presentation and the Intergovernmental Panel on Climate Change dogma that CO2 is the cause of modern global warming carries with it some dangerous assumptions. First, all of the computer models start with the assumption that as CO2 increases, so does global warming (so you can't prove global warming with computer models). Second, all we have to do is reduce CO2 emissions, and global warming will go away.
The single most important point of this column is that if we assume that we are the cause of global warming and that therefore we can fix it and thus make no preparations to cope with the warming itself, then global disaster surely awaits us.
Recent papers (available online at the site below) provide geologic evidence that CO2 may not be the cause of recent global warming, despite the media blitz. The global climate has been warming (and cool-ing) not just since manmade CO2 has risen, but over the past several centuries, long before rising CO2. Here are some geologic facts that cast doubt on the contention that CO2 is the cause of modern global warming:
Since 1977, both manmade atmospheric CO2 and global temperatures have risen, but during the previous 30 years (1945 to 1977), when atmospheric CO2 was increasing rapidly, global climates actually cooled, raising the question, if increasing CO2 is the cause of global warming, why did global climates cool during the most dramatic rise in CO2? If rising CO2 causes global warming, temperatures should have increased rather than decreased during this period (1945 to 1977).
Although atmospheric CO2 is now at an all time high, 80 percent of manmade CO2 emissions occurred after 1945. However, more than half of the global warming of the past century occurred before 1945, mostly between 1890 and 1940, when it could not have been caused by increased atmospheric CO2.
Global temperatures dropped sharply (about 4 degrees Fahrenheit) from the Medieval warm period (about 1200 A.D. to 1500 A.D.) to the Little Ice Age (about 1500 A.D. to about 1850 A.D.). During the Little Ice Age, a million people died of starvation and disease due to repeated crop failures. Since then, global temperatures have risen about 7 F, well before the rise in manmade atmospheric CO2. This global warming, which was more than seven times the amount of warming in the past century, cannot be attributed to manmade atmospheric CO2 because CO2 was low during that period.
The inescapable conclusion of these data is that CO2 could not be responsible for global warming of the past century because the only time that both CO2 and global temperature both increased was from 1977 to the present. Prior to 1977, global temperatures rose with no increase in CO2, or global temperatures dropped with increasing CO2.
These are but a few examples of the kind of geologic evidence of past global climate changes that were far more severe than those of the past century. These geo-logic data show that Earth's climate has fluctuated widely without any influence of atmospheric CO2, manmade or otherwise. The important point here is that no direct evidence exists that CO2 is the cause of modern global warming, and geologic evidence conclusively shows that far greater global climate changes have occurred that could not have been caused by CO2.
If global warming is not caused by atmospheric CO2, then the computer models that predict global catastrophe are meaningless, and a real danger lies in assuming that if we can only reduce atmospheric CO2, global warming will cease. To be sure, global CO2 needs to be reduced, but if we assume we can fix the problem, rather than planning on how to cope with continued global warming, dire results can be expected.
For more details, go online to the Geologic Society of America's Web site and paste in this URL: http://gsa.confex.com/gsa/2006AM/finalprogram/abstract_108164.htm. Click on: "Presentation Handout" at the bottom of the page for the text version of the global warming paper. Click on: "Presentation Handout" at the bottom of the page for slides of the second global warming paper.
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