Carbon Dioxide: Friend or Foe?
May 20, 2013
Differing opinions about the link between carbon dioxide and climate change have been in the news lately. On May 10, the New York Times reported that the level of carbon dioxide has reached its highest level in millions of years and warned that "this represents a march toward disaster." The day before, a Wall Street Journal opinion piece argued that increased carbon dioxide in the atmosphere will benefit our increasing population by increasing agricultural productivity.
It's no wonder people are confused.
According to Harrison H. Schmitt and William Happer, professors of engineering and physics respectively, carbon dioxide has gotten a bad rap. They argue that of all the world's essential chemical compounds, none has a worse reputation than carbon dioxide. The authors assert that carbon dioxide has been "demonized by advocates of government control of energy production," but in fact, it's a boon to plant life and has little correlation with global temperature. And, they say that there isn't the slightest evidence that more carbon dioxide in the earth's atmosphere has caused more extreme weather.
On the other hand, scientific monitors have reported that carbon dioxide has reached an average daily level that surpassed 400 parts per million for the first time in modern history, and that evidence suggests that the level of carbon dioxide in the atmosphere hasn't been this high for at least three million years, before humans evolved. Some scientists believe that this increase in carbon dioxide promises huge changes in the climate and sea levels.
Peter P. Tans, who runs the carbon dioxide monitoring program at the National Oceanic and Atmospheric Administration, says that the rise "symbolizes that so far we have failed miserably in tackling this problem," and Ralph Keeling, who runs another monitoring program at the Scripps Institution of Oceanography in San Diego, asserts that the rise "means that we are quickly losing the possibility of keeping the climate below what people thought were possibly tolerable thresholds."
According to the Times, scientists have learned that going back around 800,000 years, the carbon dioxide level was about 180 parts per million during the ice ages, and moved to about 280 parts during the warm periods in between. These scientists believe that global temperatures and CO2 levels are tightly linked, and that the last time that carbon dioxide levels were this high, the world's ice caps were smaller and sea levels were as much as 60 or 80 feet higher.
However, Messrs. Schmitt and Happer suggest that the current 400 parts per million is low by standards of geological and plant evolutionary history. They assert that levels of 3,000 parts per million were common during the Paleogene period (beginning about 65 million years ago) when plants and animals flourished on land and in the oceans. In fact, they argue that operators of greenhouses artificially increase the carbon dioxide levels in their structures to 1,000 parts or more to improve the growth and quality of their plants.
So, who is right?
Messrs. Schmitt and Happer state that crop yields in recent dry years were less affected by drought than crop of the dust-bowl droughts of the 1930s because of increased carbon dioxide levels. They believe that humanitarians should be arguing in favor of increased carbon levels in order to help feed the world's rising population. And, other climate change contrarians point out that carbon dioxide actually represents a very small portion of the atmosphere – about .04 percent.
But, climate scientists mostly reject those arguments asserting that even at low levels, carbon dioxide traps heat near the surface of the earth and this impacts our climate. And, unless greater efforts are made to reduce carbon emissions soon, the goal of limiting global warming will become impossible without severe economic disruption.
A recent article in the New York Times Science Times section (May 14), examines the link between levels of carbon dioxide and predicted rises in the earth's temperature. Some scientists now believe that climate change might be slow enough and limited enough for society to adapt without major disruptions. These experts think that contrary to previously published reports, the earth's temperature will not rise five to eight degrees, but only perhaps three or four. They also assert that the higher estimates of eight degrees are pretty unlikely.
Other climate scientists believe that even a change of four or five degrees will have a major impact on the earth's climate, causing weather extremes like heat waves and torrential rains. They also warn that human behavior being what it is, we may see carbon dioxide levels climb to three or four times their current levels before emissions are finally reined in.
Obviously, carbon dioxide is an essential part of life on earth and keeping it from spinning completely out of control seems like a good thing. The question really is: how much of a good thing is too much? Scientists and politicians don't agree on the answer to this question, so companies and their employees are left to make what they think is the wisest and most prudent decisions about whether – and how much – to reduce their own carbon footprints, or to let them grow unencumbered.
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P.S. Did you know that plants – just in the Northern Hemisphere -- pull about 10 billion tons of carbon out of the air each year?