In response to claims made by Michael Ivey’s letter [“Carbon Dioxide Does Not Cause Global Warming,” Dec. 25 Xpress], I have provided some clarification from the Intergovernmental Panel on Climate Change.
Mr. Ivey states that “CO2 is not a pollutant and has never caused the atmosphere to warm.”
From Climate Change 2007: Working Group I: The Physical Science Basis:
“The reason the Earth’s surface is this warm is the presence of greenhouse gases, which act as a partial blanket for the longwave radiation coming from the surface. This blanketing is known as the natural greenhouse effect. The most important greenhouse gases are water vapour and carbon dioxide. The two most abundant constituents of the atmosphere — nitrogen and oxygen — have no such effect. … Human activities intensify the blanketing effect through the release of greenhouse gases. For instance, the amount of carbon dioxide in the atmosphere has increased by about 35 percent in the industrial era, and this increase is known to be due to human activities, primarily the combustion of fossil fuels and removal of forests. Thus, humankind has dramatically altered the chemical composition of the global atmosphere with substantial implications for climate.”
In another statement, Mr. Ivey states that the IPCC “admits that there has been no warming over the last 16 years.”
From Climate Change 2007: Working Group I: Frequently Asked Question 3.1 “How Are Temperatures on Earth Changing?”:
“Expressed as a global average, surface temperatures have increased by about 0.74 degrees Celsius over the past hundred years. However, the warming has been neither steady nor the same in different seasons or in different locations. There was not much overall change from 1850 to about 1915, aside from ups and downs associated with natural variability but which may have also partly arisen from poor sampling. … Warming, particularly since the 1970s, has generally been greater over land than over the oceans.”
I do not think that Mr. Ivey has provided evidence against the claim that “carbon dioxide is causing the Earth’s atmosphere to heat up.”
— Arnold Gnilka
Weaverville
