There has been an assertion made about climate change in two recent letters that CO2 levels follow temperature change, in essence that rising temperatures are causing CO2 levels to rise (“Anthropogenic Warming — it is far from settled,” in the Oct. 16 edition of the Daily Journal and “The truth about CO2,” in the Oct. 29 of the Daily Journal). This line of reasoning about the current phenomenon of global warming and rising CO2 levels, however, does not accurately tell the whole story. The connection between rising temperatures and increasing CO2 levels is relevant to the four glacial-interglacial cycles during the last 450,000 years, with the last glacial period ending about 10,000 years ago. This is well before recorded human civilization began — certainly before humans started mining and burning fossil fuels — and is not applicable to current trends regarding CO2 and temperature increase.
At the end of each of the last four glacial periods, initial increases in temperature are explained by changes in the Earth’s orbit around the sun. This causes ocean temperatures to rise and the subsequent release of dissolved CO2 into the atmosphere as warmer water does not hold as much dissolved CO2. Soda quickly going “flat” on a warm day is an excellent example.
As oceans released their dissolved CO2, this amplified the warming trend, leading to more CO2 being released and creating a positive feedback loop. The effect of orbital changes alone is too weak to cause such a temperature variation and end an ice age, and there is no evidence that this is what is happening now.
The last 140 years do show an increase in CO2 levels produced through burning of fossil fuels (combustion uses oxygen and produces carbon dioxide). Current rising global temperatures can be best explained by the rising CO2 levels from this source.
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Keep the discussion civilized. Absolutely NO personal attacks or insults directed toward writers, nor others who make comments.
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PLEASE TURN OFF YOUR CAPS LOCK.
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