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Letter: Misrepresenting Climate Science

To the Editor:

Daniel Botkin (Forum, Feb. 8) looks at evidence for global warming and finds it “contradictory.” Unfortunately, far from putting balance into the discussion, he misrepresents the scientific evidence. He claims that, because the paleontological record indicates changes in carbon dioxide follow changes in temperatures by about 600 to 1,000 years, carbon dioxide cannot be responsible for current global warming. But the role of carbon dioxide is more complex. Past climate change has been initiated by changes in the Earth’s orbit called the Milankovitch cycles. These warmed the oceans enough to cause them to expel large amounts of carbon dioxide, and this became the primary driver of the warming. Overall, about 90 percent of the global warming occurred after the increase in carbon dioxide. An excellent antidote to Mr Botkin’s nonsense is a presentation by Richard Alley called “The Biggest Control Knob: Carbon Dioxide in Earth’s Climate History” (available on YouTube).

Our current warming is occurring far more rapidly than the 100,000 years required for a full interglacial cycle, and the carbon dioxide is not coming from the ocean but from humans. Contrary to his assertion, while the solar activity has been a driver of climate change in the past, the sun has shown no upward trend in activity for more than 35 years, so it is not responsible for current warming.

Botkin says that global temperatures are not “tracking” carbon dioxide. But climate is a complex system, and scientists don’t expect a steady increase in global temperatures. One can “cherry-pick” other periods that show no upward trend but if you look the long-term record, the trend is unmistakable.

Global warming is indeed a scientific issue. But the actions we take or fail to take today will have a significant negative impact on generations to come. That, to me, is a moral issue as well.

Michael Hillinger

Etna