Global warming complex

Jack DeBaun’s Sept. 28 letter (“Listen to climate scientists”) about climate change is inaccurate. He stated that “The only factor that now correlates with this rapid rise in worldwide temperatures is the increase in human-caused atmospheric carbon dioxide.”

Correlation is a statistical measurement of the relationship between two variables, which would involve comparing each possible global warming variable (e.g., the Milankovitch theory, volcanic eruptions, meteoroid impacts, plate tectonics, etc.) with carbon dioxide concentrations. No such correlation exists.

DeBaun failed to mention that global warming occurred about 425,000, 325,000, 275,000 and 125,000 years ago (an average of about every 100,000 years). Man was certainly not responsible, and the global temperatures spiked then returned to normal. Why?

DeBaun failed to consider that past warming spikes roughly “coincide” with the Milankovitch cycle (about every 100,000 years the global climate spikes due to the Earth’s orbit around the sun). DeBaun failed to mention the fact that our planet is in a natural warming trend because it is coming out of a glacial age (peaked at about 20,000 years ago).

Global warming is a complex issue and to date, no “correlation” has been established.

Doug Scott

Spokane