SPOKANE — Theories about increasing global temperatures fail to take into account the impact of factors other than the amount of carbon dioxide in the atmosphere and the cyclic nature of climate, a well-known meteorologist told farmers on Feb. 2.
Art Douglas, professor emeritus at Creighton University in Omaha, Neb., spoke about global warming during his presentation at the Spokane Ag Expo and Pacific Northwest Farm Forum.
One problem he sees is relying on air temperature records.
“I trust sea surface temperatures more than I do air temperature,” Douglas said. “Air temperature is screwed up by cities. You have a whole mix of things that can screw up an air temperature record.”
Much has been said because the last two years were the warmest on record, with the globe warming by 0.7 degrees centigrade.
However, Douglas said that carbon dioxide and global temperature patterns from the last 50 years seem to match cyclical patterns going back 400,000 years.
He showed two charts — one of the carbon dioxide content of the atmosphere and one of the air temperatures — that were produced using Antarctic ice core samples and go back 400,000 years. In those cycles, global temperatures increase as the amount of carbon dioxide increases — and both cycle lower after reaching a peak before building back up.
Douglas said the recent warming trend can be attributed 50-50 to human activity and natural climate variability.
Assigning contributions to global warming solely by each carbon dioxide emissions ignores the impacts of other climate cycles and sun spots, Douglas said.
“Historically speaking, we’re in a very cold period and a low CO2 period in terms of the planet,” Douglas said.