Climate cited as New World fire influence

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SALT LAKE CITY, July 30 (UPI) -- Cooling climate, not population loss from disease, led to fewer fires in the New World in the years after Christopher Columbus' arrival, researchers say.

After the so-called "voyages of discover" by European explorers, fires in New World forests and fields diminished significantly, a trend some have attributed to decimation of native populations by European diseases.

But researchers at the University of Utah say their studies suggest global cooling resulted in fewer fires because both had preceded Columbus in many regions worldwide.

"The drop in fire [after about A.D. 1500] has been linked previously to the population collapse," geography Professor Mitchell Power, the study's principle author, said.

"We're saying no, there is enough independent evidence that the drop in fire was caused by cooling climate," he said in a university release.

The Utah study analyzed worldwide charcoal samples spanning 2,000 years.

Following Columbus in 1492, explorers brought European diseases such as smallpox that "decimated populations in the Americas -- 10 million to 100 million dead, with most estimates in the 60 million range," Power acknowledges.

"The decrease in fire on a very large scale -- globally and in the Americas -- was controlled by this cooling climate, which began prior to the population collapse, and climate alone is sufficient to explain large scale changes in burning.

"All these people died abruptly -- Mayans, Incas, Aztecs and down in Patagonia -- they were all affected."

While Power agrees population collapse may have meant less biomass burning in some local regions of the Americas, he said his study indicates the reduction in fire was actually global and began before Columbus in most areas, most likely due to climate cooling.

He points to the Little Ice Age, a period when Earth's climate grew colder, estimated to have started between the 1200s and the end of the 1400s and ending in the early 1800s.