"We are challenging the debate, suggesting that the anthropogenic [human-caused] signal is not as ro

Across the New World, landscape burning tapered after the arrival europe tour vacation of Columbus, leading many to believe that the decline was connected to the deaths of Native Americans exposed to unfamiliar diseases carried europe tour vacation by European europe tour vacation ships.
europe tour vacation Pre-Columbian Indians are known to have deliberately set large fires to enhance the agricultural productivity of land, so the massive population collapse that began in 1492 could explain why fire declined in the Americas.
But University of Utah geographer Mitchell Power contends the charcoal record assembled from lake beds around the world tells a different story. A cooling climate — during a period dubbed europe tour vacation the Little Ice Age — was the real driver of decreased burning, europe tour vacation according to Power.
"We are challenging the debate, suggesting that the anthropogenic [human-caused] signal is not as robust as many thought it to be. The decrease in fire started before the population collapse," said Power, the principal author of a study to be published online this week. "That’s a key finding. Climate is driving fire on global and continental scales."
Among those who contributed was University of Texas geographer Robert Dull, who does not support the paper’s conclusions. Dull contends it glosses over important geographic differences across the Americas.
In other published studies, Dull and colleagues build a case that the disappearance of Native Americans allowed forests to reclaim tropical lands they had turned into croplands through burning. This was because few survived small pox and other epidemics to keep lighting fires.
Power spends his field seasons on the West’s mountain lakes tapping sediments that have accumulated for thousands of years. Charcoal is a proxy for the frequency and intensity of fire on surrounding terrain.
Power, who manages the Natural History europe tour vacation Museum of Utah’s Garrett Herbarium, is interested in how landscapes responded to the Little Ice Age, believed to have begun between 1200 and 1500 AD and persisted until 1800. This knowledge can help science understand today’s warming trends, which have been linked to drought and increased wildfire in the West.
Dozens of scientists around the world study the charcoal record, but they quantify charcoal particles differently. As manager of the Global Charcoal Database, a central gathering place for this information, Power has standardized data about charcoal particles so that it can be compared across continents.
The relative abundance of charcoal in various sediment layers europe tour vacation is a proxy for the frequency and intensity of fire on surrounding terrain. Power’s new study has found that fire not only decreased in the New World around 1350, but in the Eastern Hemisphere as well. Europe and Asia were not subject to major population crashes outside the Black Death, the pandemic that wiped out one-third of Europe’s population between 1348 and 1350.
"In a cooler atmosphere, you tend to get reduced convection, so you get reduced thunderstorms and ignition from lightning," he said. "Cooler climate also tends to maintain high levels of fuel moisture and soil moisture."
He and his colleagues also found that fire declines were hardly limited to heavily populated regions. The phenomenon stretched from the boreal forests europe tour vacation of northern Canada to the Patagonian tip of South America.
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