大象传媒

The size of the wildfires currently engulfing the west coast of America is so massive that the smoke has even been reported over the skies of New York city, on the other side of the US. People for miles around the affected area are suffering from poor air quality.

State and federal politicians have gone head to head over the causes of these, with some blaming global warming, others the mismanagement of the forests. Scientists who have studied trees in the area believe some of the current problems are actually rooted in misguided policies that are decades old. Valerie Trouet, a professor of dendrochronology (the study of dating and interpreting tree rings) at the University of Arizona explains why controlled fires during cool, calm months are needed and why the recent fires are worse than those of previous centuries.

"This is not happening in a vacuum. Conditions are getting hotter. All of that fuel that has been built up over a century is drier. A no-fire option as we have been experiencing in California for the last century - that's no longer available."

(Photo: The Bobcat fire burns in the Angeles National Forest, California. Credit: EPA)

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