Against the supposition that forest fires in Alaska, Canada and Siberia warm the climate, scientists have discovered that cooling may occur in areas where burnt trees allow more snow to mirror more
sunlight into space.
This finding suggests that taking steps to prevent northern forest fires to limit the release of greenhouse
gases may warm the climate in northern regions. Usually large fires destroyed
forests in these areas over the past decade. Scientists predict that with
climate warming, fires may occur more frequently over the next several centuries
as a result of a longer fire season. Sunlight taken in by the earth tends to
cause warming, while heat mirrored back into space tends to cause
cooling.
This is the first study to analyze all aspects of how northern fires influence climate. Earlier studies by
other scientists have suggested that fire in northern regions speed up climate
warming because greenhouse gases from burning trees and plants are released into
the atmosphere and thus trap heat.
Scientists found that right after the fire, large amounts of greenhouse gases entered the atmosphere
and caused warming. Ozone(臭氧)
levels increased, and ash from the fire fell on far-off sea ice, darkening the
surface and causing more radiation from the sun to be taken in. The following
spring, however, the land within the area of the fire was brighter than before
the fire, because fewer trees covered the ground. Snow on the ground mirrored
more sunlight back into space, leading to cooling.
“We need to find out all possible ways to reduce the growth of greenhouse gases in the atmosphere.”
Scientists tracked the change in the amount of radiation entering and leaving
the climate system as a result of the fire, and found a measurement closely
related to the global air temperature. Typically, fire in northern regions
occurs in the same area every 80 to 150 years. Scientists, however, found that
when fire occurs more frequently, more radiation is lost from the earth and
cooling results. Specifically, they determined when fire returns 20 years
earlier than predicted, 0.5 watts per square meter of area burned are soaked
up by the earth from greenhouse gases, but 0.9 watts per square meter will
be sent back into space. The net effect is cooling. Watts are used to measure
the rate at which energy is gained or lost from the earth.
机器翻译绕行,好的加分
机器翻译请绕行
追答那不好意思,谁能翻译谁翻译去