One of the main causes of sudden warming in western Canada in the early 21 th century was an unprecedented epidemic of bark beetles that have destroyed great part of forests in this part of North America, say scientists in a paper published in the journal Nature Geoscience.
It is believed that emissions of carbon dioxide and other greenhouse gases as well as deforestation and other human activities are the main drivers of climate change. In particular, the increase in average temperature by 1 degree Celsius in the western and northern Canada is associated with the "contribution" of man in the process.
Group of environmentalists led Manesse Holly (Holly Maness) from the University of California at Berkeley (USA) has found that it is not so by examining satellite images of Canadian forests over the past few seasons.
As the researchers note, in the last decade of forest in British Columbia and other provinces in Western Canada are subjected to massive attack by bark beetles Dendroctonus ponderosae. In normal circumstances these beetles act as orderlies forests, destroying the weak and diseased trees. However, in recent years the population has grown by over mild winters and dry summer months, as a result, began to destroy the bark beetles and healthy areas of the forest.
Manesse and her colleagues evaluated the effects of their "attacks" in the forests of Canada with images obtained climatic MODIS satellite from 2000 to 2010.
In particular, the researchers tracked the average temperature of the day and night over some areas of forests, measured amount of vapor, which is released into the atmosphere flora, as well as other factors analyzed. Next, the authors compared the data with how badly affected the forest from bark beetle attacks.
It was found that the highest temperatures during the day were observed in those parts of the forest, in which almost all of the trees were destroyed colonies Dendroctonus ponderosae.
Believed to environmentalists, the phenomenon can be explained by the fact that the forest "cool" soil, releasing water molecules in the atmosphere, and other volatile substances that absorb the solar energy and do not let the soil warm up. Dead trees destroyed by bark beetles, do not emit steam into the atmosphere, causing daytime temperatures rise.
According to calculations Manesse and her colleagues, the spread of bark beetles in the forests in western Canada led to a reduction of emissions by 19% steam, which increased heating of the soil by 8%. This resulted in an increase of average temperatures by one degree Celsius.
The authors believe that further expansion of the "epidemic" bark can lead to other negative consequences — changes in precipitation and wind direction. At the moment, these climate changes are unlikely, since the areas of forests, "captured" bark beetle, far enough apart from each other.