听力原文： American researchers say cutting down trees in snow regions might help counter the effects of global warming. The findings highlight the complexity of the planet as it'd previously been understood that mass deforestation contributed to global warming. It's been a woe cry for environmentalists in recent years 'Mass deforestation contributes to global warming.' But that argument may now have to be revised. Scientists in the United States have run a simulation of the effects of large-scale clearing. And they find that if trees were to be cut down in the icy northern regions, it would actually cool down the Earth. The reason: snow reflects sunlight and the great pine forests of Russia, Europe and Canada shade tens of thousands of hectares of reflective snow. What might help control global warming according to American researchers?