Researchers at Lawrence Livermore Laboratory have found evidence linking cooling earth temperatures between the years 1000 and 1900 to widespread deforestation. Though scientists have known ground cover affects temperature, the new findings indicate drastic climate changes attributable to land use. From a bird's-eye view, forests appear darker than agricultural land, for example, fields of grain or corn.
Dark colors tend to absorb sunlight, trapping the heat that warms the planet.
By contrast, lighter colors reflect solar rays back into space, resulting in cooler temperatures as the sunlight bounces away from the earth. Using data collected from geological observations, including studies of old tree ring widths and densities, scientists had long recognized the earth's climate cooled up to 2 degrees F between the years 1000 and 1900. Researchers theorized replacement of forests by agriculture and other land-use changes might have contributed to that change. The tests showed the regions that cooled more were the same regions where there were deforestations and dense human activity. It's saying there's one more factor we have to account for when we want to predict future climates.