Nick Fetty | September 12, 2014
A study from Yale University suggests that the conversion of forests into cropland over a 150-year period has caused “a net cooling effect on global temperatures.”
The report, published in the journal Nature Climate Change by Yale School of Forestry and Environmental Studies professor Nadine Unger, found a reduction in the quantity of biogenic volatile organic compounds (BVOCs) released into the earth’s atmosphere. These compounds “control the atmospheric distribution of many short-lived climate pollutants, such as tropospheric ozone, methane, and aerosol particles.”
Unger used computer modeling to calculate a 30 percent decline in BVOC emissions between 1850 and 2000 – much of which was attributed to the conversion of forested areas into crop land – and a .18 degree Fahrenheit (.1 degree Celsius) reduction in global temperatures. During roughly this same period the amount of land worldwide being used for crops increased from 14 percent to 37 percent.
This reduction in global temperatures is dwarfed by the 1.08 degree Fahrenheit (.6 degree Celsius) increase caused by carbon emissions. Also, Unger was sure to point out “that the findings do not suggest that increased forest loss provides climate change benefits, but rather underscore the complexity of climate change and the multitude of factors involved.”
According to the Iowa Data Center, there were approximately 30,800,000 acres of farmland in Iowa in 2013.