Climate Number: Two Tons
Over the past 250 years, the amount of carbon dioxide (CO2) in the atmosphere has risen from 280 parts per million to almost 400. Plants use sunlight to convert this atmospheric carbon into the sugars and starches that make up their tissues. As the amount of carbon in the atmosphere changes, plant growth patterns change as well. Longer growing seasons, the period of the year when freezing temperatures do not restrict growth, as well as warmer temperatures in general, also affect plant growth. All three of these climate trends (more CO2, longer growing seasons and higher temperatures) have been occurring in the forests of America’s Mid-Atlantic region over the past century. During this period, plant growth in these forests accelerated. Each acre accumulates a certain amount of “biomass” each year, which reflects how much carbon these forests take out of the atmosphere and store in their bodies. Each acre of Mid-Atlantic forest is now accumulating about two more tons of biomass each year than they did in 1900.
For Comparison: Two tons is about the same weight as two mature Hereford bulls.
Seasons: Spring, Summer, Fall
Sources: McMahon, SM et al. “Evidence for a recent increase in forest growth.” Proceedings of the National Academy of Sciences 107 (2010): 3611-3615 and “Forests are Growing Faster, Ecologist Discover; Climate Change Appears to be Driving Accelerated Growth.” Science Daily 2 February 2010. Accessed Online 28 February 2010 <http://www.sciencedaily.com/releases/2010/02/100201171641.htm>)
