Beech trees are currently found throughout much of the eastern United
States (left panel). This distribution is determined largely by the climate.
Changes in climate as a result of the increasing concentrations of carbon
dioxide and other greenhouse gases are expected to change the optimum
growing range for beech trees, thereby changing their distribution. Predictions
of future climate conditions from the climate models of the NOAA
Geophysical Fluid Dynamics Laboratory (GFDL) and the NASA Goddard
Institute for Space Studies (GISS) have been used to estimate the types of
shifts in optimum growing range that could occur a century hence as a result
of changes in the concentrations of greenhouse gases alone (thus representing
an extreme condition). While this warming will likely be delayed somewhat
as a result of sulfate aerosol injections, the results suggest that the optimum
growing ranges may shift roughly 300 miles to the north, changing the
character of forests. The figure is adapted from M.B. Davis and C. Zabinsky,
Changes in geographical range resulting from greenhouse warming: Effects
on biodiversity in forests. In: Global Warming and Biological Diversity [R.L.
Peters and T.E. Lovejoy (eds.)]. Yale University Press, New Haven, CT (1992).