This study investigated the relationship between climatic variables and the abundance of red pine (PinusresinosaAit.). Two aspects of this climate–abundance relationship were addressed. First, a model was developed to fit the present day range and abundance of red pine using available climatic variables in the expectation of better understanding the processes controlling distribution. Second, general circulation models were used to explore the implications of a 2 × CO2(greenhouse warming) environment on the range and abundance of red pine. Using a response surface, growing degree-days (base 10 °C), and precipitation explained 54% of the variance in an independent data set of red pine volume per unit area. Possible explanations for the present day boundaries of red pine are competition for the southern limit, insufficient moisture for the southwestern limit, and insufficient warmth during the growing season at the northern limit. The greenhouse warming simulation suggested a dramatic northeastward shift of 600–800 km in the potential range of red pine and a decrease in total area, but it also suggested higher volumes per unit area.