We told you so 20+ years ago!

We review 25+ years of published climate impacts projections for the continental United States under a variety of climate scenarios and compare them with observations from field and remote sensing. Summers have become warmer and drier, fire season longer, drought stress more severe, endemic pests more lethal, vegetation shifts obvious. We present results from a dynamic global vegetation model that has been used since 1995 to simulate ecosystem responses to a variety of climate futures. Strengths and weaknesses of the vegetation model and its drivers are listed but overall results show that despite its obvious shortcomings, the model simulated fairly well the observed trends and the order of magnitude of the changes. One major conclusion of the study is that uncertainty with climate and vegetation model projections is much less than that of human choices and sociopolitical decisions which affect land use and greenhouse gas emissions.