The results of the VEMAP activity are important scientifically because they are the first results that quantify the large-scale effects of the CO2 effect relative to quantitative estimates of actual forest growth. They confirm the growing suspicion of ecologists that CO2 fertilization is merely one of a number of processes resulting in the total uptake of carbon by ecosystems. They contradict the suggestion that North American ecosystem uptake balances its emissions of fossil fuel. The results suggest that when policies are made that requiring knowing ecosystem carbon uptake, policymakers must be aware that ecosystem carbon uptake can vary from year to year by large amounts. Therefore, short-term measurement periods could be very misleading. The high variability of ecosystem processes demonstrate why long term ecological measurements and research is so critical and urgently needed.