Impact of CO2 doubling in the global climate simulated by a atmosphere general circulation model with variable grid

Abstract

The objective of this work is to evaluate climate changes caused by atmospheric CO2 concentration duplication. The LMD-Z atmosphere general circulation model (AGCM) was used (Laboratoire de Météorologie Dynamique - France). The model was integrated for a fifty years period and only the last forty years were used for analyses. This experiment have made two simulations: the first using the current CO2 concentration (control case) and the second using this concentration doubled (duplication case). Both were made with a variable spatial resolution with maximum of it centered in Rio de Janeiro. This way, there is a significant increase of model resolution in this region. To verify climate changes, anomaly fields generated by the model (duplication case minus control) were studied. It was possible to observe some characteristic effects of this type of experiment, such as great temperature increasing at surface in polar regions and in upper levels at low latitudes, cooling in stratosphere and intensification of hydrological cycle.