General circulation models (GCMs or global climate models) have been designed to simulate the planet's future climate. In the past 30 years climate modelers have been improving the GCMs' spatial resolution from the first assessment report (FAR-1995) to the fourth report (AR4-2007) for the IPCC (Intergovernmental Panel for Climate Change) to meet the needs of climate change impacts models simulating finer scale processes. The scale has changed from ~500 km x 500km grid cells to ~110 x 110 km grid cells (see figure to right; source of graphics: IPCC 2007).