Using a climate model, we changed the Earth’s rotation direction from counter-clockwise to clockwise, keeping the period of 24 hours the same. The purpose of this experiment was to better understand how various climate variables are affected by Earth’s rotation. The results give insight into patterns of today’s climate, and help to frame discussion of future climate changes. The model used was GFDL CM2c, a course climate model that utilizes coupled ocean-atmosphere physics. The model was run for a 100-year control simulation, followed by a 700-year reverse rotation simulation. Model output revealed drastic changes in many of Earth’s climate variables. The main effect was that atmospheric flow pattern switched directions, with westerlies becoming easterlies, and vice versa. Because of this, ocean currents switched to opposite sides of ocean basins and there was a new distribution of sea surface temperature. As a result of these changes, global precipitation and temperature patterns were greatly affected. Some dry areas, such as the Sahara Desert, were now wetter, and some wet areas, such as the southeastern U.S., were now deserts. Albedo and ice coverage increased in the Northern hemisphere, possibly due to the ocean circulation changes. Unexpectedly, the thermohaline circulation weakened significantly in the Atlantic Ocean while a similar circulation developed and strengthened in the Pacific Ocean. These results are fascinating and important for testing current knowledge of the climate system.