Human Influence on the Climate System

Climate either from the earth as a whole or in one country or location is often described as the weather recorded over a long period. It is defined in terms of long-term averages and other weather statistics, including frequencies of extreme events. The climate is far from static. As the weather changes daily, the climate changes, over a period of several years, decades, and millennia and longer, corresponding to the geological history of the earth. These changes, caused by internal and external factors for the climate system, are naturally intrinsic to the climate itself. However, not all climate change is caused by natural processes. People also exercised influence. By building cities and changing land use…