Slide 3 : Climate change
When the average and extreme events betray a long term transformation in the overall climatic conditions, it is termed climate change. The earth has experienced considerable change in climatic conditions, due to natural variations in the solar cycle, and the composition of the atmosphere. Even orogeny, which is the development of new surface features and transformation of ocean basins through geological processes, causes long term climate change. In recent prehistory, the human race has experienced climate change: the most recent ice age ended about 10,000 years ago, and today we are experiencing a relative climatic optimum. It is telling that although biologically modern humans have been around for more than 150 000 years, human civilization and agriculture only occurred once the earth warmed to the current levels.