One of the lesser-known pollution facts concerns thermal pollution. Thermal pollution is the increase of temperature caused by human activity. An example of this includes warming lake water, which happens when factories use cool water from a lake to cool their plant and then pump the now warm water back into the lake. Thermal water pollution can cause huge damage to many aquatic ecosystems because there are many fish and other aquatic organisms that have adapted to particular temperature of the water and once this temperature changes they often fail to adapt and die in the process as a result of thermal shock.