A thermostat in an oven When you set an oven to a certain temperature, the ovens thermostat is set so that if the temperature is more than a few degrees hotter it will turn off. If the temperature is more than a few degrees cooler, it will turn on again. The thermostat acts as a feedback, and regulates the oven s temperature. This is a negative feedback because it takes the initial change and prevents it from going too far. If temperatures warm up because of an enhanced greenhouse effect, then the area covered by snow cover and sea ice will probably decrease.
Climate models are mathematical simulations of the climate system that are programmed on computers.
Since the earth system is so complicated, the models are always not exact replicas of the planet, but are necessarily much more simple. They are used to simulate the climate of the earth under current conditions, under past conditions, and for a range of possible future conditions. Many areas of scientific research do not require models because people can perform experiments. For example, if a chemist wants to know what happens when a certain combinations of chemicals are mixed together under certain conditions, a controlled experiment can be arranged where all the chemicals are combined under specified temperature, pressure, and humidity. However, since we only have one planet earth, we cannot run many experiments.