Climate models use various methods to simulate the interactions of the atmosphere, oceans, land surface, and ice. All climate models take account of incoming energy as short wave electromagnetic radiation, chiefly visible and short wave infrared, as well as outgoing energy as long wave infrared electromagnetic radiation from the earth. Any imbalance results in a change in temperature. The most talked about models of recent years have been those relating temperature to emissions of carbon dioxide. These models project an upward trend in the surface temperature record, as well as a more rapid increase in temperature at higher altitudes. Researchers at the Max Planck Institute for Meteorology in Hamburg have developed a new model that specifies the maximum volumes of carbon dioxide that humans may emit to remain below the increased climate warming of two degrees Celsius. To do this, the scientists incorporated into their calculations data relating to the carbon cycle, namely the volume of carbon dioxide absorbed and released by the oceans and forests.