For example, wind-driven surface currents like the Gulf Stream carry large amounts of heat from the tropics to colder latitudes, which warms the atmosphere above. Other surface currents carry cold water towards the equator, which cools the atmosphere. Over most of the oceans, surface water is warmer, and so less dense, than the water beneath it. This discourages surface water from sinking downwards into the deep ocean. It is the primary mechanism whereby heat and dissolved carbon in surface water is transported down to the ocean depths, where they may remain for a thousand years or more.
Ice reflects a significant amount of incoming solar energy back out into space.
The biosphere is made up of living organisms on land and in the seas. It helps to regulate climate through its role in the carbon cycle. Furthermore, land vegetation has a significant effect on surface reflectivity, heat, moisture, and energy. Because of the complexity of the biological processes involved, scientists can make only very general estimates of the biosphere s role in the climate system. Much more research will be needed before the biosphere s contribution to climate variation can be quantified.