Biotic pump

The theory of a biotic pump pertains to the importance of forests in the water cycle, specifically, in determining the levels of rainfall a region will receive. It states that an increased amount of evaporation or transpiration will cause a reduction in atmospheric pressure as clouds form, which will subsequently cause moist air to be drawn to regions where evaporation is at its highest. In a desert this will correspond to the sea whereas in a forest, moist air from the sea will be drawn inland. The theory predicts two different types of coast to contentinental rainfall patterns, first in a forested area one can expect no decrease in rainfall as one moves inland in contrast to a deforested region where one observes an exponential decrease in annual rainfall. Whereas it is true current global climate models fit these patterns as well, it is argued this is due to parametrization and not the veracity of the theories.[1]

This theory is in contradiction of the more traditional view that surface winds are solely a direct product of differences in surface heating and heat released from condensation.[2][3] The creators of the theory argue that phase changes in water play a greater role in atmospheric dynamics than currently acknowledged.