Land-cover impacts on global climate can be divided into two major categories: biogeochemical and biogeophysical. Biogeochemical processes affect climate by altering the rate of biogeochemical cycles, thereby changing the chemical composition of the atmosphere. Biogeophysical processes directly affect the physical parameters that determine the absorption and disposition of energy at the Earth's surface. Albedo, or the reflective properties of the Earth's surface, alters the absorption of solar radiation and hence energy available at the Earth's surface. Surface hydrology and vegetation transpiration characteristics affect how energy received by the surface is partitioned into latent and sensible heat fluxes. Vegetation structure affects surface roughness, thereby altering momentum transport and heat transport. Summarizing the effects of land-cover change on climate has been difficult because different biogeophysical effects offset each other in terms of climate impacts and, on global and annual scales, regional impacts are often of opposite sign and are therefore not well represented in annual global average statistics. One of the methods used to separate the above-mentioned impacts is through the use of complex models together with global land cover data.
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