Publication Abstracts

Henderson-Sellers and Gornitz 1984

Henderson-Sellers, A., and V. Gornitz, 1984: Possible climatic impacts of land cover transformations, with particular emphasis on tropical deforestation. Climatic Change, 6, 231-257, doi:10.1007/BF00142475.

The climatic impact of albedo changes associated with land-surface alterations has been examined. The total surface global albedo change resulting from major land-cover transformations (i.e. deforestations, desertification, irrigation, dam-building, urbanization) has been recalculated, modifying the estimates of Sagan et al. (1979). Tropical deforestation (11.1 million ha/yr, or 0.6% /yr, Lanly, 1982) ranks as a major cause of albedo change, although uncertainties in the areal extent of desertification could conceivably render this latter process of similar significance. The maximum total global albedo change over the last 30 yr for the various processes lies between 0.00033 and 0.00064, corresponding to a global temperature decrease of between 0.06 K and 0.09 K (scaled from the 1-D radiative convective model of Hansen et al., 1981), which falls well below the interannual and longer period variability.

An upper bound to the impact of tropical deforestation was obtained by concentrating all vegetation change into a single region. The magnitude of this modification is equivalent to 35-50 yr of global deforestation at the current rate, but centered on the Brazilian Amazon. The climatic consequences of such tropical deforestation were simulated, using the GISS GCM (Hansen et al., 1983). In the simulation, a total area of 4.94×106 km2 of tropical moist forest was removed and replaced by grass/crop cover. Although surface albedo increased from 0.11 to 0.19, the effect upon surface temperature was negligible. Hwoever, other climate parameters were altered. Rainfall decreased by 0.5-0.7 mm/day and both evapotranspiration and total cloud cover were reduced. This absence of a temperature decrease in spite of the increased surface albedo arises because the reduction in evapotranspiration has offset the effects of radiative cooling. The decrease in cloud cover also counteracts the increase in surface albedo. These locally significant changes had no major impact on regional (Hadley or Walker cells) or the global circulation patterns.

We conclude that the albedo changes induced by current levels of tropical deforestation appear to have a negligibly small effect on the global climate.

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BibTeX Citation

@article{he04000r,
  author={Henderson-Sellers, A. and Gornitz, V.},
  title={Possible climatic impacts of land cover transformations, with particular emphasis on tropical deforestation},
  year={1984},
  journal={Climatic Change},
  volume={6},
  pages={231--257},
  doi={10.1007/BF00142475},
}

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RIS Citation

TY  - JOUR
ID  - he04000r
AU  - Henderson-Sellers, A.
AU  - Gornitz, V.
PY  - 1984
TI  - Possible climatic impacts of land cover transformations, with particular emphasis on tropical deforestation
JA  - Climatic Change
VL  - 6
SP  - 231
EP  - 257
DO  - 10.1007/BF00142475
ER  -

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