Climate Science

The Effects of Land-Use Change

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Science  22 Mar 2013:
Vol. 339, Issue 6126, pp. 1360
DOI: 10.1126/science.339.6126.1360-b

Land-use changes around the world are affecting local and regional climate, but the exact patterns of these changes remain poorly understood. Georgescu et al. modeled the hydroclimatic effects of the boom in sugarcane production within south-central Brazil, where most of the sugarcane plantations are located and where further intensification is expected. In their model, conversion from other cropland or savannah to sugarcane leads to a cooling by around 1°C at the peak of the growing season, because sugarcane reflects more incoming sunlight than does the former land cover. Warming by ∼1°C is found after harvest. Rainfall changes were more difficult to predict, but the authors suggest that a net annual drop in the transfer of water from land to atmosphere could lead to reduced rainfall. Christidis et al. analyzed past observations and model results to find out whether land-use changes across the world have had an effect on temperature extremes. Trees absorb more incoming sunlight than grassland; thus, replacing trees with grasslands tends to cool the climate. The authors find that this effect of land-use change can be detected in mean and extreme warm temperatures, although the effect is much smaller than the warming caused by other human influences on the climate. These two studies suggest that land-use changes must be included in projections of future climate change.

Geophys. Res. Lett. 10.1002/grl.50206; 10.1002/grl.50159 (2013).

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