科研之友
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摘要
Identifying the drivers of changing continental runoff is key to understanding current and predicting future hydrological responses to climate change. Potential drivers of runoff change include changes in precipitation and evaporation caused by climate warming, physiological responses of vegetation to elevated atmospheric CO2 concentrations, increases in lower-atmosphere aerosols and anthropogenic land-cover change. In this study, we present a series of simulations using an intermediate-complexity climate and carbon cycle model to assess the contribution of each of these drivers to historical and future continental runoff changes. We present results for global runoff, in addition to northern latitude runoff that discharges into the Arctic and North Atlantic oceans, to identify any potential contribution of increased continental freshwater discharge to changes in North Atlantic deep-water formation. Between 1800 and 2100, the model simulated a 26% increase in global runoff and a 32% runoff increase in the northern latitude region. This increase was driven by a combination of increased precipitation from climate warming and decreased evapotranspiration caused by the physiological response of vegetation to elevated CO2. When isolated, climate warming (and associated changes in precipitation) increased runoff by 16% globally and by 27% at northern latitudes. Vegetation responses to elevated CO2 led to a 13% increase in global runoff and a 12% increase in the northern latitude region. These changes in runoff, however, did not affect the strength of the Atlantic Meridional Overturning Circulation, which was affected by surface ocean warming rather than by runoff-induced salinity changes. This study indicates that physiological responses of vegetation to elevated CO2 may contribute to changes in continental runoff at a level similar to that of the direct effect of climate warming.
- 出版日期2012
