PNAS:欧洲免耕农业受到气候变化的影响

没有耕作的农田表现出了反照率和碳截存增加，这些特性可能部分缓解气候变化，然而免耕管理尚未在欧洲广泛采用。

为了研究在欧洲气候下全面转换为免耕管理的潜在影响，Edouard L. Davin及其同事测量了耕作和免耕农田的反照率，并且使用这些结果为可能的温度变化建模。

在法国南部的一块实验性小麦田中，免耕管理让平均反照率在夏季增加了50%。这组作者使用一个区域气候模型预测了更高的反照率将会在总体上降低气温，而这种致冷效应在极端炎热的夏季可能高达2摄氏度。这组作者说，这些结果提示，免耕管理可能在局部尺度上对缓解极端温度有效果。这类极端气温尽管罕见，它们对于生态系统具有不成比例的冲击。

此外，采用免耕实践可能在欧洲具有大的缓解潜力，因为它是全世界农业最密集的区域，而免耕实践尚未被广泛实施。

原文摘要：

Preferential cooling of hot extremes from croplandalbedo management

Edouard L. Davin, Sonia I. Seneviratne, Philippe Ciais, Albert Olioso and Tao Wang

Changes in agricultural practICEs are considered a possible option to mitigate climate change. In particular, reducing or suppressing tillage (no-till) may have the potential to sequester carbon in soils, which could help slow global warming. On the other hand, such practices also have a direct effect on regional climate by altering the physical properties of the land surface. These biogeophysical effects, however, are still poorly known. Here we show that no-till management increases the surface albedo of croplands in summer and that the resulting cooling effect is amplified during hot extremes, thus attenuating peak temperatures reached during heat waves. Using a regional climate model accounting for the observed effects of no-till farming on surface albedo, as well as possible reductions in soil evaporation, we investigate the potential consequences of a full conversion to no-till agriculture in Europe. We find that the summer cooling fromcropland albedo increase is strongly amplified during hot summer days, when surface albedo has more impact on the Earth’s radiative balance due to clear-sky conditions. The reduced evaporation associated with the crop residue cover tends to counteract the albedo-induced cooling, but during hot days thealbedo effect is the dominating factor. For heatwave summer days the local cooling effect gained from no-till practice is of the order of 2 °C. The identified asymmetric impact of surface albedo change on summer temperature opens new avenues for climate-engineering measures targeting high-impact events rather than mean climate properties.

作者：eurekalert