Climate benefits of changes in agricultural practices in the context of heat wave mitigation

Abstract:

About half of the terrestrial biosphere is under direct human influence through land management (i.e., agricultural areas and managed forests). Changing management practices is therefore a promising avenue for climate change mitigation. The mitigation potential arising from changes in land management practices has been mainly evaluated in terms of carbon storage and GHG emissions [2]. On the other hand, these practices can also influence climate by altering the physical properties of the land surface, but these effects have received less attention so far.

Here we show that peak temperatures during heat heaves can be attenuated through cropland albedo management [2]. We first present observational evidence that a substantial summer albedo increase can be obtained by switching from conventional to no-till agriculture. Then, using a regional climate model, we investigate the biogeophysical effect of a full conversion to no-till management over Europe. The cooling effect owing to albedo increase under no-till farming appears to be strongly amplified during warm events. This is due to the low cloud cover during these events, thus leading to a more efficient radiative cooling from albedo change. This implies a strong potential of no-till farming to mitigate heat wave impacts. The reduced evaporation associated with the crop residue cover tends to counteract the albedo-induced cooling, but during hot days the albedo effect remains the dominating factor. For heatwave summer days the local cooling effect gained from no-till practice is of the order of 2 degrees. These findings strongly suggest that the biogeophysical effect of management practices should be considered in the design of climate mitigation policies involving land management.

References:

[1] Smith, P. et al. (2014): Agriculture, Forestry and Other Land Use (AFOLU). In Climate Change 2014: Mitigation of Climate Change. Contribution of Working Group III to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, NY, USA.

[2] Davin, E.L. et al. (2014): Preferential cooling of hot extremes from cropland albedo management, Proc. Natl. Acad. Sci. U. S. A. Published online, doi:10.1073/pnas.1317323111.