Preferential cooling of hot extremes from cropland albedo management

Abstract

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 from cropland 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 the albedo 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 climateengineering measures targeting high-impact events rather than mean climate properties.

Evapotranspiration in Northern Agro-Ecosystems: Numerical Simulation and Experimental Comparison

“…In this study, the value of albedo was set as 0.2 for the dry period [33], while a value of 0.15 was applied for the wet period in agriculture land in subarctic region according to previous studies in the same agricultural setting [34].…”

Essentials of Endorheic Basins and Lakes: A Review in the Context of Current and Future Water Resource Management and Mitigation Activities in Central Asia

“…Increasing vegetation, both in urban and agricultural areas, has been demonstrated to have multiple benefits such as the reduction of "heat island" effects in cities and improved sustainability of food production [126,128]. Davin et al [129] demonstrated that no-till farming has the potential to off-set summer heat waves by local preferential cooling effects from a cropland albedo increase. Conservative agriculture projects with minimal tillage and crop rotation, already implemented in some parts of CA, have also been proven to foster carbon sequestration (thereby off-setting CO 2 emissions) and reduce soil erosion, as well as increasing crop yields [130].…”

Mapping and linking supply- and demand-side measures in climate-smart agriculture. A review

“…Cover crops and no-till farming can mitigate climate change by both carbon sequestration and an increase in surface albedo (Davin et al 2014;Kaye and Quemada 2017). The cooling effect of no-till farming due to an increased albedo is especially strong during hot summer days.…”

“…4. Regarding energy use, 0.5% of the global energy consumption could be saved by increasing agriculture's energy efficiency of below-average countries to the global average (Schneider and Smith 2009 reducing mean global temperatures (Davin et al 2014). The carbon sequestration potential was found to be often overestimated, as organic carbon in the top soil layer increases rather as a result of redistribution over depth than an actual increase (Powlson et al 2014).…”