In order to tackle climate change, agriculture can be an important driver of changing climate trends and achieving climate neutrality, taking into account biogeochemical and biogeophysical effects. With the support of ClieNFarms project, this work diagnosed albedo effects of different farming measures in short time windows using European flux data and cropland site records, so as to understand the biogeophysical impact of management activities on surface radiation.
Reinhard Prestele
IMK - IFU
Agricultural land managed under conservation agriculture (CA) is proposed to contribute to climate change mitigation and adaptation through reduced emission of greenhouse gases, increases solar radiation reflection, and the sustainable use of soil and water resources. Including the parameterization of CA into Earth System Models has been limited due to the lack of global spatially explicit datasets describing where this form of management is practiced. Here, we present an approach to downscale national-level estimates of CA to a 5 arcmin regular grid, based on multicriteria analysis. We provide a best estimate of CA distribution and an uncertainty range in the form of low and high estimates of CA distribution, reflecting the inconsistency in CA definitions. Moreover, we design two scenarios of the potential future development of CA combining present-day data and an assessment of the potential for implementation using biophysical and socioeconomic constraints.
Subsequently, we implement this representation of CA into the Community Earth System Model and show that the quality of simulated surface energy fluxes improves when including more information on how agricultural land is managed. We also compare the climate response at the subgrid scale where CA is applied. We find that CA generally contributes to local cooling of hot temperature extremes in mid-latitude regions where it is practiced, while over tropical locations CA contributes to local warming due to changes in evapotranspiration dominating the effects of enhanced surface albedo. Finally, we examine the climate change mitigation potential of CA by comparing simulation with present-day CA extent to a simulation where CA is expanded to all suitable crop areas. Here, our results indicate that while the local temperature response to CA is considerable cooling, the grid-scale changes in climate are counteractive due to negative atmospheric feedbacks. Our results underline that CA has a non-negligible impact on the local climate and that it should therefore be considered in future climate projections.
