Modelled biophysical impacts of conservation agriculture on local climates

Abstract

Including the parameterization of land management practices into Earth System Models has been shown to influence the simulation of regional climates, particularly for temperature extremes. However, recent model development has focused on implementing irrigation where other land management practices such as conservation agriculture (CA) has been limited due to the lack of global spatially explicit datasets describing where this form of management is practiced. Here, we implement a 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 (~1°C) of hot temperature extremes in mid‐latitude regions where it is practiced, while over tropical locations CA contributes to local warming (~1°C) due to changes in evapotranspiration dominating the effects of enhanced surface albedo. In particular, changes in the partitioning of evapotranspiration between soil evaporation and transpiration are critical for the sign of the temperature change: a cooling occurs only when the soil moisture retention and associated enhanced transpiration is sufficient to offset the warming from reduced soil evaporation. Finally, we examine the climate change mitigation potential of CA by comparing a 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 (>2°C), the grid‐scale changes in climate are counteractive due to negative atmospheric feedbacks. Overall, our results underline that CA has a nonnegligible impact on the local climate and that it should therefore be considered in future climate projections.

Global climate response to idealized deforestation in CMIP6 models

“…This highlights the need for improving the process understanding of soil carbon dynamics (e.g. Chen et al, 2015;Don et al, 2011;Giardina et al, 2014;Luo et al, 2017), fluxes (Atkin et al, 2015;Huntingford et al, 2017) and biomass carbon stocks (Erb et al, 2017) using observations and field experiments.…”

Plants with less chlorophyll: A global change perspective

“…Sustainable LRMreg strategies, their implementation and the potential effects on RF SW have been recently reviewed in a number of publications (Bright et al, 2017; Hirsch et al, 2017, 2018; Lugato et al, 2020; Seneviratne et al, 2018). LRMreg options can be briefly summarized in three categories of albedo modification, (i) with artificial solutions, (ii) with land/crop management approaches and (iii) with bio‐based strategies:…”

“…Soil mulching with crop residues and no‐tillage management can reflect more incoming light and mitigate the impact of heatwaves (Davin et al, 2014). Other practices aimed at keeping the soil surface covered by vegetation in all instances, such as double cropping or cover‐crops, are considered to have a beneficial impact on both the local and global climate, via changes in surface albedo and increases in carbon sequestration (Hirsch et al, 2018; Lugato et al, 2020). In spite of its high complexity, afforestation undoubtedly plays a role in climate mitigation.…”

Could crop albedo modification reduce regional warming over Australia?

“…Indeed, existing practices can be altered to increase crop albedo by using different varieties, adopting conservative agriculture via no-till farming to keep darker organic materials below the ground (and hence increase the albedo of the surface), use of irrigation for cooling, as well as other management approaches. These techniques have been the subject of numerous studies (Davin et al, 2014;Doughty et al, 2011;Hirsch et al, 2018Hirsch et al, , 2017Seneviratne et al, 2018;Wilhelm et al, 2015) and they broadly conclude that land-based SRM has little impact on the global mean temperature, but can be an effective method to achieve regional cooling. These regional effects can be viewed as an advantage as it removes the issues associated with unintended remote impacts and does not require global governance structures as with large-scale SRM.…”