Can climate‐effective land management reduce regional warming?

Abstract

Limiting global warming to well below 2°C is an imminent challenge for humanity. However, even if this global target can be met, some regions are still likely to experience substantial warming relative to others. Using idealized global climate simulations, we examine the potential of land management options in affecting regional climate, with a focus on crop albedo enhancement and irrigation (climate‐effective land management). The implementation is performed over all crop regions globally to provide an upper bound. We find that the implementation of both crop albedo enhancement and irrigation can reduce hot temperature extremes by more than 2°C in North America, Eurasia, and India over the 21st century relative to a scenario without management application. The efficacy of crop albedo enhancement scales with the magnitude, where a cooling response exceeding 0.5°C for hot temperature extremes was achieved with a large (i.e., ≥0.08) change in crop albedo. Regional differences were attributed to the surface energy balance response with temperature changes mostly explained by latent heat flux changes for irrigation and net shortwave radiation changes for crop albedo enhancement. However, limitations do exist, where we identify warming over the winter months when climate‐effective land management is temporarily suspended. This was associated with persistent cloud cover that enhances longwave warming. It cannot be confirmed if the magnitude of this feedback is reproducible in other climate models. Our results overall demonstrate that regional warming of hot extremes in our climate model can be partially mitigated when using an idealized treatment of climate‐effective land management.

Potential of global land water recycling to mitigate local temperature extremes

“…In RES50_CROP this region has almost no grid cells where LWR is applied We could show that the developed LWR scheme reduces extreme temperatures -but is it also able to offset half a degree Figure S7). This is in accordance with Hirsch et al (2017), and shows that increased irrigation may offer some respite from climate change, but does not alter the long term trends.…”

“…This state-of-the-art model has been extensively evaluated (Hurrell et al, 2013;Meehl et al, 2013), and was used to study irrigation (Sacks et al, 2009;Hirsch et al, 2017;Thiery et al, 5 2017) as well as SM-climate feedbacks using SM prescription (Koster et al, 2004;Seneviratne et al, 2013;Hauser et al, 2017).…”

“…There is a number of studies investigating the impact of irrigation 10 on climate with global climate models (Sacks et al, 2009;Cook et al, 2011;Guimberteau et al, 2012;Krakauer et al, 2016; de Vrese et al, 2016;Hirsch et al, 2017;Thiery et al, 2017). For mean temperatures, most studies report a small cooling effect.…”

“…The influence of LWR on the surface temperature (TS) can be investigated with the help of the energy balance decomposition (Luyssaert et al, 2014;Akkermans et al, 2014;Thiery et al, 2015;Hirsch et al, 2017). Taking the derivative of the surface 10 energy balance yields the contribution of each term to the LWR-induced change in TS:…”

Inconsistent Responses of Hot Extremes to Historical Land Use and Cover Change Among the Selected CMIP5 Models

“…In their study, the asymmetric responses of hot extremes due to albedo enhancements were also confirmed. Similarly, Hirsch et al () found that climate‐effective land management (e.g., cropland albedo enhancement and irrigation) could also produce similar asymmetric cooling responses of hot extremes. Nevertheless, all the aforementioned cases are based on single‐model simulations, and whether these findings can be consistently reproduced in multimodel cases remains unknown.…”