Climate impacts of radiative forcing driven by agricultural land-use and land-cover changes in northern Canada

Changes in land-use and land-cover (LULC) influence global climate by modifying both greenhouse gas (GHG) fluxes and surface albedo. However, the influence of surface albedo on the local energy budget is often overlooked when developing management strategies for climate change mitigation. We used data from a satellite albedo product derived from MODIS (Moderate Resolution Imaging Spectroradiometer) data to estimate changes in surface albedo and associated shortwave radiative forcing (RF) caused by agricultural LULC transitions in the Peace Region of northwestern Canada. We quantified changes in shortwave RF associated with key land-cover changes from 2000 to 2022. Over this period, land area used for perennial crops and pasture production declined (>350,000 ha) due mainly to conversion to annual croplands. Conversion of deciduous forests and perennial croplands to annual croplands induced a cooling effect due to increased albedo, with estimated RF equivalent -0.054 ± 0.002 kg CO₂ m^-2 yr^-1 and -0.016 ± 0.003 kg CO₂ m^-2 yr^-1, respectively. In contrast, transition from perennial croplands and shrublands to deciduous forests resulted in a warming effect with RF equivalent to 0.034 ± 0.002 and 0.007 ± 0.002 kg CO₂ m^-2 yr^-1, respectively. Land-use practices that reduce surface albedo and reduce shortwave RF can sometime contribute as much to climate change as soil carbon loss or GHG emissions reduction. Effective management strategies for climate change mitigation must consider both the biogeochemical and biogeophysical effects of LULC changes.