Surface cooling potential of wetlands across the Prairie Pothole Region of Canada

Wetlands provide many ecosystem services such as carbon sequestration, climate regulation, biodiversity and water quality enhancement. Through evaporative cooling, wetland ecosystems also play a significant role in the regulation of local and regional climate by creating microclimates, which benefit local flora and fauna. In this study, the cooling effect of wetlands was evaluated by examining the differences in aerodynamic temperature (T${}_{aero}$) between wetlands and nearby croplands in the Prairie Pothole Region of Canada. The cooling effect refers to the reduction of air or surface temperature through evapotranspiration and thermal dissipation from the environment. We utilized turbulent flux and meteorological data gathered through eddy covariance measurements over three years (2021–2023) from three distinct wetland sites and two cropland types. Our findings reveal that during the growing season (May to September), wetlands exhibit significantly lower temperatures compared to the croplands, with mean daytime cooling (T${}_{aero}$ reduction) ranging from 1.4 °C to 3.0 °C. On hot days (air temperature $>$ 25 °C), wetlands with more open water provided even greater cooling, reducing temperatures by up to 5.4 °C compared to nearby croplands. Each wetland is characterized by unique biophysical properties such as surface and aerodynamic conductances, which result in distinct energy flux dynamics generating different mechanisms driving the daytime cooling. Higher evaporative fraction strongly drives the cooling effect in wetlands compared to croplands. These results underscore the notable cooling potential of wetlands and highlight their importance in regulating local and regional climates, ultimately contributing to the understanding of how wetland conservation, restoration and management can contribute to natural climate solutions.