Lakes Modify the Magnitude and Timing of the Northern Hemisphere Terrestrial Cryosphere Radiative Effect

Abstract Vast areas of Earth's Northern Hemisphere are covered in lakes that form seasonal ice cover, yet their influence on the terrestrial Cryosphere Radiative Effect (CrRE t ) has not previously been quantified. Here we use 22 years of satellite data to constrain the contribution of lakes to CrRE t . We find that, per unit area, lakes have a significantly higher CrRE t than land (−14.4 vs. −8.2 W/m 2 ). Therefore, even though lakes cover 3.7% of our study domain, lakes contribute 6.3% of Northern Hemisphere CrRE t . Lake contribution to CrRE t is even greater in late spring as well as in the Boreal Forest where lakes can contribute more than 25% of CrRE t . Lakes' higher CrRE t results from both earlier snowmelt on land and lakes' comparatively greater increase in albedo while snow‐covered. Overall, our analysis advocates for the inclusion of lake CrRE t processes in climate models and highlights a previously understudied impact of lakes on climate.