Climate change impacts on ocean light in Arctic ecosystems beyond sea ice

Abstract Climate change will drive sea ice loss, resulting in increased light availability across polar marine ecosystems, but the consequences of these changes are largely unknown. We quantify how future conditions for sea ice and snow, storm-driven waves, clouds, ozone, and chlorophyll will affect the seasonal absorption and reflection of light in Arctic seas. Using CMIP6 inputs and a spectral radiative transfer model, we predict a 20-50% increase in visible light by 2100 in the Northern Bering/Chukchi and Barents Seas ecosystems. For cold-water fish species, warmer summers and reduced phytoplankton will decrease survival in summer, while asynchrony in prey and light availability will decrease survival in fall. Warmer-water species will be less impacted. Coupled with ocean warming, increased light availability will accelerate changes in Arctic ecosystems, compromising the growth and survival of Arctic species in transitional zones and facilitating the northward expansion of boreal species.