Climate model forecasts of surface-level solar spectrum variation: effects on photovoltaics and crop photosynthesis

Abstract

Accumulation of greenhouse gases and aerosols in the atmosphere alter the spectrum of sunlight that reaches the Earth’s surface. The change in spectrum affects the output of photovoltaics and crop photosynthesis. To forecast the global impacts, atmospheric parameters from five climate models in the Coupled Model Intercomparison Project (CMIP) were input to the radiative transfer model SMARTS to generate representative spectra over six decades (2018-2082). Geographic and temporal variation was then forecast for the spectral responses of one-, two- and three-junction photovoltaic cells, and three crop plants: corn, wheat, and rice. Results for photovoltaics show baseline global outputs lower than for the standard spectrum, particularly for solar cells with more than one junction. In the decades ahead, photovoltaic output declines due to increased water vapor absorption, but crop photosynthesis is largely unaffected. For both photovoltaics and crop photosynthesis, forecast long-term decreases in atmospheric aerosols lead to net production increases over most of the globe.