The intensification of Arctic warming as a result of CO2 physiological forcing

Abstract

Stomatal closure is one of the main physiological responses to increasing CO2 concentration, which leads to a reduction in plant water loss. This response has the potential to trigger changes in the climate system by regulating surface energy budgets-a phenomenon known as CO2 physiological forcing. However, its remote impacts on the Arctic climate system are unclear. Here we show that vegetation at high latitudes enhances the Arctic amplification via remote and time-delayed physiological forcing processes. Surface warming occurs at mid-to-high latitudes due to the physiological acclimation-induced reduction in evaporative cooling and resultant increase in sensible heat flux. This excessive surface heat energy is transported to the Arctic ocean and contributes to the sea ice loss, thereby enhancing Arctic warming. The surface warming in the Arctic is further amplified by local feedbacks, and consequently the contribution of physiological effects to Arctic warming represents about 10% of radiative forcing effects. Plants respond to increasing CO2 concentrations in the atmosphere by stomatal closure which causes a reduction of evapotranspiration and thus latent heat flux. Here, the authors show that this CO2 physiological forcing strengthens Arctic warming through increasing sea ice loss and local feedbacks.