Global lake phytoplankton proliferation intensifies climate warming

Abstract

In lakes, phytoplankton sequester atmospheric carbon dioxide (CO₂) and store it in the form of biomass organic carbon (OC); however, only a small fraction of the OC remains buried, while the remaining part is recycled to the atmosphere as CO₂ and methane (CH₄). This has the potential effect of adding CO₂-equivalents (CO₂-eq) to the atmosphere and producing a warming effect due to the higher radiative forcing of CH₄ relative to CO₂. Here we show a 3.1-fold increase in CO₂-eq emissions over a 100-year horizon, with the effect increasing with global warming intensity. Climate warming has stimulated phytoplankton growth in many lakes worldwide, which, in turn, can feed back CO₂-eq and create a positive feedback loop between them. In lakes where phytoplankton is negatively impacted by climate warming, the CO₂-eq feedback capacity may diminish gradually with the ongoing climate warming.