Abstract

Global warming is presently accelerating, raising the question whether all climate forcing and feedback mechanisms have been accounted for. Here a metabolic climate forcing and feedback mechanism is introduced, providing an explanation for the observed accelerated global warming. Based on more than 400,000 meteorological observations at various latitudes, it is shown that temperatures at the Earth's surface increasingly depart from thermodynamic equilibrium conditions towards warming at all examined geographical locations because of a long-lasting imbalance between the exothermic metabolic process of ecosystem respiration and the endothermic metabolic process of photosynthesis. Following the principles of the metabolic theory, metabolic imbalances are attributed to warmer temperatures stimulating ecosystem respiration at the same time as photosynthesis becomes light constrained. Since metabolic imbalances are expected to continue until ecosystem respiration becomes substrate limited, there is an urgent need to navigate climate mitigation towards measures that can slow down ecosystem respiration.