Potential feedbacks between loss of biosphere integrity and climate change

Abstract

Individual organisms on land and in the ocean sequester massive amounts of the carbon emitted into the atmosphere by humans. Yet the role of ecosystems as a whole in modulating this uptake of carbon is less clear. Here, we study several different mechanisms by which climate change and ecosystems could interact. We show that climate change could cause changes in ecosystems that reduce their capacity to take up carbon, further accelerating climate change. More research on – and better governance of – interactions between climate change and ecosystems is urgently required.Individual responses of terrestrial and marine species to future climate change will affect the capacity of the land and ocean to store carbon. How system-level changes in the integrity of the biosphere interact with climate change is more uncertain. Here, we explore the consequences of different hypotheses on the interactions between the climate–carbon system and the integrity of the terrestrial and marine biospheres. We investigate mechanisms including impairment of terrestrial ecosystem functioning due to lagged ecosystem responses, permafrost thaw, terrestrial biodiversity loss and impacts of changes in marine biodiversity on the marine biological pump. To investigate climate–biosphere interactions involving complex concepts such as biosphere integrity, we designed and implemented conceptual representations of these climate–biosphere interactions in a stylized climate–carbon model. We find that all four classes of interactions amplify climate change, potentially contributing up to an additional 0.4°C warming across all representative concentration pathway scenarios by the year 2100 and potentially turning the terrestrial biosphere into a net carbon source, although uncertainties are large. The results of this preliminary quantitative study call for more research on – and better integrated governance of – the interactions between climate change and biosphere integrity, the two core ‘planetary boundaries’.