Professor Gabriel Yvon-Durocher (University of Exeter) - Ecological and evolutionary constraints on the temperature dependence of the carbon cycle: from genes to ecosystems

Forecasting and mitigating damaging levels of climate change is set to be the defining scientific challenge of our age. Central to this is an understanding of the mechanisms underpinning carbon cycle feedbacks with the climate system. The cycling of C between the biosphere and the atmosphere is mediated by its transformation and flux through ecosystems. Atmospheric CO2 is fixed by photosynthesis, exchanged between organisms via their interactions (e.g., predation, mutualism), and re-emitted to the atmosphere through the by-products of their metabolism (e.g., respiratory CO2 production). Thus, C-cycle responses to climate warming are likely to manifest through shifts in patterns and processes that span multiple levels of ecological organisation (e.g. individual, population, community, ecosystem). I will provide evidence of the physiological mechanisms that constrain metabolic thermal acclimation and adaptation responses to warming at the population-level in aquatic algae. I will demonstrate how long-term experimental warming affects the structure, composition, diversity and functioning of planktonic communities. Finally, I will show how the temperature dependence of the key fluxes in the global carbon cycle scale from organisms to ecosystems. I will demonstrate that respiration, photosynthesis and methane flux have differential temperature sensitivities that cause the emission balance of greenhouse gases (CO2 & CH4) to be temperature dependent, which may have fundamental implications for understanding future feedbacks between the biosphere and climate change.