Doubling of CO2 will cause global plant photosynthesis to increase by a third, study from CRESCENDO´s scientists conclude

Vegetation and soil are currently slowing down global warming by absorbing about a quarter of human emissions of carbon dioxide (CO2). This land carbon sink is believed to be in part due to increases in photosynthesis. This new study in the journal Nature shows that doubling of the CO2 concentration in the atmosphere will cause global plant photosynthesis to increase by about one third. As well as its role in the climate system, photosynthesis also provides the primary food-source for life on Earth. The study therefore has relevance to the future health of ecosystems, as well as to the challenge of slowing climate change.

The research was carried-out by scientists from the German Aerospace Center (DLR) and the University of Exeter in the UK, in a collaboration supported by the European Union through the CRESCENDO project.

The measurements made on Hawaii and in Alaska show an increasing amplitude of the seasonal cycle, but what does this mean for the future? The lead author of the study, Dr Sabrina Wenzel of the DLR-Institute of Atmospheric Physics, explains: “our study shows a link between the increase in CO2 amplitude that a model simulates and the CO2-fertilization that it predicts. This in turn means that the observed increase in the CO2 amplitude can be converted into a much improved estimate of the CO2-fertilization”, which the authors call an Emergent Constraint. Co-author Professor Peter Cox, of the University of Exeter, summarises the consequences of the study: “despite nutrient limitations in some regions, our study indicates that CO2-fertilization of photosynthesis is currently playing a major role in the global land carbon sink.” However, ”this means that we will need to work even harder to reduce CO2 emissions, as we should expect the land carbon sink to decline as we begin to stabilize CO2”, Peter Cox adds.

What are the implications for climate change policy?

The following webinar given by Prof Peter Cox (University of Exeter, UK) describes the study in detail and its implications for climate change policy.

Further reading:

Projected land photosynthesis constrained by changes in the seasonal cycle of atmospheric CO2. Sabrina WenzelPeter M. CoxVeronika Eyring & Pierre Friedlingstein. Nature (2016) |  Doi:10.1038/nature19772 | Received 15 June 2015 | Accepted 08 August 2016 | Published online 28 September 2016 |