January 16, 2017

Ecosystem climate feedbacks in a CO2 rich world

Ecosystem climate feedbacks in a CO2 rich world 400 x 400 px

This project investigates how increasing atmospheric CO2 concentration impacts on greenhouse gas release from wetlands which provides an important feedback on the global climate.

Today natural wetlands are the greatest emitters of atmospheric methane, a process of which plants are important controls. By the end of this century atmospheric CO2 concentrations may reach 800 ppm which is likely to increase plant C assimilation. Over geological time periods with high atmospheric CO2 levels have been postulated to be linked to high atmospheric methane concentrations and together cause a temperature rise. This has coincided with palm plant functional types growing at high latitudes suggesting much higher temperatures in polar regions. The proposed mechanism for increased CH4 concentrations in the atmosphere in response to elevated CO2 is greater plant root biomass and release of root exudates providing substrate for methane producing bacteria creating a positive climate feedback. This project will test this hypothesis experimentally providing (i) validation of model assumption underpinning palaeoclimate models and (ii) understanding of how elevated atmospheric CO2 from human fossil fuel emissions impacts wetland methane emissions.

For the work we will use growth room experiments, in which we will elevate CO2 levels and control temperature, to determine if different plant functional type contrast in their response to elevated CO2 and contribution to methane production.

The specific hypothesis the project will test are:

H1: The increase in below ground C allocation, and hence methane emissions, in response to elevated CO2 will be greatest for productive plant functional types (e.g. palms) and lowest for unproductive plant functional types (e.g. mosses) .

H2: Elevated CO2 increases CH4 emissions from high latitude wetlands.

H3: Elevated CO2 promote larger root system resulting in greater plant mediated transport of methane to the atmosphere.

The project includes travel to the Arctic and the tropics and provides training in biogeochemistry and plant physiology.

For further details please contact Dr Sofie Sjogersten