The effects of pollution on plants and climate

This research project is a modelling based study to understand the global effects of pollution on the land carbon cycle, and from this the overall climate impacts. The pollutants tropospheric ozone and reactive nitrogen (nitric oxide and ammonia) have direct impacts on climate. They also affect the carbon cycle, as ozone is damaging to plant growth whereas reactive nitrogen fertilizes plant growth. These effects on plants change the amount of carbon taken up from the atmosphere and stored in the vegetation and soils. These effects can persist for several decades, leading to long term climate change long after the original pollutants have disappeared. This research has a particular importance for understanding the impacts of air quality pollution on climate, and could inform air quality policy makers of the benefits or otherwise of pollution control. It has been suggested that these biogeochemical effects could be large, with ozone significantly reducing the carbon uptake, and lack of nitrogen being a key limiter for CO2 fertilisation.

The Met Office have coupled together the models of atmospheric chemistry (UKCA), which calculates surface ozone and nitrogen deposition, and the land surface (JULES), which calculates the impact of ozone on photosynthesis and nitrogen limitation, into the Earth system model to account for the impact of chemistry on vegetation and climate. The student will work with the Met Office on using this model to calculate the impacts of different projections of future pollution levels on the growth of vegetation and the quantities of carbon stored in the plants and soil.

Do polluted or clean futures increase or decrease vegetation productivity? What is their overall impact on CO2 and global warming?