In recent years, biogeochemical components have become recognised as key components of the climate system. Without representation and understanding of these components, accurate projections of 21st century climate are not possible.

Interactions between climate, the carbon cycle (including terrestrial and oceanic ecosystems), atmospheric chemistry and aerosols form a complex web of feedbacks and dependencies. Representing these processes in 21st century climate projections is one of the biggest scientific challenges in Earth Systems research, and is a key aim of the next generation of Hadley Centre climate models.

Here I will present results from recent research, which includes:

- acceleration of climate change by positive feedbacks between climate and the carbon cycle

- feedbacks between planktonic DMS production, aerosols, cloud formation and climate (the so-called CLAW hypothesis)

- climate changes induce vegetation changes and hence changes to isoprene emissions and surface ozone, and also dust production

- increasing ozone leads to a decrease in vegetation productivity

- climate changes lead to both increased methane production through changes to northern wetlands, and decreased atmospheric lifetime of methane through increased water vapour

I will also present future plans to further couple together components of the Earth System, such as:

- interactions between dust production and iron-fertilisation of ocean biology

- acidification of the ocean by absorbed anthropogenic CO2

- impact of climate change on the atmospheric chemistry of OH and H2O2 and hence on sulphate aerosol burdens