Carbon dioxide in the atmosphere is a 'greenhouse gas' and contributes significantly to global warming. The amount of carbon dioxide in the atmosphere depends on human activities, such as burning fossil fuel, and also the behaviour of the ocean and terrestrial biosphere. Understanding how the global carbon cycle works is essential for us to predict how it, and the climate system, may behave in the future. The coupled climate-carbon cycle project at the Hadley Centre addresses this issue by including models of the carbon cycle within its existing climate models.

The following pages aim to describe the role of the carbon cycle in climate change, how the models represent it, and what the results are when these models are included in climate change simulations.

• Introduction. A discussion of the role of the global carbon cycle in climate, and a description of both the ocean and land based components of it.
  • the global carbon cycle
  • the ocean carbon cycle
  • the terrestrial carbon cycle

• Models. Descriptions of the ocean and terrestrial carbon cycle models, and how they are included in existing climate models.
  • the ocean carbon cycle model, "HadOCC"
  • the terrestrial carbon cycle model, "TRIFFID"
  • the coupled climate-carbon cycle model

• Results. Results from several experiments with the coupled climate-carbon cycle model are presented here. The model predicts accelerated global warming due to feedbacks between the climate and the carbon cycle. Some validation results are also shown, which describe how we assess whether the model is realistic.
  • predictions of accelerated climate change
  • including extra climate forcing
  • validating the model against observed carbon cycle behaviour

• Ongoing research. We are continually working to improve our understanding of the global carbon cycle. These links describe recent or planned research and improvements to the models.
  • ongoing ocean carbon cycle research
  • ongoing terrestrial carbon cycle research

• References. list of references cited within thes pages