UK Earth System Model (UKESM)

Human activities are strongly influenced by the climate of the Earth and the numerous biogeochemical processes that shape our environment.

In turn, that environment is increasingly being affected by anthropogenic activities such as the burning of fossil fuels and the expansion of industry and agriculture. There is an urgent need for projections of the future states of our climate and environment to support planning at a global scale and help design adaptation or mitigation responses.

Scientists use complex computer models to project what the Earth’s climate will look like over the coming decades and to support international efforts to address global change. Traditionally these models have concentrated on the physics of climate (e.g. temperature change), but increasingly these are being expanded to become models of the Earth System, capable of simulating key physical climate and biogeochemical processes. Importantly it is not enough to represent these processes in isolation, rather they must be coupled to represent important interactions and feedbacks, for example between emissions of trace gases from the land surface and atmospheric aerosols that are linked to cloud formation

The UK Earth System Model (UKESM) project is a collaborative effort between NERC and the Met Office to develop, apply and analyse the next generation of Earth System Models, representing a wider range of processes and the links between them.

The project aims to answer questions such as:

• How will the Earth system respond to future emissions of greenhouse gases (GHGs), aerosols, trace gases and land use change? Can reliable projections of this response be developed?
• How will Earth’s natural carbon sources and sinks change in response to climate change and future GHG emissions?

UKESM has two overriding objectives:

1. To develop and apply a world-leading Earth System Model
2. Grow a community of UKESM scientists

The UK Centre for Ecology & Hydrology’s (UKCEH) work in UKESM centres on the land surface and its interactions with the atmosphere, particularly the carbon and nitrogen cycles, and the exchanges of trace gases such as ozone between the atmosphere and the land.

A key tool is the Joint UK Land Environment Simulator (JULES) which describes the state of vegetation and soil across the globe. JULES is the land surface component of UKESM and can also be used separately to facilitate detailed study of land surface processes. UKCEH leads the development of JULES, along with the Met Office, and seeks to inform model development by channelling the wealth of observations and multi-disciplinary knowledge from across the organisation.

UKCEH’s contribution to UKESM consists of three main parts:

• Development of new science in JULES. Focussing on Carbon and Nitrogen cycling in plants and soils, plant physiology (adaptation and acclimation of photosynthesis), and trace gas transfers (e.g. deposition of ozone onto plants).
• Work as part of the UKESM core team. This work largely concerns the creation, running and analysis of the full UKESM model, using some of the world’s most powerful computers. UKCEH will also be leading the UK’s contribution to the Land Surface, Snow and Soil Moisture Model Intercomparison Project (LS3MIP). 
• Evaluation of model performance. UKCEH will be evaluating UKESM using a wide range of in-situ and earth observation data, initially using the ILAMB toolkit. Through its membership of the National Centre for Earth Observation UKCEH will also focus on the land surface energy balance and its response to precipitation.

The first version of the new model, UKESM1, will be the main UK contribution to the 6th Coupled Model Intercomparison Project (CMIP6), which in turn provides key underpinning support for the activities of the International Panel for Climate Change (IPCC). As the IPCC provides the scientific basis that underlies negotiations at the UN Climate Conference, UKESM will be contributing to global efforts to understand and predict climate change.

UKESM1 will be released in 2017, after which activities will centre on running and analysing the model, and developing alternative configurations of the model (e.g. higher resolution).Throughout the project, there will also be a development of component models targeted towards UKESM2, with a preliminary version expected around the end of the current project in 2021.

For more information visit JWCRP 

A full list of partners includes; Met Office, National Centre for Atmosphere Science, National Oceanography Centre, Centre for Ecology & Hydrology, National Centre for Earth Observation, Plymouth Marine Laboratory, British Antarctic Survey, Centre for Polar Observation and Modelling and British Geological Survey.