The UK Earth system modelling project.

Lead Research Organisation: NERC Centre for Ecology and Hydrology
Department Name: Hydro-climate Risks


Global climate change is one of the leading environmental threats facing mankind. To develop appropriate mitigation and adaptation strategies requires accurate projections of the future state of the Earth's climate. To address this, the research community have developed Global Climate Models (GCMs) that describe the main physical processes in the coupled climate system. These mathematical-computer models are integrated forwards in simulated time, from a pre-industrial period (before ~1850) to present-day, forced by observed estimates of key greenhouse gases (e.g. carbon dioxide, methane, ozone), aerosols and land-use. The models are then continued into the simulated future forced by a range of greenhouse gas, aerosol and land-use scenarios representing plausible future socio-economic development pathways. Each of the time-evolving model future climates are then compared to the pre-industrial and present-day climates from the same model. This analysis results in an ensemble of climate change estimates, linked to each of the applied development pathways, that can be used to assess potential socio-economic and ecological impacts and aid in the development of climate change mitigation and adaptation policies.

GCMs have recently been further developed into Earth system models (ESMs). A key difference between ESMs and GCMs is the former include an interactive description of the global carbon cycle. Climate change is primarily driven by human emissions of carbon dioxide which traps a fraction of the Earth's emitted radiation in the atmosphere, warming it and the Earth's surface. This direct warming from increasing carbon dioxide can be amplified or damped by various feedbacks in the climate system (e.g. involving water vapour, clouds or sea-ice). A key determinant of the climate change impact of human-emitted carbon dioxide is how much of the emitted gas actually stays in the atmosphere where it can interact with the Earth's emitted radiation. Presently, around 50% of the carbon dioxide emitted by humans stays in the atmosphere, the remaining 50% being taken up, in roughly equal measures, by the terrestrial biosphere and the world oceans. There is increasing evidence to suggest the efficiency of these natural carbon reservoirs in absorbing human-emitted carbon dioxide may change in the future, being sensitive to both the concentration of carbon dioxide in the Earth system and to the induced climate change. A reduction in the uptake efficiency of Earth's natural carbon reservoirs would result in a larger fraction of emitted carbon dioxide remaining in the atmosphere and thereby a larger climate change (warming) for a given cumulative emission of carbon dioxide.

To address the need to simulate both the changing global climate and the carbon cycle response to a changing climate and changing atmospheric composition, we are developing the 1st UK Earth system model, based on the core physical GCM, HadGEM3, developed at the Met Office. This development is a major collaboration between NERC centres and the Met Office, integrating a large body of core research and development into a single, world-leading ESM. This proposal aims to secure the NERC funding to maintain this collaboration. The project will support the final development and community release of the 1st UKESM models, as well as application of these models to a range of collaborative science experiments carried out at the international level to support the IPCC AR6. The project has a major emphasis on evaluating the full range of climate and biogeochemical processes and interactions simulated by UKESM1 models with an aim to increase confidence in future projections made with the models. The project will also generate and analyse a suite of such projections and deliver a set of robust estimates of Earth system change to UK government, business and the public. Finally, the project will initiate long-term development of a 2nd version of the UKESM model, for release ~2023.

Planned Impact

The main beneficiaries of the project will be:The IPCC and intergovernmental policy makers, including: UK government: particular DEFRA and DECC, DFID, DfT and MoD; UK governmental agencies and industries requiring climate services information.

Maximising the UK Contribution to the IPCC AR6
An important motivation for UKESM1 is the delivery of science to underpin the UK contribution to IPCC AR6, peer reviewed scientific outputs of UKESM1 are expected to contribute to: Working Group (WG) I assessment of the scientific aspects of climate change; WGII assessment of the vulnerability of socio-economic and natural systems to climate change, and adaptation options; WGIII, assessment options for mitigating climate change.

Both the UKESM models themselves and the resulting simulation-data will be made openly available to the NERC research community, supporting a wide spectrum of Earth system science over and above that performed directly in this project. In addition, the UKESM core group will provide support to a number of UK universities planning contributions to other Model Intercomparison Projects (MIPs) in CMIP6. The result of this national collaboration will be an unprecedented UK contribution to CMIP6 and, through this, also an unprecedented contribution to IPCC AR6. Importantly, this contribution will be a national effort, coordinated across the 8 NERC centres in this project, MOHC and UK universities.

Science into Policy:
The Met Office Hadley Centre (MOHC) will benefit from this project through an enhanced capacity to investigate future Earth system change and provide knowledge support to UK government . The ensemble of future projections made with UKESM1 will be made available to the UK research community, with an emphasis on supporting the UK climate impacts research. CMIP6 simulation-data will form the backbone of future data sets used by the Copernicus Climate Change Service (C3S), charged with providing underpinning climate services data to European governments, business and the public. UKESM1 simulations will therefore constitute the primary UK contribution to C3S. We will ensure a subset of the UKESM1 projections produce output required for dynamical downscaling over the UK using either the Met Office Hadley Centre (MOHC) Regional Climate Model of the new MOHC-NERC coupled UK Environmental Prediction model. This activity will be carried out external to the UKESM project by MOHC scientists. The resulting high-resolution (~1.5-4km grid box resolution over the UK) projections, covering the UK and adjacent coastal waters, will be a major resource for UK planners and stakeholders concerned with the risks and opportunities associated with global change. The knowledge developed from the combination of UKESM1 projections and accompanying downscaled data will be an important support for UK government departments involved in planning and policy negotiations with respect to future global change.

Wealth Creation:
There is a growing demand for information on potential future climate states, apparent in the emerging 'Climate Services' sector. The UKESM project will feed information into this sector with a wide range of potential beneficiaries, including agriculture/food security, transport and the insurance sector. This This link can be both directly from the project, through downstream research (e.g. in climate impacts) using UKESM1 data, through use of dynamically downscaled UKESM1 data covering various regions of the globe and through UKESM1 projections being part of the Copernicus Climate Change Service.

Media Relations and Public Engagement:
There is an increasing need for the public to be informed about the science of climate change, how climate projections are made, including explanation of where projection uncertainties arise and how they impact our the delivery of robust future climate estimates. We will endeavour to contribute to this requirement through public presentations and information sheets.


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Description The UK Centre for Ecology & Hydrology (UKCEH) is the project lead for land-related aspects of the UK Earth System Model. UKCEH provides staff to the UKESM core development team and also undertakes model development to add new science or processes.

(1) Core: UKCEH staff developed and tested areas of the land-surface component of UKESM1. The CEH core team members contributed to the UKESM models runs undertaken for international modelling activities (CMIP6), created the CO2 emission driving data used in some of the CMIP6 runs and contributed to papers describing and assessing the model.

The LTSM UKESM project (and the Met Office) delivered the UK contribution to CMIP6. The output from CMIP6 will inform the IPCC's sixth assessment report.

(2) Development: CEH also contributes new science or processes for incorporation into future version of UKESM. This includes: (a) improved representations of plant physiological processes in JULES, including the Medlyn model of stomatal conductance, the Farquhar model of photosynthesis, and thermal acclimation of photosynthetic capacity; (b) the ECOSSE model of soil carbon and nitrogen biogeochemistry in JULES; and (c) an improved representation of atmospheric deposition processes and transfer of the deposition code base from the UKCA atmospheric chemistry module to JULES.

The paper by Mercado et al. (2018) showed the importance of temperature adaptation and acclimation on current and future land-carbon storage. Further, allowing for acclimation reduces the spread in global climate model projections.

The paper by Kelley et al. (2019) highlighted the added importance of understanding long-term changes in the controls on fire and the effect of fire trends on ecosystem function. Fires have received increased attention and is a current gap in UKESM1. A new, Bayesian-based optimization scheme that has been developed to help constrain fire processes in the UKESM is also showing promising results in other areas of the model, including vegetation dynamics and leaf reflectance parameters, as well as use in fire event attribution studies.
Exploitation Route Outputs of the different model runs can be used for climate impacts studies
Sectors Environment,Government, Democracy and Justice

Title UKESM1 
Description CEH staff (as part of the larger, cross-centre LTS-M UKESM project) have produced the first version of the UK Earth System Model (UKESM1), which is the first UK national Earth System Model. This is a computer model of the main components of the earth system that are required to understand and predict how the Earth's climate may evolve over the coming century. After further testing it will be made available to the wider academic community. 
Type Of Material Computer model/algorithm 
Year Produced 2018 
Provided To Others? No  
Impact None yet. 
Title UKESM1 CMIP6 simulation data 
Description UKESM1 simulations constitute the main contribution from the UK to the World Climate Research Program sponsored 6th Coupled Model Intercomparison Project (CMIP6). All UKESM1 CMIP6 data is being made openly available to international researchers at the UK Earth System Grid Federation (ESGF) node at the Centre for Environmental Data Analysis (CEDA), see: 
Type Of Material Database/Collection of data 
Year Produced 2019 
Provided To Others? Yes  
Impact CMIP6 data forms one of the main internation climate modelling supports for the 6th Assessment Report of the IPCC. 
Description Blue Dot Music and Science Festival 2019 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact UKESM participated in the 2019 Blue Dot Music and Science Festival, held at Jodrell Bank Observatory, July 18 to 21 2019. (

The festival attracted tens of thousands of visitors and our stand, entitled 'UKESM: A Model Earth' consisted of a brilliant display, with puzzles, an interactive quiz and climate oriented games suitable for children and families. In addition, the primary attraction at the stand was the interactive Pufferfish globe, on which we displayed six videos illustrating different aspects of the coupled Earth system and future Earth system change. Among the videos shown, visitors had the opportunity to explore latest simulation results from the 1st version of the UK Earth system model (UKESM1), released to UK researchers last February 2019 (for more information visit
Year(s) Of Engagement Activity 2019
Description Into The Blue, Manchester - contribution to UKESM stand 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Regional
Primary Audience Public/other audiences
Results and Impact We contributed to and participated in the UKESM contribution to this NERC-run event. The stand attracted a large number of visitors over several days and staff were very busy explaining our work to hundreds of people over the course of the event.
Year(s) Of Engagement Activity 2016
Description Royal Society Summer Science Exhibition 2017 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Public/other audiences
Results and Impact Members of staff were part of the project-wide UKESM team that ran "A model earth" exhibit during the event. Our exhibit was centred around a projecting globe which shows climate simulations on a 3-D globe. There were about 10k people though the doors each day and we presented our science at a range of levels. We had games and give aways for infant to early secondary school people along with more in depth posters and leaflets for older juniors and adults. The interactions with visitors also covered this range, from simple questions to in-depth discussions.
Year(s) Of Engagement Activity 2017