UK Earth System Modelling News

December 2021

The UK Earth system modelling project is a joint venture between the Met Office and the UKRI Natural Environment Research Council (NERC) to develop and apply a world-leading Earth System Model.

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Introducing particle associated copepods in MEDUSA

by Julien Palmiéri; Thomas Anderson; Andrew Yool; Adrian Martin; Dan Mayor

Understanding the controls on ocean particle sinking and remineralization is critical to quantifying and predicting global carbon budgets. Particle fragmentation is a key factor in particle flux attenuation. Previous work by Mayor et al. (2020) suggests that particle-associated copepods (PAC) may be responsible for this fragmentation. To understand whether PAC are important at the global scale, here we translate their local-scale work to a global, 3D version of MEDUSA. This initial work finds that the resulting MEDUSA-PAC model is very promising.  Read more…

Likely future(s) of global wildfires

by Douglas Kelley, Camilla Mathison, Chantelle Burton, Megan Brown, Andrew Sullivan, Elaine Baker, Tiina Kurvits

“The risk posed by wildfire to people and the environment is increasing as a result of numerous factors, including but not only climate change” is a key finding from the upcoming UNEP report “Spreading like Wildfire: The Rising Threat of Extraordinary Landscape Fires”. For this report, we simulated the likelihood of all possible future burning levels whilst accounting for uncertainties in fire modelling and future climate. We demonstrate that many parts of the world show likely and robust future changes in burnt area – some of which may be avoidable with emission reduction.  Read more…

Earth System Modelling and the evolutionary history of South America

by Hiromitsu Sato, Douglas I Kelley.

Modelled vegetation reconstructions for the LGM

While ESMs often look to the future, Earth system modelling techniques can also provide insights into past vegetation distributions and tackle some of the biggest paleoecology and human development questions. The South American refugia hypothesis describes how the growing and shrinking of forest and savannas over glacial cycles explain modern day biodiversity. Hiro Sato, from the Ontario Forest Research Institute, explains the refugia hypothesis’ background and describes how we combine dynamic vegetation modelling with the fossilised pollen record to reconstruct forest and savanna locations during the Last Glacial Maximum. Read more…


Jeremy Walton, Catherine Hardacre and Lee de Mora.

Jeremy, Catherine and Lee from the UKESM core group welcome you to the COP26 Green Zone

UKESM was invited to participate in a number of activities related to COP26, which included a presence in the COP26 Green Zone (open to the public).  We developed a range of short video storyboards to explain our work on Earth system modelling using UKESM1 and the implications of our results for projected future changes in global temperatures and other climate variables (see UKESM YouTube channel) and quizzes, which formed the centrepiece of our exhibits at COP26.  Read more…

Recent Events

UKESM- Climate Impacts Workshop

The UKESM team recently held an online workshop, bringing together UKESM modellers with a number of UK-based climate impacts researchers. The aim of the workshop was to share knowledge and increase collaboration between the two communities with a view to developing a range of concrete collaborations that use UKESM simulations in climate change impact analysis.

The workshop consisted of a set of talks introducing impacts research and a set introducing the UKESM model and its application. There were also a couple of open discussion sessions to start a dialogue leading to further, more targeted collaboration.

Five climate impact areas were discussed; Water resources, wildfires, climate change and air quality, marine ecosystems and sea level rise. We look forward to some more targeted discussions in 2022. If you are interested in finding out more or would like to be involved, please contact


UKESM in the research literature


UKESM2 – the next generation..

A UKESM2 planning meeting was held on November 4th. The meeting set out development plans and associated timelines for the next UKESM2 model. It also enabled developers to get an overview of the main science targeted for UKESM2 and any potential interactions between individual science changes. Developers presented their developments and progress on testing and evaluation. Alistair Sellar (head of Global Model Evaluation and Development at the Met Office) provided an update on the HadGEM3-GC5 physical climate model on top of which UKESM2 will be built. GC5 will include a new sea ice model, SI3 (Sea Ice modelling Integrated Initiative), and the ocean model will be upgraded to NEMOv4 along with a number of other improvements across the model physics. GC5 aims to be frozen early in 2022 after which UKESM2 development can really begin in earnest.

UKESM2 will largely include the same Earth System components as in UKESM1, with the notable addition of interactive ice sheet models for both Greenland and Antarctica and interactive fires coupled to the terrestrial carbon cycle and atmospheric composition. The former development is important for assessing sea level risks while the latter will improve our ability to investigate ecosystem resilience and biogeochemical feedbacks. The standard model configuration will also be driven by emissions of CO2 and CH4 as opposed to being concentration driven, with closed cycles of both gases. While an emission driven capability for CO2 was included for C4MIP with UKESM1, the CH4 emission capability is a new development and enables the inclusion of important CH4 feedbacks from natural sources such as wetlands, fires and permafrost.

In addition, a number of science enhancements to existing UKESM1 components and their coupling within the full ESM are envisaged. These include nitrate aerosol being added to the GLOMAP-MODE aerosol scheme. Nitrate is envisaged to be an increasingly important aerosol source as anthropogenic emissions of sulphur dioxide reduce, representing this species will allow a more accurate assessment of the impact of agricultural practices and air pollution measures on air quality and climate response. Coupling to land and ocean nitrogen cycles will also be explored. UKESM1 has significantly higher total column ozone over the historical period as well as stronger ozone depletion post 1960 than other CMIP6 models. A number of improvements to the stratospheric-tropospheric UKCA chemistry model will be implemented which will significantly improve stratospheric ozone in UKESM2. A number of other improvements are also in the pipeline but for brevity are not listed here.

Planning meetings will increase in frequency in 2022. For further information please contact Jane Mulcahy ( or Colin Jones (