Long-term Global Change Science Highlights
Implementing the UK's first Earth System Model
The National Centre for Atmospheric Science is leading the development of the UK’s state-of-the-art Earth System Model, called UKESM1. Scientists are using the model to run simulations of the Earth’s past, present and future climate, and projections for the next century will feed into global policy decisions.
An Earth System Model uses a large set of equations to simulate the global climate system, including the physical climate, the global carbon cycle, atmospheric chemistry, vegetation and land-based ice-sheets.
Following the development of UKESM1, the model is now being run in the first set of simulations for the Couple Model Intercomparison Project Phase 6 (CMIP6). CMIP is a worldwide project where scientists share, compare and analyse the outcomes of Earth System models and global climate models.
Currently, scientists use the model to run simulations of the historical climate, spanning the period from 1850 to present day. These computer experiments are based on observed concentration of atmospheric carbon dioxide, as well as estimates of man-made emissions of aerosol and aerosol precursors, human-induced land use change and emissions of other important trace gases.
Historical simulations provide an important opportunity to evaluate UKESM1 against a range of real-world observations, for instance from the Climatic Research Unit.
The historical simulations also provide a stepping-stone for using UKESM1 to make Earth System projections for the next century. These long-term projections use a range of plausible future greenhouse gas and aerosol emission pathways, combined with different assumptions about future land use.
Climate projections will help inform government policies worldwide through initiatives such as the Intergovernmental Panel on Climate Change, which provides an internationally recognised authority on climate change.