The new set of simulations using global climate models enable users to analyse changes in future climate that are coherent in space and time on a horizontal spatial scale of around 60km.
Using the global projections
The global projections provide a set of plausible future climate outcomes that often cover a large fraction of the range of the probabilistic projections. The projections offer data for those who prefer to work directly with climate model output. They can support a wide range of impacts studies and provide data with full spatial and temporal coherence and a wider range of variables and time resolutions. These are important for applications requiring assessment of multiple drivers of changing hazards.
You should use the global projections if you’re interested in:
- Analysing climate at multiple geographical locations at the same time should there be a physical connection between the climate characteristics at these locations, e.g. assessing climate change impacts on the rail network across the whole of the UK (note that some may prefer the enhanced spatial detail offered by the regional projections)
- Using daily data and being able to calculate a larger set of metrics than that available in the probabilistic projections.
- Analysing drivers and impacts of year-to-year variability. The probabilistic projections, global and regional projections all include information on interannual variability. In addition, the global projections support analysis of physical and dynamical processes (e.g. conditions in the North Atlantic and the state of the Arctic) that give rise to the climate variability experienced over the UK. The global and regional projections also support investigation of the resulting high-impact events.
- Geographical regions outside of the UK and Europe. Note that the regional projections also
- Providing large scale or historical context for regional changes (note that the regional projections start in 1981 and cover the North Atlantic and Europe only). For example, see UKCP18 Factsheet on Weather Types [1.3MB] or the UKCP18 Land Projections Science Report on weather types.
Method used to develop the global projections
The set of 28 simulations of future climate for the high emission RCP8.5 scenario (see RCP guidance) is made up of 15 simulations of the new Met Office Hadley Centre climate model (HadGEM3-GC3.05; hereafter GC3.05) and 13 simulations from the CMIP5 multi-model ensemble that was used to inform the IPCC 5th Assessment. Together, these two sets of simulations provide a greater span of outcomes that results from uncertainties in our knowledge of future climate. The GC3.05 are based on a new perturbed parameter ensemble (PPE) that yields plausible variants of the base model. The CMIP5 model simulations were filtered to retain only the most plausible models.
The global projections are new to UKCP18 at the request of users to enable investigation of international impacts that may have implications for the UK such as international food availability. The inclusion of GC3.05 is also a major step forward because it has a better representation of many aspects of European weather than earlier models, including a better representation of storm tracks and UK precipitation variability.
Further supporting information can be found in Guidance and Science Reports and include:
- Factsheets that summarise the key findings for the available variables across all the projections.
- A summary of the results, methods, evaluation and limitations of the global projections in Section 2 of the UKCP18 Science Overview report.
- Detailed description of the methodology and scientific results in Section 3 of the UKCP18 Land Projections report.
- UKCP18 Marine and Derived Projections reports.