8  The latest update can be found at http://www.metoffice.gov.uk/climate/uk/about/state-of-climate
9  http://www.nationalarchives.gov.uk/doc/open-government-licence/version/3/
10 https://www.ipcc.ch/report/ar5/ 
What can users expect from UKCP18?
There are three components to UKCP18: observations of historic climate, marine projections and projections over land.  
These components are described below and summarised in Table 1.  UKCP18 will provide each of these components at 
a higher spatial and temporal resolution than UKCP09 and with more information on different types of uncertainty.
OBSERVATIONS 
Annual report: State of the UK Climate. Downloadable data. 
The “State of the UK Climate” report for 2017 will be included as part of the UKCP18 package, 
bringing the observed data right up to date.  This annual update8 covers trends, the multi-
decade climate record and significant weather events such as the early July 2015 hot spell 
and the exceptionally mild and wet December of the same year.
Quality controlled UK observational datasets from the Met Office observing network, provided 
at spatial resolutions to match the land projections and for pre-defined administrative regions 
and river basins, will be available under an Open Government Licence9.  For variables such as 
temperature and precipitation these data sets will span the late 19th Century to the present 
day and will be provided for daily, monthly, seasonal, annual and long term averages. 
MARINE PROJECTIONS 
Sea level rise. Storm surge. Past event case studies.
Sea-level rise projections will extend to 2100 and will include contributions from glaciers, 
ice sheets, freshwater reservoirs, groundwater and thermal expansion.  Outputs will include 
an estimate of the year-to-year changes in sea level rise and a “plausible but highly unlikely” 
scenario known as H++.  A new feature of UKCP18 will be assessing the credibility of making 
sea level rise projections to 2300. The projections will use the latest information from the 
CMIP5 models and application of the methods used in the Intergovernmental Panel on 
Climate Change’s (IPCC) Fifth Assessment Report10.  
The UKCP09 storm surge projections will be updated to provide new estimates of the change 
in high water levels over the 21st Century.  These estimates will be based on a combination of 
projected mean sea level change and projections of change in the extremes due to changes in 
atmospheric storminess.  These “storminess” projections will use the same surge model used 
in operational weather forecasting, using the wind and pressure from the CMIP5 ensemble to 
drive the surge.  New understanding of the modification of large-scale sea level change signals 
as they pass from the open ocean onto the shelf sea around the UK will be incorporated into 
the UKCP18 marine projections.  UKCP18 will also include storm surge historical case studies 
derived from applying plausible future sea level change to historical extreme events.