UKCP18

United Kingdom Climate Projections 2018 (UKCP18) are a suite of climate models created by the Met Office and the successor of UKCP09. There are climate projections for four emission scenarios, ranging from low to high. The different scenarios used are the Intergovernmental Panel on Climate Change (IPCC) Representative Concentration Pathways (RCP). The lowest (RCP 2.6) will see an increase in global mean surface temperature of 1.6°C. by 2081-2100. The highest (RCP8.5), current worst case will see a temperature increase of 4.3°C.

RCP Scenarios  

RCPs cover a range of climate outcomes, and it must be considered that these include a range of assumptions including many human factors such as population growth and technological advances. The values RCP2.6, RCP4.5, RCP6.0 and RCP8.5 correspond to the radiative forcing target for 2100s. This is the difference between the incoming and outgoing solar radiation (energy from the sun) at the top of the atmosphere. Higher concentrations of greenhouse gases will see larger amounts of radiation remaining in Earth’s atmosphere, increasing global temperatures. 

Major Improvements

The major improvements from UKCP09 to UKCP18 include new weather and climate observations, more recent model predictions, and the addition higher resolution outputs. Its goal is to help decision-makers assess their exposure to climate related risks. Organisations such as the Department for Flood and Rural Affairs (DEFRA) also utilise it to inform communities about risks they face, such as coastal communities that will be affected by rising sea levels. All UKCP outputs are reviewed by an independent panel of international climate experts referred to as the Peer Review Panel (PRP).

UKCP18 Coverage

UKCP18 provides predictions of how temperature, rainfall, cloud cover, humidity, sea level rise, and storm surges will change under a range of climate scenarios. It is important to provide predictions under a range of scenarios, as there is a large degree of uncertainty regarding how much more greenhouse gases will be emitted over the next few centuries. Predictions for the UK are provided at a 12 km grid and 2.2 km grid scale, as well as global 60 km grid outputs. The finer scale of the UK specific predictions allows realistic simulations of localised events such as heavy rainfall. Temperature, rainfall, cloud cover and humidity are projected to the year 2100. Sea level rise is projected up to 2300. It is important to note that sea level will continue to rise even after global temperature stabilises, as it takes a significant length of time for the Earth to re-equilibrize at to the elevated temperatures (e.g., the seas warm more slowly than the atmosphere).

UK Future Climate

The findings of the UK Met Offices climate models can be summarised as follows. Across all areas of the UK temperatures will warm. Warming will be higher in summer than in winter, and higher in the south than the north. The prevalence of heatwaves in summer will dramatically increase under all scenarios, but more so under high emissions scenarios. Across the majority of the UK, winter precipitation will increase significantly. Summer rainfall is expected to decrease, but when it does rain, it is expected that storms will be more intense than has previously been typical. Sea level will rise around the UK; however, sea level rise will be more significant in the south due to geological processes which are causing northern UK to slowly rise. The magnitude of sea level rise will increase with higher emissions scenarios.