High-impact low-likelihood (HILL) climate scenarios for the UK

Overview

Climate change risk assessments in the UK are based on the UK Climate Projections 2018 (UKCP18), produced by the Met Office. These describe changes under different assumptions about future greenhouse gas emissions. Some applications, however, need ‘worst-case’ or ‘credible maximum’ scenarios: what is the worst that could plausibly happen? This project therefore developed a series of high-impact low-likelihood (HILL) climate scenarios for the UK, designed to complement UKCP18 projections. One set of HILL scenarios describes plausible ‘worst-case’ projections for change to 2100, and another describes plausible extreme months and seasons. Both sets include narrative storylines and illustrative quantifications.

You can download the outputs from this project via the links below. 

HILL climate scenarios overview

This report provides a summary of transient high-impact low-likelihood scenarios and extreme anomalies. Click on this link to download the 19-page document (PDF format).

HILL scenarios report

This report presents two sets of high-impact low-likelihood (HILL) climate scenarios for the UK. The scenarios are designed to supplement and contextualise the UKCP18 climate projections, and to meet requirements of users for plausible high-end or worst-case climate scenarios. Click on this link to download the 63-page document (PDF format).

HILL scenario background report

This report outlines the evidence used to define a series of high-impact low-likelihood climate scenarios for the UK. The scenarios consist of a narrative storyline and an accompanying illustrative quantitative characterisation. The scenarios  themselves are described in more detail in the accompanying scenarios report. Click on this link to download the 134-page document (PDF format).

Use and interpretation of worst case climate scenarios in the UK

This report reviews the current use and interpretation of ‘extreme’ and ‘worst-case’

climate scenarios in the UK, based on guidelines for risk and adaptation assessment, actual assessments that have been undertaken, Adaptation Reports produced as a requirement of the Climate Change Act, and approaches used in emergency planning. Click on this link to download the 37-page document (PDF format).