Climate change impacts and risks at global warming of 1.5ºC to 4ºC: latest research findings

16:15 Tuesday 28 May


Room S6


Richard Betts (United Kingdom) 1; Lamprini Papadimitriou (United Kingdom) 2; Michalis Vousdoukas (Italy) 3; Gustavo Naumann (Belgium) 4; Francesco Dottori, (Belgium) 5; Wojtek Szewczyk (Belgium) 5; Jason Lowe (United Kingdom) 6

1 - University of Exeter and Met Office; 2 - Cranfield Water Science Institute, Cranfield University; 3 - Institute of Environment and Sustainability; 4 - Joint Research Centre (JRC); 5 - Joint Research Centre (JRC), European Commission; 6 - Met Office Hadley Centre

We will present and discuss new research findings on the impacts of climate change at global warming of 1.5°C, 2°C, 3°C and 4°C, at both global scales and in selected countries. Focus impacts will include water availability, river and coastal flooding, food insecurity and human heat stress. The research is the result of a highly interdisciplinary project, the HELIX project (High-End cLimateImpact and eXtremes) finished in October 2017 and with more than 90 peer-reviewed publications.

Target audience

Both the scientific community and policy makers. The HELIX research responded to an EU call for developing a number of future scenarios of the natural and human world as a consequence of 1.5°C, 2°C, 4°C and 6°C global warming. Using two high-resolution full-complexity Atmospheric General Circulation Models (GCMs), EC-Earth and HadGEM3, and regional climate models, we drove models of biophysical impacts of climate change such as fresh water availability, river flooding, crop yield and biodiversity loss, as well as to calculate an index of vulnerability to food insecurity, at levels of global warming of 1.5°C, 2°C, 4°C and 6°C relative to the pre-industrial climate.

HELIX has delivered policy-relevant conclusions to inform EU policy makers by contributing to the IPCC Special Report on global warming of 1.5°C. the audience of our session will get an overview of the conclusions reached, the methods used and an opportunity to discuss with the panel on the conclusions presented.

Proposed format for the session

Our session will consist of seven presentations, lasting 15 minutes each including questions and discussion.

Contributing Authors abstracts

1. Presenting author: Lamprini Papadimitriou, Cranfield Water Science Institute (CWSI), Cranfield University.

Outline: In a post-Paris Agreement world, where the aim to limit global warming to 1.5 or 2oC to significantly reduce the risks and impacts of climate change has been achieved, adaptation is still needed to address the impacts of these lower levels of warming. In this work, we use a multi-sectoral integrated modelling platform to evaluate the impacts of a +1.5oC world to the end of the 21st century under alternative Shared Socioeconomic Pathways for Europe. A range of adaptation strategies are tested and evaluated for their ability to improve SDG-related indicators. We find that considerable impacts are present across sectors even under the safe levels of +1.5oC of global warming. In applying adaptation strategies, SDG related sectoral ‘winners’ and ‘losers’ vary between strategies, SSPs and regions and unavoidable trade-offs are found between sectors. Finally, the strong dependency of the responses on the selected socio-economic scenario highlights the importance of integrated approaches in climate change adaptation planning, also constrained by scenario context.

2. Presenting author: Michalis Vousdoukas, Joint Research Centre (JRC), European Commission – Rising coastal flood risk in Europe and worldwide.

Outline: The present contribution reports the methodology and outcome of coastal flood risk assessments done using the integrated risk assessment tool LISCoAsT (Large scale Integrated Sea-level and Coastal Assessment Tool). We assess future flood risk along Europe coupling different greenhouse gas emission and socioeconomic scenarios. Our analysis shows that by 2100, the global average 100-year extreme sea level (ESL) is projected to rise by 34-76 cm under a moderate-emission-mitigation-policy scenario and by 58-172 cm under a business as usual scenario. Rising ESLs are mostly driven by thermal expansion, followed by contributions from ice mass-loss from glaciers, and ice-sheets in Greenland and Antarctica. ESL rise would render a large part of the tropics exposed annually to the present-day 100-year event from 2050. By the end of this century this applies to most coastlines around the world. Such intensification of ESLs will drive an increase in flood losses along Europe. EAD is projected to increase 2-3 orders of magnitude, EAD/GDP% rises from 0.01% to 0.29-0.86% by 2100, and EAPE increases from 100,000 to 1.5-3.6 million people. All the above imply substantial adaptation challenges.

3. Presenting Author: Gustavo Naumann, Joint Research Centre (JRC), European Commission – Global drought projections under different levels of warming

Outline: Droughts affect societies worldwide with often devastating consequences over long periods. They affect a wide range of sectors, from food security, drink water provision to energy production. Drought can cause conflicts when water restrictions are required and could trigger unwanted migration. Droughts are caused by an imbalance between the natural supply of water through precipitation and evapotranspiration demand by the earth and ecosystems. This imbalance can be exacerbated through the human use of water. Natural supply and demand depend on temperature and spatiotemporal precipitation patterns, which will alter in view of climate change.

Here we present the results of a global drought hazard analysis that was carried out in the framework of the HELIX project. It aims at quantifying future drought conditions under a range of Specific Warming Levels (1.5°C, 2°C and 3°C warming compared to pre-industrial times). Drought changes with respect to historical conditions are derived from a peak over threshold analysis using the SPEI multiscalar drought index that represents both the supply and demand sides of the surface moisture balance.

4. Contributing author: Francesco Dottori, Joint Research Centre (JRC), European Commission – Future scenarios of European and global river flood risk in a warming world

Outline: Knowledge on the costs of natural disasters under climate change is key information for planning adaptation and mitigation strategies of future climate policies. River floods are one of the costliest natural hazards and the ongoing rise of global temperature may further increase impacts on economy and society.

Here we present the results of different studies aimed at quantifying future flood risk at European and global scale under a range of temperature (1.5°C, 2°C, 3°C and 4°C warming) and socio-economic scenarios, carried out in the framework of the HELIX project.

All studies combine ensemble climate projections for the current century with state-of-the-art models and datasets to quantify hazard, exposure and vulnerability to river flooding. Models are used to estimate human losses, direct economic damage and subsequent indirect impacts.

All studies indicate a clear positive correlation between atmospheric warming and future flood risk at global scale, with a substantial increase in socio-economic impacts over a vast majority of countries.

Impacts are notably higher under increased warming, but at the same time, variability between model projections also increases, leading to greater uncertainty regarding flood impacts at higher warming levels. Flood impacts are further shown to have an uneven regional distribution, with the greatest losses observed in the Asian continent at all analysed warming levels.

5. Contributing author: Wojtek Szewczyk, Joint Research Centre (JRC), European Commission – Global economic impacts from climate change

Outline: The HELIX project has studied the economic effects due to climate change in agriculture, energy, river floods and coastal areas. The economic analysis uses a multi-sector, multi-region general equilibrium model to assess how the direct sectoral impacts would affect the overall economy. The economic overall impacts are calculated in terms of production (GDP) and welfare (consumption). A set of climate scenario was considered, including the 2°C future.

6. Contributing author: Jason Lowe, Met Office Hadley Centre

Outline: to follow