Attributing impacts of external climate drivers on extreme weather in Africa

Lead Research Organisation: University of Reading
Department Name: Meteorology


Given limited progress in reducing greenhouse gas emissions and uncertain potential for adaptation to many impacts, attention in vulnerable regions and sectors is turning to the question of "loss and damage". Who should bear the costs of human influence on climate that cannot be neutralized by adaptation? This debate is impeded by lack of robust estimates of what these costs are. Despite concerted efforts to compile inventories of emissions, we still have no agreed method of establishing how countries, companies or individuals are being adversely affected by anthropogenic climate change in the context of other drivers of regional environmental change.

Many of the most important impacts of climate change are related in some way to high-impact weather events (HIWEs), such as floods, storms, and droughts. Compiling an impact inventory requires documenting the impacts of individual events and how these events are affected by multiple climate drivers and internal climate variability. We will build on research into HIWEs and their impacts under THORPEX-Africa.

Studies assessing the link between climate change and extreme weather have so far focused primarily on mid-latitude phenomena and the impact of rising greenhouse gases. Yet in many tropical regions, short-lived climate forcings (SLCFs) such as sulphate, mineral and black carbon aerosols and tropospheric ozone may have played a larger role in changing patterns of weather risk to date. Substantial reductions in anthropogenic SLCFs could be achieved in only 20 years. Including measures already planned to reduce emissions of sulphate aerosol precursors, SLCFs may dominate near-term changes in weather risk. Climate impact assessments used for adaptation planning typically focus on net multi-decadal anthropogenic change, dominated by greenhouse-induced warming. Few address uncertainty in SLCF forcing and response. Hence relying on these and extrapolation of recent trends risks "adapting to yesterday's problem" as key drivers of regional weather are reversed.

Assessing the influence of external drivers on extreme weather is challenging because the most important events are typically rare. The only solution is to rely on simulation models, whose reliability can be tested and if necessary re-calibrated using well-established procedures developed for seasonal forecasting. We will also use the land-surface model JULES for indirect validation in regions with sparse meteorological data. Large ensembles of climate model simulations at relatively high resolution are required for robust statistics of extreme weather events, allowing for uncertainty in both external drivers and simulation models.

This project makes use of the weatherathome worldwide volunteer computing project. We will quantify the role of various external climate drivers on changing risks of extreme weather in Africa by implementing a regional climate model over the CORDEX-Africa domain and simulate observed weather statistics over recent decades using multi-thousand-member ensembles, systematically excluding the influence of different climate drivers to quantify their effects.

Attribution studies of HIWEs to date have typically focussed on hydrometeorological events themselves, rather than modelling all the way through to their impacts. This can lead to "over-attribution": if a record-breaking weather event occurs that has been made more likely by some external driver, people tend to blame most of the impact of that event on that driver. But much of this impact might also have been caused by a lesser, non-record-breaking, event. Hence accurate assessment requires explicit modelling of changing impact risk, not simply weather risk, so a major focus of this project will using JULES to investigate various impacts and working with impact modellers across Africa to assess the implications of our weather simulations for changing impact risk in other sectors.

Planned Impact

End-to-end attribution of climate change impacts is a pressing issue not only for the for the Intergovernmental Panel on Climate Change but especially for users of climate information in farming, decision makers for infrastructure development and adaptation. The interdisciplinary nature of the problem makes co-generation of knowledge essential: attribution of hydro-meteorological anomalies alone is insufficient to demonstrate impact. Calculation of actual harm requires a deep understanding of local confounding factors and changing vulnerability. We propose to address this through demonstration projects (attribution of floods in Kenya, droughts in East Africa and vegetation changes over parts of the continent) and providing funding for two workshop to initiate a network of collaborations within Africa using the established links within THORPEX Africa, the consortia of Regional Climate Outlook Forums (RCOF) in Eastern and Western Africa, and Oxfam projects in drought and flood prone regions of the African continent. At these workshops we aim to bring together a large group of impact modellers using the data provided by the proposed research in Oxford to start the process of compiling an inventory of climate impacts over Africa.

Valuing anthropogenic modification of weather and climate is the ultimate goal of this research. On the ten-year research horizon, there is a clear need for a global inventory of the impacts of climate change to complement current inventories of climate drivers such as national emissions data. This will provide an essential ingredient for evidence-based mitigation and adaptation policies, but will need a firm grounding in the link between climate and extreme weather, drawing on routine attribution assessments which address all weather events, not simply high-profile disasters. This is an especially pressing requirement in Africa which is expected to be hard hit by impacts of climate change in the very near future, is least resilient to changing risks of extreme weather events, and has an underdeveloped inventory at present as impact assessment depends on understanding of meteorological mechanisms and impacts of hydro-meteorological events on agriculture, infrastructure and livelihoods. This will require a sustained international effort: this project will develop and prove some of the necessary methods and demonstrate their feasibility and value in most vulnerable regions of Africa. The workshops are planned to initiate an inventory of climate change impacts from within the African continent itself.

With this close collaboration with established facilitators of climate information for and from Africa as THORPEX and RCOF and linking this to impact assessment in Oxford and provided by Oxfam, we develop also a bottom-up approach to quantifying the actual costs (and benefits) of climate change over Africa which represents a radical departure from the top-down approach of typical Integrated Assessment Models used to calculate the Social Cost of Carbon, which parameterise the net impact of extreme weather, providing limited scope for disaggregation of costs and benefits. In effect, we are addressing the question "what did human influence on climate actually cost me (my company or country) last year?" as opposed to "what would we expect the cost of anthropogenic climate change to be in a typical year of the current decade?"

Additionally we plan to further develop citizen science capacity through collaborations between members of and modellers in the project team, supported by information provided on, to understand how climate modelling works, examine evidence of the impact of human influence on climate and inform the attribution of extreme weather events to anthropogenic climate change.
Description In 2013 the Warsaw International Mechanism (WIM) for loss and damage (L&D) associated with climate change impacts was established under the United Nations Framework Convention on Climate Change (UNFCCC). For scientists, L&D raises ques-tions around the extent that such impacts can be attributed to anthropogenic climate change, which may generate complex results and be controversial in the policy arena. This is particularly true in the case of probabilistic event attribution (PEA) science, a new and rapidly evolving field that assesses whether changes in the probabilities of extreme events are attributable to GHG emissions. If the potential applications of PEA are to be considered responsibly, dialogue between scientists and policy makers is fundamental.
Two key questions are considered in this research provided the opportunity for in-depth insights into stakeholders' views on firstly, how much is known and understood about PEA by those associated with the L&D debate? Secondly, how might PEA inform L&D and wider climate policy? Results show debate within the climate science community, and limited understanding among other stakeholders, around the sense in which extreme events can be attributed to climate change. However, stakeholders do identify and discuss potential uses for PEA in the WIM and wider policy, but it remains difficult to explore precise applications given the ambiguity surrounding L&D. This implies a need for stakeholders to develop greater understandings of alternative conceptions of L&D and the role of science, and also identify how PEA can best be used to support policy, and address associated challenges.
Exploitation Route Results were used to support discussions within the then newly formed Climate Change Committee in Senegal in 2016 to address extreme precipitation and flooding in urban Senegal. Our case study work showed that national adaptation decision-makers recognise climate as a driver of increasing flood occurrence, but perceive the impacts to be primarily caused by issues around urban planning, including settlements in flood-prone areas and a lack of drainage infrastructure. The key stakeholders addressing these issues are the government ministries responsible for urban planning and water and sanitation.
Stakeholders thought event attribution results could be relevant in order to plan for similar events in the future, understand which events are impacts of climate change, and to encourage support in international climate negotiations. However there are many barriers to integrating this science into planning in Senegal at this stage, which may be reflected in other developing countries. These include the limited climate information currently incorporated into planning and decision-making and a lack of coordination between the stakeholders addressing flooding. These barriers will need to be critically examined in line with current understanding and communication of science-policy in adaptation. There is a focus on addressing current rather than future risks, as the impacts of flooding in urban Senegal need to be addressed in order to protect the most vulnerable communities now. Decisions are prioritising addressing current urbanisation issues and do not focus on considering integration of longer-term climate information. Understanding whether events and impacts are caused by climate change may not be directly relevant for this. However if such short-term planning is to be resilient in the long-term and protect vulnerable communities from flooding impacts in the decades ahead, decisions on urban planning, drainage infrastructure and other adaptation actions will need to incorporate relevant and accessible knowledge about how the risks of extreme events are likely to change in the future.
Sectors Agriculture, Food and Drink,Environment,Financial Services, and Management Consultancy,Government, Democracy and Justice,Transport

Description Climate change committee in Senegal - considered findings from research for their national adaptation planning process (and particularly wrt fishing industry). They engaged with the Cauldron game and we have maintained the partnership since through Prof Amadou Gaye (UCAD and Senegal Climate Change Committee).
First Year Of Impact 2015
Sector Environment
Impact Types Cultural,Societal

Description ANACIM ACE Africa 
Organisation Senegal Meteorological Service
Country Senegal 
Sector Public 
PI Contribution Hosted a workshop to raise the issue of using extreme event attribution in Senegal for shaping the NAPA
Collaborator Contribution Contributed to the workshop presentations and supported the seminar
Impact Partnership to develop further research around attribution science for application in Senegal
Start Year 2015
Description PAC 
Organisation Practical Action
Country United Kingdom 
Sector Charity/Non Profit 
PI Contribution Technical support and Knowledge Exchange about the science of attribution to Practical Action team (UK, Kenya)
Collaborator Contribution Pull through to East African event around Loss and Damage policy (February 2017)
Impact Pull through to East African event around Loss and Damage policy (February 2017)
Start Year 2017
Description Red Cross Crescent Climate Centre 
Organisation Red Cross/Red Crescent Climate Centre
Country Netherlands 
Sector Charity/Non Profit 
PI Contribution Technical design, test and implementation of the Cauldron Game. Creation of the Creative Commons License
Collaborator Contribution Conceptual design and support for testing
Impact engagement of policy makers and academics through game play at high level (e.g. COP21) and academic events (see listings)
Start Year 2014
Title Game for brokering dialogue around complex climate issues 
Description The CAULDRON (Climate Attribution Under Loss and Damage: Risking, Observing, Negotiating) Game Suarez, P, Parker, HR, Cornforth, RJ, Otto, FEL, James, R and Boyd, E. (2014). Open access material published under a Creative Commons License 
IP Reference  
Protection Copyrighted (e.g. software)
Year Protection Granted 2014
Licensed Yes
Impact Creative Commons approved Stakeholders from Africa and Europe have requested copies of the game for game play and then fed back comments for potential improvements Game has been developed - v3 now available Oxfam blogs drew attention to it: Also at CC Expo: Games used most recently to enhance understanding of attribution of extreme weather events and application to Loss and Damage negotiations for the Senegal National Climate Change Committee
Description ACE Africa small write shop in April prior to the Community Based Adaptation Conference in Nairobi to discuss indicators od loss and damage, and how to measure it. 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Policymakers/politicians
Results and Impact Secured invite via AfClix for project team to participate in a small write shop hosted by the UNEP prior to the Community Based Adaptation Conference in Nairobi to discuss indicators of loss and damage, and how to measure it.
Year(s) Of Engagement Activity 2015
Description ACE EGU Loss and Damage Poster 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Study participants or study members
Results and Impact Session organised and poster presentation made about how research about extreme events and impacts be developed to support international climate policy
Year(s) Of Engagement Activity 2015
Description European Geosciences Union (EGU) General Assembly 2016 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact Discussed results with other researchers in the field and got ideas for further research
Year(s) Of Engagement Activity 2016
Description Framing Climate Change Loss and Damage after Paris 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach National
Primary Audience Professional Practitioners
Results and Impact Shared results of study with key people involved with loss and damage negotiations and had opportunities for discussions
Year(s) Of Engagement Activity 2016
Description Use of Cauldron Game 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Postgraduate students
Results and Impact 20+ PG students attended a seminar and game play of the Cauldron to learn about attribution science and its use in policymaking.
Year(s) Of Engagement Activity 2019
Description Workshop on extreme events, climate change and loss and damage 
Form Of Engagement Activity A formal working group, expert panel or dialogue
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Professional Practitioners
Results and Impact Workshop led to information for us on understandings of extreme events and challenges in decision making. Also introduced participatory tools such as the CAULDRON game to participants, and we will now provide them with the materials to be able to run this game themselves. The workshop also generated valuable discussion between participants and led to a further meeting at MRUHCV and contacts for interviews to gain more research data and have further discussions about the usefulness of the science.
Year(s) Of Engagement Activity 2016