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 School of Geography and the Environment

Attributing impacts of external climate drivers on extreme weather

Project description

drought in EthiopiaHow is climate change already affecting Africa? The aim of ACE-Africa is to answer this question for one of the most vulnerable parts of the world. The project looks at whether and to what extent climate change is already affecting the magnitude and frequency of extreme weather events on the continent. It also investigates the impacts of such extreme weather events on river flow and crops.

The most extreme weather events, by definition, are relatively rare, so their occurrence is dominated by chance. Attribution depends on simulation models, whose reliability can be tested and if necessary recalibrated using well-established procedures developed for seasonal forecasting. This project makes use of the large-ensemble capability provided by the weather@home volunteer computing network, in which members of the public are now performing multi-thousand-member ensemble weather simulation experiments.

Accurate assessment of the influence of external climate drivers requires explicit modelling of impact risk, not simply weather risk, so the project team works with impact modellers across Africa to assess the implications of our weather simulations for changing impact risk.

In Africa in particular, where vulnerability is high, there is a clear need to mitigate adverse impacts of extreme weather events on society, the economy and the environment. Better weather warnings should lead to increased prevention and preparedeness, which could reduce loss and damage as well as response and recovery costs. ACE is thus coupled with a boundary organisation, AfClix (Africa Climate Exchange,, with the aim of integrating the expertise and actions of relevant institutions, agencies and stakeholders to broker important ground-based dialogue around ideas of ‘loss and damage’.  Particular focus will be on looking at attribution, thinking about who bears the cost of adaptation and how that influences subsequent behaviour of decision-makers in Africa. Comparative case studies based in Senegal and Kenya will help improve our understanding about linkages between society and climate change in these countries.

Project objectives

  1. To demonstrate the need for and nature of the evidence base for the attribution of harm to external climate drivers. This will be relevant both for loss and damage assessment in climate change negotiations, and for the assessment of trends in extreme weather events in the context of other drivers of environmental change.
  2. To demonstrate the importance of accurate attribution of any changes in weather risks for adaptation planning, to avoid ‘adapting to yesterday’s problems’ as the balance of external drivers changes over the coming decades.
  3. To quantify the impact of changes in short-lived climate pollutants and regional climate forcings, in addition to the impact of warming induced by greenhouse gases, on weather extremes in Africa.
  4. To provide potential users of event attribution results with multi-thousand-member event-sets of regional climate model output. This will help to assess the impact of external drivers on the statistics of African weather.
  5. To compare the impact of changing risks of extreme weather with other impacts of anthropogenic emissions. This will provide context for the role of changing risks of meteorological extremes in the attribution of harm.
  6. To provide members of the public with the opportunity to contribute directly to research on climate change in a vulnerable region and demonstrate the power of an evidence-based approach to climate impact attribution.