The growing science of attributing extreme weather to climate change – It’s time for a conversation

James Painter and Peter Walton of Oxford University interviewed 50 policy-makers and development practitioners to find out how they are using the ‘growing’ science that links extreme weather events to human-made climate change. Here, they report on the findings.

First it was Hurricane Harvey. Then Hurricane Irma. Now Hurricane Maria. On the other side of the world – but with much less media attention – the flooding caused by exceptional monsoon rains created havoc in India, Nepal and Bangladesh.

In Texas, the 17 trillion US gallons of rain (roughly 26 million Olympic swimming pools) dumped on the state by Hurricane Harvey set a new high for a tropical system in the US.

Unfortunately, President Trump’s response to a question on the link to climate change was to say there had been ‘bigger hurricanes in the past’. EPA head Scott Pruitt commented that this was no time to discuss climate change, as it would be ‘insensitive’ to hurricane victims.

As USA Today countered in an editorial, this was precisely the moment to have that discussion.

In general, much of the media coverage was a step forward in covering the link between these extreme events and climate change. Instead of asking if these events were caused by climate change, much of the media analysis focused on the role climate change played compared to other factors, how much more likely they were becoming, and why their impacts are increasing.

However, what was missing from much of the mainstream media coverage was discussion of the growing science of extreme event attribution (EEA), and more importantly, of how policy makers may be able to use this science to help to plan for such events in the future.

EEA science has successfully been used to determine the role anthropogenic climate change has played in changing the risks of given events across a wide range of sectors, regions and climatic events. There have now been 140 case studies published, mostly about the USA, Europe and Australia.

However, the understanding of how decision-makers receive, assimilate and use EEA is still relatively unexamined. In contrast to the 140 studies of EEA, there have been very few, both in the academic and grey (NGO) literature, on the role that EEA does, and can, play as a climate service for different types of policy makers.

Understanding the details of that context of where, how and by whom EEA information can be used is critical in targeting the research outputs to ensure that decision-making is appropriate and effective.

Even less research has been done to identify stakeholder needs in developing regions. So that is one of the reasons we wanted to talk to a range of policy makers in Ethiopia, Kenya and India (Delhi and Ahmedabad, Gujarat) to get a better understanding of what general climate information they used, whether they knew about EEA and used it, under what circumstances it might be useful in the future, and its limitations.

Full details of how we conducted our study and whom we interviewed in the three countries are in our final report on stakeholder responses. We talked to nearly 50 policy-makers from a wide range of economic sectors (for example, planning, energy, agriculture) and stakeholders (government ministries and NGOs mostly).

There are important caveats to what we found, but overall our conclusion was that the interviewees generally did see a positive role for EEA science across the three countries – but that the role is very much dependent on the stakeholder and the context of the decision being made.

The different country contexts clearly affect the extent and manner in which EEA is, and could be, received, used and applied. Our experience was that greater scepticism was shown in India regarding the science and its role, whereas interviewees in Kenya and Ethiopia were more accepting and positive as to its application.

Some of our other findings were that:

• Interviewees found a number of limitations with EEA statements about individual events, although these were not universal. Primarily the science was currently seen as ‘lacking’ in a number of areas: relevance to decision makers [Ethiopia and Kenya]; lacking details of impacts [Kenya]; as a forecasting tool [India and Ethiopia]; translation into non-technical language [all three countries].
• Saliency, legitimacy and credibility are critical aspects of climate information if it is to meet users’ needs. Interviewees saw that the EEA science had credibility although concerns were raised when an EEA statement may not show any climate signal as this would run counter to the general message about the importance of climate change and its impacts.
• Many interviewees saw that the EEA statements had saliency, although this was less present in India, and particularly in the research institutes.
• Legitimacy was the weakest aspect of the EEA statements with concerns raised in East Africa about the technical/scientific language, complexity of the graphical information and sometimes conflicting information.

The television images of the tragic impact of the recent weather extremes make it hard to think of anything positive. But they may prompt policy makers to think more about the need for improved resilience building, disaster risk management, and reduced vulnerability.

Extreme event attribution is one of many tools that can support them. Timely and accurate information about climate change’s role in these extreme events could allow all of us to understand the extent to which these different types of events are becoming the ‘new normal’.

One thing is clear. Much more work with policy makers needs to be done.

As one Kenyan interviewee put it, “At the moment I’m not sure the policy community fully understands what EEA means. Educating needs to happen in terms of letting them know the full implications and what they can do with the information.”