Quantifying and Understanding the Changing Risk of Climate on Water and Food Security in Southern Africa

Why are African countries among the most vulnerable to climate variability and change?

Sub-Saharan Africa is not necessarily more exposed to climate hazards than other regions of the world. But, with some of the least developed and lowest income emerging economies, it has a lower capability to manage those risks. Much of my work during the AXA Chair was focused on demonstrating the links between a changing climate and food and water security. For example, heat stress means that many crops are at their thermal limits and reach lower yields. Rather than simply documenting climate change, this approach allows us to define its societal impacts.

What has your work revealed about the changing nature of climate risk and how human activity affects this?

The main focus of my Research Chair was quantifying how the risks of different types of climate hazard have changed because of human influence on climate, and how that “attributable change” in climate hazard alters risk on the ground. One focus has been water security, for which we used the 2016-2018 Cape Town multi-year drought as a case study. We found that while the likelihood of the rainfall drought had increased threefold, there was a four-fold increase in the risk of hydrological drought—so, the impact on the ground was amplified compared to the climate change signal. Another threat to water security in the Western Cape area is alien vegetation, such as the thirsty, non-native pine and acacia trees that are invading the mountain catchments and exacerbating the water security issue. Our modeling revealed that removal of alien vegetation would reduce, but not entirely offset, the water security risk.

A second focus was on sovereign drought insurance. For this, I collaborated with the African Risk Capacity, which offers insurance to African nations to help them deal with the immediate response costs of drought on food security. Insurers use risk models to estimate the likelihood of particular perils using historical climate data, and then calculate a premium. When applying our attribution methodology to this risk model, we found that climate change has dramatically increased the costs of insurance in some countries.

How have your findings helped southern Africa to build resilience and adapt management?

As well as engagement with the African chapter of the Principles for Sustainable Insurance, we have shown that methods used to estimate perils need to be updated to better understand the risk that insurers are offering products for. More generally, quantifying how the likelihood of different perils have changed has helped to reflect on risk management approaches and whether they’re fit for purpose. Our Cape Town work, for instance, has implications for designing future water resource systems.

Yet, it takes a long time for ideas to propagate through to action on the ground. In Africa, many countries have suboptimal or non-existent climate observation networks, which makes quantitative risk work difficult. Many countries in southern Africa are also reluctant or unable to invest in updating systems, especially as resources are already thinly stretched.

Does your work have implications for human health?

There’s been limited work done in Africa on climate-health relationships. Professor Lara Dugas, a new AXA Research Chair at UCT, and I are interested in whether it is possible to detect climate change signals within longitudinal human health data, as well as the effects of climate on nutritional status. This could have implications for managing food security.

How has the AXA Chair facilitated climate change research in southern Africa?

The AXA Chair enabled me to support the development of MSc and PhD students and postdoctoral researchers, including Dr Romaric Odoulami, now a leading expert in assessing the risk and benefits of solar geoengineering of climate, Dr Petra Holden who is working on modelling trade-offs between Nature Based Solutions to climate, and Christopher Trisos who I have supported in building his own Climate Risk Lab at the ACDI in Cape Town.

As well as being good leverage for additional research funding, the AXA Chair also enables ownership of the research agenda, and allows researchers overwhelmed with teaching commitments—which is common in Africa—to be more productive.

How important is it to have long-term funding?

Having that financial stability for 5 years allowed me to think strategically without worrying about salaries and short-term funding gaps. Importantly, having three 5-year periods for the successional chair program means that we can respond to the emerging research agenda as our understanding of climate risk and responses evolves.

What are your hopes for your AXA Chair successors?

Understanding climate risk is important, but I’d like the future AXA Chairs to focus more on solutions to critical vulnerabilities and high-risk settings in Africa, such as the growing population combined with levels of informality and lack of infrastructure. Food security and water security are also going to be ongoing issues. 

How has AXA facilitated key collaborations within southern Africa and abroad?

Another development in the last 5 years has been creation of the ARUA Centre of Excellence in Climate and Development, which is a partnership between the Universities of Cape Town, Nairobi, and Ghana. Climate risk is included as a strong theme in that. My involvement in the Intergovernmental Panel on Climate Change 6th Assessment report, published in 2022, also inspired fruitful collaborations and allowed us bring our climate change attribution work into the Africa chapter of the Working Group II IPCC report.

How important has it been to communicate your research findings?

Developing long-term relationships and trust is key. At the ACDI, we take a transdisciplinary approach, which involves bringing societal actors on board and consulting with them on an ongoing basis, such as engaging as an expert with resilience managers in the city of Cape Town or the local department of water affairs. In this way, we can help people to think about challenges and potential avenues for change.

How has the AXA Chair contributed to your professional growth?

Being freed up to focus on research was transformational for me, and I’m very grateful for that. Applying for the AXA Chair also meant I had to think carefully about the 5-year research plan, so it gave me real focus.

October 2022