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Food security is a growing concern around the world, with two billion people experiencing moderate to severe food insecurity in 2019, according to the Food and Agriculture Organization of the United Nations. Food security consists of four interconnected pillars: availability of food (how much is produced), access to food (can people afford food), use of food (how food prepared and consumed) and stability (the stability of food supply and consumption).
Large-scale droughts can have cascading effects on these four pillars. They can reduce yield, which can lead to spikes in food prices, trigger changes in consumption and lead to unstable food supply and consumption. The effects of these climatic extremes are often felt most by subsistence farmers who become less self-sufficient and are therefore forced to purchase their staple foods in local markets.
If prices soar during low yielding years, food can become too expensive for them, pushing poor households into food insecurity.
So far, scientists have mainly focused on estimating how climate change has affected droughts and crop yields. Less is known if and how climate change influences the other three pillars of food security.
By analyzing the case of the 2007 food crisis in Lesotho, we found that climate change was indeed a key driver of this food crisis, even if it was not straightforward.
What we found
The food security situation in Lesotho can be described as precarious. The country produces only 30% of maize – the main staple food – at the national level. The predominantly rain-fed agriculture makes it vulnerable to the effects of drought. Maize remaining to meet domestic food demand is imported from neighboring South Africa, with maize prices in Lesotho being heavily influenced by maize prices in South Africa.
Given the close proximity between the two countries, a drought affecting Lesotho is also likely to affect South Africa. This would lead to a drop in production in both countries. This happened in 2007, when the most severe drought on record by satellite hit both countries simultaneously. The drought led to a poor harvest in both countries, resulting in a sharp decline in maize exports to Lesotho.
This was accompanied by an increase in the price of corn, which doubled what it was two years before the event. In total, emergency food aid for 20% of Lesotho’s population was needed.
To explore how climate change altered the likelihood of a drought of this severity occurring, we used an “extreme event attribution” methodology. While extreme events are expected to occur from time to time due to the natural variability of the climate system, certain types of extremes occur more frequently in a warming world. Event attribution methodologies, based on both observed weather data and climate models, help estimate how often some type of extreme event occurs in the warmer world we live in today. (factual world). This is then compared to occurrences of a similar event in such a cool world as at the start of the Industrial Revolution (counterfactual world).
We have found that due to man-made climate change, the likelihood of a drought as severe as in 2007 or worse in each country has increased fivefold. On top of that, the co-occurrence of such a drought in the two countries has doubled in probability due to climate change.
We also assessed the influence of climate change on the probability of food scarcity, which is not only driven by the presence or not of a drought, but also strongly dependent on food availability in trade-dependent countries and household purchasing power. We took a similar approach to droughts, using the idea of comparing factual worlds – the world we live in – and counterfactuals, the world that could have been without climate change.
To do this, we sampled many plausible counterfactual scenarios of the food security situation with and without climate change. We explored 10,000 different counterfactual scenarios to explore the full range of possibilities and test the sensitivity of the food system. We found that in a world without climate change, food scarcity would have been much less likely. There are even scenarios where it could have been avoided altogether.
We estimate that climate change has reduced the number of self-sufficient farming households in Lesotho by 50%. It reduced the purchasing power of households by 37%. It is important to note that climate change has exacerbated an already vulnerable food situation in the country. Agricultural production has been declining for years due to soil erosion, poor land use practices and declining soil fertility. As a result, climate change can push Lesotho’s already precarious food security overboard and make it unsustainable during years of drought.
Coping strategies
To our knowledge, this is one of the first studies to disentangle climate and vulnerability factors quantitatively to understand whether and to what extent climate change is a driver of disaster impacts, and how it occurs. compares to other potential factors. This type of information helps to better understand how climate change affects the multiple dimensions of food insecurity and how the effects of disasters can reinforce existing inequalities.
This is crucial because it shows that in planning for adaptation, focusing only on the role of climate change is not enough and can even lead to poor adaptation if social drivers and the role of vulnerability are ignored.
Our quantitative framework allows us to prove that climate change is already affecting food security in the places most vulnerable to the climate. It also provides an assessment of the relative importance of inequalities and other vulnerabilities in the food system.
Lesotho is used here as an example, but the characteristics of the country’s food supply, with high import dependence, rain-fed agriculture and extreme climate variability, are also observed in many other African countries. We therefore hope that this type of analysis will help develop more effective adaptation strategies to make food supply systems more climate resilient now and in the future.
Friederike Otto receives funding from UKRI, BNP Paribas Climate Foundation, ECF, Horizon 2020.
Jasper Verschuur does not work, consult, own stock, or receive funding from any business or organization that would benefit from this article, and has not disclosed any relevant affiliation beyond their academic appointment.
By Friederike Otto, Associate Director, Environmental Change Institute, University of Oxford and
Jasper Verschuur, PhD student, University of Oxford
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