Expectations are that sufficient food will remain available in the Northern hemisphere, but in regions such as Sub-Saharan Africa or South Asia, falling crop yields may lead to higher food prices and a sharp rise in hunger. In an international research team we set out to investigate whether international trade can relieve these regional differences, and turns out, it does.
To address this question we used a combination of global climate, crop and economic land use models to project the impact of climate change on agricultural yields, food availability and hunger by 2050. With 60 integrated scenarios - and at some point even a set of more than 500 scenarios (these did not make the final cut, but stay tuned for future work!) - we decided to use an econometric framework to analyze the results. We wanted to find out whether the role of trade becomes larger under climate change, whether the effects are robust across climate change scenarios, and whether climate change shifts the pattern of comparative advantage.
We indeed found evidence of a larger trade effect under climate change, though not in all regions. The fun part is that here we can also discuss what came out differently than expected, or just became redundant. We analyzed for example in a Bayesian econometric framework the sensitivity of the results to the assumption on CO2 fertilization (it was robust!), but in the end we had to replace it with an additional set of 54 scenarios (where it stayed robust, luckily!). In turn, these new scenario runs reveal, however, a large sensitivity of mapping climate change impacts from one crop to the other, which we will need to take into account in future research. Based on the literature, our expectation was that climate change radically shifts the pattern of comparative advantage. We did not found evidence for this in any of our indicators, at least not for the four main crops we investigated (corn, wheat, rice and soya). It remains to be seen whether this conclusion will also hold under the new upcoming climate change projections from CMIP Phase 6.
In summary, our study finds an increase in global climate-induced hunger when trade is restricted, and a reduction when trade barriers are removed. This implies that international trade is to be considered as part of the set of adaptation measures to climate change, particularly because trade is most important for regions that are most adversely affected by climate change. Yet, we find that trade liberalization has also potential negative effects: regions could experience a lower food availability from increased exports when barriers that prevent imports are not removed. Trade integration should thus very carefully be implemented to cover the full range of barriers.
It is tempting to think the work is done: through many cycles of testing, analyzing and reviewing, a comprehensive study of international trade, climate change and hunger emerged. But as the saying goes, the more you know, the more you realize you do not know. What about the climate impacts that we could not take into account? What about climate change differences at sub-regional or sub-national scale? What about the within-country distributional effects of trade and climate change? And what are the implications of all this in light of the COVID-19 crisis? That's for the next post!
The full article, Global hunger and climate change adaptation through international trade, is accessible via https://www.nature.com/articles/s41558-020-0847-4.