I’ve covered the expansion of cities and rapidly increasing urbanization from the air pollution perspective and what that could mean for the auto and fuels industries, but a study released this week and featured in The Guardian delves into the agricultural perspective. The major finding from the study is that as cities continue expanding and “megafying” they will eat up valuable cropland and undermine the productivity of already stressed agricultural systems.
The authors say the significance is:
“Urbanization’s contribution to land use change emerges as an important sustainability concern. Here, we demonstrate that projected urban area expansion will take place on some of the world’s most productive croplands, in particular in megaurban regions in Asia and Africa. This dynamic adds pressure to potentially strained future food systems and threatens livelihoods in vulnerable regions.”
Roughly 60% of the world’s cropland lies on the outskirts of cities which is concerning, the authors say, because this peripheral habitat is, on average, also twice as productive as land elsewhere on the globe. The agricultural losses they calculated in the study, published in Proceedings of the National Academy of Sciences, translates to a 3 to 4% dip in global agricultural production.
It may not seem like a huge figure but on a regional scale, across countries and different crops (some of which are biofuels feedstocks) the effects become more pronounced. The authors found that in Africa and Asia will bear 80% of the projected losses. Note that a number of countries in these regions have or will be putting into place biofuels mandates and the primary drivers behind that are economic development/job creation and diversifying energy supplies since most of these countries are also net importers of oil.
To arrive at the estimates, the story notes the researchers combined datasets on cropland location, productivity, and projected urban expansion by 2030. By superimposing these layers of information on one other, they could highlight the locations where cropland and urban spread are expected to intersect in the future. These projections reveal hotspots of loss in countries like Egypt, Nigeria, the countries that flank Lake Victoria in East Africa, and in Eastern China. China alone is expected to experience one-quarter of the global cropland loss. The figure below shows the hotspots.
A major worry voiced in the study surrounding the disappearance of this productive land is the impact it will have on staple crops such as corn, rice, soya beans, and wheat, which are cornerstones of global food security. Many of these crops occur in areas that will be consumed by urban spread in years to come. Some of this loss can be compensated for by agricultural expansion and intensification, but the authors say it isn’t possible everywhere as many regions are already limited by their inability to adapt to urban encroachment.
The authors conclude:
“The next few decades will be a period of large-scale urban expansion, and in many parts of the world, this will take place on prime cropland. Our findings show that, for a few countries, the loss of cropland will significantly reduce the total share of national cropland. As most of the cropland expected to be converted is more productive than the global average, efforts will need to compensate for that loss, whether by intensifying remaining cropland or by expanding agricultural production into new areas. The results suggest that strategies and policies to effectively steer patterns of urban expansion will be critical for preserving cropland. In an increasingly interconnected world, the sustainability of urban areas cannot be considered in isolation from the sustainability of resources and livelihoods elsewhere.”
Here are a few implications I can see from a review of the study: