Irrigation can be a powerful tool for increasing global food supply. In fact, more than a billion additional people can be fed through sustainable irrigation without converting natural spaces into farmland, according to a new study by Lorenzo Rosa of the Carnegie Institution for Science.
“Population trends indicate that we will need to double global food production by 2050,” explained Rosa. “To accomplish this, we will either need to clear more land or farm more efficiently, despite the increased stresses of a warming world.”
Converting land into farms can further exacerbate climate change, while reducing biodiversity. Using modern technology, low crop yields in existing farmland could be improved.
However, these intervention strategies must be evaluated to determine which ones will lead to a greater increase in food production, while maintaining the lowest environmental impact.
Climate change is expected to both shift precipitation patterns and increase heat stress on plants. This means that rain alone cannot be relied on to support the increasing demand for food.
One strategy for improving the productivity of farmland is irrigation. Irrigated crops are twice as productive than those that rely only on rainfall. However, irrigation already accounts for between 85 and 90 percent of human water consumption.
Is it possible to use irrigation to increase food production without creating water shortages? To do so, we must consider sustainable irrigation methods. Sustainable irrigation uses groundwater and local available water sources without depletion beyond what precipitation can replace.
To maximize agricultural productivity while minimizing environmental impacts of water use, Rosa set out to determine which strategies could be utilized. He found that under current conditions, there is enough water available from local, renewable sources to expand sustainable irrigation over 35 percent of farmland around the world. This would boost crop productivity to feed 1.4 billion more people.
Sounds simple – but factoring in the effects of climate change makes this much more complex. As temperatures rise, water could start to evaporate faster, decreasing the efficiency of irrigation. On the other hand, elevated levels of atmospheric carbon dioxide could make crops grow somewhat more productively, which might offset this concern. These competing factors demonstrate the need for further research.
The study indicates that constructing long-term water storage reservoirs could enable sustainable irrigation to feed 1.2 billion more people than relying on renewable water resources alone.
Specifically, the United States, Russia, Brazil, and Nigeria were identified as having the greatest potential for sustainable irrigation under extreme warming conditions using water storage facilities. This could also be feasible in Latin America, Eastern Europe, and Sub-Saharan Africa.
Despite this, many factors remain unknown, such as the potential effects on water quality due to increased fertilizer, and the socioeconomic and land-use impacts of constructing infrastructure. However, the study makes a clear case that sustainable irrigation could alleviate poverty and hunger, while decreasing environmental risks.
“Ensuring sufficient and equitable access to food while reducing agriculture’s environmental impacts is one of the greatest societal challenges of the 21st century,” concluded Rosa.
Thoughtful uptake of irrigation could potentially help meet our growing demands for food with minimal impacts.
The study is published in the journal Environmental Research Letters.