Falling harvests could soon follow growing deserts

Falling harvests could soon follow growing deserts

By Tim Radford

A hotter world will mean more deserts and falling harvests − bad news for food producers and for all of us.

LONDON, 18 May, 2021 − By the end of the century falling harvests could jeopardise as much as a third of present levels if greenhouse gas emissions continue uncontrolled.

That is because climatic regions that right now and for most of human history have been home to reliable crops of grains, pulses, fruits and vegetables, and safe grazing for cattle, sheep, goats and so on, could become too hot, too dry, or too wet.

And these things could happen too quickly for farmers either to adapt, or crops to evolve. Land that had for generations been considered “safe climatic space” for food production could be shifted into new regimes by runaway global heating, according to a new study in the journal One Earth.

“Our research shows that rapid, out-of-control growth of greenhouse emissions may, by the end of the century, lead to more than a third of current global food production falling into conditions in which no food is produced today − that is, out of safe climatic space,” said Matti Kummu, of Aalto University in Finland.

“The good news is that only a fraction of food production would face as-of-yet unseen conditions if we collectively reduce emissions, so that warming would be limited to 1.5° to 2°Celsius.”

Very big If

In 2015, almost all the world’s nations met in Paris and agreed to act to contain global heating to “well below” 2°C above the average for most of human history by 2100.

Six years on, that promise now looks increasingly ambitious: despite declarations of good intent, the planet is heading for a temperature rise of 3°C or more by 2100. The Paris target of 1.5°C could be surpassed in the next two decades.

The One Earth study is yet another in a chain of findings that confirm that much of the worst possible consequences of global heating could be contained if − and only if − there is concerted and determined global co-operation to abandon fossil fuel use and to restore natural ecosystems.

Professor Kummu and his colleagues report that they examined ways of considering the complex problem of climate and food. Geographers have identified 38 zones marked by varying conditions of rainfall, temperature, frost, groundwater and other factors important in growing food or rearing livestock.

The researchers devised a standard of what they called “safe climatic space” and then considered the likely change in conditions for 27 plant crops and seven kinds of livestock by the years 2081to 2100, under two scenarios. In one of these, the world kept its promise and controlled warming to the Paris targets. In the other, it did not.

“The increase in desert areas is especially troubling because in these conditions barely anything can grow without irrigation”

And they found − an increasingly common finding − that climate change is likely to hit the poorest nations hardest: that is, those people who have contributed the least to global heating could once again become its first casualties.

Under the more ominous scenario, the areas of northern or boreal forests of Russia and North America would shrink, while the tropical dry forest zone would grow, along with the tropical and temperate desert zones. The Arctic tundra could all but disappear.

The areas hardest hit would be the Sahel in North Africa, and the Middle East, along with some of south and south-east Asia. Already-poor states such as Benin, Ghana and Guinea-Bissau in West Africa, Cambodia in Asia and Guyana and Suriname in South America would be worst hit if warming is not contained: up to 95% of food production would lose its “safe climatic space.”

In 52 of the 177 countries under study − and that includes Finland and most of Europe − food production would continue. Altogether 31% of crops and 34% of livestock could be affected worldwide. And one fifth of the world’s crop production and 18% of its livestock would be most under threat in those nations with the lowest resilience and fewest resources to absorb such shock.

“If we let emissions grow, the increase in desert areas is especially troubling because in these conditions barely anything can grow without irrigation,” said Professor Kummu. “By the end of this century, we could see more than 4 million square kilometres [1.5m sq miles] of new desert around the globe.” − Climate News Network


Cover image by Clément Bardot, via Wikimedia Commons

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