Rapidly rising heat will cut maize harvests

Soon the corn could roast on the cob long before the maize harvests are due. That could be far sooner than anyone expects.

LONDON, 3 April, 2019 − European scientists have bad news for the world’s farmers: within a decade, maize harvests will suffer as global temperatures will have reached a level that will turn the once-in-a-decade extremes of heat and drought into the new normal.

That will mean that the worst production losses ever felt by the maize farmers will happen with increasing frequency, if global planetary temperatures reach 1.5°C above the long-term average for almost all human history.

The world is already 1°C hotter on average than it was before the Industrial Revolution and its increasing dependence on fossil fuels to power the global economies.

And if the temperature reaches 2°C, researchers warn, farmlands where maize once flourished will be hit by heat and drought events never before experienced. The big agribusiness giants will be hurt – and so will the small subsistence farmers who depend on their crop to keep their families alive.

“At the 2°C warning level . . . our projections suggest that global maize production will suffer from unprecedented losses”

Already the warming in the last few decades has begun to hit yields: the scientists reckon that maize yield within the 28 European member states is 290,000 tonnes a year lower than it would have been without global warming.

Significantly, 195 nations met in Paris in 2015 to agree to co-operate to keep average global warming down to if possible “well below” 2°C by 2100. Their target was a rise of no more than 1.5°C.

At the present rate of action – to switch to solar and wind power, to restore the world’s forests – the planet is on course to warm by 3°C by the close of the century.

But a new study by the European Union’s Joint Research Centre in Ispra, Italy, published in the journal Earth’s Future, is not worried about the average, but about the extremes that, over the course of a year, make up that average, and drive up the loss of one particular crop: maize.

Vulnerabilities

Maize is now the world’s biggest single crop: the US is the most important producer but the EU ranks fourth in the world, producing an average of 65 million tonnes a year for food and cattle fodder. This warm climate crop is at certain points in its growing season vulnerable to heat stress and to drought. And heat stress seems increasingly certain.

Researchers have warned, repeatedly, that higher average planetary or regional temperatures will mean increasingly intense, frequent, prolonged and potentially dangerous extremes of heat. And those areas already vulnerable to drought are likely to see much more of it, while other regions will become more at risk of catastrophic flood.

Agricultural scientists have already confirmed that untimely spells of heat and drought have started to slash cereal yields as measured across whole regions, or per field.

Hunger warning

And although the US has increased production, this too will be vulnerable to further warming. The World Meteorological Organisation has just warned of an already warmer, hungrier world.

The European researchers report that their analysis of past and future maize production surveys a range of outcomes: in one of these, the worst could start to happen as early as 2020. They suggest greater efforts to meet the goals set in Paris but even with those, farmers and agriculture ministries will need to find ways to adapt.

Their report ends bluntly. “We found that global warming will substantially increase the risk of maize production losses in most world regions, including the United States. The climatic events affecting historical global maize production once every 10 years will become normal at the 1.5°C global warming level, which is reached in the 2020s in most of the analysed climate model simulations,” they write.

“At the 2°C warning level (approximately late 2030s) our projections suggest that global maize production will suffer from unprecedented losses.” − Climate News Network