Global farming feels the impacts of global heating

Global heating has already set back farming around the world, and wiped out seven years of steady advance.

By Tim Radford

Climate change has begun to harm the world’s farmers. Compared with a notional world in which global heating is not being driven ever higher by fossil fuel use, a new study finds that the riches to be gleaned from the soil have fallen by 21%.

This, the researchers say, is as if the steady advance in agricultural productivity worldwide − in crop breeding, in farming technologies and in fertiliser use − has been eroded everywhere by more extreme temperatures, more prolonged droughts and more intense rainfall.

“We find that climate change has basically wiped out about seven years of improvements in agricultural productivity over the past 60 years,” said Ariel Ortiz-Bobea, an economist at Cornell University in the US.

“It is equivalent to pressing the pause button on productivity growth back in 2013, and experiencing no improvements since then. Anthropogenic climate change is already slowing us down.”

He and colleagues from Maryland and California report in the journal Nature Climate Change that they developed new ways of looking at farm costs and yields that could account for climate- and weather-related factors. The findings are potentially alarming.

Productivity drops

In the last century, the planet has warmed by at least 1°C above the long term average for most of human history, and is heading for 3°C or more by the end of this century.

By 2050, the total global population could have risen to 10bn: more than two billion extra mouths to be fed. But during the last 60 years, growth in agricultural productivity in the US has been slowed by somewhere between 5 and 15%. In Africa, in Latin America and the Caribbean, growth has slowed by between 26 and 34%.

A study of this kind − comparing the present world with one that might have been − is always open to challenge, and farmers have always had to gamble on good weather and cope with bad harvests.

But over the last seven years, researchers have repeatedly confirmed that a hotter world promises to be a hungrier one. Studies have found that yields of wheat, maize and rice are all vulnerable to climate change.

They have warned that higher temperatures and more atmospheric greenhouse gases could actually affect the nutritional values of legumes, fruit and vegetables, and that changes in weather patterns − in droughts, rainfall and heat waves − will hit harvests.

“Most people perceive climate change as a distant problem. But this is something that is already having an effect”

And since the higher temperatures that global heating brings  inevitably threaten more intense, more prolonged and more extensive heat extremes and droughts, the chances of calamitous harvest failure in more than one continent at the same time will be much greater: global famine could follow.

So the latest study simply provides another way of confirming anxieties already expressed. This time there is a new perspective: the attrition of climate change began decades ago. In the constant race to keep up with demand and compensate for possible loss, the farmers may be falling behind. Technological progress has yet to deliver climate resilience.

“It is not what we can do, but where we are headed,” said Robert Chambers, of the University of Maryland, a co-author. “This gives us an idea of trends to help see what to do in the future with new changes in the climate that are beyond what we’ve previously seen.

“We are projected to have almost 10 billion people to feed by 2050, so making sure our productivity is stable but growing faster than ever before is a serious concern.”

And Dr Otiz-Bobea said: “Most people perceive climate change as a distant problem. But this is something that is already having an effect. We have to address climate change now so that we can avoid further damage for future generations.” − Climate News Network