Climate change

Britain’s crops brace for invasion by hundreds of exotic pests and pathogens

Britain should expect “many hundreds” more pests and pathogens to invade the country in the coming years, endangering vast volumes of food production, the author of a new report has warned.

the independent,

2 September, 2013

Crop-damaging pests such as fungi, beetles and moths are moving into new territories at a rate of up to 7 kilometres a year, according to research.

An accelerating global trade in crops is transporting pests around the world in ever larger numbers while climate change is allowing them to prosper in previously inhospitable locations. This is putting the world’s already-stretched food supplies under even greater strain, said the report, published in the journal Nature Climate Change.

Numerous new pests have already landed on UK shores and prospered in recent decades, in many cases aided by climate change, according to Daniel Bebber of Exeter University, who was lead author of the report.

Examples include Dutch Elm disease, caused by the Ophiostoma ulmi fungus that is carried by the bark beetle – with both species operating more effectively under warmer conditions – and ash dieback, caused by the Chalara fraxinea fungus.

With climate change set to continue, more insects, fungi, bacteria and viruses are likely to follow, Mr Bebber said.

The Colorado potato beetle is a particular cause for concern, Mr Bebber said. Warming appears to have allowed it to move from Russia through Scandinavia where the cold winters would normally knock the beetle back. There is “very much a danger” that it could invade the UK, he said.

In some cases, the warming climate will drive pests away, but these cases are likely to be rarer, he said.

“It’s a serious issue. If a new fungus evolves in the UK that can’t be controlled, farmers could lose thousands of hectares of production,” said Mr Bebber, adding that an influx of new pests could greatly increase the volume of pesticides used. This could have significant side-effects, for example by potentially harming bee populations, he said.

Pests moving polewards threaten global food security

Carbon Brief,

2 September, 2013

Fungi, insects and bacteria look set to pose an increasing threat to global food production in years to come, new research reveals. As temperatures rise, crop-destroying pests and diseases are spreading from the tropics toward the poles at a rate of nearly three kilometres per year.

The rising problem of pests in some of the world's most productive farmland presents a real threat to global food security, as climate change makes higher latitudes like the US and Europe more hospitable to pests that wouldn't otherwise survive.

How bad is the pest problem?

For farmers worldwide, pests are already a serious problem. They are responsible for the loss of between  10 and 16 per cent of all crops during production, and result in further losses after harvest i.e. due to infestations in food stores.

From microscopic fungi, bacteria and viruses to insects and other animals, there are numerous different species which affect everyday staples like cereals, potatoes, fruit and vegetables. These pests have evolved to breed quickly and disperse easily, allowing them to move readily to find new hosts.

Given the right amount of warmth and moisture, these pests thrive and grow. The new study suggests that changes to these aspects of the climate are allowing pests to become established in previously unsuitable regions.

The UK government identified increasing pest numbers as a potential problem in its  2012 assessment of the climate risks facing the country. At the time, there wasn't enough evidence to confidently say how pests would affect farmers' yields, but studies like this might start to change that.

Poleward shift

Using records dating back to the 1960s, researchers from the University of Exeter & the University of Oxford spotted that a wide range of pests were spreading from the tropics towards the poles. While international trade in food helps spread pests further and faster than other species, it's changes in the climate which allow the pests to take hold, say the authors.

Their study shows pests' poleward shift is happening at a rate of about 2.7 kilometres per year - give or take a bit. By our maths, that's about 135 kilometres over the last 50 years, or 27 kilometres per decade.Compared to how fast other wild species are moving towards the poles - about 18 kilometres per decade - it's clear pests are spreading much quicker.

The pace of pest spread is not surprising though - in fact it's pretty much exactly what scientists expect, given the temperature rise earth has experienced in recent decades. This makes the authors confident that as a result of climate change, pests could compromise crop harvests worldwide, including high latitude regions like Europe and the US where agricultural productivity per unit land area is highest.

So climate change is bad news for crops?

If this research is correct, the indirect impacts of climate change could have considerable consequences for global food production. The authors warn:

"If climate change [makes] it easier for crop-destroying organisms to spread, renewed efforts to monitor the occurrence of pests and diseases and control their transport will be critical in controlling this growing threat to global food security."

But as the paper also acknowledges, future global food security depends on a number of physical and socio-economic factors i.e. population growth. Looking at just one aspect of how climate change might affect crops can be misleading, as research published last week  showed.

At the moment, it looks like growing crops could get a lot tougher in the future. Whether technological advances can keep pace with climate change remains to be seen.