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21 Aug 2018
Atlantic circulation collapse could cut British crop farming, study suggests
Crop production in Britain will decrease dramatically if climate change causes the collapse of a vital pattern of ocean currents, new research by the University of Exeter suggests.
The paper, published in the Nature Food journal, looks at what would happen if the Atlantic Overturning Circulation (AMOC), which transports heat from the tropics to the UK, collapses because of climate change.
Dr Paul Ritchie of the University of Exeter warned AMOC collapse would leave Britain cooler, drier and unsuitable for many crops, causing the ‘widespread cessation of arable farming’ across the UK.
“Such a collapse would reverse the effects of warming in Britain, creating an average temperature drop of 3.4degC and leading to a substantial reduction in rainfall (-123mm during the growing season).
“These changes, especially the drying, could make most land unsuitable for arable farming,” he said.
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Minimise risk
The study examines a ‘fast and early’ collapse of the AMOC, which is considered ‘low probability’ and ‘rare’ at present, though the AMOC has weakened by an estimated 15 per cent over the last 50 years.
However, Professor Tim Lenton, director of the Global Systems Institute at the University of Exeter, said worst-case scenarios must be considered when calculating risks.
He said: “Any risk assessment needs to get a handle on the large impacts, if such a tipping point is reached, even if it is a low-probability event.
“The point of this detailed study was to discover how stark the impacts of AMOC collapse could be.”
The study follows a recent paper by Prof Lenton and colleagues, which warned that economic assessments detailing the potential future risks of climate change, had ‘grossly underestimated’ many of the ‘most serious consequences for lives and livelihoods’.
The new study therefore reinforces the message that ‘we should be wise to act now to minimise the risk of passing climate tipping points,’ Mr Lenton said.
Economic costs
Professor Ian Bateman of Exeter’s Land, Environment, Economics and Policy Institute, echoed these concerns, warning AMOC collapse and the resulting temperature drop could lead to a ‘host of economic costs for the UK.’
He said: “With the land area suitable for arable farming expected to drop from 32 per cent to 7 per cent under AMOC collapse, we could see a major reduction in the value of agricultural output.
“In this scenario, we estimate a decrease of £346 million per year – a reduction of over 10 per cent in the net value of British farming.
“It is important to note the wider effects for the UK and beyond will be very negative as import costs rise steeply and the costs of most goods climb.”
Net zero
The NFU highlighted the importance of the research, saying long-term strategic plans are needed to ’improve the resilience of farm businesses’ to help farmers deal with ’greater volatility’.
An NFU spokesperson said: "The farming industry is often at the mercy of extreme and changeable weather like the droughts and floods we have seen in recent years.
"Possible climate risks are why the NFU has set an ambitious aspiration for farming to become net zero by 2040."
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