Predicted
environmental changes could significantly reduce global production of
vegetables
London School of
Hygiene & Tropical Medicine
The study, led by the
London School of Hygiene & Tropical Medicine (LSHTM), is the first
systematically to examine the extent to which projected changes such as
increases in temperature and reduced water availability could affect the
production and nutritional quality of common crops such as tomatoes, leafy
vegetables and pulses.
If no action is taken
to reduce the negative impacts on agricultural yields, the researchers estimate
that the environmental changes predicted to occur by mid- to end-century in
water availability and ozone concentrations would reduce average yields of vegetables
and legumes by 35% and 9% respectively. In hot settings such as Southern Europe
and large parts of Africa and South Asia, increased air temperatures would
reduce average vegetable yields by an estimated 31%.
Environmental changes,
including climate change, water scarcity and biodiversity loss, are predicted
to become more profound in the 21st century -- posing significant challenges to
global agriculture, food security and nutrition.
While there is growing evidence that predicted future changes in temperature and rainfall will lead to significant reductions in the yields of many staple crops such as rice and wheat, the impacts on vegetables and legumes -- important constituents of healthy diets -are largely unknown.
While there is growing evidence that predicted future changes in temperature and rainfall will lead to significant reductions in the yields of many staple crops such as rice and wheat, the impacts on vegetables and legumes -- important constituents of healthy diets -are largely unknown.
To address this evidence gap the researchers conducted a systematic review of all the available evidence from experimental studies published since 1975 on the impacts of changes in environmental exposures on the yield and nutritional quality of vegetables and legumes. Experiments included in the review were conducted in 40 countries.
The team then
estimated the effects on the yields and nutritional quality of crops of changes
in key environmental exposures, including increases in greenhouse gases
(tropospheric carbon dioxide and ozone), reduced water availability for
irrigation and rising ambient temperatures.
Previous research has
shown that raised levels of carbon dioxide would increase crop yields, but this
study identified for the first time that these potential yield benefits are
likely to be cancelled out in the presence of simultaneous changes in other
environmental exposures.
The researchers warn
that in the absence of substantial efforts to respond to predicted future
environmental changes, reductions in the yields of vegetables and legumes will
substantially alter their availability globally. Such changes may affect the
affordability and consumption of vegetables and legumes in the mid- to
long-term and this could have significant impacts on population health all
around the world.
Dr Pauline Scheelbeek,
lead author at LSHTM, said: "Our study shows that environmental changes such
as increased temperature and water scarcity may pose a real threat to global
agricultural production, with likely further impacts on food security and
population health.
"Vegetables and
legumes are vital components of a healthy, balanced and sustainable diet and
nutritional guidelines consistently advise people to incorporate more
vegetables and legumes into their diet. Our new analysis suggests, however,
that this advice conflicts with the potential impacts of environmental changes
that will decrease the availability of these important crops unless action is
taken."
To mitigate the risks
that future environmental changes pose to these crops, researchers say that
innovations to improve agricultural production must be a priority, including
the development of new crop varieties as well as enhanced agricultural
management and mechanisation.
Professor Alan
Dangour, senior author at LSHTM, said: "We have brought together all the
available evidence on the impact of environmental change on yields and quality
of vegetables and legumes for the first time.
"Our analysis
suggests that if we take a 'business as usual' approach, environmental changes
will substantially reduce the global availability of these important foods.
Urgent action needs to be taken, including working to support the agriculture
sector to increase its resilience to environmental changes and this must be a
priority for governments across the world.
"But our study
also identifies the broader policy relevance of environmental change.
Vegetables and legumes are essential constituents of healthy diets and so
efforts to ensure that their global availability is not threatened by predicted
environmental changes must also be high on the global public health
agenda."
The authors
acknowledge limitations of the study, including the fact that collated evidence
on the impact of environmental changes on the nutritional quality of vegetables
and legumes was limited and the research team identified this as an area
requiring more evidence generation.
The study was funded
by the Wellcome Trust as part of its Our Planet, Our Health programme.
Dr Howie Frumkin, Head
of Our Planet, Our Health at Wellcome, said: "Improvements in agricultural
technology have dramatically boosted the world's food production over the last
80 or so years. But we mustn't be complacent. Environmental changes, including
more chaotic weather patterns and a warming climate, threaten our ability to
feed the world's people.
"This excellent
review highlights that some of the most important foods, and some of the
world's most vulnerable people, are at highest risk. This research is a wake-up
call, underlining the urgency of tackling climate change and of improving
agricultural practices."