Global warming will have profound consequences on where and how food is produced, and also lead to a reduction in the nutritional properties of some crops, experts say in a new book.
All of this has policy implications for the fight against hunger and poverty and for the global food trade.
"Climate Change and Food Systems" collects the findings of a group of scientists and economists who have taken stock of climate change impacts on food and agriculture at global and regional levels over the past two decades.
"The growing threat of climate change to the global food supply, and the challenges it poses for food security and nutrition, requires urgent concerted policy responses," wrote FAO Deputy Director-General Natural Resources, Maria Helena Semedo, in her foreword to the volume.
She also stressed the need for a "sharper focus on important drivers of climate adaption, including the potential role of trade as a driver to mitigate some of the negative impact of climate on global food production."
Pressure on agriculture and food systems, particularly in developing countries
Climate change is adding to the challenge of rapidly increasing global demand for agricultural commodities for food, animal feed and fuel in the face of population growth and rising in income levels.
Agriculture is highly dependent on local weather conditions and, therefore, is expected to be highly sensitive to changes in climate in the years to come.
In particular, warmer, drier conditions nearer the equator are likely to reduce agricultural production in those areas, while moderate warming may, at least in the short term, benefit crops production further away.
"Climate change is likely to exacerbate growing global inequality as the brunt of the negative climate effects is expected to fall on those countries that are least developed and most vulnerable," said the book's editor, Aziz Elbehri, of FAO's Trade and Markets Division.
The book examines how several technologies targeting climate change adaption can also have mitigation co-benefits, involving trade-offs. For example, current crop-based biofuels contribute to mitigation as renewable energy, but can exacerbate emissions through processes such as deforestation.
Threat to nutrition and health, water resources
The book also underscores the potential impact climate change could have on health and nutrition by exacerbating the prevalence of hidden hunger - the chronic lack of vitamins and minerals - and obesity.
A higher concentration of carbon dioxide - the primary greenhouse gas emitted through human activities - lowers the amount of zinc, iron and protein, and raises the starch and sugar content in some of the world's major food crops such as wheat and rice.
The nutrition and health implications of this could be substantial. In India, where up to a third of the rural population is at risk of not meeting protein requirements, the higher protein deficit from non-legume food crops could have serious health consequences.
The book goes on to underscore how in many regions of the world, increased water scarcity due to climate change would reduce the capacity to produce food, with serious implications for food security, nutrition and health.
It cites recent research that has assessed the global impact of diet change on both irrigated and rain-fed water consumption patterns. Some results suggest that reducing animal products in human diets offers the potential to save water resources up to the amount required to feed 1.8 billion people globally.
It is widely accepted that water is not a typical commodity, but rather, a resource that is geographically specific, with access determined by rights and often managed by public institutions. The book recognises that a balanced approach between market instruments and institutional structures is required to safeguard water availability and access.
The book cites studies that indicate that trade would probably expand under climate change - with flows increasing from mid to high latitudes towards low-latitude regions, where production and export potential would be reduced.
At the same time, more frequent extreme weather events, such as droughts and cyclones, can adversely impact trade by disrupting transportation, supply chains and logistics.
The book suggests that while global markets can help stabilise prices and supplies, and provide alternative food options for regions negatively impacted by climate change, trade alone is not a sufficient adaptation strategy.
It also requires a domestic adaptation strategy that allows countries and regions to avoid heavy dependence on imports, which tend to increase vulnerability to price volatility.
Another challenge is the need to align trade policy with climate objectives and ensure that open trade plays its role as an adaptation mechanism without impeding mitigation objectives.
A structured policy dialogue
The book's contributing authors make the case for a "structured dialogue" involving a range of stakeholders, including scientific experts, policy makers, civil society and the private sector, to assess and verify global, regional and local impacts to inform and support policy action related to climate change.
This could take the shape of a forum providing a portal on climate change impact evidence for agriculture and policy for trade and food security. Such a forum could support policy processes and initiatives targeting food and nutrition security and provide the best scientific evidence on climate impacts at the appropriate scale.