Food, Agriculture and Climate Change

Crops and Climate

Climate change threatens the global food supply as certain crops become more expensive and scarce, with implications ranging from more chronic hunger to changes in common cuisine. Many crops will see negative impacts from the extreme weather, droughts, floods, higher temperatures and season shifts that climate change brings.

Price increases from climatic extremes in key production zones have demonstrated the sensitivity of agriculture to climate change. Rising temperatures and water stress in the US have already led to lower crop yields for corn, which typically relies on rainfall instead of irrigation. One 2011 study suggesting that global corn yields were 3.8 percent smaller than they would have been without warming. That decrease is sizable, akin to Mexico halting all corn production. That study also suggests that wheat yields were 5.5 percent less, while a 2016 study projected that global wheat yield could decline between 4.1 and 6.4 percent for each global temperature increase of 1°C, with losses as high as 8% in India. For a country already struggling to feed its population, a decrease like this has a high toll in terms of human suffering.

Coffee production requires a very particular climate, so as the world warms, the area of suitable land for this crop is projected to be cut in half. Over 120 million people around the world, many of whom live in poverty, rely on the coffee economy for their livelihood. In best-case scenarios, 38 percent of land suitable for indigenous Arabica coffee is expected to disappear by 2080, though it could be as high as 90 percent.

Global fisheries are also threatened by climate change as oceans warm and become more acidic. Fish provides the animal protein needs of nearly three million people, and fisheries support the livelihoods of 10-12% of the world’s population. If carbon emissions continue unabated, global fisheries could lose up to $10 billion per year in revenue, significantly impacting income levels and food security worldwide.

Oysters and other shellfish face an uncertain future, as the ocean absorbs carbon dioxide emissions. This changes the acidity of the water and inhibits the growth of shells. Problems are already evident, with one oyster farm experiencing a 75 percent die-off.

Many crops, including cherries, almonds, apricots, grapes, pears, peaches and walnuts, require a chilling period or cool nighttime temperatures. But rising temperatures have reduced these cooling times, according to the NCA. Across many warm regions of the world, like the Mediterranean and southwestern North America, winter chill will decrease significantly. In some regions, like Southern Australia and South and North Africa, winter chill could disappear entirely by 2100, making it impossible to grow crops that require a cold winter.

That lack of cold winter is a great help, however, to weeds and pests. Rising temperatures and shifting rainfall will change how insects, weeds and diseases interact with crops, generally leaving the crops at a disadvantage. The higher CO2 levels also boost weed growth, making it that much harder for crops to thrive.

Food Production and Climate

Producing food contributes to climate change in many ways, including deforestation and emissions from tractors and machinery. In addition, food production results in rising methane and nitrous oxide emissions levels. Animal agriculture produces methane, a powerful greenhouse gas (GHG), primarily from livestock’s digestive tracks. Wasteful fertilizer use releases nitrous oxide, another powerful GHG with nearly 300x the warming potential of CO2. The emissions of these two dangerous pollutants make agriculture the leading emitter of non-CO2 GHGs.

After factoring in agriculture and the deforestation that takes place to clear land for farming, food production-related emissions grow to be just under a quarter of the total global gas emissions, about 10 to 12 gigatons annually, according to the IPCC. Other research suggests that the food system as a whole emits 19-29 percent of all GHG emissions. The FAO calculates that the livestock sector alone produces 14.5 percent of total global GHGs.

Since 1990, agriculture emissions have risen by 11 percent. This is spurred by a 54 percent increase in methane and nitrous oxide emissions from livestock manure, with an additional 17 percent increase in emissions resulting from soil management and fertilization. Due to population growth and ‘westernizing’ diets, global demand for meat and dairy are projected to increase 76 and 65 percent respectively by 2050, compared with a 2005-07 baseline. To limit global warming to below 2°C, it will be imperative to decrease the demand for livestock or drastically improve agricultural efficiency.

Emissions can be limited by addressing diets, consumption and production methods. Smarter livestock handling, technology-enabled monitoring of fertilizer application, simple changes in field layout, and manure management could cut down emissions intensity. Groups like Solutions from the Land are working with American farmers to find smart ways to reduce livestock’s climate impact without sacrificing production, and the US Department of Agriculture’s Climate Hubs portal helps farmers adapt to and mitigate climate change. Internationally, groups such as the International Livestock Research Institute and the Global Research Alliance on Agricultural Greenhouse Gases are looking at ways to decrease agriculture’s carbon footprint while achieving food security.

On the consumption side, a shift away from diets heavy in animal-based foods can reduce the climate impact of agriculture while freeing up land and resources to feed people directly. The World Resources Institute estimates that food production will have to increase 70 percent to feed a global population growing to 9.6 billion by 2050 – and that almost a third of this “70 percent food gap” can be achieved just by shifting diets toward a greater share of plant-based foods. China, taking public health and obesity as well as climate change into account, incorporated a goal to reduce meat consumption by 50 percent into their 2016 dietary guidelines. 

Food Waste and Climate

Although nearly 800 million people around the world are hungry or food insecure, one-third of global food produced is never eaten – a total of 1.3 billion tons with a value of $750 billion.  This waste has staggering environmental and human impact. Even modest progress in reducing food waste provides ample returns, with the World Bank finding that it would only take a one percent reduction in post-harvest losses to provide $40 million in economic gains, mainly for smallholder farmers who represent the majority of the undernourished population globally.

Food can be lost or wasted at multiple stages from farm to landfill. Generally, food lost later in the supply chain is more environmentally costly, because energy has gone into processing, transporting, refrigerating and preparing it. According to the FAO, over 40 percent of food loss in developing nations happens after harvest or during processing; in developed countries, over 40 percent of loss occurs when food is thrown away by consumers or retailers.

Producing all that food is no small feat. Around 10 percent of energy in the US is spent on putting food on people’s plates. The national agricultural sector takes up half of total land and accounts for 80 percent of fresh water consumption. According to the NRDC, however, 40 percent of food grown in the US goes uneaten— over 20 pounds of food per person per month.

Compounding food waste’s climate impact, organic matter that rots in landfills breaks down without oxygen and produces methane, a potent greenhouse gas with 28 to 36 times the warming potential of CO2. The food rotting in landfills amounts to nearly 25 percent of US methane emissions. This problem is getting worse, with nearly a 50 percent increase in food waste since 1974. This means that over a quarter of US freshwater consumption and approximately 300 million barrels of oil per year are spent on growing and creating food that no one eats, but still contributes to climate change.