Effects of climate change on agriculture

There are numerous effects of climate change on agriculture, many of which are making it harder for agricultural activities to provide global food security. Rising temperatures and changing weather patterns often result in lower crop yields due to water scarcity caused by drought, heat waves and flooding. These effects of climate change can also increase the currently-rare risk of several regions suffering simultaneous crop failures, which would have significant consequences for the global food supply. Many pests and plant diseases are also expected to either become more prevalent or to spread to new regions. The world's livestock are also expected to be affected by many of the same issues, from greater heat stress to animal feed shortfalls and the spread of parasites and vector-borne diseases.^: 746

The increased atmospheric CO₂ level from human activities causes a CO₂ fertilization effect, which offsets some of the detrimental effects on agriculture due to climate change. However, it has little effect on C4 crops like maize, and comes at the expense of lower levels of essential micronutrients.^: 717 On the coasts, some agricultural land is expected to be lost to sea level rise, while melting glaciers could result in less irrigation water being available. On the other hand, more arable land may become available as frozen land thaws. Other impacts include erosion and changes in soil fertility and the length of growing seasons. Negative impacts on food safety from bacteria like Salmonella or mycotoxin-producing fungi, also increase as the climate warms, increasing costs and food loss.

There has been extensive research into the impact of climate change on individual crops, particularly the four staple crops—corn (maize), rice, wheat and soybeans—that are responsible for around two-thirds of all calories consumed by humans (both directly and indirectly as animal feed). Yet, there are still other important uncertainties involved – from future population growth, which will only increase global food demand for the foreseeable future, to the related yet largely separate challenges of soil erosion and groundwater depletion. On the other hand, a range of improvements to agricultural yields, collectively known as the Green Revolution, has already lifted yields per unit of land area by between 250% and 300% since the 1960, and some of that progress may be expected to continue.^: 727

Altogether, there is a consensus that global food security will change relatively little in the near-term: 720 million to 811 million people were considered undernourished in 2021, with ~200,000 at a "catastrophic" level of food insecurity. Compared to that figure, climate change is expected to place an extra 8 to 80 million people at risk of hunger by 2050 (depending on the intensity of future warming and the effectiveness of adaptation measures).^: 717 Continued economic and agricultural development will likely improve food security for hundreds of millions of people by then. Research and predictions that extend further into the future (to 2100 and beyond) are rather limited, and some scientists have voiced concerns about the impact on food security from currently-unprecedented extreme weather events enabled by the future climate. Nevertheless, published scientific literature includes no expectation of a widespread global famine within the 21st century.

A range of measures for climate change adaptation may reduce the risk of negative climate change impacts on agriculture. Those measures include changes in management practices, agricultural innovation, institutional changes, and climate-smart agriculture. To create a sustainable food system, these measures are considered as essential as changes needed to reduce global warming in general.