Effects of climate change on agriculture
Lesson 3 of the climate change information module of the climate atlas
Introduction
Climate change is already affecting agriculture, with effects unevenly distributed across the world. Overall, negative impacts on agriculture of climate trends have been more common than positive ones. Positive trends are sometimes evident in some high-latitude regions, whereas negative trends are observable at lower latitudes. The overall relationship between climate change and yields is often crop and region specific, depending on differences in baseline climate, management and soil, and the duration and timing of crop exposure to various conditions. The figure below shows a summary of studies with projections for crop yields. Most studies show a decrease in crop yields, especially at the end of the century. Each additional decade of climate change is expected to reduce mean yields by roughly 1%, which is a small but nontrivial fraction of the anticipated roughly 14% increase in productivity per decade needed to keep pace with demand. The drop in food production will increase food prices.
Lobell et al. (2008) identified South Asia and southern Africa as two regions that, in the absence of adaptation, would suffer the most negative impacts on several important crops. Knox et al. (2012) estimated an expected 8% negative yield impact in both regions by 2050 averaged over crops, with wheat, maize, sorghum, and millets more affected than rice, cassava, and sugarcane.
Climate change can affect agriculture through multiple factors, which are often connected to each other. This lesson will show how climate change can affect agriculture.
Source: IPCC
Climate, Agriculture and the Challenges Ahead
Climate change can affect agriculture through multiple factors, which are often connected to each other. This lesson will show how climate change can affect agriculture.
Increasing temperatures
Responses to temperature may vary according to whether yields are limited by low or high temperatures. However, there is evidence that high temperatures will limit future yields through heat stress, even in cool environments. Studies have documented a large negative sensitivity of crop yields to extreme daytime temperatures around 30°C. For example, the Russian heat wave of 2010 and subsequent export ban contributed to the more than doubling of global wheat prices by the end of the year.
Besides crops, livestock is also influenced by increasing temperatures. High temperatures will decrease animal feeding and growth rates. For example, Wall et al. (2010) show that that, in some regions in the United Kingdom, milk yields will be reduced and mortality increased because of heat stress throughout the current century, with annual production and mortality losses amounting to some £40 million by the 2080s under a medium-high greenhouse gas emission scenario.
In addition, global warming could lead to an increase in pest insect populations and viruses, harming yields of crops and livestock. Changes in temperature can result in geographic shifts through changes in seasonal extremes, and thus, for example, overwintering and summer survival. Also, the number of breeding cycles of insects, such as the coffee nematodes in Brazil, can increase (Ghini et al., 2008).
Extreme heat damaging South-Korea's agriculture
Changing water availability
Water is a critical input for agricultural production and plays an important role in food security. Irrigation systems are used to balance the need for water. However, their sources may dry up in periods of drought. Also, in many developing countries, cropland is not always irrigated.
For instance, Africa is sensitive to increasing droughts because for many of its crops, it is at the edge of physical thresholds beyond which yields decline. In Ethiopia, future shifts in precipitation will significantly increase the chance that Ethiopia’s coffee farmers experience poor yields in any given season. The likelihood of a 25 percent or greater drop in coffee yields in a given year currently stands at 3.2 percent but could climb to 4.2 percent by 2030—a 31 percent increase; that is, a cumulative likelihood of 28 percent over the next decade (McKinsey).
The relationship between crops and precipitation is complicated as the timing of watering is important. Therefore, it is important to understand how climate change will affect the seasonality of precipitation, which is region specific.
Source: McKinsey
Drought Tolerant Crops give hope to Kenyan farmers: Martin Lumala's Story
Extreme weather events
The risks of extreme weather events are increasing. These events can partially or completely damage regional crop production. Extreme rainfall results in floods, erosion, and increased runoff.
Extreme weather hurts production of Filipino rice farmers
Exercise: Essay question
Describe whether agriculture is already being influenced by climate change in your region. What are your suggestions to adapt to climate change to reduce the risk?
Well done! you have completed the third lesson of module 1. Now you can continue with the fourth lesson.
