Climate Change and Food Security: Threats and Adaptation

Climate Change and Food Security: Threats and Adaptation

by Junyi Chen, Bruce A. McCarl and Anastasia Thayer

Draft chapter for Food Security in an Uncertain World : An International Perspective

edited by Andy Schmitz

The Intergovernmental Panel on Climate Change (IPCC) (2013, 2014b) indicates climate change and its drivers have increased temperatures, changed precipitation, reduced snow and ice, raised sea levels, caused more extreme events and elevated concentrations of carbon dioxide (CO2) among other influences. Projections are that climate change will continue even if greenhouse gas (GHG) emissions are greatly reduced (IPCC, 2014c; McCarl, 2015). Risks are not uniformly distributed and in particular poor people living in the least developed countries appear to be likely to suffer the most (IPCC, 2014c).

Agriculture is highly vulnerable to such changes. In many regions, climate change portends an increase in undernourishment and a weakening of food security (Butt et al., 2005; IPCC, 2014a). Brown et al. (2015) lists food security impacting pathways including rising temperatures, higher precipitation variability, more extreme events, and more pests and diseases. A short run increase in extremes can destroy crops and damage local infrastructure enhancing risks to food security (WFP, 2014). In the long run we may see reduced yields and increased variability in places. Some regions may become unsuitable for traditional crops. Seas may inundate producing lands and reduce local water supplies (WFP, 2014). Also, glacial and earlier snow melt will influence the annual timing, quantity and quality of water (WFP, 2014).

Furthermore, climate change is projected to continue to threaten or exacerbate current risks and slow down the global progress regarding to achieving food security as a result (Brown and Funk, 2008; WFP, 2014; FAO, 2008; FAO, 2016; Brown et al., 2015).

This paper will provide an overview of the existing research findings on climate change and food security linkages, covering the climate change related drivers, types of effect, and potential adaptations finishing with a section on potential future research.

Climate Change and CO2 as Observed and Projected

Warming surface temperatures remains the most recognized impact. Global surface temperatures have increased 1.03oC from 1880-2015 (NOAA, 2016). Looking forward, projected warming depends on emissions which lead to several scenarios. Under the highest IPCC (2013) emissions scenario (RCP 8.5), average global temperature is expected to increase by about 4oC by 2100. Although the lowest IPCC scenario (RCP 2.6) only projects 1oC of warming, this scenario is not likely as it is predicated on peak CO2 emissions occurring in the year 2020 and then declining and becoming negative by 2100 (IPCC, 2014c). The more likely range is that by 2040, global surface temperature will increase by about 1oC and that warming will likely exceed 1.5oC by 2100 (IPCC, 2014c). These projections suggest that increasing global temperatures will continue and thus the risks to food security will persist at least for the next few generations.

In terms of drivers the Earth’s atmospheric CO2 content has risen by over 45% since pre industrial times , while methane is 150% higher and nitrous oxide 20% higher (IPCC, 2014c).

Precipitation is expected to experience changes in frequency and distribution with precipitation intensity increasing (IPCC, 2014c). However, the effects are not expected to be uniform; as the high latitudes and Equatorial Pacific are expected to experience an increase but subtropical dry regions are expected to experience decreases (IPCC, 2014c). In addition, individual precipitation events are expected to become more intense and periods of droughts are expected to become more frequent and severe (IPCC, 2014c; Brown et al., 2015). Furthermore, the IPCC projects that many areas will experience lower soil moisture and river flows (IPCC, 2014c).

Climate change is also expected to increase the frequency and intensity of extreme weather events (IPCC, 2014c). Some such impacts are already being observed including more frequent hot days and less cold ones, more frequent droughts, more wet periods, and increased rainfall intensity (IPCC, 2014c; NOAA, 2016). The IPCC projects that the area at risk for monsoons will increase with increased precipitation and a longer season (IPCC, 2014c).

While warming land temperatures dominate discussions on climate change, the oceans are absorbing most of the heat (IPCC, 2014c). Specifically, from 1971-2010 the oceans absorbed 90% of the energy where the atmosphere only absorbed 10% (IPCC, 2014c). This led to increases in ocean surface temperatures of 0.11oC per decade since 1971 (IPCC, 2014c). Also, the ocean has absorbed about 30% of the CO2 emissions which has changed ocean pH (IPCC, 2014c) and impact the ecosystems of fish, shellfish and other marine species which provide food and income for many coastal communities.

Warming surface temperatures are causing melting of the Greenland and Antarctic ice sheets plus glaciers worldwide, along with decreasing snow cover (IPCC, 2014c). This alters hydrologic cycles and, along with thermal expansion, causes sea level rise. Global sea level rise amounted to 0.19m since 1901-2010 with an accelerating rate in the last 30 years (IPCC, 2014c). Sea level rise is expected to continue. The IPCC estimates that it will impact conditions on 70% of all coastlines.

In addition, there are indirect drivers including: pest incidence, soil fertility, plant water needs, irrigation water supplies, population and growth, and markets (Porter et al., 2014). It is the intersection of the direct and indirect climate drivers which pose a threat to food security. Modeling and identifying the how these factors will change under different climate scenarios is critical in determining how production and other risks to food security.

Food Security Implications and Findings

The statements above show food security is likely to be affected. Here we review findings from studies regarding food production and access.

Food production

Many studies have addressed potential or observed climate change impacts on crop, livestock, fishery production, and production costs.

Cropping

Cropping systems are likely to be impacted from changes in: temperature and precipitation, frequency of extreme events, pest incidence, soil fertility, irrigation water supplies and soil moisture plus CO2 and ozone (IPCC, 2014c). The magnitude and severity of these effects varies based on local conditions.

Today, crop estimates suggest (with medium confidence) that global wheat and maize yields have decreased in many places as a result of global warming (Porter et al., 2014) although there have also been yield increases in regions where previously production was limited by cold (Attavanich et al., 2013). For other crops such as rice and soybeans, impacts on yield have been found to be small (medium confidence) (IPCC, 2014c). Yield changes are highly regional with some research showing that from 1980-2008 in China, increases in air temperature slowed growth rates by 1.5% for wheat and corn but had no observed effect for rice or soybeans (Brown et al., 2015). Research in India from 1960-2002, shows increasing air temperatures were associated with a 5% or more reduction in rice yield-growth rates (Brown et al., 2015) highlighting the regionally varying effects.

The literature is beginning to detect trends across multiple study areas such as the finding that increases in the number of hot nights has led to increased rice yields but decreases in quality (Porter et al., 2014). Additionally, climate change also has been found to influence technological progress and have heterogeneous impacts across regions (Villavicencio et al., 2013).

To add another layer of complexity, while researchers agree that frequency of extreme events is expected to increase, which puts agricultural production at risk, only limited research has quantified the impacts of extreme weather impacts on crop production with effects found from such items as hot days (Schlenker and Roberts, 2006) hurricanes (Chen and McCarl, 2009), ENSO phases (Chen et al., 2001), drought measures and rainfall intensity (Attavanich and McCarl, 2014).

Finally, in terms of productivity, not only are yields influenced but there are incidences of climate induced losses in land area. This arises from three principal sources. First, climate change induces sea level rise which can threaten low lying land areas which currently supports rice production as examined by Chen et al. (2012). Sea level rise puts other crops at risk including fruits and vegetables (see Chang et al., 2012 who examine this in Taiwan). Second, climate change enhanced extreme events in the form of flooding can severely erode lands degrading crop producing lands (Blaikie and Brookfield, 1987; WMO, 2005). Third, climate change can stimulate the spread of invasive species which can in turn cause land degradation (Flanagan et al., 2015). Fourth, increased temperatures and changes to historical precipitation patterns can alter climate conditions and soil moisture which can lead to increased desertification (Reed and Stringer, 2015).

Yields are also sensitive to other climate change related factors. In particular, increases in CO2 concentrations can also increase yields for some crops. C3 crops such as wheat, rice, cotton, soybeans, potatoes, and sugar beets respond positively to increased CO2 levels while yields of C4 crops such as corn, sorghum, and sugarcane do not--although C4 crops exhibit yield increases under moisture stress conditions (Porter et al., 2014, Attavanich et al., 2014). Additionally, climate change has been argued to induce ozone increases which in turn have been found to depress yield levels of wheat, soybeans, maize and rice (Porter et al., 2014). In the end, whether yields increase or decrease due to changes in atmospheric composition of these gases will depend on the relative concentrations and interplay with other climate drivers.

Climate change not only affects production but also alters production costs. In particular, Koleva at al. (2010) show that climate change alters pesticide usage and can increase costs. If pest incidence increases, this may decrease yields and enhance storage losses. Furthermore, researchers suggest that climate change mitigation efforts could increase energy and fertilizer costs and cause land to be diverted from agriculture to trees or bioenergy feedstocks (McCarl and Schneider, 2001). These changes could make agricultural production more costly for farmers and increase crop prices for consumers.

While much of this research has focused on changes to averages, another aspect of food security is the variability of production. Studies have shown that climate change factors increase the variability of crop yields (Attavanich and McCarl, 2014) and of production costs (Chen and McCarl, 2001). Climate change can also damage roads through extreme events and possible market access during critical periods. It should be noted that accounting for changes in the distributions and variability of these events is difficult when modeling climate change impacts.

Livestock

Most climate change effects on livestock production are a result of increased stress from increases in temperatures and changes to feed availability. Many studies have shown that temperature increases have a negative impact on livestock production including (1) alterations in feed-grain availability and price as follows from the crop productivity arguments above; (2) changes in pasture and forage crop production and quality (Polley et al., 2013); (3) altered animal health, growth, milk production and reproduction (Gaughan et al., 2009) and (4) shifts in disease and pest distributions (Perry et al., 2013). In fact, Voh et al. (2004) find that a lack of thermally-tolerant breeds of cattle is already a major constraint on production in Africa. These studies show that livestock will likely experience decreased productivity, increased mortality, and increased costs for production which will impact food availability through changes in quantity available and price.

On the other hand, findings of a positive impact on livestock production in cold limited areas nearer the poles have arisen.

Fisheries

Food security may also be affected through changes to fisheries due to altered ocean temperatures, acidification, salinity, sea level, and extreme events (Porter et al., 2014). Research has found that in the last 25 years ocean fish have moved their distribution poleward or to deeper and cooler waters (Brown et al., 2015). Shifting fish locations means that people have to travel further to find the same species and may decrease fishing effort perhaps completely. Also, higher ocean salinity and acidification disrupts calcification for reefs, mollusks and other shelled creatures which will impact availability for human consumption and food sources across the ecological chain (Brown et al., 2015).

Along with impacts to the fish and aquaculture, fishing communities are likely to be impacted by extreme weather events and rising sea level. Additionally, changes in freshwater water resources due to alterations in precipitation patterns and ice and snow coverage impose risks to inland fishery production and aquaculture plus diminished freshwater inflows to bays and estuaries that may impact fishery reproduction and abundance (Porter et al., 2014). As with changes to crop and livestock production, climate change will likely limit available feed resources, increase cost of production, and thus, increase prices.

Food Access

Food access captures an individual’s ability to gain access to food and along with the factors listed above, includes: availability of farmable land, stores and other market locations, pricing structures, and adequate income or other sources to purchase and acquire food. Most of the literature on climate change impacts to food access focuses on expected changes to prices. Urban consumers, rural non-farming consumers, and food producers who are net buyers, are all expected to be negatively impacted by increasing food prices as food may no longer be affordable (Porter et al., 2014). It is unclear what the welfare impacts to food producers are as they also gain income from the higher prices (Hertel, 2016). In particular in many areas where feed security is an issue, many of the food consumers are also subsistence farmers – food producers. Findings consistently across climate change studies show that in cases where climate change is yield reducing, food prices increase and in turn so does farmer incomes (Butt et al., 2006). This creates a contradictory setting where yield and production is down but income increases which suggests that the negative impacts of climate change might less harmful than predicted when just considering changes to yields (Hertel, 2016).

In addition to direct production impacts, alterations of the current system are expected to impact other aspects of food availability including but not limited to: processing, storage, transportation, and trading. Climate change will directly influence these systems most noticeably through disrupting historical temperature and precipitation patterns, frequency of extreme events, and adding vulnerability or uncertainty into historical systems. Increased temperatures will necessitate more refrigeration and cooling of products from the time of production to consumption (Brown et al., 2015). Increased temperature and changes to air moisture concentrations could lead to spoilage or more costly storage and transportation (Brown et al., 2015). Shifts to the locations of packaging and processing facilities might occur as climate change shifts production locations (Brown et al., 2015). Finally, transportation and food supply lines can be impacted by extreme weather events or shifting temperature and precipitation patterns. Other impacts are secondary such as increasing pests and other diseases rendering food inedible or lost (Brown et al., 2015). Additionally changes to nutritional content have been observed under increased temperature and CO2 (Brown et al., 2015). Thus the nutrition aspect of food security might be put at risk.