Climate Change and Crop Production

Foundations for Agroecosystem Resilience

Noureddine Benkeblia, Noureddine Benkeblia

• Publisher: CRC Press
• Year: 2018
• ISBN:
  9781315391847
• Edition: 1
• Topic: Scienze biologiche
• Subtopic: Ecologia

Presenting an overview of agroecology within the framework of climate change, this booklooks at the impact of our changing climateon crop production and agroecosystems, reporting on how plants will cope with these changes, and how we can mitigate these negative impacts to ensure food production for the growing population. It explores theways that farmerscan confront the challenges of climate change, with contributed chapters from around the world demonstrating the different challenges associated with differing climates.Examples are provided of the approaches being taken right now to expand the ecological, physiological, morphological, and productive potential of a range of crop types.

• Describes the effects and responses of the macro and micro levels of crops under the different components of climate change
• Reports on the adaptation and resilience of food production systems within the changing climate
• Covers how plants cope with the changing climate including physiological, biochemical, phenotype, and ecosystem responses
• Provides an in-depth discussion on the importance of agricultural education connected to climate change

Giving readers a greater understanding of the mechanisms of plant resilience to climate change, this book provides new insights into improvingthe productivity of an individual crop species as well as bringing resistance and resiliency to the entire agroecosystem. It offers a strong foundation for changing research and education programs so that they build the resistance and resilience that will be needed for the uncertain climate future ahead.

Chapter 1

Climate Change and Crop Production

Set the Stage for Resilience

Noureddine Benkeblia, Rachel E. Schattman, Sarah Wiener, and Gabrielle Roesch-McNally

Contents

1.1Introduction

1.2Background

1.2.1Driving Causes of Climate Change

1.2.2Direct and Indirect Effects of Climate Change on Cropping Systems

1.2.2.1Effects of Climate Change on Agricultural Economies

1.2.2.2Socioeconomic Impacts of Climate Change on Agricultural Production

1.3Climate Change Adaptation and Crop Production Agroecosystems

1.3.1Technology and Development

1.3.2Policy Mechanisms and Programs

1.3.3Resilience in Agroecosystems

1.4Future Directions and Research Priorities

1.5Conclusions

References

1.1Introduction

According the Intergovernmental Panel on Climate Change (IPCC), climate change is defined as “any change in climate over time, whether due to natural variability or as a result of human activities” (IPCC 2007). The standard period over which climate-related variables (e.g., temperature, precipitation, and wind) are observed is 30 years. Because of agroecosystems’ inherent vulnerability to changes in weather patterns, climate change can have profound effects on these systems. While some effects of climate change may have positive implications in some regions and agricultural sectors, it is estimated that climate change will have a progressively negative net impact on global agriculture between now and the end of the century (Hatfield and Takle 2014; Went 1957). These impacts will likely challenge farmer livelihoods, rural agricultural communities, and global food security. In this chapter, we summarize the driving causes of climate change, as well as the effects that climate change currently has and will continue to have on cropping systems, socioeconomic factors, and agriculture and biodiversity in agroecosystems. We also discuss some climate change adaptation strategies relevant to agroecosystems including conservation practices, support for biodiversity, tools and technology development, and policies and programs used to mitigate climate risk. We will end with a review of agroecological resilience to climate change and propose some future research priorities to enable greater agroecosystem resilience in the future.

1.2Background

1.2.1Driving Causes of Climate Change

Global climate change is caused by the release and accumulation of greenhouse gas (GHG) emissions into the Earth’s atmosphere. The concentration of GHGs such as carbon dioxide (CO2), methane (NH4), nitrous oxide (N2O), and other trace gases influences how much heat is captured in the atmosphere, also known as the radiation balance of the Earth (Hardy 2003). This leads to several important changes at a global level: warming of the oceans, sea level rise, acidification of ocean water, an increase in average air temperatures, changes in minimum and maximum daily temperatures, and shifting precipitation patterns (IPCC 2014a,b). These changes are already occurring. For example, the second half of the twentieth century was notably the warmest on record at that time (Mann et al. 1999), and average temperatures continue to set records into the first half of the twenty-first century.

Anthropogenic contributions to GHG emissions have dramatically increased since the Industrial Revolution, driven by both population growth and increasing industrialization (Crowley 2000; IPCC 2014a,b). As anthropogenic emissions have increased, positive feedback loops have accelerated the warming process. For example, a warmer atmosphere caused by increased GHG concentrations leads to increased amounts of water vapor, which contributes to further warming in addition to more extreme weather events (Archer 2007). A second example is when warming leads to thawing in arctic regions, which in turn releases previously captured sinks of methane and thus accelerates warming and release of additional NH4 (Walter et al. 2006). Due to these positive feedback cycles, if all human contributions to GHGs stopped today, climate change trends would continue for decades to come (Hansen et al. 2017).

Agriculture, including crop and animal production systems, contributes to the total global anthropogenic GHG emission rates that drive modern climate change. Some estimates say that agricultural land use is responsible for up to 25%–33% of GHG emissions globally (Clark and Tilman 2017). Though overall GHG contributions from agriculture increased over the past 50 years, agricultural production increased at a greater rate, meaning that the contributions per unit of production have decreased. Per-unit reductions also vary significantly between global regions (Bennetzen et al. 2016). Additionally, not all agricultural sectors contribute equally to GHG emissions: in a recent review of agriculture in China, animal production systems were found to have a significantly higher carbon footprint than vegetable production systems, but there are notable variations within these systems depending on production approaches (e.g., open field versus greenhouse production) (Yue et al. 2017).

1.2.2Direct and Indirect Effects of Climate Change on Cropping Systems

Anthropogenic climate change is already altering biological systems, including plant and animal communities, on a global scale (Horton et al. 2014; Parmesan and Yohe 2002). This has both direct and indirect implications for agroecosystems and specifically for agricultural businesses and communities. Direct impacts include changes in average, minimum, and maximum temperatures, precipitation patterns, and frequency of extreme weather events. All of these changes are expected to lead to varying crop yield decreases in some, though not all, cropping systems, especially nearing the end of the twenty-first century (Hatfield et al. 2011). Temperature plays an especially important and complex role in crop yield, profitability, and food security. All plant species, including agricultural crops, have temperature thresholds above which they will not develop properly. For example, a 1°C increase in average temperature will lead to an 8%–10% decrease in corn yield and a 9% decrease in rice yield (Abrol and Ingram 1996).

In addition to increasing average temperatures, climate change also leads to increasing minimum temperatures. The effects of increasing minimum temperatures on perennial crops (such as apples) can include early bud break in temperate regions, which can lead to yield decreases if a late frost follows. These crops require an accumulation of cold temperatures (i.e., chilling hours) in order to produce at rates that are profitable in commercial production systems (Hatfield and Takle 2014; Horton et al. 2014; Wolfe et al. 2008). Some annual crops are also affected by warming minimum temperatures. For example, warmer temperatures can lead to decreased rates of carbohydrate accumulation in corn crops and consequently lower yields (Ruiz-Vera et al. 2015; Wolfe et al. 2017). Meanwhile, increasing maximum temperatures can lead to lower marketable yields due to disruption of pollination and fruit development. For example, corn (Zea maize) experiences decreased pollen viability in temperatures above 35°C, and kernel growth can be delayed in temperatures above 30°C (Hatfield et al. 2011; Hatfield and Prueger 2015).

Of course, temperature is not the only climate change factor that influences crop fitness, and changes in environmental conditions caused by climate change do not affect all crops equally. Crop responses to CO2, temperature, and precipitation changes vary, and these responses are further complicated by other differences such as crop family and variety, regional topography, and more (Cutforth et al. 2007; Hatfield et al. 2011; Morgan et al. 2005). For example, two groups of crop plants, C4 plants (i.e., grasses such as corn, sugarcane, amaranth, and many weeds) and C3 plants (i.e., beans, rice, wheat, potatoes), use different cellular processes for photorespiration (Ghannoum 2009; Hamilton et al. 2008; Sage and Pearcy 1987). Of the two, C4 plants are more efficient in high CO2 environments because they minimize photorespiration (Taylor et al. 2009; Ziska 2000, 2001). This makes C4 plants less sensitive to high ambient air temperature, while C3 plants are relatively more sensitive. As CO2 levels continue to rise, it is likely that C4 plants will experience preferential benefits, while C3 plants struggle to thrive. It has been found that the accumulated influence of temperature and precipitation since 2008 has already led to a decrease in median yields of four major food crops: soy, rice, maize, and wheat. Some exceptions include regional increases in these crops including Argentina (soy), China (rice and maize), and some parts of the United States (wheat). It is likely that these trends will continue into the future (Lobell and Gourdji 2012; Lobell et al. 2011).

Indirect effects of climate change on agroecological systems also impact crop production. Lengthening growing seasons can disrupt plant and insect relationships, which can both decrease the harm to crops from herbivorous insects while also interrupting the benefits crops derive from pollinators (Hegland et al. 2009). Severe weather events (which will become more frequent and severe because of climate change) are important drivers of disease emergence in crops (Anderson et al. 2004). Since environmental factors (e.g., temperature, humidity, precipitation, and soil conditions) play a major role in plant pathology (Sutherst 1990), it is assumed that new plant diseases and increased severity of these diseases will be observed as weather patterns continue to shift over the coming decades (Elad and Pertot 2014; Pautasso et al. 2012). However, crop systems will be affected differently by infectious agents depending on host susceptibility to these diseases, the infection mechanisms, as well...