485
7
Food Security and
Food Production Systems
Coordinating Lead Authors:
John R. Porter (Denmark/UK), Liyong Xie (China)
Lead Authors:
Andrew J. Challinor (UK), Kevern Cochrane (South Africa), S. Mark Howden (Australia),
Muhammad Mohsin Iqbal (Pakistan), David B. Lobell (USA), Maria Isabel Travasso (Argentina)
Contributing Authors:
Netra Chhetri (USA/Nepal), Karen Garrett (USA), John Ingram (UK), Leslie Lipper (Italy),
Nancy McCarthy (USA), Justin McGrath (USA), Daniel Smith (UK), Philip Thornton (UK),
James Watson (UK), Lewis Ziska (USA)
Review Editors:
Pramod Aggarwal (India), Kaija Hakala (Finland)
Volunteer Chapter Scientist:
Joanne Jordan (UK)
This chapter should be cited as:
Porter
, J.R., L. Xie, A.J. Challinor, K. Cochrane, S.M. Howden, M.M. Iqbal, D.B. Lobell, and M.I. Travasso, 2014:
Food security and food production systems. In: Climate Change 2014: Impacts, Adaptation, and Vulnerability.
Part A: Global and Sectoral Aspects. Contribution of Working Group II to the Fifth Assessment Report of the
Intergovernmental Panel on Climate Change [Field, C.B., V.R. Barros, D.J. Dokken, K.J. Mach, M.D. Mastrandrea,
T.E. Bilir, M. Chatterjee, K.L. Ebi, Y.O. Estrada, R.C. Genova, B. Girma, E.S. Kissel, A.N. Levy, S. MacCracken,
P.R. Mastrandrea, and L.L. White (eds.)]. Cambridge University Press, Cambridge, United Kingdom and
New York, NY, USA, pp. 485-533.
7
486
Executive Summary ........................................................................................................................................................... 488
7.1. Introduction and Context ....................................................................................................................................... 490
7.1.1. Food Systems .................................................................................................................................................................................... 490
7.1.2. The Current State of Food Security ................................................................................................................................................... 490
7.1.3. Summary from AR4 ........................................................................................................................................................................... 491
7.2. Observed Impacts, with Detection and Attribution ................................................................................................ 491
7.2.1. Food Production Systems .................................................................................................................................................................. 491
7.2.1.1.Crop Production ................................................................................................................................................................... 491
7.2.1.2.Fisheries Production ............................................................................................................................................................. 493
7.2.1.3.Livestock Production ............................................................................................................................................................ 494
7.2.2. Food Security and Food Prices .......................................................................................................................................................... 494
7.3. Assessing Impacts, Vulnerabilities, and Risks
7.3.1. Methods and Associated Uncertainties ............................................................................................................................................. 494
7.3.1.1.Assessing Impacts ................................................................................................................................................................ 494
7.3.1.2.Treatment of Adaptation in Impacts Studies ........................................................................................................................ 497
7.3.2. Sensitivity of Food Production to Weather and Climate .................................................................................................................... 497
7.3.2.1.Cereals and Oilseeds ............................................................................................................................................................ 497
7.3.2.2.Other Crops .......................................................................................................................................................................... 499
7.3.2.3.Pests, Weeds, Diseases ......................................................................................................................................................... 500
7.3.2.4.Fisheries and Aquaculture .................................................................................................................................................... 500
7.3.2.5.Food and Fodder Quality and Human Health ....................................................................................................................... 501
7.3.2.6.Pastures and Livestock ......................................................................................................................................................... 502
7.3.3. Sensitivity of Food Security to Weather and Climate ......................................................................................................................... 502
7.3.3.1.Non-Production Food Security Elements .............................................................................................................................. 502
7.3.3.2.Accessibility, Utilization, and Stability .................................................................................................................................. 502
7.3.4. Sensitivity of Land Use to Weather and Climate ............................................................................................................................... 504
7.4. Projected Integrated Climate Change Impacts ....................................................................................................... 505
7.4.1. Projected Impacts on Cropping Systems ........................................................................................................................................... 505
7.4.2. Projected Impacts on Fisheries and Aquaculture ............................................................................................................................... 507
7.4.3. Projected Impacts on Livestock ......................................................................................................................................................... 508
Box 7-1. Projected Impacts for Crops and Livestock in Global Regions and Sub-Regions under Future Scenarios ................... 509
7.4.4. Projected Impacts on Food Prices and Food Security ....................................................................................................................... 512
Table of Contents
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7.5. Adaptation and Managing Risks in Agriculture and Other Food System Activities ............................................... 513
7.5.1. Adaptation Needs and Gaps Based on Assessed Impacts and Vulnerabilities ................................................................................... 513
7.5.1.1.Methods of Treating Impacts in Adaptation Studies—Incremental to Transformational ...................................................... 513
7.5.1.2.Practical Regional Experiences of Adaptation, Including Lessons Learned ........................................................................... 518
7.5.1.3.Observed and Expected Barriers and Limits to Adaptation ................................................................................................... 518
7.5.1.4.Facilitating Adaptation and Avoiding Maladaptation ........................................................................................................... 518
7.5.2. Food System Case Studies of Adaptation—Examples of Successful and Unsuccessful Adaptation ................................................... 518
7.5.3. Key Findings from Adaptations—Confidence Limits, Agreement, and Level of Evidence .................................................................. 519
7.6. Research and Data Gaps—Food Security as a Cross-Sectoral Activity ................................................................... 520
References ......................................................................................................................................................................... 520
Frequently Asked Questions
7.1: What factors determine food security and does low food production necessarily lead to food insecurity? ...................................... 494
7.2: How could climate change interact with change in fish stocks and ocean acidification? ................................................................. 507
7.3: How could adaptation actions enhance food security and nutrition? ............................................................................................... 514
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Chapter 7 Food Security and Food Production Systems
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Executive Summary
The effects of climate change on crop and terrestrial food production are evident in several regions of the world (high confidence).
Negative impacts of climate trends have been more common than positive ones. {Figures 7-2, 7-7} Positive trends are evident in some high-
latitude regions (high confidence). Since AR4, there have been several periods of rapid food and cereal price increases following climate extremes
in key producing regions, indicating a sensitivity of current markets to climate extremes, among other factors. {Figure 7-3, Table 18-3} Several of
these climate extremes were made more likely as the result of anthropogenic emissions (medium confidence). {Table 18-3}
Climate trends are affecting the abundance and distribution of harvested aquatic species, both freshwater and marine, and
aquaculture production systems in different parts of the world. {7.2.1.2, 7.3.2.4, 7.4.2} These are expected to continue with negative
impacts on nutrition and food security for especially vulnerable people, particularly in some tropical developing countries {7.3.3.2}, but with
benefits in other regions that become more favorable for aquatic food production (medium confidence). {7.5.1.1.2}
Studies have documented a large negative sensitivity of crop yields to extreme daytime temperatures around 30°C. {WGII AR4
Chapter 5, 7.3.2.1} These sensitivities have been identified for several crops and regions and exist throughout the growing season (high
confidence). Several studies report that temperature trends are important for determining both past and future impacts of climate change on
crop yields at sub-continental to global scales (medium confidence). {7.3.2, Box 7-1} At scales of individual countries or smaller, precipitation
projections remain important but uncertain factors for assessing future impacts (high confidence). {7.3.2, Box 7-1}
Evidence since AR4 confirms the stimulatory effects of carbon dioxide (CO
2
) in most cases and the damaging effects of elevated
tropospheric ozone (O
3
) on crop yields (high confidence). Experimental and modeling evidence indicates that interactions between CO
2
and O
3
, mean temperature and extremes, water, and nitrogen are nonlinear and difficult to predict (medium confidence). {7.3.2.1, Figure 7-2}
Changes in climate and CO
2
concentration will enhance the distribution and increase the competitiveness of agronomically
important and invasive weeds (medium confidence). Rising CO
2
may reduce the effectiveness of some herbicides (low confidence). The
effects of climate change on disease pressure on food crops are uncertain, with evidence pointing to changed geographical ranges of pests and
diseases but less certain changes in disease intensity (low confidence). {7.3.2.3}
All aspects of food security are potentially affected by climate change, including food access, utilization, and price stability (high
confidence). {7.3.3.1, Table 7-1}
There remains limited quantitative understanding of how non-production elements of food security will be
affected, and of the adaptation possibilities in these domains. Nutritional quality of food and fodder, including protein and micronutrients, is
negatively affected by elevated CO
2
, but these effects may be counteracted by effects of other aspects of climate change (medium confidence).
{7.3.2.5}
For the major crops (wheat, rice, and maize) in tropical and temperate regions, climate change without adaptation will negatively
impact production for local temperature increases of 2°C or more above late-20th-century levels, although individual locations
may benefit (medium confidence). {7.4, Figure 7-4} Projected impacts vary across crops and regions and adaptation scenarios,
with about 10% of projections for the period 2030–2049 showing yield gains of more than 10% and about 10% of projections
showing yield losses of more than 25%, compared to the late 20th century. {Figure 7-5} After 2050, the risk of more severe
impacts increases. {Figure 7-5} Regional Chapters 22 (Africa), 23 (Europe), 24 (Asia), 27 (Central and South America), and Box 7-1
show crop production to be consistently and negatively affected by climate change in the future in low-latitude countries, while
climate change may have positive or negative effects in northern latitudes (high confidence).
Climate change will increase
progressively the inter-annual variability of crop yields in many regions (medium confidence). {Figure 7-6}
489
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Food Security and Food Production Systems Chapter 7
On average, agronomic adaptation improves yields by the equivalent of ~15-18% of current yields {Figure 7-8, Table 7-2}, but the
effectiveness of adaptation is highly variable (medium confidence) ranging from potential dis-benefits to negligible to very
substantial (medium confidence). {7.5.1.1.1}
Projected benefits of adaptation are greater for crops in temperate, rather than tropical, regions
(medium confidence) {7.5.1.1.1, Figures 7-4, 7-7}, with wheat- and rice-based systems more adaptable than those of maize (low confidence).
{Figure 7-4} Some adaptation options are more effective than others (medium confidence). {Table 7-2}
Global temperature increases of ~4°C or more above late-20th-century levels, combined with increasing food demand, would
pose large risks to food security globally and regionally (high confidence). Risks to food security are generally greater in low-
latitude areas. {Box 7-1, Table 7-3, Figures 7-4, 7-5, 7-7}
Changes in temperature and precipitation, without considering effects of CO
2
, will contribute to increased global food prices by
2050, with estimated increases ranging from 3 to 84% (medium confidence).
Projections that include the effects of CO
2
changes, but
ignore O
3
and pest and disease impacts, indicate that global price increases are about as likely as not, with a range of projected impacts from
–30% to +45% by 2050. {7.4.4}
Adaptation in fisheries, aquaculture, and livestock production will potentially be strengthened by adoption of multi-level adaptive
strategies to minimize negative impacts. Key adaptations for fisheries and aquaculture include policy and management to maintain
ecosystems in a state that is resilient to change, enabling occupational flexibility, and development of early warning systems for extreme
events (medium confidence). {7.5.1.1.2} Adaptations for livestock systems center on adjusting management to the available resources, using
breeds better adapted to the prevailing climate and removing barriers to adaptation such as improving credit access (medium confidence).
{7.5.1.1.3}
A range of potential adaptation options exist across all food system activities, not just in food production, but benefits from
potential innovations in food processing, packaging, transport, storage, and trade are insufficiently researched. {7.1, 7.5, 7.6,
Figures 7-1, 7-7, 7-8}
More observational evidence is needed on the effectiveness of adaptations at all levels of the food system. {7.6}
490
Chapter 7 Food Security and Food Production Systems
7
7.1. Introduction and Context
Many definitions of food security exist, and these have been the subject
of much debate. As early as 1992, Maxwell and Smith (1992) reviewed
more than 180 items discussing concepts and definitions, and more
definitions have been formulated since (DEFRA, 2006). Whereas many
earlier definitions centered on food production, more recent definitions
highlight access to food, in keeping with the 1996 World Food Summit
definition (FAO, 1996) that food security is met when “all people, at all
times, have physical and economic access to sufficient, safe, and nutritious
food to meet their dietary needs and food preferences for an active and
healthy life. Worldwide attention on food access was given impetus
by the food “price spike” in 2007–2008, triggered by a complex set of
long- and short-term factors (FAO, 2009b; von Braun and Torero, 2009).
FAO concluded, “provisional estimates show that, in 2007, 75 million
more people were added to the total number of undernourished relative
to 2003–05” (FAO, 2008); this is arguably a low-end estimate (Headey
and Fan, 2010). More than enough food is currently produced per capita
to feed the global population, yet about 870 million people remained
hungry in the period from 2010 to 2012 (FAO et al., 2012). The questions
for this chapter are how far climate and its change affect current food
production systems and food security and the extent to which they will
do so in the future (Figure 7-1).
7.1.1. Food Systems
A food system is all processes and infrastructure involved in satisfying
a population’s food security, that is, the gathering/catching, growing,
harvesting (production aspects), storing, processing, packaging,
transporting, marketing, and consuming of food, and disposing of food
waste (non-production aspects). It includes food security outcomes of
these activities related to availability and utilization of, and access to,
food as well as other socioeconomic and environmental factors (Ericksen,
2008; Ericksen et al., 2010; Ingram, 2011). This chapter synthesizes and
evaluates evidence for the impacts of climate on both production
and non-production elements and their adaptation to climate change
(Figure 7-1).
T
he impacts of climate change on food systems are expected to be
widespread, complex, geographi cally and temporally variable, and
profoundly influenced by socioeconomic conditions (Vermeulen et al.,
2012). Changes in food system drivers give rise to changes in food
security outcomes (medium evidence, high agreement), but often
researchers consider only the impacts on the food production element
of food security (Figure 7-1). Efforts to increase food production are
nevertheless increasingly important as 60% more food will be needed
by 2050 given current food consumption trends and assuming no
significant reduction in food waste (FAO et al., 2012).
7.1.2. The Current State of Food Security
Most people on the planet currently have enough food to eat. The vast
majority of undernourished people live in developing countries (medium
evidence, medium agreement), when estimated based on aggregate
national calorie availability and assumptions about food distribution
and nutritional requirements. More precise estimates are possible with
detailed household surveys, which often show a higher incidence of
food insecurity than estimated by FAO. Using food energy deficit as the
measure of food insecurity, Smith et al. (2006) estimated average rates
of food insecurity of 59% for 12 African countries, compared to a 39%
estimate from FAO for the same period (Smith et al., 2006). While there
is medium evidence, medium agreement on absolute numbers, there is
robust evidence, high agreement that sub-Saharan Africa has the highest
proportion of food-insecure people, with an estimated regional average
of 26.8% of the population undernourished in 2010–2012, and where
rates higher than 50% can be found (FAO et al., 2012). The largest
numbers of food-insecure persons are found in South Asia, which has
roughly 300 million undernourished (FAO et al., 2012). In addition to
common measures of calorie availability, food security can be broadened
to include nutritional aspects based on the diversity of diet including
not only staple foods but also vegetables, fruits, meat, milk, eggs, and
fortified foods (FAO, 2011). There is robust evidence and high agreement
that lack of essential micronutrients such as zinc and vitamin A affect
hundreds of millions of additional people (Lopez et al., 2006; Pinstrup-
Andersen, 2009).
Food systems adapted to
ensure availability, access,
utilization, and stability
Drivers
Responses
Climate and atmosphere
Non-climate factors
Temperature
Precipitation
Carbon dioxide
Ozone...
Production aspects
Food security
Non-production aspects
Crops
Livestock
Fish...
Soil fertility
Irrigation
Fertilizers
Demography
Economics
Socio-politics...
Incomes
Processing
Transport
Storage
Retailing...
Figure 7-1 | Main issues of the chapter. Drivers are divided into climate and non-climate elements, affecting production and non-production elements of food systems, thereafter
combining to provide food security. The thickness of the red lines is indicative of the relative availability of refereed publications on the two elements.
491
Food Security and Food Production Systems Chapter 7
7
F
ood insecurity is closely tied to poverty; globally about 25 to 30% of
poor people, measured using a US$1 to US$2 per day standard, live in
urban areas (Ravallion et al., 2007; IFAD, 2010). Most poor countries
have a larger fraction of people living in rural areas and poverty rates
tend to be higher in rural settings (by slight margins in South Asia and
Africa, and by large margins in China). In Latin America, poverty is more
skewed to urban areas, with roughly two-thirds of the poor in urban
areas, a proportion that has been growing in the past decade (medium
evidence, medium agreement). Rural areas will continue to have the
majority of poor people for at least the next few decades, even as
population growth is higher in urban areas (medium evidence, medium
agreement) (Ravallion et al., 2007; IFAD, 2010).
The effects of price volatility are distinct from the effects of gradual
price rises, for two main reasons. First, rapid shifts make it difficult for
the poor to adjust their activities to favor producing higher value items.
Second, increased volatility leads to greater uncertainty about the future
and can dampen willingness to invest scarce resources into productivity
enhancing assets, such as fertilizer purchases in the case of farmers or
rural infrastructure in the case of governments. Several factors have
been found to contribute to increased price volatility: poorly articulated
local markets, increased incidence of adverse weather events, and
greater reliance on production areas with high exposure to such risks,
biofuel mandates, and increased links between energy and agricultural
markets (World Bank, 2012). Vulnerability to food price volatility
depends on the degree to which households and countries are net food
purchasers; the level of integration into global, regional, and local markets;
and their relative degree of volatility, which in turn is conditional on their
respective governance (robust evidence, medium agreement) (HLPE,
2011; World Bank, 2012).
7.1.3. Summary from AR4
Food systems as integrated drivers, activities, and outcomes for food
security did not feature strongly in AR4. Summary points from AR4 were
that, with medium confidence, in mid- to high-latitude regions moderate
warming will raise crop and pasture yields. Sight warming will decrease
yields in low-latitude regions. Extreme climate and weather events will,
with high confidence, reduce food production. The benefits of adaptation
vary with crops and across regions and temperature changes; however,
on average, they provide approximately a 10% yield benefit when
compared with yields when no adaptation is used (WGII AR4 Section
5.5.1). Adaptive capacity is projected to be exceeded in low-latitude
areas with temperature increases of more than 3°C. Local extinctions
of particular fish species are expected at the edges of their ranges (high
confidence) and have serious negative impacts on fisheries (medium
confidence).
7.2. Observed Impacts,
with Detection and Attribution
7.2.1. Food Production Systems
Formal detection of impacts requires that observed changes be compared
to a clearly specified baseline that characterizes behavior in the absence
o
f climate change (Chapter 18). For food production systems, the number
and strength of non-climate drivers, such as cultivar improvement or
increased use of irrigation and fertilizers in the case of crops, make
defining a clear baseline extremely difficult. Most non-climatic factors are
not very well characterized in terms of spatial and temporal distributions,
and the relationships between these factors and specific outcomes of
interest (e.g., crop or fish production) are often difficult to quantify.
Attribution of any observed changes to climate trends are further
complicated by the fact that models linking climate and agriculture
must, implicitly or explicitly, make assumptions about farmer behavior.
In most cases, models implicitly assume that farming practices or
technologies did not adjust in response to climate over the period of
interest. This assumption can be defended in some cases based on
ancillary data on practices, or based on small differences between using
models with and without adaptation (Schlenker and Roberts, 2009).
However, in some instances the relationship between climate conditions
and crop production has been shown to change over time because of
management changes, such as introduction of irrigation or changes in
crop varieties (Zhang et al, 2008; Liu et al., 2009; Sakurai et al., 2012).
7.2.1.1. Crop Production
Many studies of cropping systems have estimated impacts of observed
climate changes on crop yields over the past half century, although they
typically do not attempt to compare observed yields to a counterfactual
baseline, and thus are not formal detection and attribution studies.
These studies employ both mechanistic and statistical approaches
(Section 7.3.1), and estimate impacts by running the models with
observed historical climate and then computing trends in modeled
outcomes. Based on these studies, there is medium confidence that
climate trends have negatively affected wheat and maize production
for many regions (Figure 7-2) (medium evidence, high agreement).
Because many of these regional studies are for major producers, and a
global study (Lobell et al., 2011a) estimated negative impacts on these
crops, there is also medium confidence for negative impacts on global
aggregate production of wheat and maize. Effects on rice and soybean
yields have been small in major production regions and globally (Figure
7-2) (medium evidence, high agreement). There is also high confidence
that warming has benefitted crop production in some high-latitude
regions, such as northeast China or the UK (Jaggard et al., 2007; Chen
et al., 2010; Supit et al., 2010; Gregory and Marshall, 2012).
More difficult to quantify with models is the impact of very extreme
events on cropping systems, as by definition these occur very rarely and
models cannot be adequately calibrated and tested. Table 18-3 lists some
notable extremes over the past decade, and the impacts on cropping
systems. Despite the difficulty of modeling the impacts of these events,
they clearly have sizable impacts (Sanchez et al. 2014) that are apparent
immediately or soon after the event, and therefore not easily confused
with effects of more slowly moving factors. For a subset of these events,
climate research has evaluated whether anthropogenic activity has
increased or decreased their likelihood (Table 18-3).
A sizable fraction of crop modeling studies were concerned with
production for individual sites or provinces, spatial scales below which
492
Chapter 7 Food Security and Food Production Systems
7
the changes in climate conditions are attributable to anthropogenic
activity (WGI AR5 Chapter 10). Similarly, most crop studies have focused
on the past few decades, a time scale shorter than most attribution
studies for climate. However, some focused on continental or global
scales (Lobell and Field, 2007; You et al., 2009; Lobell et al., 2011a), at
which trends in several climatic variables, including average summer
temperatures, have been attributed to anthropogenic activity. In
particular, global temperature trends over the past few decades are
attributable to human activity (WGI AR5 Chapter 10), and the studies
discussed above indicate that this warming has had significant impacts
on global yield trends of some crops.
In general, little work in food production or food security research has
focused on determining whether climate trends affecting agriculture
can be attributed to anthropogenic influence on the climate system.
However, as the field of climate detection and attribution proceeds to
finer spatial and temporal scales, and as agricultural modeling studies
expand to broader scales, there should be many opportunities to link
climate and crop studies in the next few years. Importantly, climate
attribution is increasingly documented not only for measures of average
conditions over growing seasons, but also for extremes. For instance,
Min et al. (2011) attributed changes in rainfall extremes for 1951–1999
to anthropogenic activity, and these are widely acknowledged as
important to cropping systems (Rosenzweig et al., 2002). Frost damage
is an important constraint on crop growth in many crops, including for
various high-value crops, and significant reductions in frost occurrence
since 1961 have been observed and attributed to greenhouse gas (GHG)
emissions in nearly every region of the world (Zwiers et al., 2011; IPCC,
2012).
Increased frequency of unusually hot nights since 1961 are also
attributable to human activity in most regions (WGI AR5 Chapter 10).
These events are damaging to most crops, an effect that has been
observed most commonly for rice yields (Peng et al., 2004; Wassmann
Median
–10 to –5 –5 to –2.5 –2.5 to 0 Not
significant
>0 –6 –4 –2 0 2
(
N = 19)
(27)
(46)
(10)
(2)
(
54)
(18)
(10)
(13)
(12)
Yield impact of climate trend (% per decade)
(a)
(b)
Yield impact of climate trend (% per decade)
5
10
15
20
Number of estimates
0
25
Maize
Rice
Soy
Wheat
No CO
2
Yes CO
2
Process
model
Statistical
model
Te mp e rate
Tropical
Region
Model type
Crop type
CO
2
25th
75th
90th
Percentile
10th
Figure 7-2 | Summary of estimates of the impact of recent climate trends on yields for four major crops. Studies were taken from the peer-reviewed literature and used different
methods (i.e., physiological process-based crop models or statistical models), spatial scales (stations, provinces, countries, or global), and time periods (median length of 29
years). Some included effects of positive carbon dioxide (CO
2
) trends (Section 7.3.2.1.2) but most did not. (a) Number of estimates with different level of impact (% yield per
decade). (b) Boxplot of estimates separated by temperate vs. tropical regions, modeling approach (process-based vs. statistical), whether CO
2
effects were included, and crop.
Boxplots indicate the median (vertical line), 25th to 75th percentiles (colored box), and 10th to 90th percentiles (white box) for estimated impacts in each category, and numbers
in parentheses indicate the number of estimates. Studies were for China (Tao et al., 2006, 2008a, 2012; Wang et al., 2008; You et al., 2009; Chen et al., 2010), India (Pathak et
al., 2003; Auffhammer et al., 2012), USA (Kucharik and Serbin, 2008), Mexico (Lobell et al., 2005), France (Brisson et al., 2010; Licker et al., 2013), Scotland (Gregory and
Marshall, 2012), Australia (Ludwig et al., 2009), Russia (Licker et al., 2013), and some studies for multiple countries or global aggregates (Lobell and Field, 2007; Welch et al.,
2010; Lobell et al., 2011a). Values from all studies were converted to percentage yield change per decade. Each study received equal weighting as insufficient information was
available to judge the uncertainties of each estimate.
493
Food Security and Food Production Systems Chapter 7
7
e
t al., 2009; Welch et al., 2010) as well as rice quality (Okada et al.,
2011). Extremely high daytime temperatures are also damaging and
occasionally lethal to crops (Porter and Gawith, 1999; Schlenker and
Roberts, 2009), and trends at the global scale in annual maximum
daytime temperatures since 1961 have been attributed to GHG emissions
(Zwiers et al., 2011). At regional and local scales, however, trends in
daytime maximum are harder to attribute to GHG emissions because
of the prominent role of soil moisture and clouds in driving these trends
(Christidis et al., 2005; Zwiers et al., 2011).
In addition to effects of changes in climatic conditions, there are clear
effects of changes in atmospheric composition on crops. Increase of
atmospheric CO
2
by greater than 100 ppm since preindustrial times has
virtually certainly enhanced water use efficiency and yields, especially
for C
3
crops such as wheat and rice, although these benefits played a
minor role in driving overall yield trends (Amthor, 2001; McGrath and
Lobell, 2011).
Emissions of CO
2
often are accompanied by ozone (O
3
) precursors that
have driven a rise in tropospheric O
3
that harms crop yields (Morgan
et al., 2006; Mills et al., 2007; Section 7.3.2.1.2). Elevated O
3
since
preindustrial times has very likely suppressed global production of major
crops compared to what they would have been without O
3
increases,
with estimated losses of roughly 10% for wheat and soybean and 3 to
5% for maize and rice (Van Dingenen et al., 2009). Impacts are most
severe over India and China (Van Dingenen et al., 2009; Avnery et al.
2011a,b), but are also evident for soybean and maize in the USA
(Fishman et al., 2010).
7.2.1.2. Fisheries Production
The global average consumption of fish and other products from
fisheries and aquaculture in 2010 was 18.6 kg per person per year,
derived from a total production of 148.5 million tonnes, of which 86%
was used for direct human consumption. The total production arose
from contributions of 77.4 and 11.2 million tonnes respectively from
marine and inland capture fisheries, and 18.1 and 41.7 million tonnes
respectively from marine and freshwater aquaculture (FAO, 2012).
Fisheries make particular contributions to food security and more than
90% of the people engaged in the sector are employed in small-scale
fisheries, many of whom are found in the poorer countries of the world
(Cochrane et al., 2011). The detection and attribution of impacts are as
confounded in inland and marine fisheries as in terrestrial food production
systems. Overfishing, habitat modification, pollution, and interannual
to decadal climate variability can all have impacts that are difficult to
separate from those directly attributable to climate change.
One of the best studied areas is the Northeast Atlantic, where the
temperature has increased rapidly in recent decades, associated with a
poleward shift in distribution of fish (Perry et al., 2005; Brander, 2007;
Cheung et al., 2010, 2013). There is high confidence in observations of
increasing abundance of fish species in the northern extent of their
ranges while decreases in abundance have occurred in the southern
part (Section 30.5.1.1.1). These trends will have mixed implications for
fisheries and aquaculture with some commercial species negatively and
others positively affected (Cook and Heath, 2005). There is a similar
w
ell-documented example in the oceans off southeast Australia with
large warming trends associated with more southward incursion of the
Eastern Australian Current, resulting in southward migration of marine
species into the oceans around eastern Tasmania (robust evidence, high
agreement; Last et al., 2011).
As a further example, coral reef ecosystems provide food and other
resources to more than 500 million people and with an annual value of
US$5 billion or more (Munday et al., 2008; Hoegh-Guldberg, 2011).
More than 60% of coral reefs are considered to be under immediate
threat of damage from a range of local threats, of which overfishing is
the most serious (Burke et al., 2011; see also Box CC-CR) and the
percentage under threat rises to approximately 75% when the effect
of rising ocean temperatures is added to these local impacts (Burke et
al., 2011). Wilson et al. (2006) demonstrated that declines in coral reef
cover typically led to declines in abundance of the majority of fish
species associated with coral reefs. There is high confidence that the
availability of fish and invertebrate species associated with coral reefs
that are important in many tropical coastal fisheries is very likely to be
reduced (Section 30.6.2.1.2). Other examples around the world are
described in Section 30.5.1.1.1.
These changes are impacting marine fisheries: a recent study that
examined the composition of global fisheries catches according to the
inferred temperature preferences of the species caught in fisheries
found that there had been changes in the species composition of marine
capture fisheries catches and that these were significantly related to
changes in ocean temperatures (Cheung et al. 2013; Section 6.4.1.1).
These authors noted that the relative contribution to catches by warmer
water species had increased at higher latitudes while the contributions
of subtropical species had decreased in the tropics. These changes have
negative implications for coastal fisheries in tropical developing countries,
which tend to be particularly vulnerable to climate change (Cheung et
al., 2013; Sections 6.4.3, 7.5.1.1.2).
There is considerably less information available on climate change
impacts on fisheries and fishery resources in freshwater systems and
aquaculture. Considerable attention has been given to the impacts of
climate change in some African lakes but with mixed interpretations
(Section 22.3.3.1.4). There is evidence that increasing temperature has
reduced the primary productivity of Lake Tanganyika in East Africa and
a study by O’Reilly et al. (2003) estimated that this would have led to
a decrease of approximately 30% in fish yields. However, Sarvala et al.
(2006) disagreed and concluded that observed decreases in the fish
catches could be explained by changed fishery practices. There has been
a similar difference of opinion for Lake Kariba, where Ndebele-Murisa
et al. (2011) argued that a reduction in fisheries productivity had been
caused by climate change while Marshall (2012) argued that the declines
in fish catches can only have been caused by fishing. There is medium
confidence that, in India, changes in a number of climate variables
including an increase in air temperature, regional monsoon variation,
and a regional increase in incidence of severe storms have led to
changes in species composition in the River Ganga and to have reduced
the availability of fish spawn for aquaculture in the river Ganga while
having positive impacts on aquaculture on the plains through bringing
forward and extending the breeding period of the majors carps (Vass
et al., 2009).
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7.2.1.3. Livestock Production
In comparison to crop and fish production, considerably less work has
been published on observed impacts for other food production systems,
such as livestock or aquaculture, and to our knowledge nothing has
been published for hunting or collection of wild foods other than for
capture fisheries. The relative lack of evidence reflects a lack of study
in this topic, but not necessarily a lack of real-world impacts of observed
climate trends. A study of blue-tongue virus, an important ruminant
disease, evaluated the effects of past and future climate trends on
transmission risk, and concluded that climate changes have facilitated
the recent and rapid spread of the virus into Europe (Guis et al., 2012).
Ticks that carry zoonotic diseases have also likely changed distribution
as a consequence of past climate trends (Section 23.4.2).
7.2.2. Food Security and Food Prices
Food production is an important aspect of food security (Section 7.1),
and the evidence that climate change has affected food production
implies some effect on food security. Yet quantifying this effect is an
extremely difficult task, requiring assumptions about the many non-
climate factors that interact with climate to determine food security.
There is thus limited direct evidence that unambiguously links climate
change to impacts on food security.
One important aspect of food security is the prices of internationally
traded food commodities (Section 7.1.3). These prices reflect the overall
balance of supply and demand, and the accessibility of food for
consumers integrated with regional to global markets. Although food
prices gradually declined for most of the 20th century (FAO, 2009b) since
AR4 there have been several periods of rapid increases in international
food prices (Figure 7-3). A major factor in recent price changes has been
increased crop demand, notably via increased use in biofuel production
related both to energy policy mandates and oil price fluctuations
(Roberts and Schlenker, 2010; Mueller et al., 2011; Wright, 2011). Yet
fluctuations and trends in food production are also widely believed to
have played a role in recent price changes, with recent price spikes often
following climate extremes in major producers (Figure 7-3). Moreover,
some of these extreme events have become more likely as a result of
climate trends (Table 18-3). Domestic policy reactions can also amplify
international price responses to weather events, as was the case with
export bans announced by several countries since 2007 (FAO, 2008). In
a study of global production responses to climate trends (Lobell et al.,
2011a) estimated a price increase of 19% due to the impacts of
temperature and precipitation trends on supply, or an increase of 6%
once the beneficial yield effects of increased CO
2
over the study period
were considered. Because the price models were developed for a period
ending in 2003, these estimates do not account for the policy responses
witnessed in recent years which have amplified the price responses to
weather.
7.3. Assessing Impacts,
Vulnerabilities, and Risks
7.3.1. Methods and Associated Uncertainties
7.3.1.1. Assessing Impacts
Methods developed or extended since AR4 have resulted in more robust
statements on climate impacts, both in the literature and in Section
7.3.2. Two particular areas, which are explored below, are improved
quantification and presentation of uncertainty; and greater use of
historical empirical evidence of the relationship between climate and
food production.
The methods used for field and controlled environment experiments
remain similar to those at the time of AR4. There has been a greater use
of remote sensing and geographic information systems for assessing
temporal and spatial changes in land use, particularly in agricultural
land use for assessment of food security status (Thenkabail et al., 2009;
Frequently Asked Questions
FAQ 7.1 | What factors determine food security and does low food production
necessarily lead to food insecurity?
O
bserved data and many studies indicate that a warming climate has a negative effect on crop production and
generally reduces yields of staple cereals such as wheat, rice, and maize, which, however, differ between regions
and latitudes. Elevated CO
2
could benefit crops yields in the short term by increasing photosynthesis rates; however,
t
here is big uncertainty in the magnitude of the CO
2
e
ffect and the significance of interactions with other factors.
Climate change will affect fisheries and aquaculture through gradual warming, ocean acidification, and changes
in the frequency, intensity, and location of extreme events. Other aspects of the food chain are also sensitive to
c
limate but such impacts are much less well known. Climate-related disasters are among the main drivers of food
insecurity, both in the aftermath of a disaster and in the long run. Drought is a major driver of food insecurity, and
contributes to a negative impact on nutrition. Floods and tropical storms also affect food security by destroying
livelihood assets. The relationship between climate change and food production depends to a large degree on
when and which adaptation actions are taken. Other links in the food chain from production to consumption are
sensitive to climate but such impacts are much less well known.
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Food Security and Food Production Systems Chapter 7
7
Fishman et al., 2010; Goswami et al., 2012). There has also been an
increase in the number of Free Air Concentration Enrichment (FACE)
studies that examine O
3
instead of, or in addition to, CO
2
. In agriculture,
FACE experiments have been used for assessing impacts of atmospheric
CO
2
on grain yield, quality characteristics of important crops (Erbs et
al., 2010), elemental composition (Fernando et al., 2012), and diseases
(Chakraborty et al., 2011; Eastburn et al., 2011). A number of meta-
analyses of experimental studies, in particular FACE studies, have been
made since AR4. However, debate continues on the disparities between
results from FACE experiments and non-FACE experiments, such as in
open-top chambers or greenhouses. As reported in AR4, FACE studies
tend to show lower elevated CO
2
responses than non-FACE studies.
Although some authors have claimed that the results of the tw