243

Impacts of Global Warming on Agricultural Production and
Adaptations in Response
Kiyoshi TAKAHASHINational Institute for Environmental Studies
16-2 Onogawa, Tsukuba, Ibaraki 305-8506, Japane-mail: ktakaha@nies.go.jp

Abstract
Measures in response to global warming can be divided into two strategies: mitigation, which
reduces climate change itself by the reduction of greenhouse gases, and adaptation, which reduces theimpacts of climate change. Interest in the adaptation approach, in particular, has recently been rising bothin Japan and internationally. Agricultural production is expected to be greatly impacted by future climatechange, and enhanced knowledge through research on adaptation will be required in order to reduce these
impacts. Against such a background, this paper summarizes the concept of adaptation and describes someexisting studies on the impacts of global warming on agricultural production and studies on adaptation.
With this as a basis, the paper discusses the crucial issue of studies concerning adaptation in the agricultural sector and presents suggestions. From a policy standpoint, the significances of studies differ between
those that quantitatively estimate the impacts of global warming, taking adaptation measures into
consideration and using climate scenarios as assumptions on the one hand, and studies aimed at selecting,promoting and implementing adaptation measures suitable for reducing impact damage on the other.
While proceeding with these two types of studies in a balanced manner, it is necessary to promote close
cooperation between both research communities. An important task with regard to the former type ofstudy is further refinement of methods for assessing impacts on agricultural production taking extreme
weather phenomena such as typhoons, continuous dry periods, etc., into consideration. For the latter type,
important tasks include estimation of adaptation costs, clarification of factors that inhibit implementationof individual adaptations, and accordingly, grasping of the limitations that can be expected with regard to
future adaptations.
Key words: adaptation, agricultural impact, climate change, global warming, vulnerability

1. Introduction
1.1 Adaptation to global warming
The Third Assessment Report of the Intergovernmental Panel on Climate Change (IPCC) cites projections of an increase in globally averaged surface
temperature of 1.4°C to 5.8°C over the period 1990 to
2100 (IPCC, 2001b). Pointing out that global warming
has already become evident, the report states that it isvery likely that the 1990s was the warmest decade in
the instrumental record (1861 to 2000). In view of thehigh possibility that global warming will cause largescale, irreversible changes in global systems, response
measures are of great importance.
Measures in response to global warming can be
categorized into mitigation, in which emissions ofgreenhouse gases (GHGs), considered to be the causeof global warming, are reduced; and adaptation, in
which the adverse impacts of global warming are
Global Environmental Research
10(2)/2006: 243-252
printed in Japan

reduced by bringing about adjustment in natural ecosystems and socio-economic systems to climate change.
Policy analysis and assessment studies initially focusedon mitigation. However, now that the enormous costsof mitigation have become clear, coupled with therealization that global warming is already progressing
and that severe climate change cannot be avoided even
if all mitigation measures are fully implemented,
greater attention is being paid to adaptation. The
United Nations Framework Convention on Climate
Change stipulates that adaptation should be studied aspart of each country’s domestic measures.
1.2 Global warming and agricultural production
When temperatures rise due to global warming,changes take place in the amount of solar radiation,
precipitation, etc., and yields of cereal crops per unit
area also change. As a result, there may be cases inwhich existing agricultural areas become unsuitable for©2006 AIRIES244

K. TAKAHASHI

agriculture, and vice versa. Changes in crop yield due
to global warming can also be expected to affect prices,
production, consumption and trading of cereal crops on
the global market. For example, when cereal crop
yields decrease in major producing countries, not only
will there be an adverse economic impact on the exporting countries, but also on the importing counties
due to higher market prices and the difficulty of securing supplies.
1.3 The objectives and structure of this paper
Agricultural production is expected to be greatly
impacted by future climate change. Enhanced knowledge through research on adaptation is required inorder to reduce these impacts. The objectives of thispaper are to provide an outline of the concept of adaptation and describe some existing studies on the impacts of global warming on agricultural production andstudies on adaptation. With this as a basis, the crucial
issue of studies concerning adaptation in the agricultural sector is discussed and suggestions are presented.
First, Section 2 provides a summary of the concept ofadaptation and describes adaptation measures that
could be adopted in the agricultural sector. An overview of existing agricultural impact assessment studies
is then provided in Section 3. Lastly, Section 4 classifies studies on adaptation according to type, discussing
research tasks concerning adaptation in the agricultural
sector, and presenting some suggestions.

2. Adaptation in the Agricultural Sector
2.1 What is adaptation?
The Third Assessment Report of IPCC Working
Group II defines adaptation as “adjustment in natural or
human systems in response to actual or expected climatic stimuli or their effects, which moderates harm or
exploits beneficial opportunities” (IPCC, 2001a). In
other words, adaptation takes place when living things,
including both human individuals and groups, reduce
adverse impacts of climate change by modifying their
biological responses, patterns of behavior, systems,
facilities, etc., or when they successfully amplify
beneficial impacts of climate change.
Adaptation encompasses both those implemented toreduce directly damage due to climate change, andthose that contribute to indirect reduction of damage
due to climate change by enhancing future adaptive
capacity. For example, in an area where cultivation ofwheat has become difficult due to increasing temperatures, a shift by farmers to cultivation of heat-tolerant
crops would belong to the former category, whereas
development of an information system for farmers toenable them to learn which crops would be suitable forcultivation under a changed climate would belong to
the latter. Both types of measures can be consideredadaptations.
The Third Assessment Report also describes theclassification of sectors and systems, intentionality andtiming of implementation as the main criteria for classifying adaptations. Systems can be broadly classified
into natural systems and human systems. The movement of animals and plants to suitable habitats would
fall under the former type. Intentionality can be classified into autonomous adaptation, in which the intervention of public organizations is unnecessary, andplanned adaptation. Timing of implementation can beclassified into reactive adaptation, which is implemented after the manifestation of an impact, andproactive (or anticipatory) adaptation, which is implemented in anticipation of an impact prior to its manifestation. The adaptation of natural systems is basicallyautonomous and reactive.
Table 1 shows an example of the classification ofadaptations by Klein et al. (1999). The entity implementing adaptation could be a private individual or apublic entity such as a country or a corporation. Note,however, that an adaptation implemented by one entity
is not independent of adaptations implemented by otherentities. One example is that an adaptation by an individual is implemented within the framework of laws
and regulations of the country concerned.
2.2 What is adaptive capacity?
Adaptive capacity means the ability of a system toadjust to climate change (including climate variability
and extremes) in order to moderate potential damage,or to take advantage of opportunities or to cope withthe consequences. Namely, it is the ability to plan andimplement effective adaptations and to respond toincreasing risk and stress so as to reduce the frequency
and degree of harmful results due to impacts of climate

Table 1 Example of classification of adaptations.

Anticipatory
Natural Systems

Private
Human
Systems
PublicPurchase of insurance.
Construction of houses on stilts.
Redesigning of oil-rigs.
Early-warning systems.
New building codes, design standards.
Incentives for relocation.

Reactive
Changes in length of growing season.
Changes in ecosystem composition.
Wetland migration.
Changes in farming practices.
Changes in insurance premiums.
Purchase of air-conditioning.
Compensatory payments, subsidies.
Enforcement of building codes.
Beach nourishment.

Impacts of Global Warming on Agricultural Production and Adaptations in Responsechange.
For the implementation of adaptations, various
conditions related to wealth, scientific and technicalknowledge, information, skills, infrastructure, institutions, equity, etc., must be satisfied. These can be referred to as component factors of adaptive capacity. It
may be possible to realize some adaptation measures atlittle or no cost. However, a certain level of cost is
generally involved when implementing the majority ofeffective adaptation measures. As a precondition for
implementing a particular type of adaptation, the relevant technology must exist and be available for use.
Moreover, for the effective implementation of an
adaptation, people must first recognize the need forsome form of adaptation. In addition, knowledge concerning available adaptation measures is necessary,
together with the ability to assess measures for selection and implement those judged to be most suitable. In
the case of undertaking adaptation as a group, it isnecessary to obtain the consensus of the group members, so transparency of the decision-making system isalso necessary.
Adaptive capacity is acquired through a combination of these component factors. However, the relative
importance of each factor will differ according to thecircumstances in which adaptation is implemented, thenature of the disaster being faced and so on. Individualcomponent factors are neither independent nor exclusive, but have close mutual relationships. In an international framework, when studying the provision ofadaptation assistance to developing countries, which
are especially vulnerable to global warming, it will be
important to identify the cause of any lowering of adaptive capacity and to give assistance for the improvement and reinforcement of such capacity so that thecountries can efficiently and effectively implement
adaptations to reduce the adverse impacts of anticipated climate change and climate variability.
2.3 Increasing attention to adaptation
Measures in response to global warming fall into
two categories: mitigation (also referred to as emissions reduction), in which carbon dioxide and other
GHGs are reduced to prevent global warming fromprogressing; and adaptation, in which natural and social systems are adjusted to climatic conditions where
global warming is in progress. Throughout the world,
including Japan, mitigation measures against global
warming were first considered. One reason that can becited for this is that, while mitigation simultaneously
reduces the effects on all systems susceptible to climate
impact, adaptation affects only limited systems. In
other words, in the event of drastic global warming,
impacts are projected to manifest on diverse fields
including agriculture, water resources, health andnatural vegetation in various places worldwide. Whenthe progress of global warming is suppressed by
mitigation, each of the impacts on these multiple fields
and regions will be reduced simultaneously. On the245

other hand, adaptation measures are basically implemented by specifying a certain field and region, such as
construction of a reservoir in a region that is expected
to become susceptible to drought due to global warming, or switching agricultural crops to heat-tolerantvarieties in a region where crop growth is deteriorating
due to heat stress, so their effect is limited to the field
and region targeted by the measures. Another reason
for the initial focus on mitigation is that from the beginning, there was an understanding that overcoming
global warming by adaptation alone was impossible. If
GHGs were emitted without restraint and global
warming rapidly progressed, although the impacts onsome fields and regions could be sufficiently alleviatedby adaptation, there would be others in which unacceptable adverse impacts remained even if the maximum possible adaptation measures were implemented.
For example, suitable habitats for animals and plants
are expected to change due to global warming. If global
warming progresses drastically, however, even when
all realistic adaptation measures are adopted, the impacts cannot be completely avoided and extinctions
may occur among animals and plants that lose suitable
habitats. Therefore, since it is impossible to avoid all of
the impacts of global warming by adaptation alone, it
plays a complementary role among the entire range ofglobal warming measures.
Although efforts in the sphere of adaptation haveconsequently lagged behind in comparison with mitigation, recently there has been a rapid increase inrecognition of its importance. One of the reasons behind this trend is that studies have shown that climatechange cannot be completely suppressed even withmaximum emission reduction efforts, so the occurrenceof some impacts cannot be avoided. In particular, suchimpacts are manifesting at an early stage in developing
countries, whose adaptive capacity is low, and many
policymakers have begun to understand that improvement of the adaptive capacity of developing countries
is an urgent task. Moreover, there are cases in which,by conducting planned adaptations in advance, the totalof the amount of damage and the cost of measures canbe suppressed compared with the implementation ofreactive adaptations only (e.g. Ebi et al. (2004)).
People are also beginning to recognize that there aremany cases in which the risk of disasters (i.e., disasters
from extreme weather events) due to current climate
variability can be reduced as a side effect ofanticipatory adaptation with long-term climate change
in view (IPCC, 2001a). These are also factors in the
recent increase in attention to adaptation.
2.4 Adaptation in the agricultural sector
Examples of adaptation in the agricultural sector
include technical, administrative and policy measures,
as well as those that can be implemented at the farmlevel or that should be undertaken at the community or
governmental level, as summarized in Table 2.

246

K. TAKAHASHI
Table 2 Examples of adaptation in the agricultural sector. (created from Kurukulasuriya & Rosenthal (2003))
Adaptation options

Adaptation options

Crop insurance

Changing crop mix

Private/public programs.

Adopting new crops.

Formal/informal schemes.

Planting in different parts of farm.

Portfolio (Crop/Livestock) diversification
Replacement of plant types, cultivars, hybrids and animal
breeds with new varieties.
Alternative production techniques (adjustment of capitaland labor inputs).
Mixed farming systems of crops and livestock.
Adjusting timing of farm operations
Adjusting cropping sequence.

Irrigation
Modernization of farm operations
Long-term

Multi-cropping.

Converting land use.

Adoption of technology (e.g. use of sprinklers).
Permanent migration
Defining landuse and tenure rights
Efficient water use

Adjusting timing of irrigation.
Changing cropping intensity

Improving water distribution.

Adjusting fertilizer and other inputs.

Promoting irrigation efficiency.

Changing land use practices.

Changing crop and irrigation schedules.
Water recycling and the conjunctive use ofgroundwater.

Changing location of crop/livestock production.
Rotating or shifting production between crops andlivestock.

Rehabilitation and modernization.

Abandonment of land.
Changing the timing of activities (sowing, planting,spraying and harvesting).
Livestock management
Change in biological diversity, species.
Altering breeding management programs (i.e., changing
composition, or species distribution).
Change in grazing management (timing, duration andlocation).
Changing the location of watering points.
Changes in rangeland management practices.

Investment promotion
Developing market efficiency
Both short and long-term

Changing the timing of irrigation.
Short-term

Research and development.

Pricing reform.
Developing open markets.
Reforming agricultural markets.
Adoption of technological and other adaptation measures
Promoting trade
Developing extension services
Improving forecasting mechanisms

Modifying operation production strategies.
Changing market strategies.
Implementing feed conservation techniques/varying
supplemental feeding.

Institutional strenthening and developing decision-making
structures

Changes in tillage practices (conservation tillage)
Land contouring and terracing.
Maintaining crop residues.
Fallow and tillage practices.
Planting of hedges.
Alternative drainage method.
Construction of diversions, reservoirs and water storage.
Irrigation.
Reducing water use in land preparation.
Temporary migration
Short-term forecasts
Food reserves and storage

3. Existing Agricultural Impact Studies Taking Adaptation into Consideration
3.1 Global-scale crop productivity estimation
Existing studies assessing the agricultural impactsof global warming on a global scale include those by
Takahashi et al. (1997) and Fischer et al. (2002) using a
potential crop productivity model that was developed
based on a method for evaluating the suitability ofclimate and soil resources for cultivating crops formulated by the Food and Agriculture Organization (FAO).
Here, potential crop productivity means the achievable
yield of a crop per unit area assuming a certain level of
input. By biologically modeling the growth of cereal

crops using data on temperature, precipitation, potential evapotranspiration, photosynthetically active radiation, soil quality, topography, etc., as input information, Takahashi et al. (1997) quantitatively assessed
potential productivity at the global level of twelve
types of crops, namely, rice, winter and spring wheat,maize (tropical and temperate cultivation), sorghum(tropical and temperate cultivation), pearl millet,
cassava, sweet potato, white potato and soybean, while
Fischer et al. (2002) made similar quantitative assessments in greater detail for 154 types of crops.
Murai et al. (2005) improved on the methods of
Takahashi et al. (1997) by conducting potential productivity impact assessments, taking changes in cropImpacts of Global Warming on Agricultural Production and Adaptations in Response

species and planting dates due to climate change into
consideration. In that study, cultivated rice was categorized into four species and wheat into five species,
the growth characteristics of each were converted into
parameters, simulations were conducted under thecurrent climate to estimate potential productivity for all
crop species, and the crop species that obtained thehighest potential productivity were selected. For simulations under a future climate, in the case of crop species changing from the present state (i.e., the case ofadaptation by changing crop species), estimations were
performed for all species and those that obtained thehighest potential productivity were selected, in a process similar to that used for simulations under the current climate. On the other hand, in the case of no
species change (i.e., the case of no adaptation bychanging of crop species), simulations were performedon the assumption that the optimum species under thecurrent climate would be continuously cultivated in the
future as well. Concerning the climate conditions, themonthly climate values of the Climate Research Unit at
East Anglia University (CRU) in normal years during
the 30-year period from 1961 to 1990 for a grid of 0.5°
× 0.5° latitude and longitude were used as the baseline(current) climate, and the future climate scenario wasprepared by adding climate change data (average values from the baseline period to the period from 2036 to2065) obtained from the output results of SRES-A1B(IPCC, 2000) emission scenario1) simulations by the
CCSR/NIES (Center for Climate System Researchat the University of Tokyo / National Institute for247

Environmental Studies) model to the baseline climate
data.
Figure 1 shows the impact of climate change on thepotential productivity of wheat in 2050. Potential productivity was simulated for different adaptation conditions and the results were compared in order to study
the effects of adaptation. Developing countries havepotential capacity to improve their production throughirrigation and mechanization, so the adverse impacts offuture anticipated climate change can be expected to beoffset by implementation of adaptations such aschanging the crop species cultivated and cultivation
periods, which can be executed comparatively easily at
the farm level (adaptation case). In parts of Canada,
Europe and Russia that are currently unsuitable for
production because of low temperatures acting as an
inhibiting factor, it is projected that areas of possible
cultivation will newly appear. However, in the central
and eastern United States and other areas that currently
have good conditions for cultivation, even in the caseof adaptation a decrease in production is still expected.
On the other hand, when appropriate adaptation measures are not taken (case of no adaptation), a serious
lowering of productivity due to climate change becomes evident. Especially in the United States andSouth America, a significant decrease is projected inareas in which production is possible. As regards productivity, increases in the rate of irrigation and invested
labor can be expected in Africa, South America, andelsewhere, and the extent of decrease will be smaller
compared with the industrialized countries.

(a)

(b)

-500

0

+500 (kg/ha)

Fig. 1 Projected changes in wheat productivity due to global warming from the present
condition to 2050. (Murai et al., 2005)(a) Adaptation case (It is assumed that farmers can adapt to climate change bychanging wheat varieties and planting dates)(b) Case of no adaptation

248

K. TAKAHASHI

An overview of the results of impact studies on crop
production shows that, without taking into consideration the CO2 fertilization effect due to the increase inatmospheric carbon dioxide concentration, crop yields
are projected to increase in many mid-latitude regions
if the temperature rise is 2°C to 3°C or less, and to decrease if the temperature rise is higher than that
(Takahashi, 2005). In tropical regions, for some crops
such as rice, the temperature is close to the upper limitof the suitable growing temperature, and the main formof agriculture in practice depends on rainwater, so it ispossible that even a small temperature rise may resultin a decrease in productivity.

Sciences (JIRCAS), the National Institute for Environmental Studies (NIES), and the Research Institute of
Innovative Technology for the Earth (RITE) are conducting studies to estimate economic impacts, populations at risk of hunger, etc., using an international trademodel that takes changes in global cereal crop productivity into account. For example, according to an
analysis by Takahashi et al. (1999), when the CO2
fertilization effect is not taken into consideration, theproductivity of rice, wheat and other crops tends todecrease conspicuously, especially in low-latitude
regions. Moreover, many developing countries – inwhich people use a high ratio of their overall personal
expenditures to buy crops as food – are located in the
low-latitude regions, so these countries are susceptible
to the impact of price increases due to declining productivity.
Parry et al. (2004) performed simulations of international trade and adjustment of production andconsumption by means of an agroeconomic model,using the results of crop productivity estimations fromclimate model outputs, with SRES scenarios as assumptions together with the population and economic
growth projections of the SRES scenarios, and thereby
estimated the populations exposed to hunger risk.
Figure 2 shows the impacts of climate change on the
population at risk of hunger under the SRES scenarios(change from the reference case, which assumes noclimate change and no change in atmospheric CO2
concentration), with the CO2 fertilization effect due tothe increase in atmospheric CO2 concentration taken
into account in the left-hand graph and not taken into
account in the right-hand graph. Estimations weremade based on the assumptions of four SRES scenarios(however, with regard to the A2 and B2 scenarios, theA2a, A2b, A2c, B2a, and B2b scenarios obtained bygeneral circulation model [GCM] ensemble simulation,
which have different initial conditions as assumptions,were used). Under the A2 scenario, when the CO2
fertilization effect is not taken into account there is adecrease in crop productivity due to the occurrence ofsignificant climate change, while at the same time the

3.2 Estimation of economic impacts and population at risk
In the event of a temperature rise of 2°C to 3°C or
more, increases in food prices are projected due to suchfactors as interruptions in food supplies on a global
scale. Global warming is also projected to cause adecrease in the incomes of poor people in developing
countries and an increase in the number of people atrisk of hunger, as well as greater difficulty in securing
food due to increased incidence of extreme events. On
the other hand, the results of estimations that take theCO2 fertilization effect into consideration tend to describe a more optimistic future image (Takahashi,2005).
In Japan, the relative profitability of the agricultural
sector has declined compared with that of other production sectors since the period of high economic growth.
The volume of food imports has rapidly increased, andfood self-sufficiency in terms of caloric value has
fallen to about 40%. Although the country is almost
self-sufficient in rice, its staple food, it depends onimports for most forage crops such as wheat and maize.
As a result, there are concerns that adverse impacts oncrop yields in exporting countries due to climatechange will also affect Japan’s food situation throughsteep increases in international market prices. A
number of research groups including the Japan
International Research Center for Agricultural
With CO2 fertilization effectWithout CO2 fertilization effect

30
20
10
0
A1F1

B1a

A2a

-10
A2b

A2c

-20
-30
-40

B2a

B2b

Population at risk of hunger (millions)

Population at risk of hunger (millions)

40

700
600
500
400

2020
2050
2080

300
200
100
0
A1F1

Scenario

A2a

A2b

A2c

B1a

B2a

B2b

Scenario

Fig. 2 Impacts of climate change on the population at risk of hunger under SRES scenarios. (Parry et al., 2004)

Additional population at risk relative to the reference case which assumes no change in either climate or atmospheric CO2
concentration

Impacts of Global Warming on Agricultural Production and Adaptations in Response

population parameter shows a large increase. Therefore,
the additional population at risk of hunger due to climate change is largest (500 to 600 million people) inthis case. When the CO2 fertilization effect is taken into
account, on the other hand, the CO2 fertilization effectexceeds the adverse impacts of climate change, reflecting the high atmospheric CO2 concentration, andthe risk population is expected to decrease. Hence,
there are great disparities in the results of estimationsof the population at risk of hunger depending onwhether or not the CO2 fertilization effect is taken into
account. It is known that the magnitude of the CO2
fertilization effect is affected by such factors as soil
moisture and nutrients, competition with weeds, andthe sunlight and temperature environment. However,
the magnitude of the CO2 fertilization effect that can be
expected in actual agricultural fields has not yet been
elucidated.
3.3 Studies concerning the selection, promotion,and implementation of adaptation measures
At the initial stage, studies on the agricultural impacts of climate change focused almost exclusively on
estimating crop productivity expected in the case ofclimate change occurring over a long duration. As
described in connection with the examples mentioned
in subsection 3.1 above, certain types of adaptation
have been adopted as assumptions in such studies, andincreases or decreases in production are estimated after
taking these assumed adaptations into consideration.
However, the early implementation of adaptations has
become necessary in vulnerable regions where climatechange is gradually manifesting. This is prompting
increased attention to studies concerning the selection,
promotion and implementation of adaptation measures(hereafter referred as “studies on implementation ofadaptation”). Although productivity estimations havegenerally been made using agricultural and engineering
methodologies exclusively, social science methodologies are playing an increasingly important role in studies on implementation of adaptation.
Bryant et al. (2000) conducted an overall survey ofexisting studies on the impacts of climate change on
agriculture and agricultural adaptation taking Canada
as the target region, and examined the importance ofdecision-making by farmers in adaptation to climatic
variability and change in the agricultural sector. They
found that the methods used in studies on farmers’
decision-making regarding adaptation to environmental change encompassed questionnaire surveys,
interviews, focus groups2) which included farmers, andsurveys and analyses of measures actually taken byfarmers against variability of climate conditions in thepast. When these methods are applied, the results ofmodel estimations concerning future productivity
changes are often used as reference information given
to farmers at the time of surveys. Bryant et al. (2000)
noted in their report that many farmers were skeptical
about the reality of climate change, and that even249

among farmers who perceived such change, a significant ratio made no consistent efforts to adapt to it.
Hence, they found that formers’ perception of changes
in climatic conditions does not necessarily guarantee
they will make conscious adaptation efforts. Moreover,the survey results showed that rather than overall
climate change, many farmers placed more importanceon potentially fatal changes in conditions such as precipitation in the growing season, the incidence of earlyand late frosts, and the frequency of droughts.
According to Bryant et al. (2000), although farmers
in the province of Quebec expressed a high level ofconfidence in their ability to respond to climatic variability and hence, from their point of view, to climaticchange because of their experience of coping withinterannual climate variability in the past, their possession of various technological and management
response measures, and so on, in reality economic
losses associated with climatic conditions frequently
occur, and they have needed public relief and compensation. In other words, farmers have not necessarily
been able to adapt efficiently to interannual variabilityof climatic conditions heretofore. The report also mentions that crop insurance programs may reduce thesensitivity of producers in adjusting to changing conditions.
3.4 Vulnerability assessment
From the viewpoint of studies on measures andtheir practical application, the vulnerability of agriculture in each region needs to be estimated not only interms of vulnerability to climate stressors such as climate change and climate variability, but from an overall perspective including vulnerability to various otherstressors in the natural and social environments. Thusfar, however, global warming impact assessment studies have generally studied vulnerability by focusing
only on climate stress, and have often not taken otherstressors specifically into consideration. There is
growing recognition recently that in order to identify
practical solutions, measures should be investigatedtaking multiple stressors simultaneously into consideration, and concrete studies have begun.
For example, O’Brien, et al. (2004) studied agriculture in India taking into account biophysical factors
including soil conditions and moisture; socio-economic factors including literacy rates, degree of gender
equity, percentage of the workforce employed inagriculture and distance to major ports; and technological factors including productivity, availability ofirrigation and quality of infrastructure. Using this information, they mapped both the capacity to adapt toincreasing dryness and variability of the Indian monsoon, as well as the capacity to adapt to competition
from imports and export opportunities accompanying
the liberalization of agricultural trade. Districts withlow adaptive capacity from both perspectives were thus
shown to have a high vulnerability to multiple stressors.
As a result, many districts with a high vulnerability to250

K. TAKAHASHI

climate change and market opening (globalization)
were identified in the states of Rajasthan, Gujarat andMadhya Pradesh, as well as southern Bihar and western
Maharashtra.

4. Necessary Adaptation Studies for Policy
Support
4.1 Classification of studies dealing with adaptation
The number of studies dealing with adaptation has
been increasing in response to the growing attention
being paid to this subject. Such studies can be broadlyclassified into two types according to their objectives,with each type of study playing a different role in investigations into a future framework (Burton et al.,2002). The first type of study has the objective ofanswering the question: “To what extent can adaptation
reduce impacts of climate change?” Simulation analysis using computing models has been the principle
method used to answer this question. There are various
types of models, ranging from biophysical processmodels to statistical models and general equilibrium
models for welfare analysis. However, a common
characteristic of these models is that they use futureclimate scenarios projected by climate models as input
assumptions, and estimate future impacts of global
warming while taking the effects of adaptation into
consideration. As regards the number and types ofavailable adaptation measures, in many cases assumptions are used as preconditions. Major climate changethat has serious impacts even when adaptations are
implemented has to be avoided. Knowledge obtainedby this type of study is used for investigating the upper
limits of permissible climate change when discussing
GHG mitigation policies.
The objective of the second type of study is toanswer the question: “What adaptation policies areneeded, and how can they best be developed, applied,
and funded?” Such studies serve as a basis for theselection, promotion and implementation of adaptations suitable for reducing the impact in a targeted
region or field. Appropriate adaptations are estimatedaccording to criteria such as the magnitude of the impact reduction effect, economic efficiency, and equity.
However, since a detailed understanding of the conditions of the region is a fundamental requirement in thistype of study, limited availability of data often makes
quantitative assessments difficult. Other factors mustalso be considered such as relationships with existing
policies of a higher priority (targeted at issues otherthan global warming), secondary impacts arising fromthe implementation of adaptations, and so on, making it
difficult to generalize assessment methods. Even an
adaptation with a significant impact reduction effectcannot be considered appropriate if the cost of its implementation is extremely high compared with themagnitude of impact damage if the adaptation were not
implemented. Nor can an adaptation that is advanta-

geous to a country overall be considered to be appropriate if it creates a serious division between people who
benefit and people who lose when the details are examined. Moreover, adaptations that are incompatible
with existing higher priority policies addressing poverty reduction, disaster countermeasures, industrial
development, etc., will be difficult to adopt. Appropriate adaptations must therefore be selected, promoted
and implemented in light of the actual conditions ineach region concerned.
In this second type of study dealing with adaptation,
it is important to understand which factors have hindered or promoted the implementation of effective
adaptations to reduce vulnerability from past and present disaster cases, that is, to gain an understanding ofpast and present adaptive capacities. By grasping thepresent adaptive capacity situation, it becomes possible
to study what types of efforts are necessary in order toreduce vulnerability under the environment of achanged future climate. Moreover, since information
convenient for quantification, such as statistical data,
may be unavailable in many cases, an anthropogeographic approach is often used based on descriptivereference materials and surveys of local residents.
4.2 Research tasks
Adaptation studies can be broadly classified into
two types as described above. In order to solve theglobal warming issue, these two types of adaptation
studies need to be advanced in a balanced manner withthe close cooperation of study communities in Japanand overseas. Each type of study has a certain complementarity with the other type. For example, the resultsof quantitative estimations of impacts taking adaptation
into consideration provide an outlook for future climatechange impacts, which can then serve as a basis forjudgments related to adaptations in studies on the implementation of adaptations in individual regions.
Conversely, a deeper understanding of factors thathinder or promote the implementation of adaptations inindividual regions as well as knowledge on various
other conditions gained through studies on adaptation
implementation can be reflected in assumptions on
adaptations when performing impact assessment simulations using models, and this, in turn, will also support
refinement of the models themselves (by incorporatingsocial and other factors into the model). However, it
would appear that study communities have not always
cooperated effectively with each other up to now,
especially in Japan.
As mentioned in subsection 3.3 in connection withthe study by Bryant et al. (2000), farmers respond moresensitively to the occurrence of potentially fatal
phenomena as a nucleus for adaptation behavior than toa gradually increasing impact on productivity due togeneral climate change. Hence, for studies dealing with
the quantitative estimation of impacts taking adaptation
into consideration, namely, what changes can be expected from now on due to extreme weather events,

Impacts of Global Warming on Agricultural Production and Adaptations in Responsesuch as typhoons, continuous dry periods and heatwaves, and what impacts these will have on agricultural production, there is a strong need for further enhancement of the methods used so that more refined
estimations can be made. An important task when refining estimation methods will be to improve and expand them so as to enable as many adaptation options
as possible to be investigated and to allow adaptations
to be expressed more realistically.
A high degree of uncertainty is inevitable in each of
the processes involved in quantitative estimation of
global warming impacts, such as the projection of
future socio-economic conditions and GHG gas emissions, the projection of carbon circulation and climatechanges, the projection of impacts, and so on. The
value of the results of impact projections when applied
to policy studies is greatly enhanced when such uncertainties are specifically addressed. For example, expressing the results of future impact projections inprobability distribution form holds promise as amethod, although this approach has rarely been
adopted so far.
When assuming the conditions for investigating theupper limits of permissible climate change in discussions on GHG mitigation policies, it is necessary to get
an overview of the impact projection results fromvarious fields and regions in both a comprehensive andaggregate manner. For this purpose, it is important topromote the use of common units in impact assessment(primarily the monetary assessment of impacts), and todevelop communication tools and a database ofknowledge from impact studies so as to enable specificinformation on impact assessment options to be efficiently provided to policymakers.
In the case of studies on the implementation ofadaptation, on the other hand, various areas exist inwhich adequate scientific knowledge has not yet beenobtained, even though they represent important research tasks from the viewpoint of policy study support.
These include estimating the cost of adaptations;elucidating factors that hinder the implementation ofindividual adaptations, and clarifying what future limits on adaptations can be expected based on thatknowledge; elucidating the changes that take place inthe characteristics of adaptations over time (effects ofexperience, learning, etc.); elucidating stress factors
other than climate change; and so on. Subsection 3.3
introduced the case of studies conducted in Canada.
However, in order to answer the question, “Whatadaptation policies are needed, and how can they best
be developed, applied, and funded?” as mentioned insubsection 4.1, bottom-up type studies are necessary,and original studies focusing on Japan as the targeted
region are eagerly awaited. When the situation ofstudies in Japan is examined, although more substantial
studies are appearing which estimate potential yieldchange due to global warming, it seems that there is a
gap in the number of concrete studies related to adaptation (particularly studies on the implementation of251

adaptation) compared with the situation in Westerncountries that are advanced in the field of global
warming studies. There is an urgent need, therefore, toexpand and improve such studies so as to promote
investigations into future climate change policy inJapan and to enable Japan to take the initiative in
discussions on an international framework.

Achnowledgement
This paper is based on the results of studies entitled“Impact Assessment of Future Climate Change Using
High-Resolution Climate Change Scenarios Including
Extreme Events (B-12)” and “Comprehensive Assessment of Climate Change Impacts to Determine theDangerous Level of Global Warming and to Determine
the Appropriate Stabilization Target for Atmospheric
GHG Concentration (S-4),” which are research topicsof the Global Environmental Research Fund (GERF).
Notes
1)

Future socio-economic/greenhouse gas emissions outlook
released by IPCC in 2000 (IPCC, 2000). A family of six
scenarios was prepared – A1B, A1F1, A1T, A2, B1, and B2 –each with different assumptions concerning future developments in population, society, economy, technology and theenvironment.

2)

A survey method in which approximately ten people who havecertain common denominators are gathered together, asked
questions as a group and encouraged to engage in discussions,which the surveyor observes. This method is used when there
is a need to understand the perceptions of specific types ofpeople.

References
Bryant, C.R., B. Smit, M. Brklacich, T.R. Johnston, J. Smithers,
Q. Chiotti and B. Singh (2000) Adaptation in Canadian
agriculture to climatic variability and change. Climatic
Change, 45: 181-201.
Burton, I., S. Huq, B. Lim, O. Pilifosova and E.L. Schipper(2002) From impacts assessment to adaptation priorities: theshaping of adaptation policy. Climate Policy, 2: 145-159.
Ebi, K.L., T.J. Teisberg, L.S. Kalkstein, L. Robinson and R.F.
Weiher (2004) Heat watch/warning systems save lives.
Estimated costs and benefits for Philadelphia 1995-98. BAMS,
August 2004, 1067-1073.
Fischer, G., H. Velthlzen and F. Nachtergaele (2002) Global
Agro-Ecological Zones Assessment Methodology and Results,
IIASA.
IPCC (2000) Special Report on Emissions Scenarios, Cambridge
University Press, Cambridge.
IPCC (2001a) Climate Change 2001, Impacts, Adaptation, andVulnerability, Cambridge University Press, Cambridge.
IPCC (2001b) Climate Change 2001, Synthesis Report,
Cambridge University Press, Cambridge.
Klein, R.J.T., R.J. Nicholls and N. Mimura (1999) Coastal
adaptation to climate change: Can the IPCC Technical
Guidelines be applied? Mitigation and Adaptation Strategies
for Global Change, 4: 239-252.
Kurukulasuriya, P. and S. Rosenthal (2003) Climate change and252

K. TAKAHASHI

agriculture — A review of impacts and adaptations, World
Bank, Washington D.C.
Murai, H., K. Takahashi, T. Masui, H. Harasawa and Y.
Matsuoka (2005) Research on assessment of climate change
impacts on grain production taking account of adaptation.
Environmental systems research, 33: 97-104. (in Japanese)
O’Brien, K., R. Leichenko, U. Kelkar, H. Venema, G. Aandahl,
H. Tompkins, A. Javed, S. Bhadwal, S. Barg, L. Nygaard and J.
West (2004) Mapping vulnerability to multiple stressors:
Climate change and globalization in India. Global Environmental Change — Human and Policy Dimensions, 14: 303313.
Parry, M.L., C. Rosenzweig, A. Iglesias, M. Livermore and G.
Fischer (2004) Effects of climate change on global food pro-duction under SRES emissions and socio-economic scenarios.
Global Environmental Change, 14: 53-68.
Takahashi, K., H. Harasawa and Y. Matsuoka (1997) Climatechange impact on global crop production. Journal of Global
Environmental Engineering, 3: 145-161.
Takahashi, K., H. Harasawa and Y. Matsuoka (1999) Impacts ofclimate change on food production — An economic assessment. Journal of Global Environmental Engineering, 5: 1-9.
Takahashi, K. (2005) Latest scientific knowledge of climatechange impacts for discussing dangerous level of climatechange. Environmental Research Quarterly, 138: 59-66. (inJapanese)(Received 3 August 2006, Accepted 19 October 2006)