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Scientific-Technical Analyses of Impacts, Adaptations, and Mitigation of Climate Change 3.32 Food and Fiber

term. The exact timing and extent of this pattern is uncertain.

Climate and land-use impacts on the production of temperate Agriculture. Crop yields and changes in productivity due to forest products are expected to be relatively small. In tropical climate change will vary considerably across regions and regions, the availability of fores: products is projected to among localities, thus changing the patterns of production. decline by about half for non-climatic reasons related to Productivity is projected to increase in some areas and human activities. decrease in others, especially the tropics and subtropics (Table 2). However, existing studies show that on the whole Fisheries. Climate change effects interact with those of pervaglobal agricultural production could be maintained relative sive overfishing, diminishing nursery areas, and extensive to baseline production in the face of climate change modeled inshore and coastal pollution. Globally, marine fisheries proby general circulation models (GCMs) at doubled equiva- duction is expected to remain about the same; high-latitude lent-Co, equilibrium conditions, but that regional effects freshwater and aquaculture production are likely to increase, would vary widely. This conclusion takes into account the assuming that natural climate variability and the structure and beneficial effects of CO2 fertilization, but does not allow for strength of ocean currents remain about the same. The princichanges in agricultural pests and the possible effects of pal impacts will be felt at the national and local levels as changing climatic variability.

species mix and centers of production shift. The positive

effects of climate change—such as longer growing seasons, Focusing on global agricultural production does not address the lower natural winter mortality, and faster growth rates in highpotentially serious consequences of large differences at local and er latitudes—may be offset by negative factors such as changes regional scales, even at mid-latitudes. There may be increased in established reproductive patterns, migration routes, and risk of hunger and farine in some locations, many of the world's ecosystem relationships. poorest people-particularly those living in subtropical and tropical areas, and dependent on isolated agricultural systems in semi-arid and arid regions are most at risk of increased hunger. 3.4. Human Infrastructure Many of these at-risk populations are found in sub-Saharan Africa, south, east, and southeast Asia; and tropical areas of Climate change and resulting sea-level rise can have a number Latin America, as well as some Pacific island nations. of negative impacts on energy, industry, and transportation

infrastructure; human settlements; the property insurance Adaptation such as changes in crops and crop varieties, industry; tourism; and cultural systems and values. improved water-management and irrigation systems, and changes in planting schedules and tillage practices will be In general, the sensitivity of the energy, industry, and transimportant in limiting negative effects and taking advantage of portation sectors is relatively low compared to that of agriculbeneficial changes in climate. The extent of adaptation depends tural or natural ecosystems, and the capacity for adaptation on the affordability of such measures, particularly in develop through management and normal replacement of capital is ing countries, access to know-how and technology; the rate of expected to be high. However, infrastructure and activities in climate change; and biophysical constraints such as water these sectors would be susceptible to sudden changes, surprisavailability, soil characteristics, and crop genetics. The incre- es, and increased frequency or intensity of extreme events. The mental costs of adaptation strategies could create a serious bur- subsectors and activities most sensitive to climate change den for developing countries; some adaptation strategies may include agroindustry, energy demand, production of renewable result in cost savings for some countries. There are significant energy such as hydroelectricity and biomass, construction, uncertainties about the capacity of different regions to adapt some transportation activities, existing flood mitigation strucsuccessfully to projected climate change.

tures, and transportation infrastructure located in many areas,

including vulnerable coastal zones and permafrost regions. Livestock production may be affected by changes in grain prices and rangeland and pasture productivity. In general, analy- Climate change clearly will increase the vulnerability of ses indicate that intensively managed livestock systems have some coastal populations to flooding and erosional land loss. more potential for adaptation than crop systems. This may not Estimates put about 46 million people per year currently at be the case in pastoral systems, where the rate of technology risk of flooding due to storm surges. This estimate results adoption is slow and changes in technology are viewed as risky. from multiplying the total number of people currently living

in areas potentially affected by ocean flooding by the probaForest Products. Global wood supplies during the next cen- bility of flooding at these locations in any year, given the tury may become increasingly inadequate to meet projected present protection levels and population density. In the consumption due to both climatic and non-climatic factors. absence of adaptation measures, a 50-cm sea-level rise Boreal forests are likely to undergo irregular and large-scale would increase this number to about 92 million; a 1-m sealosses of living trees because of the impacts of projected cli- level rise would raise it to 118 million. If one incorporales mate change. Such losses could initially generate additional anticipated population growth, the estimates increase subwood supply from salvage harvests, but could severely reduce stantially. Some small island nations and other countries will standing stocks and wood-product availability over the long confront greater vulnerability because their existing sea and

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Scientific-Technical Analyses of Impacts, Adaptations, and Mitigation of Climate Change

Table 2: Selected crop study results for 2 x CO,-equivalent equilibrium GCM scenarios.

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Note: For most regions, studies have focused on one or two principal grains. These studies strongly demonstrate the variability in estimated yield impacts among countries, scenarios, methods of analysis, and crops, making it difficult to generalize

DIRECT

Scientific-Technical Analyses of Impacts, Adaptations, and Mitigation of Climate Change coastal defense systems are less well-established. Countries could economically weaken other sectors, such as banking. The with higher population densities would be more vulnerable. insurance industry currently is under stress from a series of "billion For these countries, sea-level rise could force internal or dollar" storms since 1987, resulting in dramatic increases in losses, international migration of populations.

reduced availability of insurance, and higher costs. Some in the

insurance industry perceive a current trend toward increased freA number of studies have evaluated sensitivity to a 1-m sea- quency and severity of extreme climate events. Exarnination of the level rise. This increase is at the top of the range of IPCC meteorological data fails to support this perception in the context of Working Group I estimates for 2100, it should be noted, how- a long-term change, although a shift within the limits of natural ever, that sea level is actually projected to continue to rise variability may have occurred. Higher losses strongly reflect beyond 2100. Studies using this 1-m projection show a partic- increases in infrastructure and economic worth in vulnerable areas ular risk for small islands and deltas. Estimated land losses as well as a possible shift in the intensity and frequency of extreme range from 0.05% for Uruguay, 1% for Egypt, 6% for the weather events. Netherlands, and 17.5% for Bangladesh to about 80% for the Majuro Atoll in the Marshall Islands, given the present state of protection systems. Large numbers of people also are affect- 3.5. Human Health ed-for example, about 70 million cach in China and Bangladesh. Many nations face lost capital value in excess of Climate change is likely to have wide-ranging and mostly 10% of their gross domestic product (GDP). Although annual adverse impacts on human health, with significant loss of life. protection costs for many nations are relatively modest (about These impacts would arise by both direct and indirect path0.1% of GDP), the average annual costs to many small island ways (Figure 3), and it is likely that the indirect impacts would, states total several percent of GDP. For some island nations, in the longer term, predominate. the high cost of providing storm-surge protection would make it essentially infeasible, especially given the limited availabili- Direct health effects include increases in (predominantly carty of capital for investment.

diorespiratory) mortality and illness due to an anticipated increase The most vulnerable human settle

Mediating Process

Health Outcomes ments are located in damage-prone areas of the developing world that do not have the resources to cope with

Altered rates of heat and cold-related Exposure to thermal extremes

ifloess and death (especially impacts. Effective coastal-zone man

(especially heat waves)

cardiovascular and respiratory diseases) agement and land-use regulation can

Allered frequency and/or intensity

Deaths, injuries, and psychological help direct population shifts away

disorders, damage to public health from vulnerable locations such as

CHANGE: flood plains, steep hillsides, and low

PRECIPITATION, lying coastlines. One of the poten

INDIRECT tially unique and destructive effects on human settlements is forced inter

ECOLOGICAL SYSTEMS nal or international migration of pop

Effects on range and activity of vectors

Changes in geographic ranges and

and infective parasites ulations. Programs of disaster assistance can offset some of the more

Altered local ecology of water-borne

Changed incidence of diarrheal and

and food-borne infective agents serious negative consequences of climate change and reduce the num

Altered food (especially crop)

Regional malnutrition and hunger, and ber of ecological refugees.

productivity due to changes in climate
weather events, and associated pests

consequeat impairment of child growth

and diseases Property insurance is vulnerable to

Sea-level risc, with population

Injuries, increased risks of various extreme climate events. A higher risk

infectious disease (due to migration,

displacement and damage to extreme events due to climate

Infrastructure (e.. wanitation)

crowding, contamination of drinking

water), psychological disorders change could lead to higher insurance premiums or the withdrawal of cover

Levels and biological impacts of air

Asthma and allergic disorders, other pollution, including pollens and pores

kute and chronic respiratory disorders age for property in some vulnerable areas. Changes in climate variability

Social, economic, and demographic

Wide range of public health and the risk for extreme events may

dislocations due to adverse climate be difficult to detect or predict, thus

change impacts on economy.

nutritional impairment, infectious infrastructure, and resource supply

diseases, civil strife) making it difficult for insurance companies to adjust premiums appropri

Note: Populations with different levels of natural, technical and social resources would differ ately. If such difficulty leads to insol

in their vulnerability to climate-induced health impacts. vency, companies may not be able to honor insurance contracts, which Figure 3: Ways in which climate change can affect human health.

CLIMATE

of other extreme weather events
(foods, storms, etc.)

infrastructure

TEMPERATURE

AND WEATHER

DISTURBANCES OF

incidence of vector-borne diseases

certain other infectious diseases

and development

and deaths

consequences (eg, mental health

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Scientific-Technical Analyses of Impacts, Adaptations, and Mitigation of Climate Change

in the intensity and duration of heat waves. Temperature increases that accelerate technology development, diffusion, and transfer in colder regions should result in fewer cold-related deaths. An in all sectors including the energy, industry, transportation, resincrease in extreme weather would cause a higher incidence of idential commercial, and agriculturalforestry sectors. By the death, injury, psychological disorders, and exposure to contami- year 2100, the world's commercial energy system in effect will nated water supplies.

be replaced at least twice, offering opportunities to change the

energy system without premature retirement of capital stock; Indirect effects of climate change include increases in the significant amounts of capital stock in the industrial, commerpotential transmission of vector-borne infectious diseases (e.g., cial, residential, and agricultural/forestry sectors will also be malaria, dengue, yellow fever, and some viral encephalitis) replaced. These cycles of capital replacement provide opporturesulting from extensions of the geographical range and season nities to use new, better performing technologies. It should be for vector organisms. Projections by models (that entail neces- noted that the analyses of Working Group II do not attempt to sary simplifying assumptions) indicate that the geographical quantify potential macroeconomic consequences that may be zone of potential malaria transmission in response to world associated with mitigation measures. Discussion of macroeco temperature increases at the upper part of the IPCC-projected nomic analyses is found in the IPCC Working Group Il conrange (3-5°C by 2100) would increase from approximately tribution to the Second Assessment Report. The degree to 45% of the world population to approximately 60% by the lat- which technical potential and cost-effectiveness are realized is ter half of the next century. This could lead to potential dependent on initiatives to counter lack of information and increases in malaria incidence (on the order of 50-80 million overcome cultural, institutional, legal, financial and economic additional annual cases, relative to an assumed global back- barriers that can hinder diffusion of technology or behavioral ground total of 500 million cases), primarily in tropical, sub changes. The pursuit of mitigation options can be carried out tropical, and less well-protected temperate-zone populations. within the limits of sustainable development criteria. Social Some increases in non-vector-borne infectious diseases—such and environmental criteria not related to greenhouse gas emisas salmonellosis, cholera, and giardiasis—also could occur as sions abatement could, however, restrict the ultimate potential a result of elevated temperatures and increased flooding. of each of the options.

Additional indirect effects include respiratory and allergic disorders due to climate-enhanced increases in some air pollu- 4.1. Energy, Industrial Process, and tants, pollens, and mold spores. Exposure to air pollution and Human Settlement Emissions stressful weather events combine to increase the likelihood of morbidity and mortality. Some regions could experience a Global energy demand has grown at an average annual rate of decline in nutritional status as a result of adverse impacts on approximately 2% for almost 2 centuries, although energy food and fisheries productivity. Limitations on freshwater sup- demand growth varies considerably over time and between difplies also will have human health consequences.

ferent regions. In the published literature, different methods

and conventions are used to characterize energy consumption. Quantifying the projected impacts is difficult because the These conventions differ, for example, according to their defiextent of climate-induced health disorders depends on numer. nition of sectors and their treatment of energy forms. Based on ous coexistent and interacting factors that characterize the vul- aggregated national energy balances, 385 EJ of primary energy nerability of the particular population, including environmen- was consumed in the world in 1990, resulting in the release of tal and socioeconomic circumstances, nutritional and immune 6 Gt C as CO2. Of this, 279 EJ was delivered to end users, status, population density, and access to quality health care ser- accounting for 3.7 G1 C emissions as CO2 at the point of convices. Adaptive options to reduce health impacts include pro sumption. The remaining 106 EJ was used in energy convertective technology (e.g., housing, air conditioning, water sion and distribution, accounting for 2.3 Gt emissions as purification, and vaccination), disaster preparedness, and CO2. In 1990, the three largest sectors of energy consumption appropriate health care.

were industry (43% of total CO2 releases), residential/commercial buildings (28%), and transport (22%). Of these, transport

sector energy use and related Co, emissions have been the 4. Options to Reduce Emissions and Enhance

most rapidly growing over the past 2 decades. For the detailed Sinks of Greenhouse Gases

sectoral mitigation option assessment in this report, 1990 ener

gy consumption estimates are based on a range of literature Human activities are directly increasing the atmospheric con- sources; a variety of conventions are used to define these seccentrations of several greenhouse gases, especially CO2, CH, tors and their energy use, which is estimated to amount to a halocarbons, sulfur hexafluoride (SF), and nitrous oxide total of 259–282 EJ. (N,O). CO, is the most important of these gases, followed by CH. Human activities also indirectly affect concentrations of Figure 4 depicts total energy-related emissions by major world water vapor and ozone. Significant reductions in net green- region. Organisation for Economic Cooperation and house gas emissions are technically possible and can be eco Development (OECD) nations have been and remain major nomically feasible. These reductions can be achieved by utiliz- energy users and fossil fuel CO2 emitters, although their share ing an extensive array of technologies, and policy measures of global fossil fuel carbon emissions has been declining.

Scientific-Technical Analyses of Impacts, Adaptations, and Mitigation of Climate Change

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1860

1870

1880

1890

1900

1910

1940

1950

1960

1970

1980

1990

1920 1930

Year

Figure 4: Global energy-related CO2 emissions by major world region in Gt Clyr (Marland et al., 1994: Grübler and Nakicenovic, 1992; Etemand and Luciani, 1991; Fujii, 1990; UN, 1952). Note that CPA = Centrally Planned Asia and PAO = Pacific and Oceania.

Developing nations, laken as a group, still account for a small- transfer, as well as measures to overcome a variety of non-techer portion of total global CO2 emissions than industrialized nical barriers. The potential for greenhouse gas emission reducnations-OECD and former Soviet Union/Eastern Europe tions exceeds the potential for energy use efficiency because of (FSU/EE) but most projections indicate that with forecast the possibility of switching fuels and energy sources. Because rates of economic and population growth, the future share of energy use is growing world-wide, even replacing current techdeveloping countries will increase. Future energy demand is nology with more efficient technology could still lead to an anticipated to continue to grow, at least through the first half of absolute increase in CO2 emissions in the future. the next century. The IPCC (1992, 1994) projects that without policy intervention, there could be significant growth in emis- In 1992, the IPCC produced six scenarios (IS92a-1) of future enersions from the industrial, transportation, and commercial/resi- gy use and associated greenhouse gas emissions (IPCC, 1992, dential buildings sectors.

1995). These scenarios provide a wide range of possible future
greenhouse gas emission levels, without mitigation measures.

4.1.1.
Energy Demand

In the Second Assessment Report, future energy use has been

reexamined on a more detailed sectoral basis, both with and Numerous studies have indicated that 10–30% energy-efficien- without new mitigation measures, based on existing studies. cy gains above present levels are feasible at little or no net cost Despite different assessment approaches, the resulting ranges in many parts of the world through technical conservation mea- of energy consumption increases to 2025 without new measures and improved management practices over the next 2 to 3 sures are broadly consistent with those of IS92. If past trends decades. Using technologies that presently yield the highest continue, greenhouse gas emissions will grow more slowly output of energy services for a given input of energy, efficiency than energy use, except in the transport sector. gains of 50-60% would be technically feasible in many countries over the same time period. Achieving these potentials will The following paragraphs summarize energy-efficiency depend on future cost reductions, financing, and technology improvement potentials estimated in the IPCC Second

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