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negative effects and taking advantage of beneficial changes in sudden changes, surprises and increased frequency or intensity of climate. The extent of adaptation depends on the affordability of extreme events. The subsectors and activities most sensitive to such measures, particularly in developing countries; access to climate change include agroindustry, energy demand, production of know-how and technology; the rate of climate change; and renewable energy such as hydroelectricity and biomass, construcbiophysical constraints such as water availability, soll characteristics tion, some transportation activities, existing flood mitigation and crop genetics. The incremental costs of adaptation strategies structures, and transportation Infrastructure located in many areas, could create a serious burden for developing countries; some including vulnerable coastal zones and permafrost regions. adaptation strategies may result in cost savings for some countries. There are significant uncertainties about the capacity of different Climate change clearly will increase the vulnerability of some regions to adapt successfully to projected climate change.

coastal populations to flooding and erosional land loss. Estimates

put about 46 million people per year currently at risk of flooding Livestock production may be affected by changes in grain prices and due to storm surges. This estimate results from multiplying the total rangeland and pasture productivity. In general, analyses indicate number of people currently living in areas potentially affected by that intensively managed livestock systems have more potential for ocean flooding by the probability of flooding at these locations in adaptation than crop systems. This may not be the case in pastoral any year, given the present protection levels and population systems, where the rate of technology adoption is slow and changes density. In the absence of adaptation measures, a 50-cm sea-level in technology are viewed as risky.

rise would increase this number to about 92 million; a 1-m sea-level

rise would raise it to 118 million. If one incorporates anticipated Forest products. Global wood supplies during the next century may population growth, the estimates increase substantially. Some small become increasingly inadequate to meet projected consumption due island nations and other countries will confront greater vulnerabilto both climatic and non-climatic factors. Boreal forests are likely to ity because their existing sea and coastal defense systems are less undergo irregular and large-scale losses of living trees because of the well-established. Countries with higher population densities would impacts of projected climate change. Such losses could initially be more vulnerable. For these countries, sea-level rise could force generate additional wood supply from salvage harvests, but could internal or international migration of populations. severely reduce standing stocks and wood-product availability over the long term. The exact timing and extent of this pattern is uncer. A number of studies have evaluated sensitivity to a 1-m sea-level tain. Climate and land-use impacts on the production of temperate rise. This increase is at the top of the range of IPCC Working Group forest products are expected to be relatively small. In tropical regions, I estimates for 2100; It should be noted, however, that sea level is the availability of forest products is projected to decline by about half actually projected to continue to rise beyond 2100. Studies using for non-climatic reasons related to human activities.

this 1-m projection show a particular risk for small islands and

deltas. Estimated land losses range from 0.05% for Uruguay, 1% for Fisheries. Climate change effects interact with those of pervasive Egypt, 6% for the Netherlands and 17.5% for Bangladesh to about overfishing, diminishing nursery areas, and extensive inshore and 80% for the Majuro Atoll in the Marshall Islands, given the present coastal pollution. Globally, marine fisheries production is expected state of protection systems. Large numbers of people also are to remain about the same; high-latitude freshwater and aquaculture affected - for example, about 70 million each in China and production are likely to increase, assuming that natural climate vari- Bangladesh. Many nations face lost capital value in excess of 10% of ability and the structure and strength of ocean currents remain about their gross domestic product (GDP). Although annual protection the same. The principal impacts will be felt at the national and local costs for many nations are relatively modest (about 0.1% of GDP), levels as species mix and centres of production shift. The positive the average annual costs to many small island states total several per effects of climate change - such as longer growing seasons, lower cent of GDP. For some island nations, the high cost of providing natural winter mortality and faster growth rates in higher latitudes – storm-surge protection would make it essentially infeasible, may be offset by negative factors such as changes in established especially given the limited availability of capital for investment. reproductive patterns, migration routes and ecosystem relationships.

The most vulnerable human settlements are located in damage3.4 Human infrastructure

prone areas of the developing world that do not have the resources

to cope with impacts. Effective coastal-zone management and landClimate change and resulting sea-level rise can have a number of use regulation can help direct population shifts away from negative impacts on energy, industry and transportation infrastruc- vulnerable locations such as flood plains, steep hillsides and lowture; human settlements; the property insurance industry; tourism; lying coastlines. One of the potentially unique and destructive and cultural systems and values.

effects on human settlements is forced internal or International

migration of populations. Programmes of disaster assistance can In general, the sensitivity of the energy, industry and transportation offset some of the more serious negative consequences of climate sectors is relatively low compared to that of agricultural or natural change and reduce the number of ecological refugees. ecosystems, and the capacity for adaptation through management and normal replacement of capital is expected to be high. However, Property insurance is vulnerable to extreme climate events. A higher infrastructure and activities in these sectors would be susceptible to risk of extreme events due to climate change could lead to higher



insurance premiums or the withdrawal of coverage for property in 3.5 Human health some vulnerable areas. Changes in climate variabllity and the risk for extreme events may be difficult to deteci or predict, thus making Climate change is likely to have wide-ranging and mostly adverse it difficult for insurance companies to adjust premiums impacts on human health, with significant loss of life. These impacts appropriately. If such difficulty leads to Insolvency, companies may would arise by both direct and indirect pathways (Figure 3) and it is not be able to honour insurance contracts, which could likely that the indirect impacts would, in the longer term, predominate. economically weaken other sectors, such as banking. The insurance Industry currently is under stress from a series of "billion dollar" Direct health effects include increases in (predominantly cardio storms since 1987, resulting in dramatic increases in losses, reduced respiratory) mortality and illness due to an anticipated increase in availability of Insurance and higher costs. Some in the insurance the intensity and duration of heat waves. Temperature increases in Industry perceive a current trend toward increased frequency and colder regions should result in fewer cold-related deaths. An severity of extreme climate events. Examination of the increase in extreme weather would cause a higher incidence of meteorological data fails to support this perception in the context of death, injury, psychological disorders and exposure to contamia long-term change, although a shift within the limits of natural nated water supplies. variability may have occurred. Higher losses strongly reflect increases in infrastructure and economic worth in vulnerable areas Indirect effects of climate change include increases in the potential as well as a possible shift in the intensity and frequency of extreme transmission of vector-borne infectious diseases (e.g., malaria, weather events.

dengue, yellow fever and some viral encephalitis) resulting from

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extensions of the geographical range and season for vector organ- mitigation measures. Discussion of macroeconomic analyses is isms. Projections by models (that entail necessary simplifying found in the IPCC Working Group III contribution to the Second assumptions) indicate that the geographical zone of potential Assessment Report. The degree to which technical potential and malaria transmission in response to world temperature increases at cost-effectiveness are realized is dependent on initiatives to counter the upper part of the IPCC-projected range (3-5°C by 2100) would lack of information and overcome cultural, institutional, legal, increase from approximately 45% of the world population to financial and economic barriers that can hinder diffusion of techapproximately 60% by the latter half of the next century. This could nology or behavioral changes. The pursuit of mitigation options can lead to potential increases in malaria incidence (on the order of be carried out within the limits of sustainable development criteria. 50-80 million additional annual cases, relative to an assumed global Social and environmental criteria not related to greenhouse gas background total of 500 million cases), primarily in tropical, emissions abatement could, however, restrict the ultimate potential subtropical and less well-protected temperate-zone populations. of each of the options. Some increases in non-vector-borne infectious diseases - such as salmonellosis, cholera and giardiasis – also could occur as a result 4.1 Energy, industrial process and human of elevated temperatures and increased flooding.

settlement emissions

Additional indirect effects include respiratory and allergic disorders Global energy demand has grown at an average annual rate of due to climate enhanced increases in some air pollutants, pollens and approximately 2% for almost two centuries, although energy mold spores. Exposure to air pollution and stressful weather events demand growth varies considerably over time and between different combine to increase the likelihood of morbidity and mortality. Some regions. In the published literature, different methods and convenregions could experience a decline in nutritional status as a result of tions are used to characterize energy consumption. These adverse impacts on food and fisheries productivity. Limitations on conventions differ, for example, according to their definition of freshwater supplies also will have human health consequences. sectors and their treatment of energy forms. Based on aggregated

national energy balances, 385 EJ of primary energy was consumed Quantifying the projected impacts is difficult because the extent of in the world in 1990, resulting in the release of 6 GtC as CO2. Of climate-induced health disorders depends on numerous coexistent and this, 279 EJ was delivered to end users, accounting for 3.7 GtC emisinteracting factors that characterize the vulnerability of the particular sions as CO2 at the point of consumption. The remaining 106 EJ population, including environmental and socio-economic circum- was used in energy conversion and distribution, accounting for 2.3 stances, nutritional and immune status, population density and access GtC emissions as CO2. In 1990, the three largest sectors of energy to quality health care services. Adaptive options to reduce health consumption were industry (45% of total CO2 releases), residenimpacts include protective technology (e.g., housing, air conditioning, tial/commercial sector (29%) and transport (21%). Of these, water purification and vaccination), disaster preparedness and appro- transport sector energy use and related CO2 emissions have been priate health care.

the most rapidly growing over the past two decades. For the detailed

sectoral mitigation option assessment in this report, 1990 energy 4. OPTIONS TO REDUCE EMISSIONS AND

consumption estimates are based on a range of literature sources, a ENHANCE SINKS OF GREENHOUSE GASES variety of conventions are used to define these sectors and their

energy use, which is estimated to amount to a total of 259-282 EJ. Human activities are directly increasing the atmospheric concentrations of several greenhouse gases, especially CO2, CH4, Figure 4 depicts total energy-related emissions by major world region. halocarbons, sulfur hexafluoride (SF) and nitrous oxide (N2O). CO2 Organization for Economic Cooperation and Development (OECD) is the most important of these gases, followed by CH . Human nations have been and remain major energy users and fossil-fuel CO2 activities also indirectly affect concentrations of water vapour and emitters, although their share of global fossil fuel carbon emissions has ozone. Significant reductions in net greenhouse gas emissions are been declining. Developing nations, taken as a group, still account for technically possible and can be economically feasible. These reduc- a smaller portion of total global CO2 emissions than industrialized tions can be achieved by utilizing an extensive array of technologies nations - OECD and former Soviet Union/Eastern Europe (FSU/EE) and policy measures that accelerate technology development, diffu- but most projections indicate that with forecast rates of economic and sion and transfer in all sectors including the energy, industry, population growth, the future share of developing countries will transportation, residential/commercial and agricultural/forestry increase. Future energy demand is anticipated to continue to grow, at sectors. By the year 2100, the world's commercial energy system in least through the first half of the next century. The IPCC (1992, 1994) effect will be replaced at least twice, offering opportunities to projects that without policy intervention, there could be significant change the energy system without premature retirement of capital growth in emissions from the industrial, transportation and commerstock; significant amounts of capital stock in the industrial, cial/ residential buildings sectors. commercial, residential and agricultural/forestry sectors will also be replaced. These cycles of capital replacement provide opportunities


Energy demand to use new, better performing technologies. It should be noted that the analyses of Working Group II do not attempt to quantify poten- Numerous studies have indicated that 10-30% energy-efficiency tial macroeconom.ic consequences that may be associated with gains above present levels are feasible at little or no net cost in many

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Figure 4. Global energy-related CO2 emissions by major world region in GtC/yr. Sources: Keeling, 1994; Marland et al., 1994; Grübler and Nakicenovic, 1992; Etemad and Luciani, 1991; Fujii, 1990; UN, 1952 (see the Energy Primer for reference information). parts of the world through technical conservation measures and consumption increases to 2025 without new measures are broadly improved management practices over the next two to three consistent with those of IS92. If past trends continue, greenhouse decades. Using technologies that presently yield the highest output gas emissions will grow more slowly than energy use, except in the of energy services for a given input of energy, efficiency gains of transport sector. 50-60% would be technically feasible in many countries over the same time period. Achieving these potentials will depend on future The following paragraphs summarize energy-efficiency improvecost reductions, financing and technology transfer, as well as ment potentials estimated in the IPCC Second Assessment Report. measures to overcome a variety of non-technical barriers. The Strong policy measures would be required to achieve these potenpotential for greenhouse gas emission reductions exceeds the poten- tials. Energy-related greenhouse gas emission reductions depend on tial for energy use efficiency because of the possibility of switching the source of the energy, but reductions in energy use will in general fuels and energy sources. Because energy use is growing worldwide, lead to reduced greenhouse gas emissions. even replacing current technology with more efficient technology could still lead to an absolute increase in CO2 emissions in the Industry. Energy use in 1990 was estimated to be 98–117 EJ and future.

is projected to grow to 140–242 EJ in 2025 without new measures.

Countries differ widely in their current industrial energy use and In 1992, the IPCC produced six scenarios (18922-1) of future energy energy-related greenhouse gas emission trends. Industrial sector use and associated greenhouse gas emissions (IPCC, 1992, 1995). energy-related greenhouse gas emissions in most industrialized These scenarios provide a wide range of possible future greenhouse countries are expected to be stable or decreasing as a result of gas emission levels, without mitigation measures.

industrial restructuring and technological innovation, whereas

industrial emissions in developing countries are projected to In the Second Assessment Report, future energy use has been re- increase mainly as a result of industrial growth. The short-term examined on a more detailed sectoral basis, both with and without potential for energy-efficiency improvements in the new mitigation measures, based on existing studies. Despite differ- manufacturing sector of major industrial countries is estimated to ent assessment approac.ies, the resulting ranges of energy be 25%. The potential for greenhouse gas emission reductions is


larger. Technologies and measures for reducing energy-related 4.1.3 Energy supply emissions from this sector include improving efficiency (e.8., energy and materials savings, co-generation, energy cascading, This assessment focuses on new technologies for capital investment steam recovery, and use of more efficient motors and other and not on potential retrofitting of existing capital stock to use less electrical devices); recycling materials and switching to those with carbon-intensive forms of primary energy. It is technically possible to lower greenhouse gas emissions; and developing processes that use realize deep emissions reductions in the energy supply sector in step less energy and materials.

with the normal timing of investments to replace infrastructure and

equipment as it wears out or becomes obsolete. Many options for Transportation. Energy use in 1990 was estimated to be 61-65 EJ achieving these deep reductions will also decrease the emissions of and is projected to grow to 90-140 EJ in 2025 without new sulfur dioxide, nitrogen oxides and volatile organic compounds. measures. Projected energy use in 2025 could be reduced by about a Promising approaches, not ordered according to priority, are third to 60-100 EJ through vehicles using very efficient drive-trains, described below. lightweight construction and low air-resistance design, without compromising comfort and performance. Further energy-use Greenhouse gas reductions in the use of fossil fuels reductions are possible through the use of smaller vehicles; altered land-use patterns, transport systems, mobility patterns and More efficient conversion of fossil fuels. New technology offers lifestyles; and shifting to less energy-intensive transport modes. considerably increased conversion efficiencies. For example, the effiGreenhouse gas emissions per unit of energy used could be reduced ciency of power production can be increased from the present world through the use of alternative fuels and electricity from renewable average of about 30% to more than 60% in the longer term. Also, the sources. These measures, taken together, provide the opportunity use of combined heat and power production replacing separate for reducing global transport energy-related greenhouse gas production of power and heat-whether for process heat or space emissions by as much as 40% of projected emissions by 2025. heating - offers a significant rise in fuel conversion efficiency. Actions to reduce energy-related greenhouse gas emissions from transport can simultaneously address other problems such as local Switching to low-carbon fossil fuels and suppressing emissions. air pollution

Switching from coal to oil or natural gas, and from oil to natural gas,

can reduce emissions. Natural gas has the lowest CO2 emissions per Commercial/Residential Sector. Energy use in 1990 was estimated unit of energy of all fossil fuels at about 14 kg C/G), compared to oil to be about 100 EJ and is projected to grow to 165-205 EJ in 2025 with about 20 kg C/GJ and coal with about 25 kg C/GJ. The lower without new measures. Projected energy use could be reduced by carbon-containing fuels can, in general, be converted with higher about a quarter to 126-170 EJ by 2025 without diminishing services efficiency than coal. Large resources of natural gas exist in many through the use of energy efficient technology. The potential for areas. New, low capital cost, highly efficient combined-cycle techgreenhouse gas emission reductions is larger. Technical changes nology has reduced electricity costs considerably in some areas. might include reduced heat transfers through building structures Natural gas could potentially replace oil in the transportation and more efficient space-conditioning and water supply systems, sector. Approaches exist to reduce emissions of CH, from natural lighting and appliances. Ambient temperatures in urban areas can gas pipelines and emissions of CH4 and/or CO2 from oil and gas be reduced through increased vegetation and greater reflectivity of wells and coal mines. building surfaces, reducing the energy required for space conditioning. Energy-related greenhouse gas emission reductions Decarbonization of flue gases and fuels and CO2 storage. The beyond those obtained through reduced energy use could be removal and storage of CO2 from fossil fuel power-station stack achieved through changes in energy sources.

gases is feasible, but reduces the conversion efficiency and signifi

cantly increases the production cost of electricity. Another 4.1.2 Mitigating industrial process and

approach to decarbonization uses fossil fuel feedstocks to make human settlement emissions

hydrogen-rich fuels. Both approaches generate a byproduct stream

of CO2 that could be stored, for example, in depleted natural gas Process-related greenhouse gases including CO2, CH4, N20, fields. The future availability of conversion technologies such as fuel halocarbons and SF6 are released during manufacturing and cells that can efficiently use hydrogen would increase the relative industrial processes, such as the production of iron, steel, attractiveness of the latter approach. For some longer term CO2 aluminum, ammonia, cement and other materials. Large reductions storage options, the costs, environmental effects and efficacy of are possible in some cases. Measures include modifying production such options remain largely unknown. processes, eliminating solvents, replacing feedstocks, materials substitution, increased recycling and reduced consumption of Switching to non-fossil fuel sources of energy greenhouse gas-intensive materials. Capturing and utilizing CH, from landfills and sewage treatment facilities and lowering the Switching to nuclear energy. Nuclear energy could replace baseload leakage rate of halocarbon refrigerants from mobile and stationary fossil fuel electricity generation in many parts of the world if generally sources also can lead to significant greenhouse gas emission acceptable responses can be found to concerns such as reactor safety, reductions.

radioactive-waste transport and disposal, and nuclear proliferation.

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