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CLIMATE CHANGE 1995: IPCC SECOND ASSESSMENT REPORT

negative effects and taking advantage of beneficial changes in climate. The extent of adaptation depends on the affordability of such measures, particularly in developing countries; access to know-how and technology; the rate of climate change; and biophysical constraints such as water availability, soil characteristics and crop genetics. The incremental costs of adaptation strategies could create a serious burden for developing countries; some adaptation strategies may result in cost savings for some countries. There are significant uncertainties about the capacity of different regions to adapt successfully to projected climate change.

Livestock production may be affected by changes in grain prices and rangeland and pasture productivity. In general, analyses indicate that intensively managed livestock systems have more potential for adaptation than crop systems. This may not be the case in pastoral systems, where the rate of technology adoption is slow and changes in technology are viewed as risky.

Forest products. Global wood supplies during the next century may become increasingly inadequate to meet projected consumption due to both climatic and non-climatic factors. Boreal forests are likely to undergo irregular and large-scale losses of living trees because of the impacts of projected climate change. Such losses could initially generate additional wood supply from salvage harvests, but could severely reduce standing stocks and wood-product availability over the long term. The exact timing and extent of this pattern is uncertain. Climate and land-use impacts on the production of temperate forest products are expected to be relatively small. In tropical regions, the availability of forest products is projected to decline by about half for non-climatic reasons related to human activities.

Fisheries. Climate-change effects interact with those of pervasive overfishing, diminishing nursery areas, and extensive inshore and coastal pollution. Globally, marine fisheries production is expected to remain about the same; high-latitude freshwater and aquaculture production are likely to increase, assuming that natural climate variability and the structure and strength of ocean currents remain about the same. The principal impacts will be felt at the national and local levels as species mix and centres of production shift. The positive effects of climate change — such as longer growing seasons, lower natural winter mortality and faster growth rates in higher latitudes — may be offset by negative factors such as changes in established reproductive patterns, migration routes and ecosystem relationships.

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sudden changes, surprises and increased frequency or intensity of extreme events. The subsectors and activities most sensitive to climate change include agroindustry, energy demand, production of renewable energy such as hydroelectricity and biomass, construction, some transportation activities, existing flood mitigation structures, and transportation infrastructure located in many areas, including vulnerable coastal zones and permafrost regions.

Climate change clearly will increase the vulnerability of some coastal populations to flooding and erosional land loss. Estimates put about 46 million people per year currently at risk of flooding due to storm surges. This estimate results from multiplying the total number of people currently living in areas potentially affected by ocean flooding by the probability of flooding at these locations in any year, given the present protection levels and population density. In the absence of adaptation measures, a 50-cm sea-level 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 population growth, the estimates increase substantially. Some small island nations and other countries will confront greater vulnerability because their existing sea and coastal defense systems are less well-established. Countries with higher population densities would be more vulnerable. For these countries, sea-level rise could force internal or international migration of populations.

A number of studies have evaluated sensitivity to a 1-m sea-level rise. This increase is at the top of the range of IPCC Working Group I estimates for 2100; it should be noted, however, that sea level is actually projected to continue to rise beyond 2100. Studies using this 1-m projection show a particular risk for small islands and deltas. Estimated land losses range from 0.05% for Uruguay, 1% for Egypt, 6% for the 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 affected for example, about 70 million each in China and Bangladesh. Many nations face lost capital value in excess of 10% of their gross domestic product (GDP). Although annual protection costs for many nations are relatively modest (about 0.1% of GDP), the average annual costs to many small island states total several per cent of GDP. For some island nations, the high cost of providing storm-surge protection would make it essentially infeasible, especially given the limited availability of capital for investment.

The most vulnerable human settlements are located in damageprone areas of the developing world that do not have the resources to cope with impacts. Effective coastal-zone management and landuse regulation can help direct population shifts away from vulnerable locations such as flood plains, steep hillsides and lowlying coastlines. One of the potentially unique and destructive effects on human settlements is forced internal or international migration of populations. Programmes of disaster assistance can offset some of the more serious negative consequences of climate change and reduce the number of ecological refugees.

Property insurance is vulnerable to extreme climate events. A higher risk of extreme events due to climate change could lead to higher

SUMMARY FOR POLICYMAKERS: SCIENTIFIC-TECHNICAL ANALYSES OF
IMPACTS, ADAPTATIONS AND MITIGATION OF CLIMATE CHANGE

insurance premiums or the withdrawal of coverage for property in some vulnerable areas. Changes in climate variability and the risk for extreme events may be difficult to detec: or predict, thus making it difficult for insurance companies to adjust premiums appropriately. If such difficulty leads to insolvency, companies may not be able to honour insurance contracts, which could economically weaken other sectors, such a: banking. The insurance industry currently is under stress from a series of "billion dollar" storms since 1987, resulting in dramatic increases in losses, reduced availability of insurance and higher costs. Some in the insurance industry perceive a current trend toward increased frequency and severity of extreme climate events. Examination of the meteorological data fails to support this perception in the context of a long-term change, although a shift within the limits of natural variability may have occurred. Higher losses strongly reflect increases in infrastructure and economic worth in vulnerable areas as well as a possible shift in the intensity and frequency of extreme weather events.

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CLIMATE CHANGE 1995: IPCC SECOND ASSESSMENT REPORT

extensions of the geographical range and season for vector organisms. Projections by models (that entail necessary simplifying assumptions) indicate that the geographical zone of potential malaria transmission in response to world temperature increases at the upper part of the IPCC-projected range (3-5°C by 2100) would increase from approximately 45% of the world population to approximately 60% by the latter half of the next century. This could lead to potential increases in malaria incidence (on the order of 50-80 million additional annual cases, relative to an assumed global background total of 500 million cases), primarily in tropical, subtropical and less well-protected temperate-zone populations. Some increases in non-vector-borne infectious diseases such as salmonellosis, cholera and giardiasis — also could occur as a result of elevated temperatures and increased flooding.

Additional indirect effects include respiratory and allergic disorders due to climate-enhanced increases in some air pollutants, pollens and mold spores. Exposure to air pollution and stressful weather events combine to increase the likelihood of morbidity and mortality. Some regions could experience a decline in nutritional status as a result of adverse impacts on food and fisheries productivity. Limitations on freshwater supplies also will have human health consequences.

Quantifying the projected impacts is difficult because the extent of climate-induced health disorders depends on numerous coexistent and interacting factors that characterize the vulnerability of the particular population, including environmental and socio-economic circumstances, nutritional and immune status, population density and access to quality health care services. Adaptive options to reduce health impacts include protective technology (e.g., housing, air conditioning, water purification and vaccination), disaster preparedness and appropriate health care.

4. OPTIONS TO REDUCE EMISSIONS AND

ENHANCE SINKS OF GREENHOUSE GASES

mitigation measures. Discussion of macroeconomic analyses is found in the IPCC Working Group III contribution to the Second Assessment Report. The degree to which technical potential and cost-effectiveness are realized is dependent on initiatives to counter lack of information and overcome cultural, institutional, legal, financial and economic barriers that can hinder diffusion of technology or behavioral changes. The pursuit of mitigation options can be carried out within the limits of sustainable development criteria. Social and environmental criteria not related to greenhouse gas emissions abatement could, however, restrict the ultimate potential of each of the options.

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Global energy demand has grown at an average annual rate of approximately 2% for almost two centuries, although energy demand growth varies considerably over time and between different regions. In the published literature, different methods and conventions are used to characterize energy consumption. These conventions differ, for example, according to their definition of sectors and their treatment of energy forms. Based on aggregated national energy balances, 385 EJ of primary energy was consumed in the world in 1990, resulting in the release of 6 GtC as CO2. Of this, 279 EJ was delivered to end users, accounting for 3.7 GtC emissions as CO2 at the point of consumption. The remaining 106 EJ was used in energy conversion and distribution, accounting for 2.3 GtC emissions as CO2. In 1990, the three largest sectors of energy consumption were industry (45% of total CO2 releases), residential/commercial sector (29%) and transport (21%). Of these, transport sector energy use and related CO2 emissions have been the most rapidly growing over the past two decades. For the detailed sectoral mitigation option assessment in this report, 1990 energy consumption estimates are based on a range of literature sources; a 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.

Figure 4 depicts total energy-related emissions by major world region. Organization for Economic Cooperation and Development (OECD) nations have been and remain major energy users and fossil-fuel CO2 emitters, although their share of global fossil fuel carbon emissions has been declining. Developing nations, taken as a group, still account for a smaller portion of total global CO2 emissions than industrialized nations- OECD and former Soviet Union/Eastern Europe (FSU/EE) -but most projections indicate that with forecast rates of economic and population growth, the future share of developing countries will increase. Future energy demand is anticipated to continue to grow, at least through the first half of the next century. The IPCC (1992, 1994) projects that without policy intervention, there could be significant growth in emissions from the industrial, transportation and commercial/ residential buildings sectors.

Human activities are directly increasing the atmospheric concen-
trations of several greenhouse gases, especially CO2, CH4,
halocarbons, sulfur hexafluoride (SF) and nitrous oxide (NO). CO2
is the most important of these gases, followed by CH4. Human
activities also indirectly affect concentrations of water vapour and
ozone. Significant reductions in net greenhouse gas emissions are
technically possible and can be economically feasible. These reduc-
tions can be achieved by utilizing an extensive array of technologies
and policy measures that accelerate technology development, diffu-
sion and transfer in all sectors including the energy, industry,
transportation, residential/commercial and agricultural/forestry
sectors. By the year 2100, the world's commercial energy system in
effect will be replaced at least twice, offering opportunities to
change the energy system without premature retirement of capital
stock; significant amounts of capital stock in the industrial,
commercial, residential and agricultural/forestry sectors will also be
replaced. These cycles of capital replacement provide opportunities 4.1.1
to use new, better performing technologies. It should be noted that
the analyses of Working Group II do not attempt to quantify poten-
tial macroeconomic consequences that may be associated with

Energy demand

Numerous studies have indicated that 10-30% energy-efficiency 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 improved management practices over the next two to three decades. Using technologies that presently yield the highest output of energy services for a given input of energy, efficiency gains of 50-60% would be technically feasible in many countries over the same time period. Achieving these potentials will depend on future cost reductions, financing and technology transfer, as well as measures to overcome a variety of non-technical barriers. The potential for greenhouse gas emission reductions exceeds the potential for energy use efficiency because of the possibility of switching fuels and energy sources. Because energy use is growing worldwide, even replacing current technology with more efficient technology could still lead to an absolute increase in CO2 emissions in the

future.

In 1992, the IPCC produced six scenarios (IS92a-f) of future energy use and associated greenhouse gas emissions (IPCC, 1992, 1995). These scenarios provide a wide range of possible future greenhouse gas emission levels, without mitigation measures.

In the Second Assessment Report, future energy use has been reexamined on a more detailed sectoral basis, both with and without new mitigation measures, based on existing studies. Despite different assessment approaches, the resulting ranges of energy

consumption increases to 2025 without new measures are broadly consistent with those of IS92. If past trends continue, greenhouse gas emissions will grow more slowly than energy use, except in the transport sector.

The following paragraphs summarize energy-efficiency improvement potentials estimated in the IPCC Second Assessment Report. Strong policy measures would be required to achieve these potentials. Energy-related greenhouse gas emission reductions depend on the source of the energy, but reductions in energy use will in general lead to reduced greenhouse gas emissions.

Industry. Energy use in 1990 was estimated to be 98-117 EJ and is projected to grow to 140-242 EJ in 2025 without new measures. Countries differ widely in their current industrial energy use and energy-related greenhouse gas emission trends. Industrial sector energy-related greenhouse gas emissions in most industrialized countries are expected to be stable or decreasing as a result of industrial restructuring and technological innovation, whereas industrial emissions in developing countries are projected to increase mainly as a result of industrial growth. The short-term potential for energy-efficiency improvements in the manufacturing sector of major industrial countries is estimated to be 25%. The potential for greenhouse gas emission reductions is

CLIMATE CHANGE 1995: IPCC SECOND ASSESSMENT REPORT

larger. Technologies and measures for reducing energy-related 4.1.3
emissions from this sector include improving efficiency (e.g.,
energy and materials savings, co-generation, energy cascading,
steam recovery, and use of more efficient motors and other
electrical devices); recycling materials and switching to those with
lower greenhouse gas emissions; and developing processes that use
less energy and materials.

Transportation. Energy use in 1990 was estimated to be 61-65 EJ and is projected to grow to 90-140 EJ in 2025 without new measures. Projected energy use in 2025 could be reduced by about a third to 60-100 EJ through vehicles using very efficient drive-trains, lightweight construction and low air-resistance design, without compromising comfort and performance. Further energy-use reductions are possible through the use of smaller vehicles; altered land-use patterns, transport systems, mobility patterns and lifestyles; and shifting to less energy-intensive transport modes. Greenhouse gas emissions per unit of energy used could be reduced through the use of alternative fuels and electricity from renewable sources. These measures, taken together, provide the opportunity for reducing global transport energy-related greenhouse gas emissions by as much as 40% of projected emissions by 2025. Actions to reduce energy-related greenhouse gas emissions from transport can simultaneously address other problems such as local air pollution.

Commercial/Residential Sector. Energy use in 1990 was estimated to be about 100 EJ and is projected to grow to 165-205 EJ in 2025 without new measures. Projected energy use could be reduced by about a quarter to 126-170 EJ by 2025 without diminishing services through the use of energy efficient technology. The potential for greenhouse gas emission reductions is larger. Technical changes might include reduced heat transfers through building structures and more efficient space-conditioning and water supply systems, lighting and appliances. Ambient temperatures in urban areas can be reduced through increased vegetation and greater reflectivity of building surfaces, reducing the energy required for space conditioning. Energy-related greenhouse gas emission reductions beyond those obtained through reduced energy use could be achieved through changes in energy sources.

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Process-related greenhouse gases including CO2, CH4, N2O, halocarbons and SF6 are released during manufacturing and industrial processes, such as the production of iron, steel, aluminum, ammonia, cement and other materials. Large reductions are possible in some cases. Measures include modifying production processes, eliminating solvents, replacing feedstocks, materials substitution, increased recycling and reduced consumption of greenhouse gas-intensive materials. Capturing and utilizing CH from landfills and sewage treatment facilities and lowering the leakage rate of halocarbon refrigerants from mobile and stationary sources also can lead to significant greenhouse gas emission reductions.

Energy supply

This assessment focuses on new technologies for capital investment and not on potential retrofitting of existing capital stock to use less carbon-intensive forms of primary energy. It is technically possible to realize deep emissions reductions in the energy supply sector in step with the normal timing of investments to replace infrastructure and equipment as it wears out or becomes obsolete. Many options for achieving these deep reductions will also decrease the emissions of sulfur dioxide, nitrogen oxides and volatile organic compounds. Promising approaches, not ordered according to priority, are described below.

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Switching to low-carbon fossil fuels and suppressing emissions. 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 unit of energy of all fossil fuels at about 14 kg C/GJ, compared to oil with about 20 kg C/GJ and coal with about 25 kg C/GJ. The lower carbon-containing fuels can, in general, be converted with higher efficiency than coal. Large resources of natural gas exist in many areas. New, low capital cost, highly efficient combined-cycle technology has reduced electricity costs considerably in some areas. Natural gas could potentially replace oil in the transportation sector. Approaches exist to reduce emissions of CH, from natural gas pipelines and emissions of CH, and/or CO2 from oil and gas wells and coal mines.

Decarbonization of flue gases and fuels and CO2 storage. The removal and storage of CO2 from fossil fuel power-station stack gases is feasible, but reduces the conversion efficiency and significantly increases the production cost of electricity. Another approach to decarbonization uses fossil fuel feedstocks to make hydrogen-rich fuels. Both approaches generate a byproduct stream of CO2 that could be stored, for example, in depleted natural gas fields. The future availability of conversion technologies such as fuel cells that can efficiently use hydrogen would increase the relative attractiveness of the latter approach. For some longer term CO2 storage options, the costs, environmental effects and efficacy of such options remain largely unknown.

4.1.3.2 Switching to non-fossil fuel sources of energy

Switching to nuclear energy. Nuclear energy could replace baseload fossil fuel electricity generation in many parts of the world if generally acceptable responses can be found to concerns such as reactor safety, radioactive-waste transport and disposal, and nuclear proliferation.

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