IPCC Working Group II

We continue our survey of the results of the latest assessment by the Intergovernmental Panel on Climate Change (IPCC) with the 1995 report of Working Group II--Scientific-Technical Analysis of Impacts, Adaptations, and Mitigation of Climate Change. The role of this working group has been to review the state of knowledge concerning the impacts of climate change on physical and ecological systems, human health, and socio-economic sectors. Working Group II has also reviewed the technical and economic feasibility of a range of potential adaptation and mitigation strategies.

The results of Working Group II (WGII) are relevant in evaluating whether the projected range of plausible impacts constitutes "dangerous anthropogenic interference with the climate system," as referred to in Article 2 of the United Nations Framework Convention on Climate Change, and in evaluating adaptation and mitigation options that could be used in progressing towards the ultimate objective of the Convention. In this article, material in quotes is taken verbatim from the Working Group II Summary for Policymakers. The full text can be obtained from the IPCC or from the Information Unit for Conventions.

Nature of the issue

"Human activities are increasing the atmospheric concentrations of greenhouse gases and, in some regions, aerosols. These changes in greenhouse gases and aerosols, taken together, are projected to lead to regional and global changes in climate and climate-related parameters such as temperature, precipitation, soil moisture, and sea level... The reliability of regional-scale predictions is still low, and the degree to which climate variability may change is uncertain.

However, potentially serious changes have been identified, including an increase in some regions in the incidence of extreme high-temperature events, floods, and droughts, with resultant consequences for fires, pest outbreaks, and ecosystem composition, structure, and functioning, including primary productivity.

"Human health, terrestrial and aquatic ecological systems, and socio-economic systems (e.g., agriculture, forestry, fisheries, and water resources) are all vital to human development and wellbeing and are all sensitive to changes in climate. Whereas many regions are likely to experience the adverse effects of climate change--some of which are potentially irreversible--some effects of climate change are likely to be beneficial. Hence, different segments of society can expect to confront a variety of changes and the need to adapt to them.

"Policymakers are faced with responding to the risks posed by anthropogenic emissions of greenhouse gases in the face of significant scientific uncertainties. It is appropriate to consider these uncertainties in the context of information indicating that climate-induced environmental changes cannot be reversed quickly, if at all, due to the long time scales associated with the climate system. Decisions taken during the next few years may limit the range of possible policy options in the future because high near-term emissions would require deeper reductions in the future to meet any given target concentration. Delaying action might reduce the overall costs of mitigation because of potential technological advances but could increase both the rate and the eventual magnitude of climate change, hence the adaptation and damage costs.

"Policymakers will have to decide to what degree they want to take precautionary measures by mitigating greenhouse gas emissions and enhancing the resilience of vulnerable systems by means of adaptation. Uncertainty does not mean that a nation or the world community cannot position itself better to cope with the broad range of possible climate changes or protect against potentially costly future outcomes. Delaying such measures may leave a nation or the world poorly prepared to deal with adverse changes and may increase the possibility of irreversible or very costly consequences. Options for adapting to change or mitigating change that can be justified for other reasons today (e.g., abatement of air and water pollution) and make society more flexible or resilient to anticipated adverse effects of climate change appear particularly desirable."

Vulnerability to climate change

"Article 2 of the UNFCCC explicitly acknowledges the importance of natural ecosystems, food production, and sustainable economic development. This report addresses the potential sensitivity, adaptability, and vulnerability of ecological and socio-economic systems--including hydrology and water resources management, human infrastructure, and human health--to changes in climate."

The Working Group II report reaches a number of general conclusions regarding vulnerability to climate change:

  • human-induced climate change adds an important new stress;
  • most systems are sensitive to climate change;
  • impacts are difficult to quantify, and existing studies are limited in scope;
  • successful adaptation depends upon technological advances, institutional arrangements, availability of financing, and information exchange;
  • vulnerability increases as adaptive capacity decreases; o detection will be difficult, and unexpected changes cannot be ruled out; and,
  • further research and monitoring are essential.

These conclusions are based on assessment of a wide range of potential impacts affecting terrestrial and aquatic ecosystems, hydrology and water resources management, food and fibre, human infrastructure and human health. Here, as a sample. we present a selection of the findings with regard to human infrastructure.

With regard to human infrastructure, the WGII report concludes that "climate change and resulting sea-level rise can have a number of negative impacts on energy, industry, and transportation infrastructure; human settlements; the property insurance industry; tourism; and cultural systems and values.

"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... In the absence of adaptation measures, a 50cm sea-level rise would increase this number to about 92 million; a 1m 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.

"Studies using [a] 1m projection [of sea-level rise] 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 percent 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 damage-prone areas of the developing world that do not have the resources to cope with impacts. Effective coastal-zone management and land-use regulation can help direct population shifts away from vulnerable locations such as flood plains, steep hillsides, and low-lying coastlines. One of the potentially unique and destructive effects on human settlements is forced internal or international migration of populations. Programs of disaster assistance can offset some of the more serious negative consequences of climate change and reduce the number of ecological refugees."

Options to reduce emissions and enhance sinks of greenhouse gases

Reviewing global energy trends, the WGII report observes that the 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... 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."

WGII concludes, however, that "significant reductions in net greenhouse gas emissions are technically possible and can be economically feasible. These reductions can be achieved by utilizing an extensive array of technologies, and policy measures that accelerate technology development, diffusion, and transfer in all sectors including the energy, industry, transportation, residential/commercial, and agricultural/ forestry sectors... 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." A range of options for reducing emissions are discussed and the overall effect is summarized in a series of new emission scenarios.

As far as energy demand is concerned, it is noted that "numerous studies have indicated that 10-30% energy-efficiency gains above present levels are feasible at little or no net cost in many parts of the world through technical conservation measures and improved management practices over the next 2 to 3 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 reducing energy demand-related emissions is considered in detail for the industrial, transportation, and commercial/residential sectors and means of mitigating emissions from industrial processes and human settlements are also detailed.

The energy supply assessment focuses on "new technologies for capital investment." It is considered 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.

Possible approaches include: more efficient conversion of fossil fuels; switching to low-carbon fossil fuels and suppressing emissions; decarbonization of flue gases and fuels, and CO2 storage; switching to nuclear energy; and switching to renewable sources of energy.

To assess the potential impact of combinations of individual measures at the energy system level, "thought experiments" exploring possible global energy systems were undertaken. It was concluded that "many combinations of the options identified in this assessment could reduce global CO2 emissions from fossil fuels from about 6 Gt C in 1990 to about 4 Gt C/yr by 2050, and to about 2 Gt C/yr by 2100. Cumulative CO2 emissions, from 1990 to 2100, would range from about 450 to about 470 Gt C."

Finally, options for agriculture, rangelands, and forestry were considered. It was concluded that "beyond the use of biomass fuels to displace fossil fuels, the management of forests, agricultural lands, and rangelands can play an important role in reducing current emissions... and in enhancing carbon sinks. A number of measures could conserve and sequester substantial amounts of carbon (approximately 60-90 Gt C in the forestry sector alone) over the next 50 years." Other relevant land-use and management measures include: sustaining existing forest cover; slowing deforestation; regenerating natural forests; establishing tree plantations; promoting agroforestry; altering management of agricultural soils and rangelands; improving efficiency of fertilizer use; restoring degraded agricultural lands and rangelands; recovering methane from stored manure; and improving the diet quality of ruminants.

WGII notes that cross-sectoral issues will have to be considered--for example, as a result of competing demands on resources--and warns that some geo-engineering approaches to counterbalance greenhouse gas-induced climate change that have been proposed are "likely to be ineffective, expensive to sustain, and/or to have serious environmental and other effects that are in many cases poorly understood."

With regard to policy instruments, it is observed that "mitigation depends on reducing barriers to the diffusion and transfer of technology, mobilizing financial resources, supporting capacity building in developing countries, and other approaches to assist in the implementation of behavioral changes and technological opportunities in all regions of the globe. The optimum mix of policies will vary from country to country, depending upon political structure and societal receptiveness."

In conclusion, examples are given of the kind of policies required at the national and international level to accelerate the development and implementation of technologies that will reduce emissions and enhance sinks. These include: pricing strategies; reduction or removal of subsidies that increase emissions; tradable emissions permits; utility demand-side management; and regulatory programmes.