Abatement. Refers to reducing the degree or intensity of greenhouse-gas emissions.
Adaptation. Actions taken to help communities and ecosystems cope with such changing climate conditions as the construction of flood walls to protect property from stronger storms and heavier precipitation, or planting agricultural crops and trees more suited to warmer temperatures and drier soil conditions.
Afforestation. Planting new forests on lands that have not produced forests.
Anthropogenic emissions. Greenhouse-gas emissions resulting from human activies.
Biomass fuels. Energy sources that are renewable as long as the vegetation producing them is maintained or replanted, such as firewood, alcohol fermented from sugar, and combustible oils extracted from soy beans. Their use in place of fossil fuels cuts greenhouse gas emissions because the plants that are their sources recapture carbon dioxide from the atmosphere.
Carbon market. A popular, but misleading term for a trading system through which countries may buy or sell units of greenhouse-gas emissions in an effort to meet their national limits on emissions, either under the Kyoto Protocol or under other such agreements as arrived at by members of the European Union. The term comes from the fact that carbon dioxide is the predominant greenhouse gas and other gases are measured in units called "carbon-dioxide equivalents."
Deforestation. The direct human-induced conversion of forested land to non-forested land.
Emission-reduction unit (ERU). A unit equal to one metric ton of carbon dioxide equivalent, applicable to binding emissions-reductions targets under the Kyoto Protocol, and generated through joint implementation projects.
Emissions trading. Mechanism under the Kyoto Protocol through which parties with emissions commitments may trade units of their emissions allowances with other parties. The aim is to improve the overall flexibility and economic efficiency of making emissions cuts.
Fugitive fuel emissions. Greenhouse-gas emissions as byproducts or waste or loss in the process of fuel production, storage, or transport, such as methane given off during oil and gas drilling and refining, or leakage of natural gas from pipelines.
Greenhouse gases (GHGs). The atmospheric gases responsible for causing global warming and climate change. The major GHGs are carbon dioxide (CO2), methane (CH4) and nitrous oxide (N2O). Less prevalent — but very powerful — greenhouse gases are hydrofluorocarbons (HFCs), perfluorocarbons (PFCs) and sulphur hexafluoride (SF6).
"Hot air." Refers to the concern that some governments will be able to meet their commitment targets for greenhouse-gas emissions under the Kyoto Protocol with minimal effort and could then flood the market for emissions credits, reducing the incentive for other countries to cut their own domestic emissions.
Kyoto Protocol. An international agreement standing on its own, and requiring separate ratification by governments, but linked to the UNFCCC. The Kyoto Protocol, among other things, sets binding targets for the reduction of greenhouse-gas emissions by industrialized countries. The protocol is yet to go into effect.
Land use, land-use change, and forestry (LULUCF). Refers to the impact of land use by humans — and changes in such land use — on greenhouse-gas emissions: Expanding forests reduces atmospheric carbon dioxide; deforestation releases additional carbon dioxide; various agricultural activities may add to atmospheric levels of methane and nitrous oxide.
Leakage. That portion of cuts in greenhouse-gas emissions by developed countries — countries trying to meet mandatory limits under the Kyoto Protocol — that may reappear in other countries not bound by such limits. For example, multinational corporations may shift factories from developed countries to developing countries to escape restrictions on emissions.
No-regrets options. Technology for reducing greenhouse-gas emissions whose other benefits (in terms of efficiency or reduced energy costs) are so extensive that the investment is worth it for those reasons alone. For example, combined-cycle gas turbines — in which the heat from the burning fuel drives steam turbines while the thermal expansion of the exhaust gases drives gas turbines — may boost the efficiency of electricity generating plants by 70 percent.
Sinks. Any process that removes a greenhouse gas from the atmosphere. The major sinks are forests and other vegetation which, through photosynthesis, remove carbon dioxide. Under the Kyoto Protocol, developed countries, in their calculation of net greenhouse-gas emissions, may deduct from their totals the removal of greenhouse gases through the expansion of sinks. That may help them to meet their mandatory emissions targets. However, calculating the effects of sinks is methodologically complex and the standards for doing so still need to be clarified.
Spill-over effects. Reverberations in developing countries caused by actions taken by developed countries to cut greenhouse-gas emissions. For example, emissions reductions in developed countries could lower demand for oil and thus international oil prices, leading to more use of oil and greater emissions in developing nations, partially off-setting the original cuts. Current estimates are that full-scale implementation of the Kyoto Protocol may cause five to 20 percent of emissions reductions in industrialized countries to "leak" into developing countries.
Sustainable development. Development that meets the needs of the present without compromising the ability of future generations to meet their own needs.
Third Assessment Report (TAR). The third extensive review of global scientific research on climate change, published by the Intergovernmental Panel on Climate Change (IPCC) in 2001. Among other things, the report stated that "The Earth's climate system has demonstrably changed on both global and regional scales since the pre-industrial era, with some of these changes attributable to human activities. There is new and stronger evidence that most of the warming observed over the last 50 years is attributable to human activities."
Vulnerability. The degree to which a community, population, species, ecosystem, region, agricultural system, or some other quantity is susceptible to, or unable to cope with, adverse effects of climate change.