AAs
See assigned amounts.

AAU
See assigned amount unit.

Activities Implemented Jointly (AIJ)
The pilot phase for joint implementation, as defined in Article 4.2(a) of the United Nations Framework Convention on Climate Change, that allows for project activity among developed countries (and their companies) and between developed and developing countries (and their companies). AIJ is intended to allow Parties to the United Nations Framework Convention on Climate Change to gain experience in jointly implemented project activities. There is no crediting for AIJ activity during the pilot phase. A decision remains to be taken on the future of AIJ projects and how they may relate to the Kyoto Mechanisms. As a simple form of tradable permits, AIJ and other market-based schemes represent important potential mechanisms for stimulating additional resource flows for the global environmental good. See also Clean Development Mechanism, and emissions trading.

Adaptation
Adjustment in natural or human systems to a new or changing environment. Adaptation to climate change refers to adjustment in natural or human systems in response to actual or expected climatic stimuli or their effects, which moderates harm or exploits beneficial opportunities. Various types of adaptation can be distinguished, including anticipatory and reactive adaptation, private and public adaptation, and autonomous and planned adaptation.

Additionality
Reduction in emissions by sources or enhancement of removals by sinks that is additional to any that would occur in the absence of a Joint Implementation or a Clean Development Mechanism project activity as defined in the Kyoto Protocol Articles on Joint Implementation and the Clean Development Mechanism. This definition may be further broadened to include financial, investment, and technology additionality. Under financial additionality, the project activity funding shall be additional to existing Global Environmental Facility, other financial commitments of Parties included in Annex I, Official Development Assistance, and other systems of co-operation. Under investment additionality, the value of the Emissions Reduction Unit /Certified Emission Reduction Unit shall significantly improve the financial and/or commercial viability of the project activity. Under technology additionality, the technology used for the project activity shall be the best available for the circumstances of the host Party.

Administrative costs
The costs of activities of the project or sectoral activity directly related and limited to its short-term implementation. They include the costs of planning, training, administration, monitoring, etc.

Afforestation
Planting of new forests on lands that historically have not contained forests². See also Deforestation and Deforestation.

AIJ
See Activities Implemented Jointly.

Alliance of Small Island States (AOSIS)
The group was formed during the Second World Climate Conference in 1990 and comprises small island and low-lying coastal developing countries that are particularly vulnerable to the adverse consequences of climate change, such as sea level rise, coral bleaching, and the increased frequency and intensity of tropical storms. With more than 35 states from the Atlantic, Caribbean, Indian Ocean, Mediterranean, and Pacific, AOSIS share common objectives on environmental and sustainable development matters in the UNFCCC (United Nations Framework Convention on Climate Change) process.

Alternative development paths
Refer to a variety of possible scenarios for societal values and consumption and production patterns in all countries, including but not limited to a continuation of today’s trends. In this Report, these paths do not include additional climate initiatives which means that no scenarios are included that explicitly assume implementation of the UNFCCC or the emission targets of the Kyoto Protocol, but do include assumptions about other policies that influence greenhouse gas emissions indirectly.

Alternative energy
Energy derived from non-fossil fuel sources.

Ancillary benefits
The ancillary, or side effects, of policies aimed exclusively at climate change mitigation. Such policies have an impact not only on greenhouse gas emissions, but also on resource use efficiency, like reduction in emissions of local and regional air pollutants associated with fossil fuel use, and on issues such as transportation, agriculture, land-use practices, employment, and fuel security. Sometimes these benefits are referred to as “ancillary impacts” to reflect that in some cases the benefits may be negative. From the perspective of policies directed at abating local air pollution, greenhouse gas mitigation may also be considered an ancillary benefit, but these relationships are not considered in this assessment. See also co-benefits.

Anthropogenic emissions
Emissions of greenhouse gases, greenhouse gas precursors, and aerosols associated with human activities. These include burning of fossil fuels for energy, deforestation and land-use changes that result in net increase in emissions.

Annex I countries/Parties
Group of countries included in Annex I (as amended in 1998) to the United Nations Framework Convention on Climate Change, including all the developed countries in the Organisation of Economic Co-operation and Development, and Economies in transition. By default, the other countries are referred to as Non-Annex I countries. Under Articles 4.2 (a) and 4.2 (b) of the Convention, Annex I countries commit themselves specifically to the aim of returning individually or jointly to their 1990 levels of greenhouse gas emissions by the year 2000. See also Annex II, Annex B, and Non-Annex B countries.

Annex II countries
Group of countries included in Annex II to the United Nations Framework Convention on Climate Change, including all developed countries in the Organisation of Economic Co-operation and Development. Under Article 4.2 (g) of the Convention, these countries are expected to provide financial resources to assist developing countries to comply with their obligations, such as preparing national reports. Annex II countries are also expected to promote the transfer of environmentally sound technologies to developing countries. See also Annex I, Annex B, Non-Annex I, and Non-Annex B countries/Parties.

Annex B countries/Parties
Group of countries included in Annex B in the Kyoto Protocol that have agreed to a target for their greenhouse gas emissions, including all the Annex I countries (as amended in 1998) but Turkey and Belarus. See also Annex II, Non-Annex I, and Non-Annex B countries/Parties.

AOSIS
See Alliance of Small Island States.

Assigned amounts (AAs)
Under the Kyoto Protocol, the total amount of greenhouse gas emissions that each Annex B country has agreed that its emissions will not exceed in the first commitment period (2008 to 2012) is the assigned amount. This is calculated by multiplying the country’s total greenhouse gas emissions in 1990 by five (for the 5-year commitment period) and then by the percentage it agreed to as listed in Annex B of the Kyoto Protocol (e.g., 92% for the European Union; 93% for the USA).

Assigned amount unit (AAU)
Equal to 1 tonne (metric ton) of CO₂-equivalent emissions calculated using the Global Warming Potential.

Average cost
Total cost divided by the number of units of the item for which the cost is being assessed. With greenhouse gases, for example, it would be the total cost of a programme divided by the physical quantity of emissions avoided.

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