Climate Change

Climate Change Glossary

Terms and Definitions

The following glossary defines the key concepts, institutions, and policies that define climate change and climate change mitigation and adaption—as related to IFPRI’s climate change work.


Adaptation: Short and long-term changes to human practices that respond to the potential ill effects of climate change. Adaptation measures for agriculture include infrastructure investment (water storage), the adoption of more resilient crop varieties (those with tolerance to drought or water), and altered land use or land management practices. Adaptation measures also include emergency response plans to extreme weather events.

Afforestation: The process of planting, through seedlings or seeds, a forest on land that is not currently under forest cover, or has not been a forest for an extensive period of time.

Bioenergy: An array of energy-related products, including biofuel (biogas, bioethanol, biodiesel) and electricity, that are derived from biomass.

Biomass: Any plant-derived organic matter, including crops and trees grown specifically for energy uses, wood, crop and animal waste, and algae and aquatic plants. Biomass is the basis of bioenergy.

Carbon cycle: The natural process of carbon absorption and release by oceans, plants, animals, soils, rocks, and shells. For example, plants absorb atmospheric carbon as part of photosynthesis, and then release it into the atmosphere as respiration and biomass. Humans alter this cycle by releasing additional amounts of carbon into the atmosphere through such activities as burning fossil fuels and deforestation.

Carbon Dioxide (CO2): A colorless, odorless, and non-poisonous greenhouse gas that is found in fossil fuels, shells, rocks, soil, and plants. It is released into the atmosphere through the carbon cycle and human activities, including the extraction and burning of fossil fuels (coal, oil) for energy and deforestation.

Carbon fertilization: Increased plant growth due to an increase in carbon dioxide carbon dioxide in the atmosphere. Plants absorb carbon and convert it to oxygen as part of photosynthesis. The extent to which this sequestration effect reduces the concentration of carbon in the atmosphere is unknown.

Carbon sequestration: The process by which a carbon sink absorbs carbon dioxide carbon dioxide from the atmosphere and stores it. For example, forests absorb and store atmospheric carbon due to photosynthesis.

Carbon sink: A reservoir that absorbs carbon dioxide from another part of the carbon cycle and stores it. Natural sinks include forests, soils, peat, permafrost, and the ocean; manmade reservoirs include buildings and factories outfitted with carbon-capture technologies.

Clean Development Mechanism (CDM): A Kyoto Protocol mechanism that allows emission-reduction (or emission removal) projects in developing countries to earn certified emission reduction (CER) credits, each equivalent to one tonne of CO2. These CERs can be traded and sold, and used by industrialized countries to a meet a part of their emission reduction targets under the Kyoto Protocol. The mechanism stimulates sustainable development and emission reductions, while giving industrialized countries some flexibility in how they meet their emission reduction limitation targets. Source: The UNFCCC CDM website.

Climate Change: An increase in the Earth’s temperature, a higher occurrence of extreme weather events, an alteration in wind and participation patterns, and the shifting of seasons due to natural and manmade phenomenon that raise the concentration of greenhouse gases in the atmosphere. Climate change is also characterized by melting glaciers and rising sea levels.

Climate Change Scenario: A description of a plausible future based on current climate change knowledge and informed speculation about future changes, of the potential effects of climate change on weather patterns, worldwide food production, and other related factors. IFPRI uses a suite of demographic, economic, and environmental models to build scenarios that describe the evolution of food prices and other human welfare outcomes under climate change.

Copenhagen Accord: A non-binding agreement drafted on December 18, 2009 by a small set of countries on the sidelines of the UNFCCC meetings in Copenhagen, Denmark. It re-affirms the need for a binding international climate change treaty and lays out the elements of such a treaty.

Deforestation: The conversion of forested areas to non-forested areas, which include crops, pastures, and urban areas. Deforestation releases CO2 sequestered in trees and soil into the atmosphere. It also changes the nature of ecosystem services provided.

Drought-resistant crops: Typically refers to crops that have been subjected to plant breeding to improve their ability to survive in periods of extended water shortage.

Ecosystem services: The services that an ecosystem (a functional unit within which the dynamic complex of plant, animal, and microorganism communities interact with the nonliving environment) provides to humans. These can be broken down by their function and include: the provision of food, water, timber, fiber, and other resources; the regulation of floods, disease, wastes, and water quality; the support of cultural practices, including recreation, religion, and art; and the maintenance of biological processes through such phenomena as soil formation, photosynthesis, nutrient cycling, and so on.

Global Warming Potential (GWP): The number of units of carbon dioxide emissions that would have the same effect (in terms of mass) as one unit of another greenhouse gas emission over a specified period of time. For example, the release of one kilogram (kg) of methane would result in an effect similar to 25 kg of carbon dioxide over a 100 period; the GWP for methane is thus 25 over 100 years. The GWP of nitrous oxide (NOz) is 298 over 100 years. Source: IPCCWorking Group I Fourth Assessment Report “The Physical Science Basis”, Technical Summary. See the UNFCCC website for a chart based on the IPCC report.

General Circulation Model (GCM): A computer model used to forecast weather, understand climate, and project climate change. Also known as a Global Climate Model (GCM).

Greenhouse Gas (GHG): Gases, including carbon dioxide, methane (CH4), nitrous oxide (N2O), and others, that absorb infrared radiation in the atmosphere, then send it back to the earth’s surface, which traps heat in the atmosphere. Additional GHGs include: water vapor, chlorofluorocarbons (CFCs), hydrochlorofluorocarbons (HCFCs), ozone (O3), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF6). Source: U.S. Environmental Protection Agency, Greenhouse Gas Emission: The release of greenhouse gases into the atmosphere. Human activities (the burning of fossil fuels, deforestation, agriculture, industrial practices) and natural phenomena contribute to emissions.

Hydrology: The study of water, including its movement, distribution, quality, and relationship to the environment. The hydrologic (water) cycle encompasses the cyclical flow of water between oceans, land, and the atmosphere.

Intergovernmental Panel on Climate Change (IPCC): A scientific body based in Geneva, Switzerland that assesses climate change. It was established by the United Nations Environment Programme (UNEP) and the World Meteorological Organization (WMO) to provide the world with a clear scientific view on the current state of climate change and its potential environmental and socio-economic consequences. It reviews and assesses the most recent scientific, technical and socio-economic information produced worldwide relevant to the understanding of climate change. It does not conduct any research nor does it monitor climate related data or parameters. Thousands of scientists from all over the world contribute to the work of the IPCC on a voluntary basis. Review is an essential part of the IPCC process, to ensure an objective and complete assessment of current information. Differing viewpoints existing within the scientific community are reflected in the IPCC reports. Source: IPCC.

Kyoto Protocol: A United Nations Framework Convention on Climate Change (UNFCCC) agreement that set for developed countries binding targets for greenhouse gas emission reductions. (These targets applied to industrialized, or Annex 1, countries that ratify the agreement; non-industrialized countries, or non-Annex 1 countries, including those that ratify the agreement, are not required to meet emission reductions.) Adopted in Kyoto, Japan on December 11, 1997, it entered into force on February 16, 2005. By October 2009, 187 countries had ratified the agreement. See the UNFCCC website for more information; see the UNFCCC Parties and Observer States listing for a complete list of Annex 1, non-Annex, and Observer countries.

Land degradation: The reduction in the value, health, and productivity of land through deforestation, soil nutrient depletion, overgrazing, and irrigation.

Land use: The various ways in which humans transform the land surface.

Mitigation: Practices that reduce the probability of climate change by reducing atmospheric concentrations of GHG. Common mitigation activities include: the reduction of greenhouse gas emissions through energy diversification, cap and trade regulations, afforestation, the protection of existing forests, and sustainable land management (SLM) practices.

Payments for Ecosystem Services (PES): The practice of paying farmers and other land users to engage in the preservation, maintenance and improvement of ecosystem services. For more information, see the Payments for Environmental Services (PES) website of the Food and Agriculture Organization of the United Nations (FAO).

Reducing Emissions from Deforestation and Forest Degradation (REDD): A United Nations program that aims to create a financial value for the carbon dioxide stored in forests by offering incentives for developing countries to reduce emissions from forested lands and invest in low-carbon paths to sustainable development. In addition to addressing deforestation and forest degradation, it addresses conservation, sustainable management of forests and the enhancement of forest carbon stocks. Source: UN REDD Programme website.

Reforestation: The restocking of existing forests and woodlands that have been depleted through human activities or natural causes.

Special Report on Emissions Scenarios (SRES): A 2000 report issued by the Intergovernmental Panel on Climate Change (IPCC) that provides scenarios (forecasts of potential events based on current knowledge) of the potential drivers of future emissions, which range from demographics to economics. Download the report from the IPCC website.

Sustainable land management (SLM): A set of coordinated land-use practices that preserve the health of land, water, and vegetation. These practices, which include watershed, soil fertility, and soil erosion management and zero- or low till farming, are designed to prevent and reverse land degradation.

United Nations Framework Convention on Climate Change (UNFCCC): The United Nations body that sets the agenda for intergovernmental climate change efforts. Founded in 1994 and based in Bonn, Germany, all United Nations member countries are members. Since 1997, it has provided the framework for global climate change treaty negotiations. Major meetings took place in Kyoto, Japan and Copenhagen, Denmark.