Carbon Cycle Glossary
Anthropogenic emissions: Human–made materials (gases, particles, vapors, chemical compounds, etc.) that come out of smokestacks, chimneys, and vehicle tailpipes.
Atmosphere: The mixture of gases surrounding the Earth. The Earth's atmosphere consists of about 79.1% nitrogen (by volume), 20.9% oxygen, 0.036% carbon dioxide and trace amounts of other gases. The atmosphere can be divided into a number of layers. The layer nearest the Earth is the troposphere, which reaches up to an altitude of about 8 km (about 5 miles) in the Polar Regions and up to 17 km (11 mi.) above the equator. The stratosphere, which reaches to an altitude of about 50 km (31 mi.), is above the troposphere. The mesosphere, which extends up to 80-90 km (48-54 mi.), is above the stratosphere, and finally, the thermosphere, or ionosphere, is the layer that forms a poorly defined border with outer space. There is relatively little mixing of gases between layers.
Biogeochemistry: The study of natural processes that recycle nutrients from the environment, to organisms, and then back to the environment. Examples are the carbon, oxygen, nitrogen, phosphorus, and hydrologic cycles.
Boreal forests: The forest areas of the northern North Temperate Zone, dominated by coniferous trees such as spruce, fir, and pine.
Carbon cycle: The exchange of carbon between its four main reservoirs—the atmosphere, terrestrial biosphere, oceans, and sediments. Each of these global reservoirs may be subdivided into smaller pools, ranging in size from individual communities or ecosystems to the total of all living organisms.
Carbon dioxide (CO2): A colorless, odorless non–combustible gas that is present in the atmosphere. It is formed by the combustion of carbon and carbon compounds (such as fossil fuels and biomass), by respiration of animals and plants, by the gradual oxidation of organic matter in the soil, and by chemical processes that occur with certain geological components.
Carbon sequestration: The uptake and storage of carbon. Trees and plants, for example, absorb carbon dioxide, release the oxygen and store the carbon.
Carbon sink: A carbon reservoir that takes in and stores (sequesters) more carbon than it releases. Carbon sinks can serve to partially offset greenhouse gas emissions. Forests and oceans are both large carbon sinks.
Carbon source: A reservoir or component of the carbon cycle that releases more carbon than it absorbs. Anthropogenic emissions are a source of carbon.
Climate: The average weather, usually taken over a 30 year time period, for a particular region and time period. Climate is not the same as weather, but rather, it is the average pattern of weather for a particular region. Weather describes the short–term state of the atmosphere. It is often challenging to differentiate between weather and climate patterns.
Climate change: The long–term fluctuations in temperature, precipitation, wind, and other aspects of the Earth's climate. Although it refers to temperature fluctuations in either direction, as well as other climate variation, the media often uses it interchangeably with the term global warming. Scientists use the term both in reference to natural and anthropogenic change.
Decomposition: The breakdown of matter by bacteria and fungi. It changes the chemical composition and physical appearance of the materials. It is the process by which carbon is released from decaying biological matter.
Deforestation: The transformation of forested lands to non-forest uses. This is often cited as one of the major causes of human-induced climate change for two reasons. In the case of slash and burn clearing, the burning and decomposition of plant matter releases carbon dioxide. Also, deforestation removes trees that once consumed and stored carbon dioxide from the atmosphere. Deforestation is a type of land–use change.
Fossil fuel: Any hydrocarbon deposit such as petroleum, coal, or natural gas that can be burned for heat or power.
Flux: The rate of exchange between reservoirs.
Global warming: A popular term used to describe the increase in average global temperatures due to the greenhouse effect. It is often used interchangeably with the term climate change.
Greenhouse effect: A popular term used to describe the roles of water vapor, carbon dioxide, methane, and other gases (greenhouse gases—GHG) in keeping the Earth's surface warmer than it would be otherwise.
Greenhouse gases (GHG): Those gases, such as water vapor, carbon dioxide, tropospheric ozone, nitrous oxide, and methane, that allow solar radiation to pass through to the Earth, but block outgoing longwave radiation. Their action is compared to that of glass in a greenhouse.
Greenhouse gas inventory: A statistical compilation of greenhouse gases emitted by a community, state, country, etc. It can have both political and scientific applications.
Ice core: A vertical section of ice removed from a glacier or an ice sheet in order to study climate patterns of the past. By performing chemical analyses on the air trapped in the ice, scientists can estimate the percentage of carbon dioxide and other trace gases in the atmosphere at that time.
Intergovernmental Panel On Climate Change (IPCC): In 1988, the United Nations Environment Program and the World Meteorological Organization established the IPCC jointly. The purpose of the IPCC is to assess information in the scientific and technical literature related to all significant components of the issue of climate change. The IPCC draws upon hundreds of the world's expert scientists as authors and thousands as expert reviewers. Leading experts on climate change and environmental, social, and economic sciences from some 60 nations have helped the IPCC to prepare periodic assessments of the scientific underpinnings for understanding global climate change and its consequences. With its capacity for reporting on climate change, its consequences, and the viability of adaptation and mitigation measures, the IPCC is also looked to as the official advisory body to the world's governments on the state of the science of the climate change issue. For example, the IPCC organized the development of internationally accepted methods for conducting national greenhouse gas emission inventories.
Kyoto Protocol: This is an international agreement struck by 159 nations attending the United Nations Framework Convention on Climate Change (held in December of 1997 in Kyoto Japan) to reduce worldwide emissions of greenhouse gases. If ratified and put into force, individual countries have committed to reduce their greenhouse gas emissions by a specified amount. As of now, the United States is the only major industrialized country that hasn’t signed-on.
Longwave radiation: The radiation emitted in the spectral wavelength greater than 4 micrometers, which corresponds to the radiation emitted from the Earth and atmosphere. It is sometimes vaguely referred to as terrestrial radiation or infrared radiation.
Soil carbon: Soil is a major component of the terrestrial biosphere pool in the carbon cycle. Organic soil carbon estimates, rather than total soil carbon, are generally quoted. The amount of carbon in the soil is a function of historical vegetative cover and productivity, which in turn is dependent upon climatic variables.