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Climate Change Science

Glossary

A | B | C | D | E | F | G | H | I | J | K | L | M | N | O | P | Q | R | S | T | U | V | W | X | Y | Z

A

Adaptation
Adjustment to a new or changing environment. Adaptation to climate change refers to the ability of natural or human systems to adjust to the impacts of climate, reducing the negative impacts and/or taking advantage of beneficial opportunities.

Alternative Energy
Energy derived from non-traditional sources (e.g. biomass, solar, hydroelectric, wind).

Anthropogenic
Made by people or resulting from human activities. Usually used in the context of emissions that are produced as a result of human activities.

Atmosphere
The gaseous envelope surrounding the Earth, composed of mostly nitrogen and oxygen. The atmosphere also contains water vapour, clouds and aerosols.

B

Biosphere
The part of the Earth system comprising all ecosystems and living organisms in the atmosphere, on land, or in the oceans.

C

Carbon Cycle
All reservoirs and exchanges of carbon. The carbon cycle is usually thought of as four main reservoirs of carbon connected by pathways of exchange (e.g. burning releases carbon stored in fossil fuels). The reservoirs are the atmosphere, terrestrial biosphere (usually includes freshwater systems), oceans, and sediments (includes fossil fuels).

Carbon Dioxide (CO2)
A naturally occurring gas, and also a by-product of burning fossil fuels and biomass, as well as land-use changes and other industrial processes.

Carbon Dioxide Equivalent
A measure used to compare the emissions from various greenhouse gases. The potential of the greenhouse house to capture heat and warm the atmosphere (the global warming potential or GWP) is converted and compared to the GWP of carbon dioxide. For example, methane has a GWP 21 times that of carbon dioxide, so 1 tonne of methane is equivalent to 21 tonnes of carbon dioxide.

Carbon Sequestration
The uptake and storage of carbon. For example, trees and plants absorb carbon dioxide, release the oxygen from the molecule and store the carbon.

Climate
Average weather consisting of the changing temperature, precipitation and wind.

Climate Change
Climate change is any significant change in temperature, precipitation or wind lasting for an extended period (decades or longer).

Climate Feedback
When the result of a process in the climate system triggers changes in a second process that in turn influences the initial one. Positive feedback intensifies the original process and negative feedback reduces it.

Climate Lag
The delay that occurs in climate change as a result of some factor that changes only very slowly. For example, the effects of releasing more carbon dioxide into the atmosphere may not be known for some time because a large fraction of atmospheric carbon dioxide is dissolved in the ocean and only released very slowly back into the atmosphere.  

Climate Model
A visual way of representing the interactions of the atmosphere, oceans, land surface, and ice.

Climate System (or Earth System)
The five physical components (atmosphere, water, ice, the Earth’s crust, and ecosystems) that are responsible for the climate and its variations.

Co-Benefit
Multiple benefits from policies that are implemented for various reasons. Most policies designed to address greenhouse gas reduction also have other, equally important, results. For example, reducing certain greenhouse gases benefits climate change and also reduces smog.

Concentration
Amount of a chemical in a particular volume or weight of air, water, soil, or other medium.

Conference of the Parties
The supreme body of the United Nations Framework Convention on Climate Change (UNFCCC). It comprises more than 180 nations. It will periodically review existing commitments in light of the convention's objectives, new scientific findings, and the effectiveness of national climate change programs.

Cryosphere
One of the components of the Earth's system. The cryosphere is frozen water in the form of snow, permanently frozen ground, floating ice, and glaciers. Fluctuations in the volume of the cryosphere cause changes in ocean sea level, which directly impact the atmosphere and biosphere.

D

Deforestation
Cutting down and clearing away trees from forestland. This is one of the major causes of the enhanced greenhouse effect because the burning or decomposing wood releases carbon dioxide and the trees are no longer there to remove carbon dioxide from the air.

Desertification
The transforming of liveable land into desert through climate change or human destruction.

E

Ecosystem
Any natural environment, including living and non-living parts, functioning as a unit to create a stable system.

Emissions
The release of a gas into the atmosphere.

Emissions Factor
A value for measuring emissions based on the pollutant source, relative to the intensity of the activity. For example, grams of carbon dioxide emitted per barrel of fossil fuel consumed.

Enhanced Greenhouse Effect
The concept that the emission of greenhouse gases caused by humans has enhanced the natural greenhouse effect. This traps more infrared radiation, which in turn increasing the warmth of the climate.

F

Feedback Mechanisms
Factors which increase (positive feedback) or decrease (negative feedback) the rate of a process.

G

General Circulation Model (GCM)
A global, three-dimensional computer model of the climate system which can be used to simulate human-induced climate change.

Geosphere
The soils, sediments and rock layers of the Earth's crust, both continental and beneath the ocean floors.

Glacier
A slow moving mass of ice formed by compacting snow that accumulates faster than it melts. Glacier ice is the largest reservoir of fresh water on Earth, and second only to the oceans as the largest reservoir of total water.

Global Warming
Global warming is an average increase in the temperature of the atmosphere, which can contribute to changes in global climate patterns. Warming can occur as a result of increased greenhouse gas emissions from human activities.

Global Warming Potential (GWP)
A measurement to calculate of how much of a greenhouse gas is estimated to contribute to global warming relative to carbon dioxide.

Greenhouse Effect
Trapping and build-up of heat in the atmosphere near the Earth’s surface. If the atmospheric concentrations of greenhouse gases rise, the average temperature of Earth’s atmosphere will gradually increase.

Greenhouse Gas (GHG)
Any gas that absorbs infrared radiation in the atmosphere. Greenhouse gases include, but are not limited to, water vapour, carbon dioxide, methane and ozone.

H

Hydrologic Cycle
The process of evaporation, vertical and horizontal transport of water vapour, condensation, precipitation, and the flow of water from continents to oceans. It is a major factor in determining climate through its influence on surface vegetation, the clouds, soil moisture and snow and ice.

Hydrosphere
The component of the climate system comprising all of the Earth’s liquid water such as: oceans, seas, rivers, fresh water lakes, underground water, etc.

I

Ice Core
A cylindrical 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 a given time.

Intergovernmental Panel on Climate Change (IPCC)
The IPCC was established jointly by the United Nations Environment Programme and the World Meteorological Organization in 1988 to assess information on the issue of climate change. The world’s governments look to the IPCC as the official advisory body on the science of climate change and measures to reduce its consequences.

L

Landfill
Site for disposing garbage by spreading it into thin layers and covering it with a fresh layer of soil each day.

M

Methane (CH4)
A greenhouse gas with a global warming potential estimated at 23 times that of carbon dioxide. Methane is produced through decomposition of waste in landfills, animal digestion, decomposition of animal wastes, production and distribution of natural gas and petroleum, coal production, and incomplete fossil fuel combustion.

N

Natural Gas
Underground deposits of gases consisting of methane and small amounts of propane and butane.

Natural Greenhouse Effect
Trapping and build-up of heat in the atmosphere near the Earth’s surface due to the presence of the atmosphere and the gases it contains. If there was no natural greenhouse effect, life on Earth wouldn’t exist and the average global temperature would be -18ºC.  

Nitrogen Oxides (NOx)
Gases consisting of one molecule of nitrogen and varying numbers of oxygen molecules. Nitrogen oxides are pollutants produced in the emissions of vehicle exhausts and from power stations.

Nitrous Oxide (N2O)
A powerful greenhouse gas with a global warming potential (GWP) of 296 times that of carbon dioxide. Major sources of nitrous oxide include soil cultivation practices, especially the use of fertilizers, fossil fuel combustion and biomass burning.

P

Particulate Matter (PM)
Very small pieces of solid or liquid matter such as particles of soot, dust, fumes, mists or aerosols. The physical characteristics of particles, and how they combine with other particles, are part of the feedback mechanisms of the atmosphere.

Parts Per Billion (ppb)
Number of parts of a chemical found in one billion parts of a particular gas, liquid, or solid mixture.

Parts Per Million (ppm)
Number of parts of a chemical found in one million parts of a particular gas, liquid, or solid.

Photosynthesis
The process by which plants take carbon dioxide from the air to build carbohydrates, releasing oxygen in the process.

R

Recycling
Collecting and reprocessing a resource so it can be used again. An example is collecting aluminum cans, melting them down, and using the aluminum to make new cans or other aluminum products.

Reforestation
Planting of forests on lands that have previously contained forests but that have been converted to some other use.

Respiration
The process in living organisms of inhaling oxygen and exhaling carbon dioxide.

S

Sink
Any system that removes a greenhouse gas, an aerosol or a precursor of a greenhouse gas or aerosol from the atmosphere.

Sulfur Hexafluoride (SF6)
A very powerful greenhouse gas used in electrical transmission and distribution systems and as a non-conductor of electricity in electronics.

U

United Nations Framework Convention on Climate Change (UNFCCC)
Made up of 189 countries, the Convention on Climate Change sets an overall framework for intergovernmental efforts to tackle the challenges posed by climate change.

W

Water Vapour
The water present in the atmosphere in gaseous form. In addition to its role as a natural greenhouse gas, water vapour regulates the temperature of the planet because clouds form when excess water vapour in the atmosphere condenses to form ice and water droplets and precipitation.

Weather
Atmospheric condition at any given time or place. It is measured in terms of such things as wind, temperature, humidity, atmospheric pressure, cloudiness, and precipitation.