CBC News Indepth: Climate Change

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INDEPTH: CLIMATE CHANGE
A climate change glossary
CBC News Online | March 24, 2005

Albedo: The measure of a surface's reflectivity. The higher the reflectivity, the higher the albedo. Snow and ice have high albedo, since they are light-coloured and very reflective. Melting them exposes more dark ground, with lower albedo. Less light and heat is reflected, and the ground warms. Clearing forested lands and farming can also affect the albedo of a particular area.

Arctic: The area around the North Pole. The Arctic encompasses the Arctic Ocean and parts of Canada, Russia, Alaska, Greenland, Iceland and Norway. The island of Svalbard is also part of the Arctic. The Arctic is not a precisely defined area. The term is often used to refer to any area north of the tree line. Some use the Arctic Circle – a line of latitude at 6633' N – as the defining line. Another definition also used is the area north of the 10-degree summer isotherm. An isotherm is a line marking areas with similar temperatures.

Atmosphere: The gases that surround the Earth, in several layers. Our atmosphere is almost 80 per cent nitrogen, and about 20 per cent oxygen. There are small amounts of other gases, including the greenhouse gases.

Carbon dioxide: One of the greenhouse gases. CO₂ is a heavy, colourless gas that is formed in several ways, including by burning fossil fuels, and by the decay of animal and vegetable matter. Plants use carbon dioxide during photosynthesis.

CFCs: Chlorofluorocarbons. A type of chemical compound made up of chlorine, fluorine and carbon. CFCs were suspected of being a factor in ozone depletion. The chemicals were used in refrigeration and cleaning products, among other things, before being effectively banned by the Montreal Protocol, an international treaty on ozone depletion.

Climate change: Most generally, the variability in climate, usually globally. This phrase, however, is used in slightly different ways by different groups. Climate change can refer to any element of climate, be it precipitation, temperature, or wind patterns. It is frequently used interchangeably with the phrase global warming. Many scientists point out that global warming will not happen uniformly, and that some areas will, in fact, be cooler, so "climate change" is a more accurate description. Some organizations, including the United Nations, have used the phrase "climate change" to refer to human-caused global warming.

Diatom: Microscopic algae found in both salt and fresh water. By looking for different species that are suited to certain temperatures or levels of acidity, scientists can use changes in diatom populations as an indicator of climate change.

Glacier: An accumulation of ice, water, air and rock that forms a large, frozen mass. Glaciers form only on land. They move very slowly, compelled by gravity.

Greenhouse gases: Gases that absorb radiation in the Earth's atmosphere. Most of the atmosphere is made up of nitrogen and oxygen. But about one per cent is made up of the greenhouse gases carbon dioxide, methane, nitrous oxide, ozone and water vapour. As well, there are gases that are produced by human activity, including chlorofluorocarbons. Greenhouse gases have an effect on climate change.

Flux: The rate of volume flow of a fluid or gas per second (or other unit of time).

Isotope: One of two or more atoms in a chemical element that have the same number of protons, but a different number of neutrons, and therefore a different atomic mass. For example, the oxygen in water can have two isotopes or "flavours," 16 and 18. By looking at a ratio of the two isotopes, scientists can determine the age of an ice core.

Kyoto Protocol: International agreement to reduce greenhouse gas emissions, in order to slow global warming. The agreement sets out a schedule for countries to reduce their emissions to about five per cent below 1990 levels by 2012.
» Indepth: Kyoto

Northwest Passage: A sea route through the Arctic that links the Atlantic and Pacific Oceans. It provides a shorter sea route from Europe to Asia, but is frozen for much of the year. There are several possible routes that come up between Greenland and Baffin Island, and navigate the archipelago of the north. The U.S., Denmark and other countries do not recognize Canada's claim to sovereignty over Arctic waterways. If the passage becomes more navigable due to global warming, the question of sovereignty will become more relevant. In fall 2004, Canada conducted military exercises in the Far North, in part to demonstrate the ability to patrol the area.
» Related story: Mapping more of Northwest Passage question of Canadian sovereignty

Permafrost: Ground that is frozen year-round.

Phenology: The study of the seasonal timing of natural events. Scientists study the timing of seasonal events such as flowering, migrations, ice melting or freezing, to determine if biological and physical systems are changing.

Polynya: An area of open water, surrounded by sea ice. They are generally found in the same region year after year. These patches can vary from a few square kilometres, to thousands of square kilometres. The North Water polynya in Canadas Arctic is estimated at more than 50,000 square kilometres. Its in the northern end of Baffin Bay between Ellesmere Island and Greenland. Polynyas are formed by a combination of factors, including currents, tides and winds. Because of their exposure to the suns rays, polynyas are hosts for animals and plants, and are sometimes referred to as oases of the Arctic.

Sea ice: A thin layer of frozen seawater. Sea ice acts as an insulator between the cold air and the warmer water below.

Surface temperature record: The measurement, in degrees, of a combination of land air, marine air, and ocean surface temperature. The record has been in place since 1861, when thermometers began to be used systematically.

Tundra: Area of land with almost no tree growth that receives less than 25 centimetres of precipitation per year. Arctic tundra is marked by lichens, short grasses and some shrubs.

Tree line: The point at which climate conditions are no longer hospitable for trees. In the Arctic, it is the point at which it becomes too cold to sustain tree life. (There are other tree lines in the Antarctic, on mountains, in deserts and in other regions.)

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GLOBAL WARMING: How it works SCIENTIFIC DIFFERENCES GLOSSARY
CLIMATE CHANGE IS HAPPENING NOW:» INTERACTIVE MAP
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UNDERSTANDING CLIMATE CHANGE:THE EVIDENCE: Making the case for climate change
PHOTO GALLERIES:AMUNDSEN RESEARCH VESSEL FIELD CAMPS SEA ICE COVER
CONCLUSIONS & IMPLICATONS:HUMAN FACE OF CLIMATE CHANGE: Weather out of its mind CONCLUSION: The tip of the iceberg KEY RESOURCES
RELATED:Environment Kyoto Polar bears

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