The Earth's oceans and atmosphere are tightly linked. Together, they form a dynamic part of our climatic system:
- Sea water evaporates in the sun's warmth to form vapour in the planet's atmosphere, which falls to the Earth as rain, fog, or snow. This water, so vital to living things, then flows downstream and back to sea.
- Multitudes of microscopic marine plants, called phytoplankton, provide almost half the oxygen we breathe. They remove more CO2 from the atmosphere than all the world's rain forests combined. Vast amounts of carbon from dead marine life are also stored in the ocean floor and prevented from entering the atmosphere as CO2.
- Oceans play a huge role in absorbing solar heat and regulating climate. Their ever-moving currents spread the effects of temperature changes over large areas and prevent the Earth's atmosphere from heating or cooling too rapidly.
- Changes in such factors as the greenhouse effect and the abundance of phytoplankton can alter the temperature and circulation patterns (our oceans and atmosphere).
Nature, Culture, and Climate
Climate change may have different impacts on different cultural groups in Canada. Nature and climatological phenomena do not have the same meaning everywhere. In Judeo-Christian cultures, the sky is associated with the divine and cosmic powers. Animist and Hindu cultures are more linked with earth and ocean. Industrialized cultures are often indifferent to seasonal fluxes and are accustomed to rapid and permanent change. Traditional cultures are more associated with the cyclical nature of climate and are less habituated to change. Such differences might make some cultures more sensitive than others to Canada's changing climate.
Oceans and Atmosphere: A Current Affair
Oceans and atmosphere together form the most dynamic component of the climate system; both exchange and store energy in the form of heat, moisture, and motion. Atmospheric currents and temperatures influence ocean currents and temperatures. For example, atmospheric wind drives ocean currents and stirs surface waters, creating a mixed layer in which there is little temperature change.
The ocean, in turn, affects the atmosphere in many ways. Its currents, like vast conveyor belts, transport warmed or cooled water great distances. The Gulf Stream, for instance, moves water from the southern Atlantic to the shores of Western Europe, producing a climate that is much milder than Canada's at the same latitude. By absorbing atmospheric heat and releasing it slowly over time, the ocean makes coastal climates less extreme than continental ones.
Climatologists predict that higher water temperatures resulting from global warming could alter the course of ocean currents and cause climatic changes worldwide.
A Change in the Weather
Because of their susceptibility to changing temperatures and their ability to store huge quantities of moisture and heat, oceans may affect our weather in unwelcome ways: winter storms that originate over the North Pacific and bring severe snow squalls to Western Canada may become more frequent; and tropical storms that form over warm oceans and provide the energy for hurricane to grow and move over land may increase in number.
Canada's Crumbling Coasts
Climate change poses a particular challenge in Canada's Arctic. Here, the rate of atmospheric warming is twice as fast as in any other region. Temperatures may rise by as much as 10°C by the end of this century. Nowhere else are the impacts more evident than on the shores of the Beaufort Sea, where a combination of environmental factors, including severe storms, rising sea levels, low-lying beaches, warm waters flowing out of the Mackenzie River, and unseasonable break-up of sea ice, have destabilized the coast and accelerated its retreat. Remote-sensing images reveal extensive coastal erosion from 1973 onward. In the face of future climate change, scientists anticipate continuing shrinkage of these ecologically important shores and the loss of habitat important to polar bears, barren-ground caribou, common eiders, and many other species.
South America's Shrinking Shorelines
Loggerhead and leatherback turtles appear off Canada's coasts in summer, migrating between the North Atlantic and the Caribbean Sea. As it happens, both species are also found on the IUCN Red List of Threatened* Species. Here, the loggerhead is ranked as endangered and the leatherback as critically endangered. A serious threat to their survival is the loss of tropical nesting beaches, where life begins for these travelling turtle:
A study comparing shoreline maps of Guyana from 1972 with remote sensing images from 1992 measures the extent of coastal erosion in the South American country. It shows that parts of Guyana's shores, including sea turtle nesting beaches and biologically rich mangrove swamps, have receded by anywhere from several metres to half a kilometre in recent decades. It suggests that climatic changes, like rising sea levels and more frequent and violent storms, combined with the neglect of dikes and dams and deforestation of mangrove swamps, may be to blame. Such erosion could threaten countless species that rely on coastal habitats.
What is an Ecosystem?
An ecosystem is a natural community. It consists of "biotic" (living) and "abiotic" (non-living, life-supporting) elements. In any marine or freshwater area, such as a coastal marsh, kelp forest, pothole, or vernal pool, biotic elements (plants and animals) form an ecosystem along with abiotic elements (sun, soil, water, rocks, and atmosphere). The word ecosystem combines two words: ecology and system. "Eco" means habitat or home. "System" refers to the interdependent way all biotic and abiotic elements of a natural community fit together, like pieces in a giant jigsaw puzzle.
The biggest ecosystem of all is the "ecosphere." It includes the planet's oceans, atmosphere, continents, and all living things. A closer look reveals regional ecosystems, such as lakes, rivers, estuaries, sea coasts, and reefs. Even smaller are natural communities, such as salt marshes, tidal pools, streams, and bogs, or human communities, such as cities, towns, suburbs, and rural areas.
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