Carbon is the basis for all life on earth. This essay will explain the role of carbon

dioxide in v arious parts of the carbon cycle. This essay will examin three main, and

important parts of the carbon cycle, starting by explaning the role of the ocean in

obsorbing cabon. Next this essay will examin the human influences on the carbon cycle

and human production of carbon dioxide. Thiedly this essay will explain what controls the

carbon dioxide concentration.

The ocean holds a vast amount of carbon. Carbon dioxide in the atmosphere is

transferred into and out of the ocean continually, maintaining a balance by dissolving in

cold polar water. Plankton also play a large role in maintaning a cardon balance. Plankton

in the world oceans use carbon dioxide for growth (photosynthesis). Waste organic matter

sinks down from these ecosytems, carring cabon and nutrients away from the suface. As

on land, changes to either components of the ocean carbon cycle, chemical or biological,

have a great potential to modify climate change. Scientiests belive that the ocean currently

absorb 30-50 per cent of the cabon dioxide produced by the burning of fossil fuel. If they

did not soak up and carbon dioxide, atmospheric carbon dioxide levels would be much

higher then the current level of 355 parts per million by volume.1

The concentration of atmospheric carbon dioxide has been driven upwards over

the last 150 years by humans activities. Carbon emissions from the U.S. are now estimated

at 1.4 billion tons per year (that's 5.4 tons per person!)2 Recall that northeastern forests

alone contain adout five times that amount in wood and biomass, and you begain to

appreciate their significance on global budgets.

There are two ways in which we affect the carbon cycle. First we add new

atmospheric carbon dioxide into the mix. Power generation and other fossil fuel emissions

release about 6 billion tons of carbon per year, would wide, to the atmosphere. Compared

to the amount added naturally every year, approximately 100 billion tons3, our

contribution is small. However, the new carbon is remaining and accumulating in the

atmophere.

Second, land use changes are converting forested systems, wich are carbon sinks,

into agricultural and urban zones, which tend to be carbon sourse. For example, tropical

forests losses are estimated to add 1 billion tons of carbon per year4. Perhaps more

important, the opporunity to remove cardon dioxide from the atmosphere is greatly

reduced when the forests disappear.

Carbon dioxide is a greenhouse gas, which means that it adsords heat reflected

from the earth's surface and prevents the escape of heat into space. A delicate balance has

developed on earth, one that permits a wide variety of life forms to coexist. Too little heat

trapping results in a cold planet. Too much heat trapping results in a more energetic

atmosphere, and a less stable climate. The average surface temperature of the earth has

risen along with atmospheric carbon dioxide concentration in both the distant and the

recent past.

Humans play the largest role in the production of carbon dioxide. In 1995 the

emissions of carbon dioxide into our atmophere rose by 2 percent. Many say that the

soden increase was caused by a hot summer and cold winter with more people burning

gas. This was the largest jump in carbon dioxide emissions ever.5 Canadian carbon dioxide

emissions are mostly (98.5 percent) accounted for by the combustion of fossil fuels.6

Fossil fuels are of considerable economic value and their consumption is carefully

monitored, energy-related carbon dioxide can be estimated more reliably than any other

emissions source.

The atmosphere's carbon dioxide concentration has risen about 30 per cent since

preindustrial times, enhancing the natural green house effect. The prediction of future

climat change requires quantitative of the sources and sinks of carbon dioxide, and thier

contritributing natural and human influences. There is a natural cycling of carbon in the

environment, causing a large exchange of carbon among the atmosphere, the land

vagetation and soil, and the ocean marine biosphere. Evidence from ice core data suggests

that this natural cycle has been roughly in balance, with olay minor variation, since adout

10 000 years ago.