Greenhouse Essay, Research Paper

The Greenhouse Effect

The greenhouse effect is an increase in the atmospheric temperature caused

by increasing amounts of greenhouse gases. These gases act as a heat blanket

insulating the Earth’s surface absorbing and trapping heat radiation which normally

escapes from the earth. They include carbon dioxide, water vapor, methane,

nitrous oxide, CFC’s, and other halocarbons.

The earth’s atmosphere goes through two processes constantly. Global cooling

is the first process. This process uses the clouds which cover 60% of the earth’s

surface to reflect 30% of the solar radiation. It also uses a sulfate haze, which

is formed by sulfur dioxide from industrial sources that enter the atmosphere and

react with compounds to form a high-level aerosol. These cool the atmosphere by

blocking us from direct contact with the sun. The reflection of the sunlight is

referred to as planetary albedo and contributes to the overall cooling.

The second is the warming process. This is when light energy comes through

the atmosphere and is absorbed by Earth and transformed to heat energy at the

planet’s surface. The infrared heat energy then radiates upward into space. There

the greenhouse gases found naturally in the troposphere absorb some of the infrared

radiation. The gases insulate the Earth, but do eventually allow the heat to

escape. Without these greenhouse gases the earth would be would 33 C colder.

Global temperature is a balance of the effects of the factors leading to

global cooling, and warming. Unfortunately, increased emissions of greenhouse

gases increase the warming process. For example, every kilogram of fossil fuels

burned equals 3 kilograms of carbon dioxide ( the mass triples because each carbon

atom in fuel bond to two oxygen atoms, in the course of burning, and forms C02. )

6 billion tons of fossil fuel carbon are burned each year adding 18 billion tons

of C02 to the atmosphere. This has increase the carbon dioxide concentrations

by 25% and has cause temperatures to increase more than 0.7 C over the last hundred

years.

We hope that the forests will act as a sink for carbon dioxide but instead

they are a net source. This is because the forests are being cut and burned adding

1 to 2 billion tons annually to the 6 billion tons of carbon already from industrial

processes. Fortunately, the top 300 meters of oceans absorb most of the carbon

dioxide emitted by burning fossil fuels.

Other factors are known to increase the greenhouse effect. These factor

are water vapor, methane, nitrous oxide, CFC’s and other halocarbons. Water

vapor is also a major factor in what has been called the “supergreenhouse effect”

in the tropical Pacific ocean. Water vapor traps energy that has been radiated

back to the atmosphere. The high concentration of H2O vapor contributes

significantly to the heating of the ocean surface and lower atmosphere in the

tropical Pacific.

Methane (CH4) is a product of microbial fermentative reactions and is also

emitted from coal mines, gas pipelines, and oil wells. Methane is gradually

destroyed, but it is added to the atmosphere faster than it can be broken down.

Nitrous oxide (N2O) can be found in biomass burning, chemical fertilizers,

and fossil fuel burning. Nitrous oxide is more dangerous than some of the others

because of its long residence time of 170 years.

CFC’s and other halocarbons are found in refrigerants, solvents, and fire

retardants. Halocarbons have a greater capacity, 10 000 times, for absorbing

infrared radiation, which is about 60% more, than CO2. Although there is increase

in the application of some of these gases, they will decrease in importance in

the future leaving carbon dioxide as the primary dilemma.

In 1981, James Hansen of NASA invented a model with an ability to track

known temperature changes and link them to past and future carbon dioxide levels

as well as global temperature changes. The model suggested the combination of

CO2 and volcanic emissions was responsible for most of the observed changes in

temperature during the 1980’s. A trend of warming of more than 0.7 C coincides

with an increase of 25% in carbon dioxide.

Two major impacts of greenhouse effect are regional climatic changes and

a rise in sea levels. A climactic change will lead to variations in temperature.

Scientists expect more precipitation which may prove to be disastrous for North

America by flooding rivers and lakes.

A rise in the sea levels is anticipated because of an increase in thermal

expansion and the melting of ice caps and ice fields. Like extensive rainfalls,

a rise in the ocean will flood lakes and rivers covering land and may someday bury

continents.

In order to control the effects of global warming we must first admit that

it’s occurring, then take steps to end it. We must stop burning the trees and

not replacing them. Most importantly, we must stop polluting the air.