A Study Of Green House Chemistry Environmental Sciences

There is now general agreement in the scientific community that the average temperature of the earth is increasing and that this global warming is potentially a major problem. It is being said that average global air temperature has increased 0.3 to 0.6 C in the past century and is expected to increase an additional 1 to 3.5 C in the next century. This increase in temperature is expected to cause more frequent and intense heat waves; ecological disruptions that could lead certain types of forests to disappear and some species to become extinct; a decline in agricultural production that could result in hunger and famine; an expansion of deserts; and a rise in sea level.

BASIC MECHANISM

The Earth receives energy from the Sun in the form of visible light. This light is absorbed at the Earth's surface, and re-radiated as thermal radiation. Some of this thermal radiation is absorbed by the atmosphere, and re-radiated both upwards and downwards; that radiated downwards is absorbed by the Earth's surface. Thus the presence of the atmosphere results in the surface receiving more radiation than it would were the atmosphere absent; and it is thus warmer than it would otherwise be.

The innovative ideas and the experiments of scientists have shown us that, although we may be harming our environment by releasing chemicals that destroy the ozone layer or cause global temperatures to rise,  we may also have the potential to make significant changes in our surroundings that can heal the damage we have done.

CONTENTS

Introduction

What causes green house chemistry?

Greenhouse gases: Livegivers or Livetakers.

Greenhouse gases

What are greenhouse gases?

Carbon Dioxide

Methane

Nitrous Oxide

Fluorocarbons

Tropospheric ozone

Carbon monoxide and other reactive gases

Water vapours

What factors impact greenhouse chemistry?

Clouds

Surface albedo

Oceans

Forested areas

How do humans contribute to the Greenhouse effect?

Main causes

Man induced increase

Effect

Effect of global warming on environment.

Effect of glabal warming on society.

What is being done to reduce it?

Roles and Uses

References

INTRODUCTION

The average temperature of the earth's surface is about 15°C (59°F). The temperature largely is determined by the amount of energy absorbed from the sun versus the amount of energy emitted into space by the earth. The energy absorbed by the sun mainly covers wavelengths from the ultraviolet (< 400 nm) through the visible (400 to 700 nm) though the ultraviolet (> 700 nm).

Any change in the balance between the quantity of energy absorbed compared to the amount emitted affects climate. The "greenhouse effect" is concerned with the infrared radiation given off by the earth. Part of this radiation is absorbed by the atmosphere, rather than being lost to space. The gases in the atmosphere that absorb infrared light primarily are water (H2), carbon dioxide (CO2), ozone (O3), nitrous oxide (NO2) and methane (CH4). The gases act as a sort of insulating blanket for the earth, in the same way they would act to lessen heat loss from a greenhouse, hence the name 'greenhouse effect'. It is estimated that the mean global surface temperature of the earth would be -25°C (-13°F) if not for the absorption of energy by carbon dioxide and water.

The concentration of water vapor in the atmosphere is higher than that of carbon dioxide. Consequently, most of this energy conservation is attributable to water. We can see this effect when we look at how temperature drops less on nights with heavy cloud cover as opposed to clear skies or when we consider how large the temperature difference between day and night is in places with lower relative humidity, like the desert.

Although the concentration of carbon dioxide in the atmosphere is low (~375 ppm in 2005), it has been increasing appreciably over time. A century ago, the carbon dioxide concentration was less than 300 ppm. Human activites are accountable for this increase, including consumption of fossil fuels and extensive clearing of land (less carbon dioxide can be consumed by photosynthesis). Changes in the levels of carbon dioxide in the atmosphere are associated with changes in the earth's climate.

The "greenhouse effect" often gets a bad rap because of its association with global warming, but the truth is we couldn't live without it.

Seen from space, our atmosphere is but a tiny layer of gas around a huge bulky planet. But it is this gaseous outer ring and its misleadingly called greenhouse effect that makes life on Earth possible - and that could destroy life as we know it.

What Causes the Greenhouse Effect?

Life on earth depends on energy from the sun. About 30 percent of the sunlight that beams toward Earth is deflected by the outer atmosphere and scattered back into space. The rest reaches the planet's surface and is reflected upward again as a type of slow-moving energy called infrared radiation.

The heat caused by infrared radiation is absorbed by "greenhouse gases" such as water vapor, carbon dioxide, ozone and methane, which slows its escape from the atmosphere.

Although greenhouse gases make up only about 1 percent of the Earth's atmosphere, they regulate our climate by trapping heat and holding it in a kind of warm-air blanket that surrounds the planet.

This phenomenon is what scientists call the "greenhouse effect." Without it, scientists estimate that the average temperature on Earth would be colder by approximately 30 degrees Celsius (54 degrees Fahrenheit), far too cold to sustain our current ecosystem.

Greenhouse Gases: Lifegivers and Lifetakers

In what seems like nature's brutal irony, the gases that make life on Earth possible now threaten our very existence.On reading our greenhouse gas profiles we can find out why CO2, methane, and nitrous oxide might become benevolent climate killers - and how we can react.

Natural greenhouse gases like carbon dioxide, methane, and nitrous oxide have always been in the atmosphere. Without them, the world's average surface temperature would be a chilly -18 degrees Celsius.

Throughout Earth's history, temperatures have varied greatly, mostly depending on the concentration of greenhouses gases in the atmosphere. All signs now suggest that a major temperature change is happening again, but this time humanity is the cause.

A CO2 symbol aflame in front of a coal power plant in Germany. Carbon dioxide is the most important man-made warming agent.

The solar radiation spectrum for direct light at both the top of the Earth's atmosphere and at sea level:-

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