Abstract

All fossil fuels form carbon dioxide when they are used There is, since carbon dioxide is a major greenhouse gas, concern that continued use may change global temperatures or, more important, change global and local climates. This paper reviews the scientific evidence for an enhanced greenhouse effect and changes in global temperatures. Climates are in constant flux and are affected by many Factors. Some of these, especially ones governed by geological factors, are discussed.

Introduction

The climate and weather is constantly changing and is still often unpredictable. We seem to need to blame "Something" for bad weather, the current popular culprit is the "Greenhouse Effect", which is now usually blamed for hurricanes, droughts, floods and any other bad weather.

The Greenhouse Effect and the Enhanced Greenhouse Effect do affect the climate. A major contributor to the Greenhouse Effect is carbon dioxide. The burning of fossil fuels over the last 150 years has increased the amount of carbon dioxide in the atmosphere However it is still not proven that this has had a significant impact on climate.

This paper reviews some of the changes in climate that have occurred. It also considers some of the factors that have changed the concentrations of carbon dioxide in the atmosphere It does not, through lack of space, consider any of the many other factors, such as the Earth's orbit, fluctuations in the sun's radiation and interstellar dust as well as other Greenhouse Gases, that change our climate.

The greenhouse effect

About 50% of the sun's energy which falls on the Earth reaches the surface. The warm surface at an average temperature of 25 °C radiates energy in the infrared region back into space. Some of the gases in the atmosphere (water, carbon dioxide, CFC's methane and some other minor gases) absorb the infrared radiation and are warmed, in turn radiating infrared radiation, some back to the surface of the Earth. This is the Greenhouse Effect. If there was no Greenhouse Effect the Earth's surface would be from 30 to 45 °C colder than it is now which would mean that on a very hot summer's day in Saskatchewan, the temperature would nearly reach freezing point!

Humans are changing the composition of the atmosphere by our varied agricultural and industrial activities The resulting change in the Greenhouse Effect is called the Enhanced Greenhouse Effect which is a slight additional warming that may become as large as 1 to 5 °C by 2050 The warming itself is probably not very significant especially as it would mainly occur at night in high latitudes but the effect of the warming on the climate and the weather would be more serious.

About 90% of the Greenhouse Effect is due to the water vapor in the atmosphere (Table I) Since the amount of water in the atmosphere is very variable, it is generally ignored when presenting data (!). The contribution of carbon dioxide to the Greenhouse Effect is about 50% if water is ignored, as little as 5% when water is included.

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