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What is the greenhouse effect?

The greenhouse effect is a naturally occurring process that helps in heating the earth's surface and atmosphere. It is so called as it works in a very similar way to that of a greenhouse - sunlight passes through greenhouse glass and warms the ground inside. Heat rising from the ground warms the air; the glass prevents the air from escaping, so the greenhouse retains the heat . This process works on our planet as sunlight passes through the atmosphere and warms the planet's surface. Heat rising from the surface warms the atmosphere; gases in the atmosphere absorb some of the heat and reflect it back to the ground. There are specific gases that trap the heat within the atmosphere they are - carbon dioxide, water vapour, methane, nitrous oxide chlorofluorocarbons and tropospheric ozone.

Although the greenhouse effect is often thought of in a negative light if it were not for this climatic process the world would be a lot colder place. It is predicted that without this effect the world would be, on average, a very cold -18 °C compared to the present 15 °C.

However since the 1800's and the industrial revolution, man has released billions of tonnes of greenhouse gases into the atmosphere other than those which occur naturally for example:

• Carbon dioxide - levels of CO2 have increased 30% since 1750, major causes are CO2 emissions released by burning fossil fuels for electricity, heating, transportation and industrial processes. Also decreases in the amount of woodland as trees and plant naturally convert CO2 into oxygen.

• Methane - we release between 350 and 500 million tons of methane to the air annually. This is mainly from - raising livestock which release methane as a waste product, coal mining and drilling for oil and natural gas, rice cultivation, disposing of rubbish in landfills and burning forests and fields.

• Nitrous Oxide - each year we add 7 to 13 million tons of nitrous oxide to the atmosphere mainly by using nitrogen-based fertilizers, disposing of human and animal wastes and vehicle exhausts.

• Fluorocarbons - fluorocarbons are greenhouse gases that rarely occur naturally. They are manufactured by humans for refrigeration and other uses. Some fluorocarbons are being phased out because they damage the Earth's protective ozone layer. Newer fluorocarbons do not harm the ozone layer but still trap heat in the atmosphere, adding to the greenhouse effect.

So human influence is increasing levels of greenhouse emissions and therefore increasing the effect of a natural process - this is why it is often referred to as the enhanced greenhouse effect.

What are the likely effects this global warming could cause?

Scientists are still speculating as to what effects global warming will have. Below is a list of potential dangers we could face if the earth continues to warm up at its current rate.

Ecosystem Disruption

Increased temperatures and changes in rainfall patterns could mean destabilising of ecosystems which may threaten crops across the world. This may lead to famine in under developed regions.

Drought conditions will increase

Changes in the amount of rainfall may affect water supplies and quality, which in turn could affect agriculture, fisheries, recreation, and drinking water.

Sea levels will rise

Sea levels rise may endanger coastal areas in the Americas and Europe . Island nations like Indonesia, where more than 45 million people live at coastal elevations within a metre of sea level, will be devastated.

Diseases will spread further and faster

Warmer, wetter weather will create ideal conditions for the insects and rodents that carry malaria, encephalitis, Hantavirus, cholera, dengue fever, and other infectious diseases.

Therefore we must be all be aware of global warming and its dangers and try to do what we can to reduce the amount of greenhouse gases we release into the atmosphere.