The climate of the earth is always changing as a result of natural cycles and causes. However, within the scientific community there is overwhelming opinion that human activities are having an effect on the earth’s climate.
The effect of an increase in greenhouse gases is very important when we talk about climate change as it relates to the gases which keep the Earth warm. It is the extra greenhouse gases which humans have released which are thought to pose the strongest threat.
The Greenhouse Effect
The term’ Greenhouse Effect’ is used to describe the increase in the earths average temperature over the past 100years. However, without the 'natural greenhouse effect', life on Earth would be very different to that seen today.
The natural greenhouse effect involves heat rays from the sun passing through the atmosphere and heating the earth. The temperature of the earth then increases causing the earth to radiate heat (infrared rays) back to the atmosphere. Naturally occurring greenhouse gases such as Water vapour, Carbon Dioxide, Methane, Ozone, Halocarbons and Nitrus Oxides, in the atmosphere absorb some of the infrared rays. As the gases absorb the energy, approximately 25% of it is radiated back to earth maintaining an average earth surface temperature of approximately 15°c. Without this process the earth’s temperature would be about -15°c which would be to cold to sustain life.
Most greenhouse gases occur naturally in the atmosphere acting similar to the glass in a greenhouse, where by allowing heat through the glass and then the same glass stopping the heat escaping. However, due to human activities such as burning fossil fuels, agriculture and land clearing, man made greenhouse gases as well as natural greenhouse gases like CO2 are being produced. These gases thicken the thin layer of atmosphere allowing less heat to escape and more radiated back to the earth which in turn heats up the earth’s surface.
This is highlighted by the fact that the ten warmest years since records began in 1861 have all occurred since 1994.
Here are just a few changes that have occurred or will occur to our planet due to climate change.
- In the last 200yrs CO2 in the atmosphere has increase by 30%
- Greenhouse gas concentrations are higher than at any point in the last 800,000 years
- The August 2003 heat wave is thought to be the hottest in Europe for 500 years
- Over the last 100 years the earth surface temperature has risen by approximately 0.5°c
- Human emissions of CO2 amount to approximately 28 billion tons per year. This is likely to increase by double or possibly triple in the next century.
- The winter floods in 2000 were the worst for nearly 300 years in some areas.
- The hottest temperature ever recorded in the UK was 38.5°c in Kent in 2003.
This increase in the earth’s temperature will have many different effects on the planet.
As the earth’s temperatures warm so will the sea, causing it to expand raising the sea level. This will be further heightened by glaciers and polar ice caps melting into the sea which some scientists believe could cause a rise in sea level of more than half a metre by the end of the century. People living in low lying areas across the world could be affected.
There will be less rainfall meaning less water available for irrigation and drinking. Droughts will be more frequent and water shortages are thought to be a major concern. Northern Africa, and India are thought to be the worst effected. The same areas will see poor harvest as temperature increases and rainfall patterns change.