Climate Change - the basics
To be able to understand climate change, it is vital that the difference between weather and climate is understood.
The Met Office defines weather as: The temperature, precipitation (rain, hail, sleet and snow) and wind, which change hour by hour and day by day. Weather is what you can see out of your window, now.
Climate relates to the average weather patterns and the nature of the variations that we experience over time. This includes temperature, wind and rainfall patterns. The Earth's climate is not fixed, and in the past has changed many times in response to a variety of natural causes.
The main human influence on global climate is the emission of so called greenhouse gases, such as carbon dioxide (CO2), methane and nitrous oxide. As these gases build up in the atmosphere, they strengthen what is known as the '"greenhouse effect'". At present, over 30 billion tonnes of CO2 are emitted globally each year by burning fossil fuels, and another 7 billion tonnes by changes in land use, mainly deforestation. Atmospheric concentration of CO2 is now higher than at any time in at least the last 800,000 years.
There is now little doubt that human activity is the main cause of the increased warming observed over the last 100 years, particularly over the last 50 years.
The Greenhouse Effect
The Greenhouse effect is a natural process of heating and cooling that when balanced allows life to exist on earth. Light energy from the sun passes through the atmosphere and warms the earth. It is reflected back into space as Infrared Radiation (IR) taking the heat with it. Some IR however is trapped by gases like Carbon Dioxide in the atmosphere and the heat is retained.
Why is this a problem?
Since the 19th century, the amount of Carbon Dioxide (CO2) in the atmosphere has been steadily rising as a result of anthropogenic or human activities such as heavy industry, travel and transport which have altered the balance of the atmosphere. In the last 50 years the level of CO2 in the atmosphere has risen from 315ppm to 391ppm in March 2010. This rise is what has lead to Climate Change and is what will lead to more changes in the future.
The amount that CO2 increases in the atmosphere is directly linked to the impact on the climate, so if the rate of increase is not reduced, and the total amount of CO2 in the atmosphere does not begin to fall, any number of serious changes may occur globally including sea level rise, an increase in droughts and flooding and overall average temperatures.