Global Warming
Global temperatures are rising, leading to climate change. There are many theories as to why this is happening, however, it is likely to be a combined result of many different factors. Factors which can contribute towards global temperature change include human activity, animals, bacteria and plants, the sun and geological activity like volcanic eruptions.
Climate changes throughout history
It is known that the temperatures on the Earth have naturally fluctuated throughout history, with warm periods and also very cold periods including ice ages.
Theories to explain why there are drastic changes in Earth's temperature include astronomical events like large asteroid and comet impacts. Massive impacts like the one thought to have wiped out the dinosaurs blasts massive amounts of ejecta (dust and earth) into the atmosphere, enough to block out the sun's rays and lead to drastic global cooling. Volcanic eruptions can also release large amounts of debris into the air which have a similar effect.
Solar activity has been linked to climate change as well. There appears to be a link between periods when the Earth's temperatues have shifted and times when the sun is more or less active than usual.
Greenhouse effect
Some gases in the atmosphere such as carbon dioxide trap reflected heat from the planet and keep the Earth warm. This is essential for life on the planet, as otherwise the Earth would be far too cold for life to exist. For a comparison, it is thought that the planet Mars was once warmer and could have had liquid water. But today the atmosphere of Mars is extremely thin compared to the Earth's and the surface of the planet is permafrost.
Human activity is thought to be contributing to global warming, because we are releasing more greenhouse gases into the atmosphere than in previous times in history. Carbon dioxide (CO2) is a greenhouse has that humans are releasing through our everyday activities (such as driving cars which release CO2 in exhaust fumes) and in industrial processes. Other human activities which contribute to greenhouse gas emissions include the production of waste which goes to landfills. As rubbish in landfills breaks down, it releases methane gas which is even more powerful at trapping heat in the atmosphere than CO2.
In the natural carbon cycle, CO2 is taken out of the atmosphere by plants which use it for photosynthesis. But human activities such as deforestation are disrupting this cycle. People are cutting down forests on a large scale for things like cattle farming and wood, meaning that there are less plants recycling the carbon dioxide in the air. On top of this, sometimes the cut down forests are burned, which releases the CO2 back into the atmosphere.
In addition to this, animal activity also releases greenhouse gases. Flatulence from cows for example releases methane gas. Therefore, cutting down large areas of forest for cattle farming has a double impact on greenhouse gas release.
It's not just human activity that releases greenhouse gases. Natural activity such as rotting plants in swamplands releases methane, and massive volcanic eruptions release tons of carbon dioxide on a scale that dwarfs human made CO2. Therefore, there is some debate as to whether or not increasing levels of human produced CO2 is the current reason for global warming.
The consequences of global warming
Whether the planet's increasing temperatures are caused by humans or nature, the fact is that both cannot be discounted and ignored. Rising average temperatures are affecting the climate and producing more extreme weather, including more frequent and powerful tropical cyclones and hurricanes (such as Hurricane Katrina which devastated Mississippi in the US in 2005)
Other effects include less rainfall and increased periods of drought in areas such as eastern Africa. More dry weather there causes starvation and death when crops fail and animals die. Wells and sources of water dry up leading to humanitarian crises.
Higher global temperatures are also leading to the melting of glaciers and polar ice. The ice and snow covered regions of the planet are good at reflecting heat from the sun back into space. The melting and disappearance of this ice will have further consequences in the future by contributing to even more global warming and also the raising of sea levels across the planet. Costal areas of the planet will be at risk of flooding and could disappear under the sea.
Take action
So what can you do about global climate change? There's no denying that humans produce a lot of greenhouse gases whether or not these are the main cause of global warming. We can reduce our carbon footprint (the amount of CO2 we produce through our activities) and in some cases there are benefits including saving money and energy.
Simple changes like using more energy efficient products (like "A" rated washing machines which save power); having double glazing (and reducing heat loss in your home and therefore the need for turning on the heating); and walking to nearby destinations instead of driving can all help to reduce your carbon footprint.
Related External Links:
- Act On CO2
Find out what your carbon footprint is and how you can make simple changes to tackle climate change.