It is no secret to anyone that our planet is warming but what many of us don’t know is why and perhaps more importantly the consequences it poses. The roots of our problem lie in the form of a simple molecular compound, carbon dioxide. In 1870 the amount of carbon dioxide in the atmosphere was 290 parts per million. 144 years later, to this very date, it has risen to over 400 parts per million. But why does this cause a problem you may ask, well it is now universally accepted that an increase in levels of carbon dioxide in the earths atmosphere causes temperature to rise. Having said this, the absence of carbon dioxide in our atmosphere would have devastating consequences including the eventual extinction of human life.
When observing how temperature has changed over hundreds of thousands of year there is an obvious yet intriguing pattern. Roughly every 100,000 years we go through a cycle and during this cycle we have a glacial period and an interglacial period. When the earth orbits the sun it does not do so in a perfect circle. The eccentric orbit of the earth around the sun is caused by the gravitational pull from other planets on Earth. The gravitational pull that planets such as Venus and Jupiter exert gradually changes the eccentricity of the earths orbit. This cycle takes around 100,000 years, which explains why during this time we see two contrasting periods of climate.
Another noticeable pattern when observing how temperature and levels of carbon dioxide have changed over time is that as one rises so does the other, similarly as one decreases so does the other. Since the 19th century carbon dioxide levels in the atmosphere have rocketed and a subsequent rise in temperature as a result seems inevitable. For hundreds of thousands of years we have never seen carbon dioxide levels rise so sharply and there is substantial evidence to suggest that humans are responsible for this rise. This is because the levels of carbon dioxide and oxygen had been kept in balance. Plants use carbon dioxide for photosynthesis and release oxygen has a product and animals use oxygen and produce carbon dioxide as a product when respiring. However numerous factors such as deforestation (which reduces the amount of trees for using up carbon dioxide and producing oxygen) and burning of fossil fuels such as coal, which also produce carbon dioxide, has disrupted the balance. Notice how both deforestation and the burning of fossil fuels are a result of human activity.
As well as carbon dioxide there are 3 other main greenhouse gases which trap heat in our atmosphere; Water vapour, ozone and methane. These 4 greenhouse gases all work together to create something called the ‘greenhouse effect’. Solar energy from the sun warms the land surface of the earth because the land absorbs some of this radiation. However some radiation is reflected by the earth’s surface and atmosphere. For example, highly reflective surfaces such as snow and ice will reflect solar radiation. This solar radiation is then absorbed by the greenhouse gases in the atmosphere and is re-emitted into the lower layers of the earth’s atmosphere. It is for this reason that greenhouse gases cause temperatures to rise.
Climate change is such a fragile phenomenon because the effects that it can cause are often and sadly irreversible. The warming of our planet for example will have a huge impact on wildlife. Many animals, especially those living in colder climates, which rely on large landmasses of ice, may eventually become extinct. Climate change will have other impacts as well. It will change patterns and intensity of precipitation, water and food supplies, coastal development and energy supplies.
One of the most problematic issues associated with global warming is the rise of sea levels. Thermal expansion (which in this case is the increase in volume of seawater when it increases in temperature) will also happen. Rising sea levels will have serious implications globally. Vast areas of the world’s land mass lie just above sea level and even just a small rise in sea levels could result in the inundation of these vast areas in salt water. The implications of this could be detrimental economically as agriculture would become submerged in water and global wealth could potentially be damaged.