- Created by: Kirsty Spencer
- Created on: 03-01-11 22:01
Natural Theories Explaining Climate Change
We know that climate has changed due to:
Fossils of animals no longer living in the UK,
Landforms left by glaciers,
Samples from old ice-sheets in Antarctica,
Old photos, diaries and paintings,
Recorded dates of blossom and bird migration.
Eruption theory - Massive volcano eruptions that produce ash and gas which spread around the stratosphere stopping sunlight from reaching the earth's surface - this cools the earth. E.G. Mt. Pinatubo, Philippines, 1991.
Sun Spot theory - Black areas on the surface of the sun, more spots means more solar energy being sent towards the Earth, making it warmer. The sun is not constant, these spots can come and go.
Milankovith Orbital theory - Changes in the Earth's orbit of the sun from circular to ellipses alters the amount of sunlight that the Earth receives, the axis also tilts and wobbles.
The Enhanced Green House Effect
Global warming is the warming of the Earth's temperature caused by the Enhanced Greenhouse Effect.
Greenhouse gases such as:
CO2 from burning fossil fuels and deforestation,
Methane from paddy fields and cattle,
Nitrous oxides from aircraft engines and fertilisers
all contribute to the enhanced Green House Effect. This causes an increase in global temperatures which leads to thermal expansion and glaciers and ice sheets melting.
We have evidence to suggest that global warming is happening:
19/20 warmest years on record since 1980,
Sea ice in the Arctic has shrunk from 7.6 million square km in 1980 to only 4.4 in 2007,
Over 90% of the world's glaciers are shrinking.
Developed countries are more to blame for the Enhanced Green House effect, the average person in a developed country produced 10-25 tonnes of CO2, in the developing world, the average person produced only 1 tonne of CO2. Due to the take off in development, emerging powers such as China and India are now in line with old polluters such as Europe and the USA. China is the world's single largest polluter.
The Little Ice Age was a period of unusually cool conditions between the years of 1300-1850 AD. Cold and rain lashed Europe in the spring and summer of 1315. Wheat and oats didn't ripen and the harvest failed. The cool wet weather continued into 1316 and 1317. The Great Famine lasted 8 years from 1317-1325 in which 10-20% of Farmers died from hunger. In 1349, Bubonic Plague (Black Death) struck Europe and killed far more than those that died during the Famine.
The dinosaur extinction was possibly caused by an asteroid hitting Mexico combined with a volcanic eruption in India, the Eruption Theory has led scientists to believe that the eruption cooled the planet, because of this the plants didn't grow and this led to a knock-on effect throughout the food chain which led to extinction.
The Mega Fauna extinction was due to the climate warming which meant the Mega Fauna species as to find new areas to live, as well as not being able to find the right food in their new habitats, their movement disrupted food chains. They were also hunted to extinction by humans.
Scientists believe that by 2100:
- temperatures will rise between 1.1 and 6.4 degrees celcius,
- sea levels will rise 30-100cm,
- floods, droughts and heat waves will become more common,
- storms and hurricanes will be stronger
We cannot predict the future climate accurately as we don't know:
- the future population
- if we will switch to renewable, cleaner fuels,
- if we will lead greener lifestyles.
In 2005, Sir Nicholas Stern wrote the Stern Review on Global Warming in which he warned that we should act now to reduce global warming.
- We should spend 2% of our GDP reducing greenhouse gas pollution now or global warming could decrease our GDP by 20%. 'Spend now or pay later.'
Reduce the use of fossil fuels and switch to 'greener' renewable fuels,
Recycle more and use more public transport.
The affect of Global Warming on an MEDC
The UK is likely to become warmer, this will have it's costs and benefits.
Summer droughts and water shortages will occur, especially in the south,
More illnesses such as sunstroke and skin cancer,
Roads will melt and rail way lines will buckle,
Farmers will have to change crops to those that need less water and more sun,
Extinction of some plants and animal species as it becomes too hot for them,
Scotland's skiing resorts could be gone by 2050,
More cases of tropical diseases such as Malaria.
2) Sea levels rise meaning low lying coasts could flood,
Sea defences and flood barriers will put economic strain on the government.
3) More extreme and unpredictable weather such as heat waves, floods and storms.
Winter heating and road gritting costs will fall,
An increase in tourism which is good for the economy,
Less deaths in the Winter - especially old people from the cold,
More land can be farmed at higher altitudes,
New crops could be grown such as vines for wine as the growing seasons will be different.
The affect of Global Warming on an LEDC
A developing country such as Egypt which has low green house gas emissons (2.6 tonnes per person per year), produces less than 1% of all green house gases, has 99% of the population living in 5% of the land area and less than 10mm/yr average rainfall would not be able to cope with the impacts of Global warming.
If sea levels were to rise 50cm, 1/3 of the city of Alexandria would be underwater,
10% Nile Delta would flood causing 7 million people to leave their homes, farming to be hit leading to less food and a famine,
Less and more unreliable rainfall would lead to water shortages,
Even more desertification,
Heatwaves could lead to illness and death and an increase in diseases like Malaria.
Egypt's main water source is the Nile, as most of the water in the Nile doesn't start its journey in Egypt, HEP Dams built in Uganda, Sudan and Ethiopia could have a serious impact on the amount of water reaching Egypt leading to conflict and war. Egypt already has a debt of $30 billion.
To prevent the effects of Global warming, an international agreement was made to cut CO2 emmisions in 1997. This is called the Kyoto Protocol and needs all countries to sign up in order to be effective.