When the radiation comes in contact with the Earth’s atmosphere, part of it would pass right through as it may arrive at the right angle. The other part would be reflected by the earth’s ozone layer. This is to prevent harmful ionising radiation such as UV rays to enter the sun and of the part that successfully passes the earth’s atmosphere; some of the radiation would be ‘absorbed by the Earth’s surface’. This would warm the earth and is vital for life on earth and their processes. However not all the radiation that passes the atmosphere is absorbed by the earth. Some of it is reflected by the earth and goes back into the vacuum of space.
When some of the infrared radiation that passes through the atmosphere is absorbed, some of it would be re-emitted out in all directions. This is caused by the greenhouse molecules such as carbon dioxide and methane and in effect it results in the earth’s surface warming up.
The greenhouse effect
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A greenhouse gas is a gas in the atmosphere that traps the radiation that enters the earth’s atmosphere and prevents it from escaping into space. They do this by allowing the visible and ultra-violet light to pass through the atmosphere and reach the earth’s surface. However, when the light that hits the earth’s surface is reflected back to the atmosphere in the form of infrared radiation and heat and ‘some of the infrared radiation is absorbed and re-emitted by the greenhouse gas molecules’. (Diagram above) this warms up the planet. Some greenhouse gases are man-made such as chlorofluorocarbons (CFC’s) which is the most well-known. However, not all of them are man-made; some greenhouse gases exist naturally such as: carbon dioxide, water vapour, methane gas, ozone and nitrous oxide.
Some potential effects of global warming
Rising sea levels worldwide
Due to an increase in global temperature, sea levels would rise worldwide. This would mean places such as Antarctica and Greenland would have their ice sheets melted. As ice melts it undergoes a physical change of state. It turns into water. As the amount of water increases, it would result in the sea levels rising. This would be disastrous to many nations around the world as it could result in flooding and forcing people to migrate elsewhere. As the melting back of the ice continues, it would lead to a reduction in ‘albedo (surface reflectivity) and allows for greater absorption of solar radiation.’ (climate.org) this would result in more solar radiation being absorbed. This would increase the speed at which the planet is warming, which in effect increases the ‘melting back of snow and ice on land’ (climate.org)
Massive crop failures
In different parts of the world, different crops would grow around a certain temperature. For example to cultivate rice, hot climates and good soil would be needed. This is why rice production is mainly done in Asia and parts of Africa and cannot be profitable to be grown large-scale in the UK in a greenhouse. Due to global-warming, the temperature would rise. This could lead to the soil drying out and a lot of water lost. Without this water, the plant crops would die and without the plants roots to hold the soil together, it could lead to soil erosion from high winds and the gradual desertification of that area such as Burkino Faso which is located in the Sahel region.
Ocean acidification
When carbon dioxide is produced, not all of it goes up into the atmosphere. Some of it is absorbed by plants and used when they photosynthesise and some of it dissolves in the oceans, rivers and lakes. An increased production of co2 would mean that more carbon dioxide is being dissolved into the ocean which would lead to the ocean acidification. This acidification is due to carbonic acid being produced when carbon dioxide dissolves in the water. As a lot of thermal energy is absorbed by the oceans, the temperature of them would rise. This rise in temperature and acidity could cause the extinction of many of the marine wild-life that inhabits the sea.
Mass widespread extinction of species
If an animal cannot adapt to a change in their environment quick enough, they would die out and could become extinct. Because of global warming, the animal’s habitat would increase in temperature. Even a temperature increase of 2 degrees Celsius could result in the animal dying. For example in rivers, this increase in temperature could mean that some of the marine life such as the fishes could die. Global-warming could then result in climate change. This would mean that more extreme weather conditions could occur more frequently and if the animal is not able to adapt to these change in conditions then it wouldn’t survive. This loss of species would result in the reduction of the world’s biodiversity and with it many herbs and medicines that could be created from plants would be lost forever.
Evidence of global warming caused by natural phenomenon
Throughout history there has been events that showed that the earth’s temperature rising and also an increase in co2. One such event is the end of the ice-age. With that millions of species became extinct. In this period levels of greenhouse gases rose significantly and the temperature rose.
Volcanic eruptions spew out tones of carbon dioxide which go up into the atmosphere. This can affect the amount of carbon dioxide in the atmosphere but are identical to the amount of carbon dioxide that is locked away. This includes the trees that store carbon dioxide and the some carbon dioxide being dissolved into the oceans. Another is the idea of ‘solar cycles and cosmic rays’ (2/1/11, June 18, 2009, Jeff McIntire-Strasburg). In my opinion I think that it may not be reliable.
The volcanic eruption theory
Scientists believe that around 74,000 years ago, a super volcano erupted. This released tones of carbon dioxide into the atmosphere and caused a volcanic winter. ‘This change in climate made thousands of species go extinct and reduced the human race to about 10,000.’(2012theories) I don’t think this source might be that reliable as the creator of it may be anyone and from the name’2012 theories’ it seems that the site may be comprised of ideas but not solid facts.
The orbital theory
When the earth orbits the sun, at different times, the axis upon which it rotates on can change in its angle. This would result in certain parts of the earth receiving more solar radiation and getting warmer and could result in climate change and the change in global temperature.
The sunspot theory
A sunspot is spot or patch in the sun that occur from time to time on the surface of the sun. They are darker than the rest of the sun and these spots are the parts of the sun that give off the most solar radiation. Scientists believe that an increased number of these sunspots are linked to climate change.
Evidence of global warming caused human activity
Fossil fuels
Fossil fuels are the fossilized remains of plant organisms. They contain carbon as they were previously carbon-based life forms. These include coal, oil and natural gas. Fossil fuels are non-renewable resources because they take millions of years to form, and reserves are being depleted much faster than new ones are being formed. (2/1/11, 2,1,11, Charles Welch)
The implications of burning Fossil fuels
Humans’ burn tones of fossil fuels so that they can produce electricity. However this comes with the disadvantages. Massive amounts of carbon dioxide are released into the atmosphere every year due to this method of producing energy. This increases the total amount of carbon dioxide and can lead to:
- Rising sea levels
- Extreme weather conditions
- Extinction of species that cannot adapt quick enough
- The melting of ice caps
When people drive their cars, watch TV, or even breath carbon dioxide is produced. This gas enters the atmosphere and adds to the greenhouse effect.
Conclusion
I agree with global-warming may be due to human activities because it is apparent as we are producing more and more carbon dioxide every day due to things that may make our lives easier and more luxurious but is not cannot meet the needs of tomorrow and is not sustainable. We can see that the total levels of co2 emissions emitted by humans and the total amount of atmospheric co2 levels are linked and have a correlation.
I also think that global warming may also be having an involvement with the volcanic activity over time. However I think that it is because of human activities like deforestation that affect the amount of carbon dioxide that goes up into the atmosphere naturally through processes like respiration that can be locked away.
In conclusion I believe that natural phenomenon are a predominant cause of global warming because research by scientists indicate that changes in climate have been occurring well before the dawn of humanity. Since the industrial revolution massive amounts of co2 have been created and have risen into the atmosphere and companies like McDonalds which clear large amounts of land so that they can use it for cattle ranching. This would release the carbon dioxide that has been stored in the trees and less carbon dioxide would be able to be stored by the declined population of trees. However I believe that since the answer to this question can never be fully resolved. More focus should be given to try and combat global-warming and people should be made more environmentally aware.
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