http://yosemite.epa.gov/oar/globalwarming.nsf/content/climate.html, Last Modified on Friday, January 7th, 2000).
DIAGRAM
Without this natural greenhouse effect, temperatures would be much lower than they are now, and life as it is today would not be possible.
It’s a scientific fact that the earth has been getting hotter and there is evidence to prove this. The global mean surface temperatures have increased by 1 degree Fahrenheit in the past century, with accelerated warming it the past 20 years. The 20th century’s 10 warmest summers all occurred in the last 15 years of the century. The snow cover in the northern hemisphere and floating ice in the Arctic Ocean has decreased causing global sea levels to rise 4-8 inches over the last 100 years. (, Last Modified on Friday, January 7th, 2000, This is a very important piece of information so it was important I got it from a reliable source I know it is a reliable source because it is an official website for the USA environmental protection agency.)
This graph shows the global temperature variations for over the 20th century:
GRAPH - source: U.S national climatic data center, 2001.
By looking at the graph I can see that the mean temperatures have had two major increases over the century one from 1920-1945 and the other from 1975 onward. The increase from 1975 onward is much higher than the increase earlier on. This proves that the Earth’s temperature is rising and from 1975 is increasing more quickly.
So we know that the Earth’s temperature is increasing but why is it increasing? Scientist generally believe that human activities such as; the combustion of fossils fuels, fossil fuels burned to run factories, cars, heat homes and businesses, increased agricultural work, deforestation, landfills, industrial production and mining. Although a lot of people still disagree. (, Last Modified on Friday, January 7th, 2000)
Since the beginning of the industrial revolution, atmospheric concentrations of carbon dioxide have risen by nearly 30%. (, 1996, this is an original document written by ECO Centre staff.) Carbon dioxide is produced from burning fossils fuels for cars, heating buildings, electric lights etc. Deforestation also has an effect on the amount of carbon dioxide in the atmosphere because trees photosynthesize by taking in carbon dioxide through there pores and letting out oxygen. This means that when the trees are cut down the amount of carbon dioxide being taken in is decreasing therefore there is more left in the atmosphere. These are both human activities that are responsible for the increase of carbon dioxide. The methane concentrations have also increased by more than double. (, Last Modified on Friday, January 7th, 2000) This is from the beginning of the industrial revolution so this means that since countries started developing the amount or carbon dioxide and methane in the atmosphere has increased, but this could just be a coincidence.
On the other hand, there are a lot of arguments against humans being responsible for global warming. It is a fact that carbon dioxide is also produced by natural sources as well e.g. volcanic eruptions, decay or dead plant and animal matter, evaporation from the oceans and animal respiration. () However, the argument against this is that yes, natural sources do produce carbon dioxide as well but they also remove it at a nearly identical rate and the balance has maintained at a stable level for thousands of year prior to the industrial revolution, so there is still nothing to explain the increase in carbon dioxide concentrations.
Another argument against us being the culprits for global warming is that the climate always fluctuates either for unknown reasons and no one yet knows completely why this happens. It’s true that the Earth’s climate has had wide variations over time due to natural processes. Also the medieval warm period could disprove global warming. The current warm pattern is similar to the medieval warming period and since the medieval warm period was obviously natural, the current warming could also be cause by nature. The medieval warm period was relatively warm period lasting from the 10th century to the 14th. It has been suggested based on temperature reconstructions and model simulations that the medieval warm period may have been caused by increased solar activity or a dearth of volcanic activity. However, the initial evidence was gathered from data in Europe but more recent analyses indicate that the medieval warm period may have to been on a global scale. Also the temperatures in the medieval warm period were not as extreme as they are today. There are other natural causes of global warming that are not to do with greenhouse gases, for instance; increase output from the sun and increase absorption of heat from the sun but personally, I do not think these could be the reasons for the rising temperature as there is much more evidence on greenhouse gases and scientist no a lot more about them. (Are Humans Responsible for Global Warming, PDF document, April 2007 by James Wang, Ph.D. and Bill Chameides, Ph.D.)
In conclusion to my research, I believe that the reason for people saying that the we are not the problem is because they cannot face up to the fact it’s out fault and are just looking for something to put the blame. Although there is some evidence of it being down to natural causes, there is nowhere near as much. Also what really made me believe that we are the cause is that ever since industrial revolution the amount of carbon dioxide and methane has shot up and it is a bit of a big coincidence that this happened. When I started researching the medieval warm period however, I though that global warming today could be similar to that, until I found out that it was not a global phenomenon like it is today. All in all, I feel that we do not know enough about the earth and the climate system to attribute the present global warming to a specific cause so until we do I suppose that we won’t know. Although at the moment I strongly believe we are responsible for increased global warming.
