Global warming is defined as ‘the increase in the average temperature of the Earth's near-surface air and oceans since the mid-twentieth century’
Quote from: wikipedia
It is claimed to be caused by an increase in greenhouse gasses in the atmosphere trapping more heat from the sun and allowing less to escape. The earth absorbs the solar energy from the Sun and then reflects some of this heat at longer infrared wavelengths. Some heat escapes into space but some is also absorbed by greenhouse gasses in the atmosphere. The gas molecules absorb the energy, causing their vibrations to increase. The vibrations cause energy to be re-emitted in all directions, thus heating up the atmosphere.
The global warming controversy currently plays a large part in today’s life. We see it on the television and hear about how global warming is destroying our planet. But is it really happening and are we the main ones causing it?
DOES GLOBAL WARMING REALLY EXIST?
The case for
Rising average Global temperatures.
There is little argument that global warming exists. Scientific tests have proven that the average global temperature has increased by around 0.8°C since 1880 (facts from nationalgeographic). The Graph below has used the average temperature from 1961 to 1990 as a baseline. It shows the variation in average global temperature from this average, from 1850 to 2006.
The graph at the bottom quite clearly shows that there has been an increase in average temperature since the mid-20th Century. Recently (since 1980) it is shown to be increasing at a more rapid pace. This is causing people to worry because, although a few points of a degree does not seem much, according to the IPCC's (Intergovernmental Panel on Climate Change) Third Assessment Report, if it continues, it could cause: “A rise in sea level between 3.5 and 34.6 in. (9-88 cm), leading to more coastal erosion, flooding during storms, and permanent inundationSevere stress on many forests, wetlands, alpine regions, and other natural ecosystemsGreater threats to human health as mosquitoes and other disease-carrying insects and rodents spread diseases over larger geographical regionsDisruption of agriculture in some parts of the world due to increased temperature, water stress, and sea-level rise in low-lying areas such as Bangladesh or the Mississippi River delta.”
ARE HUMANS THE MAIN CAUSE OF GLOBAL WARMING?
Increased levels of Carbon Dioxide.
Many believe that the Carbon Dioxide produced by our cars, planes and factories is the main factor causing this increase in warming. As a greenhouse gas the increase in CO2 would ‘trap’ more heat in the atmosphere and thus raise the average temperature.
Experiments have been conducted to see if Global Warming is occurring and by how much. Samples of gases that were trapped in polar ice were analysed (Nature.com 2005). These showed that there is around 35% more Carbon Dioxide in the atmosphere at the moment than there has been for around 650, 000 years. Some scientists say this extra Carbon Dioxide must be responsible for the recent rise in global temperature.
The main causes of the large rise in levels of Carbon Dioxide are said, by the Royal Society, to be mainly due to: “the burning of fossil fuels, as well as the production of cement and the widespread burning of the world's forests. The increase in global temperature is consistent with what science tells us we should expect when the levels of Carbon Dioxide and other greenhouse gases in the atmosphere increase in the way that they have.”
Quote from: royalsociety
The Burning of forests not only creates Carbon Dioxide, but by having fewer trees, there is less photosynthesis, which uses Carbon Dioxide and creates oxygen. So extra CO2 is made and less CO2 is removed from the atmosphere, it is a lose-lose situation.
The case against
There are others however who do not agree that the situation is as clear-cut as this. They put forward a number of arguments against the above view that mankind is responsible for the increase in CO2:
1. The role of Carbon Dioxide as a Greenhouse gas.
Water vapour is the most abundant of Greenhouse gasses. It accounts for 95% of the Greenhouse affect while Carbon Dioxide only accounts for 3.6%. Around 99.999% of all water vapour comes from natural sources.
Data from: geocraft
Vladimir Shaidurov, Doctor of Physics and Mathematics Sciences at the Russian Academy of Sciences, argues that “small changes in the atmospheric levels of water, in the form of vapour and ice crystals can contribute to significant changes to the temperature of the earth's surface, which far outweighs the effects of Carbon Dioxide and other gases released by human activities. Just a rise of 1% of water vapour could raise the global average temperature of Earth's surface more then 4 degrees Celsius.”
Info and Quote from: physorg
Methane (CH4) is another greenhouse gas. According to the EPA (Environmental Protection Agency) methane is over 20 times more affective at trapping heat than Carbon Dioxide. It is emitted mostly through bovine and other animal’s flatulence, as well as “human-influenced sources such as landfills, natural gas and petroleum systems, agricultural activities, coal mining, stationary and mobile combustion, wastewater treatment, and certain industrial processes.”
Info and Quote from: epa
Historic temperature cycles.
We are worrying about global temperatures rising now but if we look to the past, we can see that there have been rises and declines in temperature before. We are also told that the rising temperature is due to large amounts of CO2 in the atmosphere, but this is put to question when fairly large rises in temperature have happened even before the Industrial Revolution. One example of temperature change, around the years 950-1100AD there was a time of warm weather called the ‘Medieval Warm Period’. During this period it was so warm that the people of England were able to grow grapes and produce wine. It is also thought that the medieval warm period made it easier for the Vikings to explore parts of northern Europe and colonise in Greenland. There was less sea ice and the temperatures were so warm that the parts of Greenland the Vikings discovered had no ice and were able to be farmed (hence the name ‘Green’land).
Another example of abnormal weather is the ‘Little Ice Age’ ranging from 1250 to 1850. It wasn’t an Ice Age as such but Average Global Temperatures are estimated to have been around 1.5°C lower than they are today. During this period livestock died, harvests failed, and people suffered from famine and disease.
The NAS report of 1975 sums up the view: "The climates of the earth have always been changing, and they will doubtless continue to do so in the future. How large these future changes will be, and where and how rapidly they will occur, we do not know"
Previous incorrect scientific arguments.
We are now made to believe that the globe has been warming up and will continue to do so. But about 30 years ago people were being told exactly the opposite: that the earth was heading for another Ice Age due to ‘Global Cooling’:
The June 24, 1974, ‘TIME’ magazine stated that: “since the 1940s the mean global temperature has dropped about 2.7° F. Although that figure is at best an estimate, it is supported by other convincing data” and that “when meteorologists take an average of temperatures around the globe they find that the atmosphere has been growing gradually cooler for the past three decades. The trend shows no indication of reversing. Climatological Cassandras are becoming increasingly apprehensive, for the weather aberrations they are studying may be the harbinger of another ice age.”
Newsweek, April 28, 1975 reported that “[meteorologists] are almost unanimous in the view that the [cooling] trend will reduce agricultural productivity for the rest of the century. If the climatic change is as profound as some of the pessimists fear, the resulting famines could be catastrophic.” and that “The evidence in support of these predictions has now begun to accumulate so massively that meteorologists are hard-pressed to keep up with it.”
(Although Newspapers are not always completely reliable, these did use evidence from scientific sources)
These two articles show us that just because the average temperature was decreasing, it was thought this would continue and cause another Ice Age. We are able to see now that they are wrong but at the time many people were convinced that it was going to happen. It shows that just because people think they can explain the changes to the climate, it doesn’t mean that they are necessarily correct.
Looking at the evidence we can see that there seems to be agreement that the Globe, at the moment, is warming up. However, the real question is: ‘are Humans the ones causing it?’
I think that it is not yet possible to tell with the information available. But I do believe that certain issues have to be raised and considered when assessing the case.
I also believe that if the globe continues to warm it will have a severe impact, but what I question is how do we know for certain that the average temperature will continue to increase and how do we know that Carbon Dioxide to blame?
Firstly, if there is so much extra Carbon Dioxide in the atmosphere then surely this should cause plants to grow faster. Thus providing more biomass to take in Carbon Dioxide, lessening the problem of deforestation’s effect on the amounts of atmospheric CO2.
Secondly, we have raised the fact that water vapour is actually a much more abundant greenhouse gas. In my view, increases in Carbon Dioxide should not affect the climate as much as increases in water vapour. As humans do not contribute significantly to the amounts of water vapour, can we really be blamed for it? The same goes for Methane, which is mainly caused by animal flatulence. There is no, reasonable way of stopping animals doing what they do naturally. However, I do realise that Carbon Dioxide is the most easily controlled and reduced greenhouse gas and thus is the one most publicised.
Thirdly, if we look at climate in the past we have seen it changing, even before the industrial revolution, where large amounts of CO2 were starting to be released. So although we are being blamed for putting too much Carbon Dioxide in the atmosphere, if it has happened before how are we suddenly responsible for the increasing temperatures. It could just be that we are on another temperature cycle and the average temperature will decrease in a number of years.
Finally, how do we know that the issue of Global warming is not completely wrong just like the Ice Age supposedly caused by Global cooling. Just as scientists then thought they had sufficient evidence to prove Global cooling, maybe scientists now (who think they have enough evidence) are wrong as well. There might be some factor that affects climate change that scientists have not yet considered or that it is influenced by something else not yet fully understood.
In conclusion, I believe that it is very difficult to see which argument is correct, as both sides have made valid points. I do hope that scientists can come to some agreement as to what is really going on and find a way to do whatever suits the situation best.