Global Warming explained
Global warming explained
Global warming is the term used about the fact that the Earth is heating up. Global warming is also mentioned as ``the greenhouse effect'' and this is basically what it is all about. When heat from the sun enters a greenhouse through the glass most of the heat is captured inside and this is the exact same effect that is causing global warming on Earth. However contrary to a normal greenhouse Earth does not have any glass surrounding it. Instead the atmosphere consists of several ``greenhouse gases'' (Natural greenhouse gases include: carbon dioxide (CO2), methane, and nitrous oxide) that cause the same effect as the glass does in a normal greenhouse.
The greenhouse of the Earth works like this: When the heat from the sun hits the atmosphere surrounding Earth some of the heat is reflected back into the universe. The rest of the heat is absorbed by the surface of the Earth. The heated Earth now emits an infrared heat into the atmosphere, where a part of it is absorbed and reflected back to the surface by the greenhouse gases. This heat is now trapped in the atmosphere heating the temperature of the Earth. The remaining infrared heat is emitted into the universe.
The term ``greenhouse gases'' is used about carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O), CFCs (Also responsible for destruction of the ozone layer), HFCs, PFCs, and sulphur hexafluoride[2]. Carbon dioxide is emitted whenever fossil fuels (e.g. oil and gasoline) are burned. Since fossil fuel is the most common energy source in the world for the last 100 years the emission of carbon dioxide has grown dramatically. Methane is the result of decomposition of organic wastes in landfills. Nitrous oxide is emitted from the industry, the agriculture and from combustion of solid waste and fossil fuels. The remaining gases are industrially produced and used for instance in old refrigerators.
The greenhouse effect has been around for centuries and it is vital for the kind of life we see on Earth today. Calculations show that without the greenhouse effect the average temperature of the Earth would be 35 degrees Celsius lower than with the greenhouse effect in action[1].
Impacts of increased global warming
The last 100 years of meteorological data shows that the average temperature of Earth has increased by one degree Celsius. At first sight this does not seem like that much but when looking at the changes the Earth is going through already that tiny temperature increase is dreadful. Glaciers are melting1 and more rain drops than usual causing severe flooding2. If the average temperature of the Earth increases more it will cause the amounts of ice on the South and the North Pole to melt resulting in sea levels to rise and flooding in areas of low-lying land in the world. These areas are among others Holland and Bangladesh. Holland has the money to build embankments but a developing country like Bangladesh has not.
A further increase of the temperature will also cause increased drought in areas already plagued with too much sun. This will hurt the agriculture both in developed countries but also in the developing countries. If the world does not act the result will be more people suffering from starvation. Animals, viruses and bacteria will also have to find new habitats with a temperature they are used to. The consequence of this is extinction of animals and the spread of new diseases in areas already populated by humans. Global warming is a threat to the health of the humans and animals.
Predictions of global warming
Predictions show that if the growth in emissions of the greenhouse gases continues temperatures on Earth will increase with up to 5.8 degrees Celsius by the year 2100. The highest increase of temperature will occur on the South and the North Pole while the biggest oceans in general will not get hotter[5].
Computers calculate the future weather conditions based on what scientists know about meteorology today and these calculations carry great inaccuracy.
Is mankind causing global warming?
That Earth is getting warmer is a fact no one questions today. However, whether the global warming is caused by humans or is a natural phenomenon still divides scientists in two groups. Environmental groups and most scientists cause humans while scientists paid by oil companies claim that global warming is a natural phenomenon caused by things not controllable by humans.
The Earth has experienced changes in the temperature earlier [6]. Last time Earth experienced a change in the climate was in the medieval age but samples from the ice core on Greenland shows that climate changes also occurred 6,000 years ago, 125,000 years ago, and 90-120 million years ago. However, the ice core also reveals the cause of these changes: natural changes, volcanoes and the like.
Around 1970 scientists began collecting temperatures from the last centuries. Although there were differences in each collection a rise in the temperature was seen in every collection. The temperature was stable until the end of the 19th century. It was also in the end of the 19th century that the industrial age began. In contrast to many of the earlier fluctuations the increase in the end of the 19th century was global.
The increase of the temperature could also have happened because of volcanic eruptions, changes in solar luminosity, or because of the natural interactions between the oceans and the atmosphere. However, more and more scientists gather around the conclusion that human emission of greenhouse gases is causing the Earth to heat up. Whether the fault of the global warming is at humans alone scientists cannot agree on. According to a study mentioned in the New York Times in 2000 [8] the earlier mentioned alternatives are not able to participate in the global warming as much as greenhouse gases. Therefore the study concludes that humans have to play the biggest role in the global warming we are experiencing now.