With the recent release of the movie entitled An Inconvenient Truth, the discourse surrounding global warming has intensified. The basis of the movie is that the vast majority of scientists agree that global warming is a genuine phenomenon which mankind is accelerating to our own detriment.Carbon dioxide and other gases warm the surface of the Earth naturally. The gases trap solar heat in our atmosphere. This is what makes our planet both unique and habitable. The problem of global warming has been linked to burning fossil fuels including coal, gas and oil. In addition, clear-cutting forests contribute to global warming because fewer trees make it more difficult for the planet to neutralize the negative effects of increased levels of carbon dioxide in the atmosphere.The movie asserts that there already exists serious evidence of the consequences our actions are having on our planet. There are multitudes of statistics which were released through the movie and describe a dire situation unless we all take action now. Scientists predict that sea levels will increase more than 20 feet within the next few decades, threatening coastal life. More startling, the Artic Ocean could be completely melted by 2050. The number of severe hurricanes is expected to steadily increase within the next few decades and heat waves will become more frequent and intense.While many are certain the concerns over global warming are legitimate others criticize its supporters. Critics claim that there is no scientific basis for believing that humans are influencing the intensity or speed of global warming. Moreover, they argue that governments and businessmen push the environmental agenda in order to instill fear in the general public. Critics believe that global warming claims are politically motivated.Whatever side of the argument someone takes there is something we could all certainly agree upon; the sustained health of the planet is the single most important collective goal of humankind. How we choose to manage it will naturally be strongly debated but its importance is irrefutable.
What makes some people critical of those who claim that global warming is legitimate, according to paragraph (4)?