“While the increase in carbon dioxide in the atmosphere is the main effect of global warming, there are other effects as well. For example, there is a marked increase in infectious diseases that have changed their range in the past few years. Cases of malaria and dengue fever have occurred as far north as New York, New Jersey and Michigan in recent years, and diseases such as encephalitis and becoming more common. The sea level has changed, affecting low-lying areas and destroying beaches and wetlands around the world. Glaciers and snow cover are gradually disappearing on all five continents. And finally, plant and animal populations are shifting and migration patterns are changing as species try to adapt to changing climates. Some species that are unable to adapt successfully have begun to decline. More severe weather events, such as droughts and flooding, are also a consequence of global warming, and a warning that action must be taken to preserve the environment now.”(From “The Sierra Club Global Warming Campaign” in J. Buckley, ed., The Harbrace Reader for Canadians, p. 273)From what perspective does the passage discuss global warming?