READ: Climate Change
Climate Change
Global Climate Change
Another major problem caused by air pollution is global climate change. Gases such as carbon dioxide from the burning of fossil fuels increase the natural greenhouse effect. This raises the temperature of Earth’s surface.
Causes of Climate Change
The average global temperature has been rising since the end of the Pleistocene which was about 11700 years ago, with some ups and downs, of course. Rising temperatures are natural for this time period. But natural causes cannot explain all the warming that's been happening in recent decades. There is some other factors at work.
Recent global warming is due mainly to human actions. The actions involve releasing greenhouse gases into the atmosphere.
What Is the Greenhouse Effect?
The greenhouse effect is a natural feature of Earth’s atmosphere. It occurs when gases in the atmosphere radiate the sun’s heat back down to Earth’s surface (see Figure below). Otherwise, the heat would escape into space. Without the greenhouse effect, Earth’s surface temperature would be far cooler than it is. In fact, it would be too cold to support life as we know it.
The Greenhouse Effect. Without greenhouse gases, most of the sun’s energy would be radiated from Earth’s surface back out to space.
Global Warming
Global warming refers to a recent increase in Earth’s average surface temperature (see Figurebelow). During the past century, the temperature has risen by almost 1°C (about 1.3°F). That may not seem like much. But consider that just 10°C is the difference between an ice-free and an ice-covered Earth.
The average annual temperature on Earth has been rising for the past 100 years.
Most scientists agree that global warming is caused by more carbon dioxide in the atmosphere (see Figure below). This increases the greenhouse effect. There is more carbon dioxide mainly because of the burning of fossil fuels. Destroying forests is another cause. With fewer forests, less carbon dioxide is removed from the atmosphere by photosynthesis.
This graph shows the recent trend in carbon dioxide in the atmosphere.