Q:

Where did global warming come from?

A:

The National Wildlife Federation explains that global warming is thought to be caused by the greenhouse effect, which is the result of certain gases in the atmosphere trapping the heat of the sun and preventing it from radiating back into space. There are many gases responsible for this effect, including water vapor, carbon dioxide and methane. Artificially-produced chlorofluorocarbons, known as CFCs, are extremely effective greenhouse agents, molecule for molecule, but are present only in small concentrations.

Know More

Full Answer

Much of the sun's light passes through the earth's atmosphere and strikes the ground. The light that's reflected back up is often of a different wavelength than the incoming light. Climate Data Information explains that these wavelengths can be absorbed by molecules of greenhouse gases, which raises the temperature of the air. Water vapor, caused by evaporation, acts over a broad range of wavelengths. Carbon dioxide and methane are just as effective at absorbing energy, but over a shorter part of the spectrum.

Climate Data Information shows how some of these gases occur naturally. Methane is a natural breakdown product of certain bacteria, and water vapor enters the air naturally as part of the water cycle. Recently, however, human agriculture and industry have dramatically increased the concentrations of these gases in the air. It is estimated that since the beginning of the Industrial Revolution, humans have emitted roughly 500 billion tons of carbon dioxide, approximately half of which remains in the atmosphere. These gases are the major cause of warming over the last century, according to the National Wildlife Federation.

Learn more in Human Impact

Related Questions

  • Q:

    How does carbon dioxide cause global warming?

    A:

    Carbon dioxide contributes significantly to global warming by entering the atmosphere and waterways through many human activities, such as farming, industrial operations and changes in land use, primarily to agricultural production. Carbon dioxide occurs naturally through some activities, such as plant respiration, volcanic activities and the interaction between oceanic waters and the surrounding air. However, human activities increase the amount of carbon dioxide in the air, which in turn offsets the delicate balance of gases in the atmosphere and air temperature.

      Full Answer >
    Filed Under:
  • Q:

    Why does global warming occur?

    A:

    Global worming is caused by the retention of the energy of the Sun in the atmosphere. The Earth is warmed by light from the Sun. This light passes through the atmosphere and strikes the surface. Some of the energy is reflected back into space, while some is absorbed by the ground, water and air. The energy that isn't radiated back into space warms the Earth.

    Full Answer >
    Filed Under:
  • Q:

    Why does global warming happen?

    A:

    The primary cause of global warming is the collection of carbon dioxide in the atmosphere. Carbon dioxide and other pollutants trap heat from the sun, making the planet warmer.

    Full Answer >
    Filed Under:
  • Q:

    How do global warming doubters explain evidence of warming?

    A:

    Skeptics refute the evidence of global warming using a number of arguments, with one such question asking how scientists expect to be taken seriously when their theories are supported by both floods AND droughts? They wonder how the presence of record breaking blizzards can support the notion as well.

    Full Answer >
    Filed Under:

Explore