What is Global Warming

    In its most commonly used sense, “global warming” refers to the gradual warming of global-average temperatures due to the slowly increasing concentrations of man-made atmospheric greenhouse gases, primarily carbon dioxide. But global warming can alternatively refer to simply the observation of warming, without implying the cause(s) of that warming. 


   The burning of fossil fuels, mainly petroleum and coal, produces carbon dioxide as one of the by-products. As of 2010, the concentration of carbon dioxide is about 50% higher than it was before the start of the industrial revolution in the late 1800's. The potential warming effect of the extra CO2 is through its ability to absorb and emit infrared radiation, which is the type of radiation the Earth continually loses to outer space in response to heating by sunlight. This makes carbon dioxide a greenhouse gas, albeit a weaker one in the atmosphere than water vapor

   The net effect of greehouse gases on is to keep the lower layers of the atmosphere warmer that they otherwise would be without those gases. Therefore, it has seemed reasonable to assume that an increase in greenhouse gases would lead to warming.

Definition provided by Weather Questions

Enhanced Greenhouse Effect and Global Warming 

        It is obvious that there are plenty of natural phenomenon that can effect the global temperatures.  The Earth produces it's own greenhouse gases like water vapor and carbon dioxide.  The term enhanced when referring to climate change means caused by humans 

Possible  Causes of Global Warming



 

Solar Flare 

 A recent study by researchers at Duke University and the Army Research Office has found new evidence of a link between solar flare activity and the earth's temperature. The work is another contribution to the ongoing debate over global warming and its causes. A strong link between solar flares and our climate, if it exists, could override the influence humans have on the temperature of our environment. One of the challenges of determining the connection between solar flare activity and the atmosphere stems from the fact that the motion of the air that blankets our planet is turbulent and complex. A sudden burst of solar activity would, in effect, be smeared out by moving air and its interaction with the earth's surface. Any temperature increase caused by a given period of solar flare activity would be difficult to determine, at best. Rather than focus on such challenging one-to-one correlations, the new study compares the form of the statistical fluctuations in solar flare activity with the form of the statistical fluctuations of the earth's temperature.

Information provided by American Institutes of Physics 

 

Volcanic Activity 

   For many years, climatologists have noticed a connection between large explosive volcanic eruptions and short term climatic change. For example, one of the coldest years in the last two centuries occurred the year following the Tambora volcanic eruption in 1815. Accounts of very cold weather were documented in the year following this eruption in a number of regions across the planet. Several other major volcanic events also show a pattern of cooler global temperatures lasting 1 to 3 years after their eruption.

Information Provided by Physical Geography 



 

 Variations in the Earth's Orbital Characteristics

 Milankovitch Theory describes the collective effects of changes in the Earth's movements upon its climate, named after Serbian civil engineer and mathematician Milutin Milanković, who worked on it during First World War internment. Milanković mathematically theorised that variations ineccentricityaxial tilt, and precession of the Earth's orbit determined climatic patterns on Earth.

The Earth's axis completes one full cycle of precession approximately every 26,000 years. At the same time the elliptical orbit rotates more slowly. The combined effect of the two precessions leads to a 21,000-year period between the seasons and the orbit. In addition, the angle between Earth's rotational axis and the normal to the plane of its orbit, obliquity, moves from 22.1 degrees to 24.5 degrees and back again on a 41,000-year cycle; currently, this angle is 23.44 degrees and is decreasing.

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Greenhouse Gases 

 When sunlight reaches Earth's surface some is absorbed and warms the earth and most of the rest is radiated back to the atmosphere at a longer wavelength than the sun light. Some of these longer wavelengths are absorbed by greenhouse gases in the atmosphere before they are lost to space. The absorption of this long wave radiant energy warms the atmosphere. These greenhouse gases act like a mirror and reflect back to the Earth some of the heat energy which would otherwise be lost to space. The reflecting back of heat energy by the atmosphere is called the "greenhouse effect".

The major natural greenhouse gases are water vapor, which causes about 36-70% of the greenhouse effect on Earth (not including clouds); carbon dioxide CO2, which causes 9-26%; methane, which causes 4-9%, and ozone, which causes 3-7%. It is not possible to state that a certain gas causes a certain percentage of the greenhouse effect, because the influences of the various gases are not additive. Other greenhouse gases include, but are not limited to, nitrous oxide, sulfur hexafluoride, hydrofluorocarbons, perfluorocarbons and chlorofluorocarbons.

Information Provided by Time for a Change