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Anthropogenic greenhouse gas emissions  are resulting in climate change.  It is difficult to conceptualize the effects of greenhouse gasses.  The effects of greenhouse gases in the atmosphere is very similar to the effects of humidity.  Humid regions are known for being very hot.  The humidity in the air traps "extra" energy in the atmosphere resulting in a net increase in temperature.  In hot humid regions temperatures generally do not cool down at night as the surface radiation is trapped by humidity in the air. Greenhouse gases cause climate change in the same way humidity does by trapping extra energy in the atmosphere.  The main difference is that greenhouse gases stay in the atmosphere almost permanently and are not localized as humidity.   Carbon dioxide is a major greenhouse gas, but other greenhouse gasses include methane, and nitrous oxides. 

Sources of radioactive forcing [IPCC]

Here is another way to explain the affects of greenhouse gasses affects on climate change.  During the day incoming solar radiation is absorbed by the atmosphere and on the surface of the earth surface (see figure below).  At night the surface of the earth radiates energy. Greenhouse gasses "trap" the radiated energy resulting in a net increase in energy in the atmosphere.   This energy results in a net increase in global temperatures. 

Estimate of the Earth’s annual and global mean energy balance. Over the long term, the amount of incoming solar radiation absorbed by the Earth and atmosphere is balanced by the Earth and atmosphere releasing the same amount of outgoing longwave radiation. About half of the incoming solar radiation is absorbed by the Earth’s surface. This energy is transferred to the atmosphere by warming the air in contact with the surface (thermals), by evapotranspiration and by longwave radiation that is absorbed by clouds and greenhouse gases. The atmosphere in turn radiates longwave energy back to Earth as well as out to space. Source: Kiehl and Trenberth (1997). [Source: IPCC]

Various global climate forces exist. Some natural and some anthropogenic.  Scientist agree that anthropogenic forces are resulting in a net increase in global surface temperature inc.  Greenhouse gases are emitted from residential, industrial, agricultural, transportation and electric sectors .   The primary anthropogenic surface temperature increase is due to increased atmospheric carbon dioxide concentrations.

Large amount of carbon dioxide are emitted to the atmosphere through combustion.  Carbon dioxide is a primary byproduct of combustion of any carbon based fuel.  For example for methane CH₄+2 O₂ -->CO₂ +2 H₂O.  One carbon dioxide is emitted for every methane burned.  The more carbon intensive the fuel the more carbon dioxide is generated through combustion.  Methane contains much less carbon then petroleum which contains much less carbon then coal.  When one mole of coal is burned many moles (>10) of carbon dioxide are emitted.

We are definitively affecting global climate, and we need to be ready for the unavoidable increase in global surface temperatures.  The reader is referred to http://www.ipcc.ch/ for detailed scientific explanation of global climate change and projected impacts. 

Global and Continental Temperature Change [IPCC]

Header: Glacier melting in Alaska (NOAA Photo Gallery, Commander John Bortniak)