from National Geographic article

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Just as the evidence is irrefutable that temperatures have risen in the last century, it's also well established that carbon dioxide in the Earth's atmosphere has increased about 30 percent, enhancing the atmosphere's ability to trap heat.

The exact link, if any, between the increase in carbon dioxide emissions and the higher temperatures is still under debate.

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Industrialization taking it's toll on the world. Decreasing the amount of plants and trees in the world in combination with the oxidation of carbon monoxide has solely caused the increase in carbon monoxide. The interesting part is that the model is not consistant...when ice melts, it melts uniformly (if in fact global warming was the cause because heat dissapates evenly) but as you see in the pictures, the ice is melting faster in certain sections denoting increases in heat in specific areas. Hmmmm, should do research.