A U.N. report shows that climate change hits poorer countries hardest.

William Orme with the United Nations Development Program explains:

"They tend to be arid, they tend to be rural, and they tend to be therefore most vulnerable to extreme weather events, drought, typhoons and deteriorating productivity of their soil resources, forest resources and fisheries," Orme said.

And global efforts to curb emissions and slow change have not helped yet. Again climate scientist Todd Sanford:

"Last year saw the largest single increase in history to the largest emissions amounts," Sanford said.

NASA satellite evidence shows solar fluctuations have only a slight impact on global temperatures.

And while the vast majority of climate scientists agree that human activities play a role in climate change, they are not certain how that affects the planet.

Fred Singer is a well known climate change skeptic. He says there is not enough evidence to link human activities, climate change and environmental impacts.

"Supposing the other side is wrong? They are forcing us to make tremendous economic sacrifices which will induce poverty in the world," Singer said.

Other climate change scientists counter that argument, saying greener technologies can be viable -- environmentally and economically.