Ice core samples, like this one collected in Antarctica in 1993, are used to support and disprove theories about climate change.

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Anthropogenic Skeptics

A 2003 research paper published in the journal Science discussed the analysis of three ice core samples taken from Antarctica. The ice was around 240,000 years old, from the third Termination period, a climactic shift which ends each ice age. The findings showed that carbon dioxide concentrations rose between 600 to 1000 years before temperatures did, and before the Antarctic glaciers began to melt. The paper's authors suggested that carbon dioxide may not be the cause of global warming, but that it contributes to the process: Rising temperatures release carbon dioxide trapped in glacial ice and elsewhere, causing global temperature to rise even further.

This paper shows that the carbon dioxide increases may follow rising temperatures, not the other way around. What's more, the ice samples suggest this is a natural process. This observation is just one of the factors that, in the eyes of anthropogenic global warming skeptics, lets humans off the hook for global warming. Although they are satisfied with findings that the Earth is in a major warming trend, anthropogenic global warming skeptics believe that science places the blame on humanity without enough scientific proof to back it up.

Skeptics of anthropogenic climate change claim that reports compiled by the Intergovernmental Panel on Climate Change are the result of diplomatic negotiations, rather than unbiased science. For example, a representative from an oil-producing state may object to including analysis which is particularly harsh toward use of fossil fuels in a report. If all of the science isn't present in the reports released by the IPCC, skeptics reason, what else is missing?

For example, in 2001, the IPCC used a graph nicknamed the "hockey stick," produced by climatologist Michael Mann, in its Third Assessment Report. The graph clearly shows the effects of human activity on climate change, with a spike upwards around the advent of the Industrial Revolution, when humanity's carbon dioxide emissions began in earnest. This graph is a dramatic representation of humankind's interference with nature and appears to be irrefutable proof of anthropogenic climate change.

But skeptics investigating Mann's methods believe that he had misused some data, specifically data from tree rings which indicated a response to carbon dioxide rather than temperature, to make his graph show the results he wanted. Mann vehemently defends his methodology.

Regardless of who or what is to blame, if anthropogenic climate change skeptics believe in global warming, then where's the rub? Read on to find out about what's at stake in the debate over climate change.