The Intergovernmental Panel on Climate Change just released the first phase of their 2013-2014 report. While proponents point to it as the magic bullet, detractors question the report calling it biased and fearmongering.
Why the fuss? Because the report takes a strong stance citing that human-emitted greenhouse gases are extremely likely (at least 95%) to be responsible for more than half of Earth's temperature increase since 1951. That's a big deal and has added fuel to the debate on this critical issue.
If you've got the time, go here for the official report:
Or any of these for summaries:
Bottom line: get informed, get engaged, have an opinion.