Sep. 27, 2013 5:32pm Liz Klimas
This week, the U.N.’s International Panel for Climate Change gathered to finalize its fifth assessment report regarding the state of the environment, stating that global warming is ”extremely likely” to have been human caused.
These are the strongest words yet on the issue — and it was something those gathered outside in Stockholm felt the need to scream about as they took it as confirmation that governments should take action. But as some screamed, others who are skeptical questioned.
People scream outside the United Nations Intergovernmental Panel on Climate Change (IPCC) to demand immediate political action on Climate debate on September 27, 2013 in Stockholm.

The panel said it was more certain than ever that humans were the cause of global warming and predicted temperatures would rise another 0.3 to 4.8 degrees Celsius this century. (Photo: JONATHAN NACKSTRAND/AFP/Getty Images)

The IPCC completed its fifth assessment report, which is important as it drive’s some governments to take action against climate change. There has long been a debate over whether action should be taken to mitigate climate change and, if so, what. (Photo: JONATHAN NACKSTRAND/AFP/Getty Images)

It took 259 authors from 39 countries and more than 54,000 comments to draft the report, which for weeks has been leaked through the media ahead of its final release.
But now a summary of the report for policymakers is out with the full 2,000-page document expected to be released Monday. It contained few surprises as many of the findings had been leaked in advance.
(From L to R) Moderator Jonathan Lynn, Secretary-General of the WMO Michel Jarraud, Chairman of the Intergovernmental Panel on Climate Change (IPCC) Rajendra K Pacahauri, Co-Chair working group 1 Thomas Stocker and Co-Chair working group 1 Dahe Qin present the first volume of its Fifth Assessment Report, first overview since 2007 of scientific evidence for climate change on September 27, 2013 in Stockholm. The report, based on a huge number of measurements globally, has been discussed this week at the IPCC’s meeting in Stockholm, bringing together hundreds of leading scientists. (Photo: JONATHAN NACKSTRAND/AFP/Getty Images)

Here are some of its key findings from the report summary:

  • Global warming is “unequivocal,” and since the 1950′s it’s “extremely likely” that human activities have been the dominant cause of the temperature rise.

  • Concentrations of CO2 and other greenhouse gases in the atmosphere have increased to levels that are unprecedented in at least 800,000 years. The burning of fossil fuels is the main reason behind a 40 percent increase in C02 concentrations since the industrial revolution.