"The world faces a stark choice -- reduce emissions or face the fury of nature." - Dr. Ute Collier, head of the WWF's Climate Change Program

Are human activities causing the climate change?

"Most of of the warming observed over the last 12 years is attributable to human activities," according to the UN Intergovernmental Panel Change.

According to a World Wide Fund for Nature report, "at least some of the damage caused by weather extremes is due to human-induced climate change."

Much of the warming that has taken place over the past 50 years is most likely attributed to an increase in greenhouse gas concentrations from humans. However, the warming over the past 100 years is attributed to natural changes. The warming over the course of the 20th century has contributed to the sea level rise.

The four warmest years of the 20th century were all recorded in the 1990s. Although periods of increased heat from the sun have warmed the Earth, many of the world's leading climatologists believe that the greenhouse gases that people produce are warming the Earth as well, according to Environmental Protection Agency.