Global warming is "unequivocal," and carbon dioxide already in the atmosphere commits the world to an eventual rise in sea levels of up to 4.6 feet (1.4 meters), the world's top climate experts warned Saturday in their most authoritative report to date.
"Only urgent, global action will do," said United Nations Secretary-General Ban Ki-moon, calling on the United States and China—the world's two biggest polluters—to do more to slow global climate change.
"Both countries can lead in their own way," Ban told reporters.
Still, he advised against assigning blame for global warming.
Climate change imperils "the most precious treasures of our planet," he said. "We are all in this together. We must work together."
Water Shortages, Extinctions, Heat
According to the UN panel of scientists, whose latest report is a synthesis of three previous ones, enough of the greenhouse gas carbon dioxide already has built up in Earth's atmosphere that it imperils islands, coastlines, and a fifth to two-thirds of the world's species.
As early as 2020, 75 million to 250 million people in Africa will suffer water shortages. Residents of Asia's large cities will be at great risk of river and coastal flooding, according to the report.
Europeans can expect extensive species loss, and North Americans will experience longer and hotter heat waves and greater competition for water. These predictions are detailed in a new report from the UN Intergovernmental Panel on Climate Change (IPCC), which shared the Nobel Peace Prize this year with former U.S. vice president Al Gore.
(Related story: "Al Gore, Climate Panel Share Nobel Peace Prize" [October 12, 2007])
The Oceans Will Rise
The panel portrays Earth hurtling toward a warmer climate at a quickening pace and warns of inevitable human suffering. It says emissions of carbon, mainly from fossil fuels, must stabilize by 2015 and go down after that.