Global warming's effects now still may be more pesky than catastrophic. But a new scientific report says that when the Earth gets a few degrees hotter, inconvenience will give way to danger, death and extinction of species.
The world faces increased hunger and water shortages in the poorest countries, massive floods and avalanches in Asia, and species extinction unless nations adapt to climate change and halt its progress, according to a report approved Friday by an international conference on global warming.
The poorest parts of the world, especially Africa and Asia, will be hit hardest, says the summary from the Intergovernmental Panel on Climate Change, issued Friday after a long, contentious editing session.
Poor countries argue that they will suffer due to global warming caused by greenhouse gasses produced in the rich industrial world. At the same time, they're being told not to produce more greenhouse gasses of their own as they try to industrialize their way out of poverty, reports CBS News correspondent Mark Phillips.
But, despite an all-night session described as very contentious, the major thrusts of the report could not be watered down. It concludes that those who are already suffering most in this world are going to suffer worst due to global warming.
"Don't be poor in a hot country, don't live in hurricane alley, watch out about being on the coasts or in the Arctic, and it's a bad idea to be on high mountains with glaciers melting," said Stanford University scientist Stephen Schneider, an author of the study.
The 23-page document, the first part released of the full 1,572-page document written and reviewed by 441 scientists, and the second of four reports, tries to explain how global warming is changing life on Earth.
The Bush administration remains opposed to mandatory caps on greenhouse gas emissions, CBS News White House correspondent Peter Maer reports. It prefers international cooperation to curb pollution. The president has argued that the mandatory caps on greenhouse gas emissions would hurt the economy.
Even though some of the scientists' direst prose was toned down or lost, the panel's report was gloomy — with a bit of hope at the end.
Africa by 2020 is looking at an additional 75 to 250 million people going thirsty because of climate change, the report said. Deadly diarrhea diseases "primarily associated with floods and droughts are expected to rise" in Asia because of global warming, the report said.
But many changes to the report, made during a meeting of government negotiators from more than 120 countries, play down some of the dangers forecast by the authors — all eminent scientists.
"Many millions more people are projected to be flooded every year due to sea-level rise by the 2080s," the report said. "The numbers affected will be the largest in the mega-deltas of Asia and Africa while small islands are especially vulnerable."
The draft version proposed by scientists had said "hundreds of millions" of people would be vulnerable to flooding, rather than "many millions."
The final report also dropped any mention of the possibility that up to 120 million people are at risk of hunger because of global warming, referring instead to "complex localized negative impacts on small holders, subsidence farmers and fishers."
The first few degrees increase in global temperature will actually increase global food supply, but then it will plummet, according to the report.
An increase of just about 2 degrees Fahrenheit could mean "up to 30 percent of the species at increasing risk of extinction," the report said. If the globe heats a few more degrees, that changes to "significant extinctions around the globe."
"The poorest of the poor in the world — and this includes poor people in prosperous societies — are going to be the worst hit," said Rajendra Pachauri, chairman of the climate change panel. "People who are poor are least able to adapt to climate change."
But even rich countries, such as the United States, say the report tells them what to watch for.
The report came as no surprise to many in the American West, where devastatingly costly wildfires have become the norm, reports CBS News correspondent Jerry Bowen. In just 34 years, the average time between discovery and control of wildfires has gone from seven and a half to 37 days, and the length of the fire season has increased by more than two and a half months.
The head of the U.S. delegation, White House associate science adviser Sharon Hays, said a key message she is taking from Brussels to Washington is "that these projected impacts are expected to get more pronounced at higher temperatures. ... Not all projected impacts are negative."
"This report ... is a challenge to government, it's a challenge to the U.S. Congress. It paints a very clear and disturbing picture of the consequences," Ben Dunham of the U.S. Public Interest Research Group told CBS News.
Schneider said a main message is not just what will happen, but what already has started: melting glaciers, stronger hurricanes, deadlier heat waves, and disappearing or moving species.
Meanwhile, a study by the University of Minnesota Duluth reports that Lake Superior has been warming even faster than the climate around it since the late 1970s due to reduced ice cover.
Summer surface temperatures on the famously cold lake have increased about 4.5 degrees since 1979, compared with about a 2.7-degree increase in the region's annual average air temperature, the researchers found. The lake's "summer season" is now beginning about two weeks earlier than it did 27 years ago.
"Milder winters are causing less ice cover. In fact, it turns out that summer temperatures are more strongly a function of how much ice there is the previous winter than of the summer climatological conditions," Jay Austin, an assistant professor with the university's Large Lakes Observatory and Department of Physics, told CBS News. Austin co-authored the study with geology professor Steve Colman.
All the changes can be traced directly to greenhouse gases from the burning of fossil fuels.
"There is a discernible human influence on these changes" that are already occurring as threats to species, flooding, extreme events such as heat waves and hurricanes, said NASA scientist Cynthia Rosenzweig, a lead author on the chapter detailing what has happened.
Martin Parry, who conducted the closed-door negotiations, said with 29,000 sets of data from every continent, including Antarctica, the report firmly and finally established "a man-made climate signal coming through on plants, water and ice."
"For the first time, we are not just arm-waving with models," Parry said.
But the models the scientists did use for their forecasts gave them plenty of confidence in their findings. Near-term effects of fewer cold days — increased food production, decreased heating bills — are more than 99 percent certain, the report said. Increased heat waves that cut food production in warmer climates and increase wildfires, demand on water and deaths from excessive heat among the poor, elderly and very young are more than 90 percent likely.
There is a better than two-out-of-three chance that more land will be affected by drought, widespread water stress, food shortages, malnutrition, and disruption to coastal life from storms, the report said.
But many of the worst effects are not locked into the future, the report said in its final pages. Humans can build better structures, adapt to future global warming threats and can stave off many by reducing greenhouse gas emissions, scientists said.
"There are things that can be done now, but it's much better if it can be done now rather than later," said scientist and report author David Karoly of the University of Oklahoma.
Because carbon dioxide stays in the air for nearly a century, it will be decades before society sees that changes make a difference on global warming effects, scientists said.
"We can fix this," by investing a small part of the world's economic growth rate, said Schneider. "It's trillions of dollars, but it's a very trivial thing."