Global warming is driving humanity toward unprecedented risks, a United Nations scientific panel reports, warning that the changes have only just begun, with the worst effects hitting the earth’s poorest people the hardest. Recent disasters such as killer heat waves in Europe, wildfires in the United States, droughts in Australia and deadly flooding in Mozambique, Thailand and Pakistan highlight how vulnerable humanity is to extreme weather, according to a sweeping new report (PDF) from a Nobel Prize–winning group of scientists, released on Monday in Japan. The dangers are going to worsen as the climate changes even more, the report's authors say, adding that no one on earth is immune. "We're all sitting ducks," Princeton University professor Michael Oppenheimer, one of the main authors of the 32-volume report from the Intergovernmental Panel on Climate Change, said in an interview. After several days of late-night wrangling, more than 100 governments unanimously approved the 49-page report summary, which is aimed at world political leaders. It contains the word "risk" an average of more than five times per page. "Changes are occurring rapidly, and they are sort of building up that risk," said the lead author of the report, Chris Field of the Carnegie Institution for Science in California.

Worse than predicted

Those risks are big and small, current and future, according to the report. They will hit rural farms and big cities. Some places will have too much water and some not enough, including drinking water. Other risks mentioned in the report involve food prices and availability and, to a lesser and more qualified extent, some diseases, financial costs and even world peace. "Things are worse than we had predicted" in 2007, when the group of scientists last issued this type of report, said report co-author Saleemul Huq, director of the International Centre for Climate Change and Development at Independent University in Bangladesh. "We are going to see more and more impacts, faster and sooner than we had anticipated." The problems have gotten so bad that the panel had to add a new, greater level of risks. In 2007, the top risk level in one key summary graphic was high and colored blazing red. The latest report adds a level, very high, and colors it deep purple. You might as well call it a "horrible" risk level, said report co-author Maarten van Aalst, a top official at the International Federation of Red Cross and Red Crescent Societies. "The horrible is something quite likely, and we won't be able to do anything about it," he said. The report predicts that the highest level of risk would first hit plants and animals, on land and in the acidifying oceans. Climate change will worsen problems that society already has, such as poverty, sickness, violence and refugees, according to the report. And on the other end, it will act as a brake, slowing the benefits of a modernizing society, such as regular economic growth and more efficient crop production, it says. "In recent decades, changes in climate have caused impacts on natural and human systems on all continents and across the oceans," the report reads. And if society doesn't change, the future looks even worse. "Increasing magnitudes of warming increase the likelihood of severe, pervasive and irreversible impacts." While the problems from global warming will hit everyone in some way, their severity won't affect people equally, coming down harder on people who can least afford it, the report says. It will increase the gaps between rich and poor, healthy and sick, young and old and men and women, van Aalst said. "Read this report and you can't deny the reality: Unless we act dramatically and quickly, science tells us our climate and our way of life are literally in jeopardy. Denial of science is malpractice," U.S. Secretary of State John Kerry said Monday in a press release. Kerry said, "No single country causes climate change, and no one country can stop it," adding that the White House Climate Action Plan aims to reduce U.S. emissions and increase renewable energy sources ahead of the U.N. Convention on Climate Change. But the report's authors say this is not a modern-day version of the Four Horsemen of the Apocalypse. Much of the caution comes from more nuanced troubles that grow by degrees and worsen other societal ills. The report also concedes that there are uncertainties in understanding and future climate risks. The report, the fifth on warming's implications, includes risks to ecosystems, including a thawing Arctic, but it is far more oriented than past versions to what it means to people. The report also notes that one major area of risk is that with increased warming, incredibly dramatic but extremely rare single major climate events, sometimes called tipping points, become more possible, with huge consequences for the globe. These are events like the melting of the Greenland ice sheet, which would take more than 1,000 years. "I can't think of a better word for what it means to society than the word 'risk,'" said Virginia Burkett of the U.S. Geological Survey, one of the study's main authors. She calls global warming "maybe one of the greatest known risks we face."

‘Poorer people lose out’