The gathering risks of climate change are so profound they could stall or even reverse generations of progress against poverty and hunger if greenhouse emissions continue at a runaway pace, according to a major new United Nations report. Despite rising efforts in many countries to tackle the problem, the overall global situation is growing more acute as developing countries join the West in burning huge amounts of fossil fuels, the Intergovernmental Panel on Climate Change said here on Sunday. Failure to reduce emissions, the group of scientists and other experts found, could threaten society with food shortages, refugee crises, the...