Four years after countries struck a landmark deal in Paris to rein in greenhouse gas emissions in an effort to avert the worst effects of global warming, humanity is headed toward those very climate catastrophes, according to a United Nations report issued Tuesday , with China and the United States , the two biggest polluters, having expanded their carbon footprints last year. “The summary findings are bleak,” the report said, because countries have failed to halt the rise of greenhouse gas emissions even after repeated warnings from scientists. The result, the authors added, is that “deeper and faster cuts are now required.” The world’s 20 richest countries, responsible for more than three-fourths of emissions, must take the biggest, swiftest steps to move away from fossil fuels, the report emphasized. The richest country of all, the United States, however, has formally begun to pull out of the […]