In 2016, nearly 200 world leaders pledged to do everything possible to limit global warming to 1.5 degrees Celsius. Since then, policymakers across the globe have designed countless laws around the assumption that warming would never cross that threshold. In 2016, nearly 200 world leaders pledged to do everything possible to limit global warming to 1.5 degrees Celsius. Since then, policymakers across the globe have designed countless laws around the assumption that warming would never cross that threshold. Earth Sciences Environment Phys.org – latest science and technology news stories