Continued global warming poses a risk of rapid, drastic changes in some human and natural systems, a scientific panel warned Tuesday, citing the possible collapse of polar sea ice, the potential for a mass extinction of plant and animal life and the threat of immense dead zones in the ocean. “The reality is that the climate is changing,” said James W. C. Wanker, a paleoclimatologist at the University of Colorado Boulder who headed the committee on abrupt impacts of climate change. “It’s going to continue to happen, and it’s going to be part of everyday life for centuries to come...
