As bushfires rage nearby, dangerously unhealthy air in Australia's biggest city climbed "off the chart" this week, experts said. On Tuesday, Sydney's air quality index rating spiked to 2,552 — 11 times what's considered hazardous. A healthy level is under 50. "We're living in a sea of smoke and particles," a local environmental science professor said.
Is climate change a factor? Yes, experts say, offering more grim tidings: Greenland's ice sheet is melting much more quickly than expected — seven times faster than in 1992 — threatening to expose 400 million people to flooding by 2100.