Sea levels could be around a meter (3.3 feet) higher and the Arctic could be ice-free in the summer by 2100, the UN’s climate science committee has concluded.

Sea-level fears: This is 10 centimeters  (3.9 inches) higher than the Intergovernmental Panel on Climate Change predicted six years ago. The change is because Antarctica is melting faster than expected. The revised estimate could be hugely significant to the 600 million people around the world who live less than 10 meters above sea level. It also suggests that countries urgently need to start spending money to shore up sea defenses, as the Global Commission on Adaptation recently warned.

The report: It was compiled by more than 100 scientists from over 80 countries, who looked at the effect that climate change will have on the oceans covering the vast majority of the Earth’s surface.

More bad news: Extreme events like storm surges, which used to happen once a century, will occur every year in many parts of the world by 2050, no matter whether greenhouse-gas emissions are curbed or not, the IPCC said. If we drastically reduced emissions, it would help mitigate some of the worst effects. However, many of the impacts outlined in the report are already “priced in” thanks to the amount of carbon we have emitted.

Impact on food: The report also warns of a vast loss of marine life as the ocean gets hotter, less oxygenated, and more acidic. This could be dangerous for the billions of people around the world who rely on seafood as their primary source of protein.

Up the pressure: The study arrives amid rising activism over climate change, and in the wake of a UN climate summit that included a lot of talk, but not much action, from the world’s biggest emitters.