The overheated atmosphere has in turn overheated the oceans

The climate emergency is bigger than many experts, elected officials, and activists realize. Humanity’s greenhouse gas emissions have overheated the Earth’s atmosphere, unleashing punishing heat waves, hurricanes, and other extreme weather – that much is widely understood.

The larger problem is that the overheated atmosphere has in turn overheated the oceans, assuring a catastrophic amount of future sea level rise.

As oceans heat up the water rises in part because warm water expands but also because the warmer waters have initiated major melt of polar ice sheets. As a result, average sea levels around the world are now all but certain to rise by at least 20 to 30 feet. That’s enough to put large parts of many coastal cities, home to hundreds of millions of people, under water.

The key questions are how soon this sea level rise will happen and whether humans can cool the atmosphere and oceans quickly enough to prevent part of this.

If seas rise 20 feet over the next 2,000 years, our children and their descendants may find ways to adapt. But if seas rise 20 feet or more over the next 100 to 200 years — which is our current trajectory – the outlook is grim. In that scenario, there could be two feet of sea level rise by 2040, three feet by 2050, and much more to come.

Two to three feet of sea level rise may not sound like much, but it will transform human societies the world over.