It may take decades to determine how high sea level will rise

Our new study, released today in Earth’s Future, links a framework for global and local sea-level rise projections with simulations of two major mechanisms by which climate change can affect the vast Antarctic ice sheet. As I explain in a Climate Impact Lab Insights post:

Consider two roads. One leads to 2 feet of global-average sea-level rise over the course of this century, and swamps land currently home to about 100 million people. The other leads to 6 feet of rise, swamping the homes of more than 150 million. Our new study, published today in the journal Earth’s Future, finds that – at least from measurements of global sea level and continental-scale Antarctic ice-sheet changes – scientists won’t be able to tell which road the planet is on until the 2060s.

But our study also shows that the world can make the 2-foot road much more likely by meeting the Paris Agreement goal of bringing net greenhouse gas emissions to zero in the second half of this century. And through detailed studies of the local physics of ice-sheet changes and more refined reconstructions of ice-sheet changes during warm periods of the geological past, scientists may become able to distinguish between the two roads sooner.

Until then, though, decision-makers at all scales – from homeowners to governments — should plan for the future cognizant of this ambiguity.

The new findings stem from an analysis that links a widely-used framework for projecting how sea level around the world will respond to climate change to a model that accounts for recently identified processes contributing to Antarctic ice loss.

Read more at Climate Impact Lab Insights.