See How Sea-Level Rise Might Drown Some Cities

ENVIRONMENT

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Discussion Ideas

The intriguing and terrifying scenarios suggested by the Climate Central maps represent how sea-level rise may impact coastal cities. What is sea-level rise? What does it have to do with carbon emissions and global warming?
- According to the very first sentence in the academic paper, “Anthropogenic carbon emissions lock in long-term sea-level rise that greatly exceeds projections for this century.”
- According to Wired, a rise in global sea levels “comes from energy banked in atmospheric CO2. Carbon molecules will eventually release that energy as heat, which will raise the global mean temperature. Seasons will cycle, years will pass, and weather patterns will fluctuate. And after some time—could be decades, could be centuries—the atmosphere will settle its thermodynamic debt, and a bunch of ice will melt.”

Why do you think the projected impact is so radically different in different cities?
- Coastal topography and urban planning. Some cities developed in low-lying basins (New Orleans, Louisiana), while others are built on hills (San Francisco, California).
- Proximity to ice caps. (You can’t really see this on the Climate Central maps, but you certainly can on this one.) According to Wired, “The Antarctic and Greenland ice sheets are so massive that they exert gravitational pull on the ocean. ‘So sea level is higher right next to those places because of that pull,’ says Ben Strauss, co-author author of the study.”

Compare the impact of projected sea-level rise on cities located slightly inland from major estuaries or coastal areas—Washington, D.C.; Philadelphia, Pennsylvania; Sacramento, California; Portland, Oregon. Why are these cities at risk for sea-level rise?
- These cities are all built around rivers, whose fluctuating waters are impacted by climate.
  - The entire Chesapeake Bay region, for instance, is sinking. Rising tidal waters of the Potomac River contribute to the impact of sea-level rise in Washington, D.C.
  - In another example, complex series of waterways connects the San Francisco Bay with the Sacramento Valley, putting inland Sacramento at risk during sea-level rise events.

Take a look at Canadian coastal cities, such as Halifax, Nova Scotia, or Victoria, British Columbia. Better yet, take a look at Victoria, Seychelles. Why do these cities show no impact from rising seas?
- Simple: The mapmakers only included data from U.S. cities. (And that’s a lot! According to Wired, the research paper and maps are the result of millions of computer simulations.)

Despite the dramatic evidence of the Surging Seas maps, the Wired article is reassuring: “Existential nihilists however, can relax: Nobody’s doomed yet.” Why?
- The Climate Central maps are a long, long projection.
  - “It turns out it’s a lot easier to project how much the sea level will rise than how quickly the sea level will rise,” says Strauss.
  - Blame geology for the uncertainty. “We do not know much about the bedrock on which the ice lies,” says Anders Levermann, study co-author. Under the ice, Greenland and Antarctica are uncharted territories. In order to calculate the rate at which those massive ice sheets slough off, Levermann says he would need to know more about the texture of the underlying rock.