The bad news is that we’re all but certain to end up with a coastline at least this flooded (20 meters or 69 feet):
The “good” news is that this might take 1000 to 2000 years (or longer), and the choices we make now can affect the rate of rise and whether we blow past 69 feet to beyond 200 feet.
Glaciologist Jason Box makes this point in a Climate Desk interview with Chris Mooney, “Humans Have Already Set in Motion 69 Feet of Sea Level Rise“:
So what can we do? For Box, any bit of policy helps. “The more we can cool climate, the slower Greenland’s loss will be,” he explained. Cutting greenhouse gases slows the planet’s heating, and with it, the pace of ice sheet losses.
This shouldn’t be a surprise to anyone who follows the scientific literature. Just last year the National Science Foundation (NSF) reported on paleoclimate research that examined “rock and soil cores taken in Virginia, New Zealand and the Eniwetok Atoll in the north Pacific Ocean.” Lead author Kenneth Miller of Rutgers University said:
“The natural state of the Earth with present carbon dioxide levels is one with sea levels about 70 feet higher than now.”
And that was only slightly less worrisome than a 2009 paper in Science that found the last time CO2 levels were this high, it was 5° to 10°F warmer and seas were 75 to 120 feet higher.
Now I tend to think that if the multiple, simultaneous devastating impacts we are headed toward by century’s end — from widespread Dust-Bowlification to 3 to 6 feet of sea level rise to 10°F warming (20°F in the Arctic) — isn’t enough to motivate action, then just how much we are going to screw up the planet after 2100 won’t do the trick.
But there are some people who understand the staggering immorality of handing over to future generations seas rising as fast as 6 to 12 inches a decade for centuries on end. How precisely would people adapt to that? As one thoughtful person recently said, failure to act on climate change “would betray our children and future generations.”
Here is a short video of the Box interview:
If we were truly doubly wise, homo sapiens sapiens, as we cleverly named ourselves, the nation would join with the world in a WWII-scale effort to actually reduce the atmospheric CO2 level from its current 394 parts per million. That would not only lower the ultimate sea level rise, but would slow down the rate of change.
Tragically, we are headed for more than a doubling of CO2 concentrations from current levels. For those truly concerned about future generations, consider that on our current emissions path, CO2 levels in 2100 will hit levels last seen when the Earth was 29°F (16°C) hotter. So that not only means an ice-free planet with sea levels more than 200 feet higher than today, but a rate of sea level rise that is beyond imagining.