National Geographic Maps Our Coastline After We Melt All Earth’s Ice, Raising Seas Over 200 Feet

CREDIT: (Credit: Shutterstock)

Homo sapiens sapiens, the species with the ironic name, is not known for long-term thinking. So if the prospect of Sandy-level storm surges happening every year (!) in a half century or so isn’t enough to get us to stop using the atmosphere as an open sewer for carbon pollution, then the prospect we are going to melt all of the Earth’s landlocked ice and raise sea levels more than 200 feet over the next couple of millenna or so ain’t gonna do the trick.

Still, National Geographic has been one of the few major magazines to consistently warn the public about the risks posed by unrestricted carbon pollution. And who better to be alarmed about how we are going to destroy the nation’s geography than National Geographic? Unsurprisingly, the deniers and confusionists, including Bjorn Lomborg himself, have suggested that somehow Nat Geo’s concern is misplaced. Sadly, it isn’t.

The best science suggests that on our current CO2 emissions path, by 2100 we could well pass the tipping point that would make 200+ feet of sea level rise all but unstoppable — though it would certainly take a long time after 2100 for the full melt-out to actually occur.

That said, the text on Nat Geo’s graphic is a little confusing and has the unfortunate effect of suggesting that we would need 22°F of global warming to melt all the ice on the planet, when that’s not what the paleoclimate record suggests.

The confusionists are preternaturally confused by all this. A leading denier website actually cites current data on sea ice (!) to refute Nat Geo, even though it is only melting landlocked ice that raises sea levels.

The deniers direct us to the Danish delayer’s widely unread Facebook page — seriously Bjorn, only “9,436 likes, 835 talking about this”? — where Lomborg asserts:

Needless scaremongering.

National Geographic is at it again. They present the world “if all the ice melted” — and they have the temerity to suggest it will happen with more global warming.

“If we continue adding carbon to the atmosphere, we’ll very likely create an ice-free planet, with an average temperature of perhaps 80 degrees Fahrenheit instead of the current 58.”

This, of course, is only the outcome of continuing ever larger carbon emissions for many hundreds of years, something that no one is realistically expecting.

Could we please have a sensible, non-scare conversation back at the venerable National Geographic?

“Temerity”? As the saying goes, I don’t think that word means what Lomborg thinks it means. All the ice is going to melt if we keep listening to inactivists like Lomborg.

No doubt Nat Geo was trying to bend over backwards to be conservative about what it would take to melt all the land-locked ice on the planet. In fact, James Hansen and other leading climatologists published an analysis that 6°C (11°F) of warming would be sufficient. They argue a doubling of CO2 levels from pre-industrial levels to 550 parts per million (we’re currently at about 400 rising 2+ ppm a year) would ultimately get us that level of warming, once some of the decadal amplifying feedbacks kick in.

Dr. Andrew Glikson, a paleoclimate scientist, discussed the literature supporting that view last year (here):

Studies of the evolution of the terrestrial atmosphere based on multiple proxies (carbon isotopes in phytoplankton and in fossil soils, plant leaf stomata pores, boron isotopes, boron/calcium ratios) confirm the upper stability boundary of the Antarctic ice sheet at about 500+/-50 ppm CO₂. Other estimates suggest 615 ppm CO₂ or near-800 ppm CO₂.

CO2 levels over past 80 million years. The original decline in temperature from the end-Eocene (~34 million years ago) and the onset of the Antarctic ice sheet occurred when CO₂ levels declined to below ~600 ppm.

CO2 levels over past 80 million years. The original decline in temperature from the end-Eocene (~34 million years ago) and the onset of the Antarctic ice sheet occurred when CO₂ levels declined to below ~600 ppm.

Unfortunately, humans are on a path to blow past 550 ppm and hit 800 to 1,000 ppm this century. The key point the anti-science crowd seems unaware of is that, as a 2009 NOAA-led study explained, impacts like sea level rise (and Dust-Bowlification) would be “largely irreversible for 1,000 years”:

…the climate change that is taking place because of increases in carbon dioxide concentration is largely irreversible for 1,000 years after emissions stop … Among illustrative irreversible impacts that should be expected if atmospheric carbon dioxide concentrations increase from current levels near 385 parts per million by volume (ppmv) to a peak of 450-600 ppmv over the coming century are irreversible dry-season rainfall reductions in several regions comparable to those of the ”dust bowl” era and inexorable sea level rise.

Lomborg’s idea of a “sensible” discussion may be one that ignores the science, but the fact is that the NOAA analysis gives the lie to the notion that it is a moral choice not to do everything humanly possible to prevent this tragedy, a lie to the notion that we can “adapt” to climate change — unless by “adapt” you mean “force the next 50 generations to endure endless misery because we were too damn greedy to give up 0.1% of our GDP each year.”

How fast can sea levels rise? That obviously depends on just how hot it gets. A stunning 2011 paper in Science concluded that paleoclimate data suggest CO2 “may have at least twice the effect on global temperatures than currently projected by computer models.” It found that on our current emissions path, CO2 levels in the air in 2100 will hit levels last seen when the Earth was 29°F (16°C) hotter — and remember, we’d expect polar regions to see a temperature rise of 50 percent to 100 percent higher than the global average.

There is evidence that seas can rise as fast as two inches per year for decades (see here and here). But there may not be any true paleoclimate analog to what is projected to happen in the next century alone — temperature rise in the Arctic may well exceed 20°F by a great deal. On top of that, the West Antarctic ice sheet is grounded below sea level and considered to be unstable (see here).

Both ice sheet loss and sea level rise are accelerating. And analyses suggest that sea level rise could hit four to six feet by 2100 on our current emissions path. After that, sea level could continue rising five to ten feet (or more) a century until all the ice melts. And even if it takes two millennia or longer for the ice to go, we may pass the tipping point at which a total melt-out is essentially unstoppable by 2100.

For those who are unconcerned about our impact on humans living in the year 3000 and beyond, consider this. How precisely would our children and grandchildren adapt in the second half of this century to sea level rise, knowing that seas are projected to rise, say, six to 12 inches a decade for a long, long, long time? How do you build ports and coastal defenses in such a world? How do you even decide how much to spend to protect cities on the East Coast at that time, knowing the inexorable sea level rise — and ever worsening storm surges — that they face?

Hal Wanless, chair of the geological sciences department at University of Miami, tells Nat Geo:

I cannot envision southeastern Florida having many people at the end of this century.”

Here is a close-up of the East Coast once Homo sapiens sapiens gets through with it:


The West Coast is in slightly better shape but as Nat Geo explains, “In California, San Francisco’s hills would become a cluster of islands and the Central Valley a giant bay. The Gulf of California would spread north past the latitude of San Diego — not that there’d be a San Diego.”

If we let this happen, we definitely need to come up with a name to replace Homo sapiens sapiens. I’d vote provisionally for Homo “sapiens” sapiens, but we might consider Fervens tardius amentes Rana, which is the best internet translation into Latin I could get for slowly boiling brainless frog.”