Southern Louisiana faces existential threat from Global Warming.

Reported in The New Orleans Advocate, Sunday, 1 May, 2016.



Sheets of Runoff fall off the Nansen Ice Shelf in the East End of East Antarctica.

According to Sunday's article, coastal researchers Donald Boesch and Virginia Burkett, known for their expertise on reasons why the state’s coast is being flooded by the Gulf, present new findings on why Global Warming is the key to whether Southern Louisiana can be saved or not. Their findings reveal that humanity, individually and collectively, must "[k]eep global temperatures from rising more than 2 degrees Celsius (3.6 degrees Fahrenheit) by 2100, and little will change in Antarctica, which means sea-level rise could be manageable and Louisiana’s coastal plan might succeed." Ditto for Greenland.

According to the following Advocate Graphic, keeping to the 2016 COP21 Paris Accords' goal of keeping below 2 degrees Celsius would limit sea level rise to one foot above today's level at the end of this Century. With Business As Usual, the SLR will reach 6 feet globally. When you factor in Peak Oil / Natural Gas / Coal and the coming decline in fossil fuel outputs into BAU, we'll likely see somewhere in between -- unless Greenland and West Antarctica collapse rapidly, then we'll get 42 feet of SLR in a short period of time. This could actually happen! At the end of the last Ice-Age, ice melt from Antarctica led to 14½ meters of SLR per Century for about a thousand years. Total SLR then was 400 feet.

If we fail the COP21 goal, "and the result could be a sudden, dramatic melting of ice on Antarctica, adding another 3 feet to the current prediction of a 3.5-foot rise in sea level by 2100 — an event that would swamp most of the southern third of Louisiana, even if the master plan is implemented."

Here is what 6 feet of SLR in Southern Louisiana looks like. Just 1 foot looks almost as bad.

The Advocate reports, and it's basically true except for the West Antarctic which is melting like Greenland, that:

Antarctica has been melting at a drip. Indeed, the melting of the ice fields of Greenland — on the northern end of the planet — has been much faster. Located in a warmer environment, those ice fields and glaciers have been pouring water into the Arctic Ocean at rates alarming climatologists. Computer models show sea levels would rise almost 20 feet if all the ice in Greenland melts.

If all the ice in Antarctica melts, those same models show the oceans would rise 200 feet, meaning Baton Rouge would be on the coast.

But there are two monkey wrenches hidden in the Advocate's article, and one is the fact that East Antarctica is beginning to melt like Greenland did less than a decade ago. The other is the effect of gravity on the sloshing sea water in the coming Global Warming induced SLR. What is gravity's effect on sea-level rise in Southern Louisiana?

From the article (boldface emphasis mine):

Any rise would be even higher on the Louisiana coast because this area would have an increasingly strong gravitational pull as Antarctica lost all that ice, Boesch said.

“So if a certain amount of ice melts and raises global sea level by 1 centimeter, in Louisiana, that rise would be 1.2 or 2.5 centimeters,” he said. “Just another reason why we (in Louisiana) have to be really concerned about these sea-level rise figures.”

So at the maximum translation 1 foot of global sea level rise is 2½ feet, 20 feet of G-SLR is 50 feet, 200 feet, 500 feet. That's a lot of water. At just 12 or 13 feet, with our 32-foot barrier walls and seaward embankments, New Orleans will certainly drown. And Baton Rouge and the rest of the state?

The elevation of Baton Rouge is 83 feet above mean sea level. The elevation of Shreveport, 209 feet above MSL. And the highest point in the state, 535 feet.

Ohhhhh, shit.

 

East Antarctica beginning to melt like Greenland did less than a decade ago.

This is not good news. I certainly did not expect to see photos of ice-melt runoff in that place, even in its East End, like this this so soon.

(Note: the East End, a term I'm nicking from London geography, is the side of West Antarctica that fronts the sea next to the Ross Ice Shelf; the West End of course would be next to the West Antarctic Peninsula south of South America.)

From the Robertscribbler:

Melt Expanding into East Antarctica as Nansen Ice Shelf Crack Produces 20 Kilometer Long Iceberg

Ever since 1999 a gigantic crack has been growing in the Nansen Ice Shelf in East Antarctica. By 2014, expansion of the crack accelerated. As of early 2016, the crevice had grown to 40 kilometers in length. Flooded by melt along the Ice Shelf’s warming surface and weakened by the heating of ocean waters from below, on April 7th, according to ESA reports, this East Antarctic Ice Shelf produced an immense 20 kilometer long iceberg. A towering block of ice covering an area larger than Manhattan floating on out toward the world’s shipping lanes.

Nansen Ice Shelf in the East End of East Antarctica.
(Image source. ESA via Robertscribbler.)

Surface melt water flooding into a great crack along the Nansen Ice Shelf. Large volumes of melt water flooding into ice shelf cracks forces them to widen even as they dive toward union with the warming waters below.

The Nansen Ice Shelf, before this most recent very large iceberg calving event, was a 10 mile wide and 30 mile long ice shelf that buttressed the Presley and Reeve Glaciers of East Antarctica. It abuts the north side of the Drygalski Ice Tongue, and runs out from Mount Nansen just inland of the coast of Victoria Land, Antarctica. And it’s yet another large shelf of ice that appears to be facing severe weakening as global average temperatures are driven above 1 C warmer than those experienced during the late 19th Century by an ongoing and reckless fossil fuel emission.

Nansen occupies a region of the world that has come under increasingly intense observation due to a number of scientific studies highlighting its accelerating rates of melt and a related risk of rapidly rising global sea levels.  Human-forced heating of the world’s ocean has caused waters warm enough to accelerate glacial melt to encroach upon Antarctica from the Southern Ocean. These warmer waters are drawn along beneath the floating ice shelves as fresh melt water flooding out along the ocean surface generates a landward-moving bottom current. These warmer waters eventually push beneath the ice shelves — eating away at their undersides.

And here is a map of Antarctica to show you exactly where the Nansen Ice Shelf is:

Image source: Science, via Robertscribbler.)

Though the most rapid rates of glacial melt dominate the Antarctic Peninsula and the region near the Pine Island and Thwaites glaciers, increasing rates of volume loss from Antarctic ice shelves have been creeping into a section of East Antarctica near the Nansen Ice Shelf along the coastline of the Ross Sea [just below where the abbreviation DRY for Drygalski Ice Tongue appears on the map]. With global average temperatures now exceeding 1 C above pre-industrial, we can expect melt and net volume loss to expand along the Antarctic coastline.

And here an enlargement of the above map showing the East End of East Antarctica where the Nansen Ice Shelf is, just to the north of the DRY [Drygalski Ice Tongue]:

What makes matter worse, is that the under-the-ice slopes of Antarctica are in retrograde; that is, the ice gets deeper the more inland you go. So the warmer waters underneath gets to melt more ice as they advance under the ice shelves and glaiciers, making them all the more unstable, so that huge pieces will break off and float away, as in this spectacular gif that I won't post in this article, you have to go to Robertscribbler to go see it, here.