Peak Sea Level - 4

Fig. 1 Greenland melt zones

I. The New Stuff

Regular readers and I know that the Greenland Ice Sheet (GIS) is getting curiouser and curiouser as we learn more and more about it.

In that department, the latest in the past few weeks around here has been a discussion about the sea level around Greenland going to fall a lot lower (Weekend Rebel Science Excursion - 48).

Yes, you read that correctly, the sea level around Greenland, counter-intuitively, is not going to rise as its ice sheet melts (The SLC Software Model Beta).

Don't feel alone in not knowing that.

It is not even well known to port professionals, some of whom are planning to build cargo shipping ports in Iceland where there will likely not be adequate sea water to fill the sea port when all the ice sheet on Greenland finally melts (Peak Sea Level - 2).

That is, unless Antarctica can send some sea water up that far, as the sea level around Antarctica falls lower too (The Gravity of Sea Level Change).

The sea level fall (SLF) around those two ice sheets will cause sea level rise (SLR) many miles away from their coastlines (A Timeline of Endangered Sea Ports).

II. Growing Controversy

But, there is some controversy about what impact, other than SLF, will be caused to the

Fig. 2 NEGIS

buttressing ice shelves around Greenland and Antarctica.

Traditionally those ice shelves slow down the ice sheet flow toward the sea (Peak Sea Level - 3).

IMO, any damage to those buttressing ice shelves will allow the ice streams, which those ice shelves have been holding back, to speed up.

Anyway, the march of the ice sheets to the sea continues (Robert Scribbler, h/t Tom).

Peak sea level has been reached along the coasts of Greenland & Antarctica, so the water exiting that area now, as the ice sheet gravity diminishes, is perhaps headed for a sea port along the East Coast of America (Greenland & Antarctica Invade The United States).

III. Dredd Blog Software Design Holds Up

Regular readers know that I designed an SLR projection program designed around the concept of ice sheet zones (The Evolution of Models - 5), and that it is being updated to deal with all SLC (The SLC Software Model Beta).

The reality of the zone concept, which that software model uses, can be seen by noting that the melt this year is mainly in the coastal zone (Fig. 1).

Both the Jakobshavn and NEGIS ice streams are melting at their terminus.

The Pacific "Blob" area of warm water does flow through the Bering Strait to the Chukchi Sea, over to the Beufort Sea, and also up "over the top" via the Arctic Ocean.

Those currents then flow across to the Greenland Sea and Fram Strait on the west side of Greenland, but split to also flow into Baffin Bay on the east side of Greenland (The Question Is: How Much Acceleration Is Involved In SLR? - 4).

The ice streams shown in Fig. 2 are being impacted by those dynamics this year, as shown in Fig. 1 (the software is designed with a "the coastal zone melts first" bias that is holding up).

I think the other bias in that software, which is that the ice buttressing will suffer from SLF near the coasts, will hold up too.

The software model will be shown to be correct in not projecting a slow down of ice stream flow toward the sea.

Any loss of, or damage to, ice shelves connected to the ice sheet but also floating on the sea, as its level falls, will be more likely to allow the ice streams on the land to accelerate (Peak Sea Level - 3).

IV. The Lowering Sea Level May Destabilize Methane Clathrates

I wrote about the Arctic methane clathrate situation recently (The Methane Hydrate / Clathrate Controversy).

It seems intuitive that as the Arctic Ocean and other seas within the Arctic Circle go through SLF, more methane hydrate / clathrate release will take place.

For one thing, the pressure level at the bottom will decrease as the volume of water atop the sea floor gets shallower.

Methane hydrates / clathrates are sensitive to pressure, so the cages may crumble at some pressure point, to allow the methane to enter the water column, then float upward toward the surface.

The piercing rays of the Sun will penetrate closer to the bottom as the sea becomes shallower, and the shallower water will likely warm up more easily during the summers.

That would also signal a time of increased loss of sea ice cover (Arctic Ice Extent: 2015 Struggles For First Place - 3).

V. Conclusion

Events are converging toward a rude awakening in the U.S., where the media are constantly talking about what is going to happen to other nations.

Yet, they are in the cross-hairs of the coming invasion (The 1% May Face The Wrath of Sea Level Rise First).

Professor Mitrovica, when he spoke in Washington, D.C., pointed out that the focus of SLC is just off the east coast of the U.S., near where he was speaking (see video below).

The next post in this series is here, the previous post in this series is here.

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Professor Mitrovica, @ Harvard

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