[dohboi]

Good catch, Keith.

It highlights how many unknowns there are with sea level rise, and how fast some of the changes might happen. New research over the last ten years that I've seen on the issue all point the same direction as this piece--glacier collapse can happen at a stunningly rapid (non-glacial!) rate.

[rockdoc123]

The article in question points to the conditions of sediment and rock material at the base of particular glaciers. This impacts basal friction and there are many other factors that affect basal friction including the presence of melt, rock and ice asperities, elevation changes etc. When the forces of gravitational spreading (a consequence of increased snowfall and accumulation), coupled with basal melt exceed the coefficient of sliding friction at the glacier base it will surge. That surge is very short term and the system returns to its previous state relatively quickly, so quickly that researchers have been hard-pressed to document glacial surges in the field. This has absolutely zero to due with climate. Glaciers in Antarctica and everywhere else have always had periods of surge followed by periods of much slower flow. This has been documented in a number of papers regarding both the peninsula and West Antarctica. The measured rates of flow and resultant net mass balance of Antarctica have been documented in numerous papers over the past decade. Those rates are averages over the period of measurement so by default they take into account numerous surge events as well as periods where ice flow has slowed below average rate. There is nothing demonstrated in this paper that would suggest either more frequent surges or continuing surges.

[Plantagenet]

Ice sheet melt rates and the rate of global sea level rise are pretty much on trend with the "worst-case" scenario postulated by the UN International Panel on Climate Change (IPCC).

sea-level-ice-sheets-track-worst-case

I'm surprised its not even worse.

But glacier melt and sea level rise are both accelerating, so its still possible for sea level to shoot past the worst case scenario of the IPCC.

Thats my best guess as to what's going to happen in coming years.

I don't see anything that will slow down CO2 emissions that produce global warming and lead to glacier melt and concomitant sea level rise.

We certainly can't count on the UN Paris Accords to help at all---they are doing less then nothing to slow global CO2 emissions.

Cheers!!

[dohboi]

Old, but maybe relevant here:

East Coast Faces Rising Seas From Slowing Gulf Stream

https://www.climatecentral.org/news/eas ... eam-15587/

[dohboi]

Seas are rising faster than ever

https://www.sciencemag.org/news/2020/11 ... aster-ever

Ask climate scientists how fast the world’s oceans are creeping upward, and many will say 3.2 millimeters per year—a figure enshrined in the last Intergovernmental Panel on Climate Change report, from 2014. But the number, based on satellite measurements taken since the early 1990s, is a long-term average. In fact, the global rate varied so much over that period that it was hard to say whether it was holding steady or accelerating.

It was accelerating, big time. Faster melting of Greenland’s ice has pushed the rate to 4.8 millimeters per year, according to a 10-year average compiled for Science by Benjamin Hamlington, an ocean scientist at NASA’s Jet Propulsion Laboratory (JPL) and head of the agency’s sea level change team.

“The [Greenland] mass loss has clearly kicked into higher gear,” agrees Felix Landerer, a JPL sea level scientist. With the help of new data, new models of vertical land motion, and—this month—a new radar satellite, oceanographers are sharpening their picture of how fast, and where, the seas are gobbling up the land.

[Yonnipun]

Dohboi, there is no sea level rise. People still live in costal areas with no problems. The whole thing is a hoax.

[Newfie]

While I won't say it is a hoax my own observation is that, at my personal touch point, its effect has been minimal. There is a place where a particular ditch was dug along the margin between the salt marsh and the swamp. If there were noticeable sea level rise it would be seen there, the trees would die back.

Now there is some small die back, but that has existed and been noted. My Father used to point out a small bit of land that was once wooded. Back in the early ‘60’s it had pretty much reverted to salt marsh. That was before our climate change induced SLR. Same thing with Tangier Island in the Chesapeake. Mitchner writes about it quite clearly, how it has been historical. The people of Tangier Island understand that the nature of their home is that it will someday disappear, and has been eroding for hundreds of years, at least.

Climate change is real, SLR is real. But it has not manifested itself to noticeable proportions in some areas. There may be places where it is measurable, but not everywhere.

The thing is that it will occur in the future do to events occurring today. That is pretty clear. But somehow if people cant see it then they cant imagine it. One crowd denies it, another imagines it is already manifest.

[vtsnowedin]

There are some areas of southeastern Maryland that have a lot of tree die back from salt water intrusion but it is not clear if it is caused by sea level rise or the land subsiding naturally. In the Mississippi delta a lot of land is subsiding due to the levy system depriving millions of acres of land of the periodic spring flooding that added new layers of silt each year in ages past. The bottom of the Mississippi's channel is now higher then the surrounding land for miles upstream from the mouth of the river. One big storm during the June rise of the river and the Old Man may decide to take a new path to the sea.

[Newfie]

Yup, it is complicated.

Long term outcomes suck.

[jedrider]

Not sure if this is due to sea level rise or just human hubris to build just anywhere they please,
but the conclusion to withdraw and retreat is sound:

Along the crumbling Sonoma coast, an ambitious project paves the way for ‘managed retreat’
https://www.latimes.com/california/story/2020-11-27/gleason-beach-managed-retreat

[Tanada]

Not sure if this is due to sea level rise or just human hubris to build just anywhere they please,
but the conclusion to withdraw and retreat is sound:

Along the crumbling Sonoma coast, an ambitious project paves the way for ‘managed retreat’
https://www.latimes.com/california/story/2020-11-27/gleason-beach-managed-retreat

Interesting article than you for posting something relevant to this important topic.

I find it very telling that one of the major objection to managed retreat is that the project will "be ugly" as if the reason for the construction is an artistic desire rather than a practical reality in a changing world. Even without sea level rise these beaches in California have been steadily eroding since the end of the last major glaciation. This move is really just practice in the face of the inevitable and the people would be well served by focusing on what has to happen to maintain their desired way of life than by pretending aesthetics are the paramount issue. That isn't to say appearance is irrelevant, but making it your top issue is rather bizarre in the face of real physical necessities.

[Newfie]

A bit of trivia about historic erosion in the Chesapeake Bay.

At one point Holland Island was home to 360 people.

https://en.m.wikipedia.org/wiki/Holland_Island

The wind and tide began to seriously erode the west side of the island, where most of the houses were located, in 1914. This forced the inhabitants to move to the mainland. Many disassembled their houses and other structures and took them to the mainland, predominantly Crisfield. Attempts to protect the island by building stone walls were unsuccessful. The last family left the island in 1918 when a tropical storm damaged the island's church. A few of the former residents continued living on the island during the fishing season until 1922 when the church was moved to Fairmount, Maryland.[3]

[jedrider]

According to several state reports including one from 2018, climate scientists expect that—relative to the year 2000—sea levels could rise at least 6 inches and as much as 12 inches in the Bay Area by 2030.

See State of California 2018 Sea-Level Rise report here.

https://www.nbcbayarea.com/investigations/unlike-any-disaster-we-have-ever-seen-says-state-agency-about-rising-seas-in-bay-area/2236314/

That seems like a relatively huge number to me. If I compare it to past prognostications such as this:

Based on their new scenarios, global sea level is very likely to rise at least 12 inches (0.3 meters) above 2000 levels by 2100 even on a low-emissions pathway.

So, just wondering. Of course, in my mind, the most catastrophic outcome wedges it's way in (and I never believed the low-end projections as being truthful). However, to have a conservative body say that sea level rise will be a lot and sooner than previously expected, then I have pause there.

[dissident]

Looks like this is some sort of tidal estimate. It is a convolution of sea level rise, storm surges and changes in currents. Water levels in various bays can be higher than the mean sea level for various reasons.

[Whitefang]

A bit of trivia about historic erosion in the Chesapeake Bay.

At one point Holland Island was home to 360 people.

https://en.m.wikipedia.org/wiki/Holland_Island

The wind and tide began to seriously erode the west side of the island, where most of the houses were located, in 1914. This forced the inhabitants to move to the mainland. Many disassembled their houses and other structures and took them to the mainland, predominantly Crisfield. Attempts to protect the island by building stone walls were unsuccessful. The last family left the island in 1918 when a tropical storm damaged the island's church. A few of the former residents continued living on the island during the fishing season until 1922 when the church was moved to Fairmount, Maryland.[3]

That picture of the last house on Holland Island is very telling: 2010, the time humanity were told we have a serieus problem, the predicament of abrupt CC.

https://en.wikipedia.org/wiki/Holland_I ... _house.jpg