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Sea Level Rise Pt. 3

Re: Sea Level Rise Pt. 3

Unread postby Gmark » Fri 23 Jul 2021, 23:39:27

ROCKMAN wrote:Plant -As you point out models are difficult. Especially since there is no such thing as an UNBIASED model. Every complex model requires many dozens (if not hundreds) of assumptions built into the model. And those assumptions always run in a range. And often a very wide range. So the modeler has to chose those values. And all to often the modeler has an objective. Human nature being what it is assumptions are chosen leading to the goal. Which isn't to say they are incorrect. But also not to say they are correct. And typically those assumptions rarely have any absolute measure of validity.

Thus one is really saying they agree with the assumptions made when they agree with the model. Which is often just agreeing with the modeler's OPINIONS.


I agree with you that the built-in assumptions to every model really complicate things, and some of those built-in assumptions are pretty subtle.

One of the primary tools used in meteorology for forecasting weather, hurricanes etc., is the 'ensemble forecast', where you take a bunch of models, put them together, and see where they agree and disagree.

You can also run your model, change the initial conditions slightly, run it again, change the initial conditions again, run it again, etc. You wind up with a bunch of models each with slightly different starting conditions. When you put them together you can see where the slightly different initial conditions don't make much of a difference to the final output.

With meteorology and climatology this is important as so many factors are not linear, and a minor change in one initial parameter can mean major changes as you move forward in time.

The other problem is that even with supercomputers, this is very time consuming and there often isn't enough time to run too many models covering too big an area. This does work for hurricanes though and is common .

Some of the modeller's I know frequently do 'back forecasts' and 'model verification', checking this week to see how last weeks forecast conformed to reality, and where the model was wrong, try to figure out whether they screwed something up with the initial conditions, or if there were other factors that came into play that they didn't expect.

The best modeller's take it very seriously. But there are a lot of junk models out there.
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Re: Sea Level Rise Pt. 3

Unread postby Outcast_Searcher » Thu 29 Jul 2021, 11:31:56

Gmark wrote:
ROCKMAN wrote:Plant -As you point out models are difficult. Especially since there is no such thing as an UNBIASED model. Every complex model requires many dozens (if not hundreds) of assumptions built into the model. And those assumptions always run in a range. And often a very wide range. So the modeler has to chose those values. And all to often the modeler has an objective. Human nature being what it is assumptions are chosen leading to the goal. Which isn't to say they are incorrect. But also not to say they are correct. And typically those assumptions rarely have any absolute measure of validity.

Thus one is really saying they agree with the assumptions made when they agree with the model. Which is often just agreeing with the modeler's OPINIONS.


I agree with you that the built-in assumptions to every model really complicate things, and some of those built-in assumptions are pretty subtle.

One of the primary tools used in meteorology for forecasting weather, hurricanes etc., is the 'ensemble forecast', where you take a bunch of models, put them together, and see where they agree and disagree.

You can also run your model, change the initial conditions slightly, run it again, change the initial conditions again, run it again, etc. You wind up with a bunch of models each with slightly different starting conditions. When you put them together you can see where the slightly different initial conditions don't make much of a difference to the final output.

With meteorology and climatology this is important as so many factors are not linear, and a minor change in one initial parameter can mean major changes as you move forward in time.

The other problem is that even with supercomputers, this is very time consuming and there often isn't enough time to run too many models covering too big an area. This does work for hurricanes though and is common .

All valid points.

OTOH, weather forecasts (and many other things models do for us) are decent, as long as the expectations for the model aren't unrealistic. (For example, I pay attention to weather forecasts up to 48 hours out for things like rain and temps, but beyond a week they're basically useless re any accuracy.) And of course, as long as one doesn't have blind faith in the veracity of models, given how imperfect they are.

They're generally a useful tool, AFTER they've been subjected to enough scrutiny to EARN scientific veracity. But they're most definitely NOT the holy grail when it comes to anything approaching "absolute truth".

Math tells us, for example, that there are a hell of a lot of problems that are basically unsolvable. Models might help put some boundaries around some of the potential solutions to allow, say, a rough gauge of sizes of solutions, but they most certainly aren't going to "solve" such problems in any significant way.
Given the track record of the perma-doomer blogs, I wouldn't bet a fast crash doomer's money on their predictions.
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Re: Sea Level Rise Pt. 3

Unread postby JuanP » Sat 04 Sep 2021, 16:33:42

"Sea-level rise becoming a hazard for suburban South Florida neighborhoods far from ocean"
Sun Sentinel
https://www.msn.com/en-us/weather/topst ... np1taskbar

"Sea-level rise may appear to be a problem only for coastal residents, a hazard that comes with the awesome views and easy access to the beach.

But neighborhoods 20 miles inland are starting to feel the impact, as the Atlantic Ocean’s higher elevation makes it harder for drainage canals to keep them dry. The problem showed up last year in Tropical Storm Eta, when floodwater remained in southwest Broward neighborhoods for days, partly because the elevated ocean blocked canals from draining the region."

Our main farming location in Miami is a few miles inland from Biscayne Bay. The elevation in the area is 2 to 4 feet above sea level. Some of the streets in the area get flooded every time it rains, sometimes for up to a week.
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Re: Sea Level Rise Pt. 3

Unread postby Newfie » Sat 04 Sep 2021, 20:12:34

Juan,

You ever consider relocating?
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Re: Sea Level Rise Pt. 3

Unread postby Subjectivist » Sun 10 Sep 2023, 18:46:28

How sea level rise worsened Idalia's surge
CHRIS MOONEY AND KEVIN CROWE THE WASHINGTON POST

Rising oceans substantially worsened the devastating storm surge that Hurricane Idalia flung at the Florida coast on Wednesday, according to scientific experts and data analyzed by The Post.

An unusual, dramatic surge in sea levels in the Gulf of Mexico, which began around 2010, could have added nearly 5 inches to the height of the waters that raced ashore, the figures suggest. More gradual sea level rise between 1939 and 2010 added about four more inches.

In many locations, this overall rise of about 9 inches in sea level could have made the difference between flooding and staying dry, experts said.

"In this region, the eastern Gulf Coast, sea level rise has been faster since 2009, 2010," said Jianjun Yin, a climate scientist at the University of Arizona who published a study in the Journal of Climate earlier this year on this recent acceleration and how it has affected hurricanes. "So with this faster sea level rise, the storm surge could get higher and higher."

The highest water level recorded in Idalia — a preliminary value of 6.89 feet above the average highest daily tide recorded during 1983-2001 — would, if confirmed, be the single highest reading the tide gauge at Cedar Key, a small island community battered by Idalia's surge, has ever measured. It eclipses the prior record, recorded in 2016, by just under a foot.

Cedar Key, where at least a third of all buildings are believed to have sustained damage during Idalia, is also home to the best long-term record of sea level in Florida's Big Bend region. Idalia made landfall Wednesday morning about 60 miles north of Cedar Key along Florida's coast.

The Post calculated the sea level trend at the Cedar Key tide gauge, divided up into two periods to emphasize the recent acceleration — a method also used in Yin's study. The analysis began in 1939 because of substantial data missing before that date. The results suggest the sea level has risen by around 9 inches since 1939 — with about half of the rise occurring in the past 13 years.

Idalia is the latest example of new high water marks being set in the Gulf during hurricanes in recent years. According to Yin's study, Hurricane Ian set a record at Fort Myers, Fla., last year, as did Hurricane Michael at Apalachicola, Fla., in 2018.

The sea level in any particular location rises and falls due to changing seasons, global weather patterns like El Nino, and the tides. It rises dramatically during hurricanes. All of these fluctuations represent departures from a mean sea level, a background state that scientists can calculate. It is this mean sea level that has risen at Cedar Key, just as it has all along the U.S. coastline and beyond as the planet warms.

According to scientists, this in turn means that when a major storm event occurs in the Gulf, it is now occurring atop a higher sea level and its storm surge can reach further inland.

"There is strong evidence that sea levels are higher on Florida's west coast than they would have been 100 years ago in large part due to human-caused climate change," said Daniel Gilford, a climate scientist with Climate Central.

Yin said his own data for sea level rise at Cedar Key are consistent with what The Post found, showing much more rapid change after 2009 or 2010. Yin added that the contribution of sea level rise to Idalia's storm surge could actually be higher than these numbers suggest, due to additional amplifying effects he believes can occur as seas rise.

The National Oceanic and Atmospheric Administration's official record of sea level rise at Cedar Key also shows large change, equivalent to nearly 10 inches since 1914. The agency goes farther back in time, but does not emphasize the recent current acceleration.

Not all of the sea level rise in question is the result of climate change. Some is due to the sinking of land rather than the rising of the ocean, for instance. But in Cedar Key, unlike in much of Louisiana and Texas, such subsidence is not a major factor. Experts at the University of Nevada, Reno, who use GPS data to track the Earth's movements, put that sinking at under a millimeter per year in this location.

Scientists are still debating the precise causes of the rapid recent sea level rise along the Gulf Coast. While Yin's study makes the case that it is tied to a slowing Atlantic Ocean circulation — a predicted effect of climate change — other research suggests that much of it may reflect the combination of climate change and natural variability in the ocean.

Either way, the sharp rise of the ocean in this region is a preview of the kind of rapid rates of change that scientists say we can expect later this century if climate change continues to worsen.

"There's no doubt in my mind that sea level rise has exacerbated the flooding that we saw," said Ben Kirtman, who directs the NOAA Cooperative Institute for Marine and Atmospheric Studies at the University of Miami.

But that's just one component of the way that climate change is worsening hurricanes, Kirtman said, adding that Idalia was also likely more intense to begin with because of warmer waters along its path.

While a higher mean sea level means higher hurricane storm surges, simply calculating how much the sea level has risen underestimates some of the effect, Kirtman said. That's because "you cross thresholds," he said.


https://www.stltoday.com/how-sea-level- ... f6057.html
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