The Fate of Atlantis? transcript

John Robson:

One of the most reliable floats in the alarmist cliché parade is the relentless man-made rise in sea levels that supposedly threatens to submerge our cities, and our civilization, and turn us all into Atlantis. But the actual rates of sea-level rise that people experience in coastal cities around the world is very small, as we’ve been showing in our Sea Level Check series, and also, very variable. And where cities are seriously threatened, it has nothing to do with sea-level rise at all, let alone man-made sea-level rise. So this is a Climate Discussion Nexus Fact Check on sinking cities.

On this subject we frequently hear from people that sea-level rise may be even “worse than expected”^TM, because the land is rising in some places, meaning that the actual sea-level change is higher than the measured rise against the land. And that is true, but there’s another side to it as well, because in many places the land is sinking, and that means that what people experience as sea-level rise is at least in part the land going down. And we were reminded of this when we came across a recent article offering a new whiz-bang app that tracks which cities around the world are sinking fastest.

And there are two remarkable things about this piece, which comes from something called “Visual Capitalist.” First, the cities that are sinking fastest tend to be in poor countries, especially in Southeast Asia. Of the 10 cities around the world sinking fastest, only one, that’s Houston, is in a wealthy country. The rest are in poorer countries in Africa and, as we say, largely in Asia.

The second remarkable thing is that in many cases where the cities are sinking fastest, the cause is clearly, and directly related to local land, and resource management, not climate change.

The “Coastal Cities” article starts with the cliché, it goes:

“With sea levels rising, there is cause for concern about the livability of major coastal cities – often huge centers of trade, and commerce, and homes to millions of people.”

Well true, but notice that it’s not New York City that’s threatened or Los Angeles or London (which, yes, is on a tidal estuary), or even Venice. And the reason why is that the problem isn’t sea-level rise.

Much nonsense is spoken on this subject. Including the Visual Capitalist piece bemoaning:

“the effects of rising sea levels (currently averaged at 3.7 mm/year).”

which, again, is climate orthodoxy these days.

And as usual, when the alarmists get all “mathy” on you, it’s important to ask what’s behind the intimidating apparent precision of these decimal places… even after someone says “satellite measurements” which invokes modern science at its finest with things like space rockets, and laser beams.

Indeed, NASA tells children reassuringly:

“NASA measures sea level around the globe using satellites. The Jason-3 satellite uses radio waves, and other instruments to measure the height of the ocean’s surface – also known as sea level. It does this for the entire Earth every 10 days, studying how global sea level is changing over time.”

But the height against what? The centre of the Earth, apparently, relative to the satellite, and then the ocean, but to what degree of precision? That web page eventually gets around to saying:

“Jason-3 orbits about 800 miles (1,300 kilometers) above Earth. Even from that far away, Jason-3 can measure the distance from itself to the ocean surface to within about one inch (about three centimeters).”

So they’re giving us results to a tenth of a millimetre, that’s one ten-thousandth of a metre, but the margin of error is about an inch or roughly 300 times that supposed precision. And since the satellites are measuring it all relative to the centre of the Earth by measuring their position relative to the centre of the Earth, what’s the margin of error for their position relative to that?

Also, isn’t the ocean wavy? Doesn’t wind actually pile water up in some places? What about tides? And what sorts of algorithmic data adjustments are being performed, for instance ones that assume sea levels are rising, add it in, and then go, look, sea levels are rising.

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And another thing. As Steven Koonin has observed, sea level rise did apparently accelerate in the early 21^st century to above the 20^th century average. But it’s not a “gotcha” because it had done the same thing for several protracted periods in the 20^th century, and then it slowed down again. Which is difficult to reconcile with this claim of a linear connection between CO2 in the atmosphere and sea-level rise that many untutored persons adhere to dogmatically. And it may very well slow down again.

So, there’s a lot to question in those measurements. But even leaving aside whether it’s possible to measure any change on the scale of worldwide sea levels down to 3.7 millimeters accuracy, what they neglect to mention is that the oceans have been rising at roughly the current rate, with many fluctuations, ever since the big melt ended around 7,000 years ago. To assert that such a thing was natural for the first 6,950 years but has been man-made for the last 50, or even natural for the first 6,850 years then man-made for the last 150, just isn’t sensible. In fact it’s impossible to imagine how one would even test such a claim, which puts it in the realm of dogma rather than science.

But the Visual Capitalist item gets to the nub of the matter when it says:

“an overlooked area is how coastal cities are themselves sinking – a phenomenon called relative local land subsidence (RLLS) – which occurs when underground materials, such as soil, rock, or even man-made structures, compact or collapse, causing the surface above to sink.”

And, it goes on to say:

“Land subsidence refers to the gradual sinking of an area of land, often caused by the over-extraction of groundwater or the compaction of the ground from the massive weight of buildings above it.”

Again, not from people exhaling CO2 or shooting it out of their tailpipes. Rather, it’s bad land use, bad planning, sloppy or corrupt execution, flawed engineering, excessive extraction of groundwater, or all of the above, and more besides.

As the piece observes, of the 44 cities found to be sinking, 30 are in Asia. And the one sinking fastest is Tianjin in Communist China, where the experts blame the problem on soil loss due to extensive underground geothermal drilling, not carbon dioxide.

In third place is Chittagong in impoverished socialist Bangladesh, where more than two thirds of the city gets regularly covered by flood tides, always has, and where competitive underground water extraction has been blamed for sinking land, not CO2.

Water extraction is also blamed for sinking the land in Ahmedabad in India, along with rapid urbanization that’s weighing down the soil, putting it in sixth place overall for speed of subsidence.

Istanbul, Turkey is in seventh place, and once again rapid water extraction is to blame. Lagos, Nigeria is in ninth, and here the issue is nearby sand mining.

Other cities on the list include Ho Chi Minh City in Vietnam, Yangon in Myanmar, Jakarta in Indonesia, Houston in Texas, and Manila in the Philippines.

And again, other than Houston, those are all in impoverished and badly-run countries. Which makes it difficult to know how to fix the problem but it doesn’t have anything to do with net zero.

I don’t mean to seem insensitive. But I think you would hesitate to invest in a state engineering project in most of those places. But if the problem is caused by corruption and government bungling, then the likely result of throwing money at mitigation efforts will be further corruption and bungling.

In our “Sea Level Check” series we have pointed out that apparent sea level rise varies enormously from place to place on our complex, dynamic planet. There are a lot of changes in the land, and that means that sea level is actually falling in many locations, often due to ongoing “isostatic rebound” from the recent removal, recent in geological terms, of the crushing weight of the glaciers in northern latitudes. But it’s also affected by erosion, accumulation, and all sorts of other local changes, many natural, many man-made.

To say so is not, as we’ve often said of other climate issues, to deny that there may be a problem. If, for instance, we discovered that a purely natural surge in warming was about to melt the Greenland ice cap, it would threaten us with devastating flooding just as surely as if a man-made one were occurring. And in the other direction, if the temperature were to start falling steadily and dramatically, either because the Holocene was winding down naturally or because of some Frankensteinian geoengineering blunder, we’d be in terrible trouble.

So the bottom line here, if you’ll pardon the phrase as the cities sink, is that nature is complicated, and it’s frequently unforgiving. On the other hand, humans are adaptable, especially if they keep calm and think things through instead of panicking and deciding to cripple their manufacturing, farming, and transportation sectors because they think that doing so will stop Poseidon or Gaia from swallowing Jakarta.

So by all means keep an eye on sea-level rise. Study long-term trends. But ask no more of the data than it can provide. Stay flexible and adaptable. Resist trendy manias and reckless responses. Keep calm and carry on doing real science.

For the Climate Discussion Nexus, I’m John Robson, and that’s our Fact Check on sea-level rise, sinking coastal cities, and whether we’re all going to suffer the fate of Atlantis, or not.