by Rud Istvan
One of the catastrophes associated with anthropogenic global warming (CAGW) is a rising sea. Is the projected rise and rate unprecedented? Will it be catastrophic?
This essay is adapted from a much longer illustrated essay just drafted for a forthcoming (somewhen) ebook on climate and energy. It practices ‘the arts of truth’ in some previous posts here, and as in that previous ebook.
There is no doubt that melting ice during interglacial periods causes mean sea level (MSL) to rise dramatically. This has been measured in coastal sediment cores all over the world. For our present Holocene interglacial, the rise was about 120 meters, mostly over about 6000 years. It slowed dramatically (but did not stop) about 8000 years ago. Much of the melt water came from the Northern Hemisphere’s great Laurentide, Scandinavian, and Siberian ice sheets, which disappeared. (JC note: paragraph edited to fix an error, as per an email from Rud and comments in the text).
MSL during the last interglacial, the Eemian (MIS 5e), peaked twice above present MSL. The first peak was at least 6.6 meters higher, and the second was least 4 meters higher, with temperatures that naturally peaked at least 3°C higher. All without any AGW help. The first Eemian rise above present MSL took about 3 millennia (22cm/century), and the first refreeze about back to it took about 4 millennia (16.5cm/century). Typical maximum melt/freeze rates, it seems.
An equivalent rate of rise may have begun again. 20th century MSL rise is estimated to have been 17cm. The IPCC projected another ±30cm by 2100 if the worst AGW scenarios occur (IPCC AR4 WG1 FAQ 5.1). That isn’t unprecedented, isn’t much, isn’t fast, so isn’t catastrophic. Even if correct, it argues for adaptation rather than mitigation.
Sure enough, just in time for the upcoming IPCC AR5 SPM, evidence for catastrophic sea level change has been discovered. As the NYT duly noted, “Babies being born now could live to see the early stages of a global calamity.”
The NYT also said, “If you are the mayor of Miami or a beach town in New Jersey, you may be asking yourself: exactly how long is all this going to take to play out?” Since I live directly on the Atlantic in Fort Lauderdale, that was a really good question. Could not take it rhetorically. So my answer follows.
The Nature Geosciences article is paywalled. Essential bits are extracted below in accordance with US fair use doctrine. The authors present paleocoral evidence that the second Eemian rise was abrupt (≈17 feet in >>1000 years, or >>45cm/century) at ≈119.5kya along the Western Australia (WA) coast around Perth. This could only have come from a collapse of potentially unstable WAIS, with possible Greenland contributions. As NYT noted, puts the C into CAGW.
Australia is not geologically stable despite being in the middle of the Indo-Australian plate. It has experienced many strong earthquakes (≥Richter 6) over recorded history. Those ‘tectonics’ cause uplift and subsidence relative to MSL. For example, the US’ famous New Madrid earthquakes of 1811-1812 occurred thousands of km from any continental plate edge. The New Madrid event caused subsidence of 6 meters in an area 5kmx30km (Tennessee Reelfoot Lake), and uplift averaging 3 meters in an area 50kmx23km (Arkansas Lake County uplift). There are nine known active fault zones ‘near’ the WA coast from south of Perth to Cape Range, along which all of the paper’s 28 paleocoral sample sites are located. The 1968 Meckering quake east of Perth (away from the WA coast) caused a 1.5 meter uplift visible across highways and railroads. That alone suggests a paleodata MSL problem in WA.
So the authors carefully established a tectonic MSL baseline at ≈119 kya in their Figure 1 for their entire surveyed coastline. (There is some uncertainty in the radiometric dates, as Figure 3 below shows.) Indeed, one site (Cape Cuvier at the southern end of Quobba Ridge) evidenced about a meter of tectonic uplift. So that datum was excluded. This site was also carefully labeled, and also excluded in the paper’s key Figure 3 analysis. Careful scientific work, it seems.
This Western Australia MSL baseline was ‘roughly level’ after GIA corrections. (Really?) The authors concluded fossil coral outcrops had not been affected by tectonics, except at Cape Cuvier. They restated this essential fact in their interview PR:
“But after mapping and surveying the Last Interglacial fossil shorelines from Augusta to Exmouth, my team and I were able to show that these ancient shorelines outcropped at similar elevations along this entire length of coastline and therefore have not been affected by tectonic movement.” Sort of true except at one place.
So the abrupt sea level rise beginning ≈119.5kya shown by crucial Figure 3 Relative Sea Level Curve for Western Australia could only be attributed to ‘sudden’ ice sheet collapse. The 30-year old unstable WAIS disintegration hypothesis was proven. Dangerous tipping points ahead! Be worried, Miami!
Except the data in SI2 say it aint so. The logic is faulty to the point of arguable deception, and NatGeo peer review did not catch some obvious issues. 11 of 19 late highstand corals in crucial Figure 3 were above the pre 119kya MSL baseline. Some others were well below. Odd. Especially given a supposedly stable coastline. Figure 3 also suggests a sudden MSL fall, which could only come from a freeze. Odder. WAIS might suddenly collapse, but it surely cannot suddenly uncollapse. Freezing should take several millennia.
SI2 enables matching each graphed ‘late highstand’ paleocoral sample to its site, in order to understand Figure 3. That is a bit tedious, and something the peer reviewers undoubtedly did not do. Here are some, plotted on a copy of Figure 3. Most of the late highstand corals were identified as genus Acroporae. The blue line is roughly prior MSL, ‘anchored at Red Bluff’ (the only hint of truth in the paper itself about this figure) by the lower reef platform coral genus Favlidae. Painstaking GIA corrections (bars/vertical arrows) are immaterial, since Figure 1 showed them all about equal in magnitude. Horizontal lines show estimated radiometric date uncertainty. More careful science, it seems.
Every red dot above the prior MSL is from a Quobba Ridge site. (Drawing a sea level line around a few possibly uplifted samples is potentially misleading.) But so are the seven same age red dots below MSL. And so is every other dot. Figure 3 isn’t the surveyed Western Australia coastline of its caption or of Figure 1. It’s only Quobba Ridge. This is easily verified without checking each datum by the summary SI2 tab 4 of all 28 site stratigraphies. SI2 is not paywalled. A single New Madrid like ‘event’ in the vicinity sometime between then and now could suffice—and at least one did, at the Cape Cuvier site of Figure 1.
By the way, Quobba Ridge is in one of Western Australia’s 9 known active tectonic zones today. The Geoscience Australia epicenter map (linked above) records 2 significant quakes exactly on the Quobba Ridge coastline itself.
Sadly for the Nature Geoscience title, Ice Sheet Collapse… during the last Interglacial, none of the other new WA-U samples from elsewhere (SI2 tab 3) show this sudden extreme rise and fall. Nor do any of the archived ‘Dutton’ samples (SI2 tab 2). The rest of the WA coastline disproves the ice sheet collapse thesis. It only shows the generally accepted Eemian double rise and fall above present MSL at ‘normal’ rates of melt and freeze.
Science got Marcotted (two previous posts) by revised coretop dating. Nature Geoscience just got O’Learyed (this post) by a gross disconnect between a figure and its title. Destruction of trust in science by the CAGW hockey stick gang continues.
JC comment: Rud Istvan is author of the following books:
Rud has also posted previously at Climate Etc.:
- Playing hockey – blowing the whistle
- Lets play hockey – again
- IEA facts and fictions
- Another hockey stick
- What climate sensitivity says about the IPCC process
- The Government-Climate Complex
- NRC’s artless untruths on climate change and food security
Editorial note: This version is changed slightly from the original, to fix an error and to make other edits to improve the presentation.