A new paper published in Science magazine suggests that ocean the floors are getting deeper and sea levels have fallen by about 170 meters (560 ft) since the Cretaceous period 80 million years ago, due to tectonic shifts. Previous estimates were between 40 to 250 meters. On this basis of this work, a fall of 120 metres is expected over the next 80 million years, which equates to just 0.015 centimetres per century. Not much when we we consider IPCC projections of sea level rise. That said, the IPCC seems to have abandoned decadal projections in their latest report and gone for a 90-year projection, following the accuracy failures of the 1990, 1995 and 2001 reports. See the January 15th post over at Prometheus: Verification of IPCC Sea Level Rise Forecasts 1990, 1995, 2001.
The research article is entitled: ‘Long-Term Sea-Level Fluctuations Driven by Ocean Basin Dynamics’
The first paragraph reads:
Earth’s long-term sea-level history is characterized by widespread continental flooding in the Cretaceous period (145 to 65 million years ago), followed by gradual regression of inland seas. However, published estimates of the Late Cretaceous sea-level high differ by half an order of magnitude, from 40 to 250 meters above the present level. The low estimate is based on the stratigraphy of the New Jersey margin. By assimilating marine geophysical data into reconstructions of ancient ocean basins, we model a Late Cretaceous sea level that is 170 (85 to 270) meters higher than it is today. We use a mantle convection model to suggest that New Jersey subsided by 105 to 180 meters in the past 70 million years because of North America’s westward passage over the subducted Farallon plate. This mechanism reconciles New Jersey margin–based sea-level estimates with ocean basin reconstructions.
The paper is also reported by Reuters, with their usual perspective on climate change.
Jennifer Marohasy BSc PhD is a critical thinker with expertise in the scientific method.
It stands to reason that the continents are becoming progressively lighter with regard to the underlying lithosphere.
“following the accuracy failures of the 1990, 1995 and 2001 reports.” – come off it – I think most would be very happy with that result given the complexities.
This seems to agree with ancient Perth Basin shorelines. I seem to recall that sea level was estimated at a bit over +200m for the Cretaceous.
What was the IPCC’s claimed precision? You have to look at that before saying they were inaccurate.
Looks like our two experts here have not picked up on the non sequitur that no ocean can fall. Perhaps sea levels could but then, when a moron, what relevance are facts?
Or might it be a misplaced metaphor? Damn this cursed conundrum (loosely paraphrased from Macbeth).
Louis, I thought you were ignoring me!
But seriously, aren’t they talking about the ocean floor, the oceanic crust? Certainly that can fall. Unless of course you don’t accept the theory of Plate Tectonics.
Mr T,
Oceanic crust is firstly an oxymoron.
Fall to where?
And I have never accepted the theory of plate tectonics, not from some esoteric theoretical stance but from observation.
So relieved we’re on speaking terms again Louis 🙂
The oceanic crust is composed of sheeted dykes and pillow basalts. Quite clearly it exists and has a chemical composition very different to continetal crust. It is also a lot thinner (only a few km instead of 30+).
It’s also exposed in New Zealand, Oman, Newfoundland, and Iceland (where you can see the mid-ocean ridge quite clearly, and even measure the rate of expansion.)
Falling is probably a poor term, sinking would be beter. And it can sink into the aesthenosphere, which is in a plastic state (similar to the mantle) – sinking of 170m is not that far.
Mr T,
your simplistic description of oceanic and continental crust tells me you don’t.
One reason I ignore you.
“[Those] who have an excessive faith in their theories or in their ideas are not only poorly disposed to make discoveries, but they also make very poor observations.”
—Claude Bernard (1813-78) French physiologist, 1865.
Some additional facts:
ANCIENT AND CONTINENTAL ROCKS DISCOVERED
IN THE OCEAN FLOORS
Boris I. VASILIEV V.I. Il’ichev Pacific Oceanological Institute, Far Eastern Branch, Russian Academy of Sciences,
Vladivostok, 690041, Russia
tesla@poi.dvo.ru
Takao YANO
Department of Environmental Science, Faculty of Regional Sciences,
Tottori University, Tottori 680-8551, Japan
yano@rstu.jp
(Editor’s note: This article is a translation of a paper by the above authors which appeared in the Journal of Science Education, Japan, v. 49, no. 7, p. 25-41, 2006, by permission from Hoshinowakai. Abstract was added by the authors.
Translation from Japanese into English by Dong R. Choi and David Pratt)
Abstract: According to the hypothesis of ocean-floor spreading, oceanic crust contains no rocks older than 200 Ma and of continental origin. The Atlantic, Indian and Pacific oceanic crusts, however, include rocks dating back to 2.55 Ga and of continental constituents, such as granitoids, gneisses, schists, granulites, and coarse-grained terrigenous clastics. These rocks have evoked ad hoc modifications to the hypothesis, e.g., ridge jumping, transform migration, oscillatory spreading, ridge propagation, small-scale, roll-like, flat, slower-circulating convection in the asthenosphere beneath spreading centers, nonspreading areas, etc. Consequently the hypothesis is losing its original simplicity and internal logical consistency. These ancient continental rocks should be understood to suggest, instead, that the basic premises of the sea-floor spreading hypothesis, as well as of plate tectonics, must be re-examined. Because the old continental rocks already found have been discovered only by accident, future drillings and dredgings will likely prove the systematic presence of ancient continental rocks in the world oceans. Several target areas for future deep-sea drillings are proposed for the Pacific.
Keywords: ancient rocks, continental rocks, Atlantic Ocean, Indian Ocean, Pacific Ocean”
In other words Mr T’s description of oceanic crust is wrong. It implies that so is the notion of plate tectonics, and thus our overall understanding of the earth’s geology.
Climate science is based on this misconception of the earth under our feet.