Some "Semi-empirical" findings!  How lucky we are!


The report below determinedly revives all the old scare about sea-level rise.  The scare has been pretty moribund for a few years now, thanks partly to some heavy hits on it by sea-level expert Nils Axel Morner.  
The underlying academic journal article ("Temperature-driven global sea-level variability in the Common Era") is here and one of the authors, young Bob Kopp, has some useful details about it here.

The article was based on some very complex statistical work and in that context we note that the authors describe their work as "semi-empirical".  What does that mean?  It simply means that their results come partly from  guesswork.  And seeing the authors are keen Warmists we can be sure in which direction their guesses tended. And, with the complex nature of their analyses, guesses at various points could make a big difference to the final outcome.  To believe their conclusions would therefore require an act of faith

And in my usual pesky way, I had a bit of a look at the details of the research.  And I note that their methods produce some pretty weird results.  They found, for instance, that sea levels FELL during the Medieval Warm Period.  Isn't warming supposed to cause sea-level RISE?  They try to get around that by reviving the old Warmist claim that the Medieval Warm Period was confined to Northern Europe -- but that is quite simply false.  Evidence of it has been found in places as far apart as Argentina, New Zealand and China.

So have these guys simply lied in order to defend their research methods?  Very nearly.  Kopp says: "Notably, both the decline in sea level and the decline in temperature occurred during the so-called European “Medieval Warm Period,” providing additional evidence that the “Medieval Warm Period” and “Little Ice Age” were not globally synchronous phenomena."

So they say that the warming outside Europe occurred at different times to the warming elsewhere.  And given the uncertainties of dating proxy data that is just barely defensible, if implausible.  It's playing fast and loose with the facts but is not an outright lie.

But their finding that the globe actually COOLED during the Medieval Warm Period  is contrary to all other evidence on the subject that I know of. You would have to have the faith of a Jehovah's Witness to believe their conclusions


Global sea levels rose faster in the 20th century than at any time in the past 3,000 years - and 'climate change is to blame'

Scientists discovered that the 5.5-inch (14cm) global rise is at least twice as much as would have been seen without global warming. In fact, they believe levels might have actually fallen if it hadn't been for soaring global temperatures.

During the 20th century, sea levels across the globe rose faster than in any of the 27 previous centuries. Scientists found that the 5.5-inch (14cm) global rise is at least twice as much as would have been seen without global warming. In fact, they believe levels may have fallen if it hadn't been for rising temperatures

During the 20th century, sea levels across the globe rose faster than in any of the 27 previous centuries. Scientists found that the 5.5-inch (14cm) global rise is at least twice as much as would have been seen without global warming. In fact, they believe levels may have fallen if it hadn't been for rising temperatures

'The 20th century rise was extraordinary in the context of the last three millennia - and the rise over the last two decades has been even faster,' said professor Robert Kopp, lead author of the report published in the Proceedings of the US National Academy of Sciences.

The pattern was revealed by a new statistical analysis technique which extracts global data from local records.

No local record measures global sea level. Instead, each measures sea level at a particular location, where it will differ from the global mean.

The statistical challenge is to pull out the global signal.

The scientists built a database of geological sea-level indicators from marshes, coral atolls and archaeological sites at 24 locations around the world, covering the past 3,000 years.

They also looked at tide gauge recordings for the last 300 years from 66 other locations.

Many of the records came from the field work of Kemp, Horton, or team members Roland Gehrels of the University of York and Jeffrey Donnelly of the Woods Hole Oceanographic Institution.

This information was used to calculate how temperatures relate to the rate of sea-level change. Using this new technique, the researchers showed that the world's sea level fell by about 11 inches (8cm) between 1000 and 1400AD, when the planet cooled by about 0.2°C.

Global average temperature today is about 1°C higher than at the end of the 19th century.

It also found that , had global warming not occurred in the 20th century, the change in sea level would 'very likely' have been between a decrease of 1.1 inch (3cm) and a rise of 2.8 inches (7cm). Instead, the world actually saw a rise of 14cm.

A companion report also found that more than half of the 8,000 coastal nuisance floods observed at US tide gauge sites since 1950 would not have occurred.

Professor Kopp estimates that sea levels will rise by 20 inches to 51 inches (50cm to 130cm) in the 21st century, if the world continues to rely on fossil fuels.

SOURCE  

The journal abstract follows

We present the first, to our knowledge, estimate of global sea-level (GSL) change over the last ∼3,000 years that is based upon statistical synthesis of a global database of regional sea-level reconstructions. GSL varied by ∼±8 cm over the pre-Industrial Common Era, with a notable decline over 1000–1400 CE coinciding with ∼0.2 °C of global cooling. The 20th century rise was extremely likely faster than during any of the 27 previous centuries. Semiempirical modeling indicates that, without global warming, GSL in the 20th century very likely would have risen by between −3 cm and +7 cm, rather than the ∼14 cm observed. Semiempirical 21st century projections largely reconcile differences between Intergovernmental Panel on Climate Change projections and semiempirical models.

doi: 10.1073/pnas.1517056113. PNAS February 22, 2016





Morner rips the Keystone Kopp

Young Bob Kopp may not have furthered his career much by his evangelism for the rising sea-level gospel.  Dr. Nils Axel Morner has some germane comments on his work below.  Prior to his retirement, Morner  headed the Department of Paleogeophysics & Geodynamics at Stockholm University

Morner, a leading world authority on sea levels and coastal erosion calls the new study and the media spin surrounding it “demagogic.”

“The PNAS paper is another sad contribution to the demagogic anti-science campaign for AGW. It is at odds with observational facts and ethical principles,” Morner wrote to Climate Depot.

Morner noted:

– global tide gauges show moderate mean rates

– many key sites and test sites show little or no rise at all

– nowhere do we find records of true “acceleration”

– satellite altimetry show a mean rise of 0.5 ±0.1 mm/yr after back-calibration

– past sea level oscillations have been faster & steeper than in the last century

Morner explained: “The paper is full of very bad violations of observational facts.”  Just one example:

This is their graph of sea level change at Christmas Island, Kiribati:



This is the tide gauge record from Christmas Island:



Morner asked: “How can anyone find a rapidly rising trend in this tide gauge record? It is flat or rather slowly falling – but in no way rising.”

“So they work – with no respect to observational facts. A true case for Fraud Investigation,” Morner added.

SOURCE

Morner didn't comment on it but Kopp's combining the Christmas Island and the Kiribati record is yet more of his weirdness.  The two places are in different oceans thousands of miles apart

Posted by John J. Ray (M.A.; Ph.D.).