Young earther, Charles Clough, misleads readers @wattsupwiththat about rising sea levels

At WUWT Anthony Watts published an article by Charles Clough (archived here). He was complaining about an article by Justin Gillis in the New York Times last February, which had the title:

Seas Are Rising at Fastest Rate in Last 28 Centuries

Here is where the title came from, in the abstract of a paper by Robert E Kopp and colleagues (my emphasis):

GSL [global sea level] rose at 0.1 ± 0.1 mm/y (2σ) over 0–700 CE. A GSL fall of 0.2 ± 0.2 mm/y over 1000–1400 CE is associated with ∼0.2 °C global mean cooling. A significant GSL acceleration began in the 19th century and yielded a 20th century rise that is extremely likely (probability P≥0.95) faster than during any of the previous 27 centuries.

Charles Clough is from the pseudo-religious cult, the Cornwall Alliance. He has signed a "declaration" rejecting climate science, which blatantly and falsely claims in part that "Recent global warming is one of many natural cycles of warming and cooling in geologic history." He's a sworn science denier. Charles is also a young earth creationist as indicated on this YouTube session (the link goes straight to the segment at 21 minutes 18 seconds in. You'll have to skip the advert). Charles Clough thinks the earth was created at the same time as the mythical creation of Adam, 6,000 years ago.

Seas are rising

Global sea level continues to rise. Here is the latest data from satellite measurements reported by the CU Sea Level Research Group at the University of Colorado, Boulder:

Figure 1 | Sea level rise from 1993 to 2015 averaged annually, from TOPEX and Jason satellite data. Data source: U Colorado Sea Level Research Group.

As the chart shows, sea level has been rising. According to the U Colorado Sea Level Research Group, the rate of increase since 1993 is 3.4 +/- 0.4 mm a year. Seas will rise a lot more and faster in coming decades and centuries as the ice melts. By the end of this century they could be more than a metre higher than now, and that will most likely be just the beginning of much higher seas.

Projections to 2100

Charles Clough, like most science deniers, is scared of being scared. He is so scared that he misrepresents research. The New York Times and WUWT article were about two recent papers in PNAS. This is what one of the papers, Mengel16, reported - a projected rise between about one foot and more than four feet over the rest of this century:

We project anthropogenic sea level rise of 28–56 cm (0.9'-1.8'), 37–77 cm (1.2'-2.5'), and 57–131 cm (1.9'-4.3') in 2100 for the greenhouse gas concentration scenarios RCP26, RCP45, and RCP85, respectively.

This is similar to what the authors of the other paper, Kopp16, reported:

They give rise to very likely (P=0.90P=0.90) GSL rise projections for 2100 CE (relative to 2000 CE) of 52–131 cm (1.7'-4.3'), 33–85 cm (1.1'-2.8'), and 24–61 cm (0.8'-2.0'), respectively.  

Both papers reported that sea level could be between around one foot to more than 4 feet higher by the end of this century, depending on how much CO2 we decide to add to the atmosphere. By contrast, Charles Clough wrongly wrote that seas would rise by between one and 2½ feet this century. He lopped off almost two feet from the worst case projection, writing:

The studies project for various hypothetical CO2 emission-increase scenarios during this 21st century a total rise in global sea level between 1 ft and 2.5 ft.

It is actually a sea level rise of between around one foot and 4.3 feet above 2000. Charles only included the projections for RCP26 and RCP45. He didn't include RCP8.5.

Sea level fell, then it rose a lot

Charles also got it wrong when he wrote about what happened since before industrialisation. Here is the relevant chart from Kopp16. It shows rising seas from a low around 2,200 years ago, then falling sea level particularly from around a thousand years ago to the 19th century, then a very steep rise, steeper than any other in the record below:

Figure 2 | (A) Global sea level (GSL) under prior ML2,1. Note that the model is insensitive to small linear trends in GSL over the Common Era, so the relative heights of the 300–1000 CE and 20th century peaks are not comparable. (B) The 90% credible intervals for semiempirical hindcasts of 20th century sea-level change under historical temperatures (H) and counterfactual scenarios 1 and 2, using both temperature calibrations. (C) Reconstructions of global mean temperature anomalies relative to the 1850–2000 CE mean (1, 2). (D) Semiempirical fits to the GSL curve using the two alternative temperature reconstructions. (E) As in B, including 21st century projections for RCPs 2.6, 4.5, and 8.5. Red lines show the fifth percentile of RCP 2.6 and 95th percentile of RCP 8.5. (F) The 90% credible intervals for 2100 by RCP. In A, B, and D, values are with respect to 1900 CE baseline; in E and F, values are with respect to 2000 CE baseline. Heavy shading, 67% credible interval; light shading, 90% credible interval. Source: Kopp16

Charles Clough misrepresents the science

As the authors reported, sea level dropped between about 1000 CE and 1900 CE, before rising rapidly over the past few decades. Contrast that with what Charles Clough misleadingly wrote:

The two reports published in the Proceedings of the National Academy of Science (PNAS) made several claims. During pre-industrial history (prior to 1860), global sea level rose at an average rate of 0.1 to 0.3 mm/yr.

What Charles did was cherry pick a couple of numbers. Kopp16 authors wrote:

GSL rose from 0 CE to 700 CE (P≥0.98) at a rate of 0.1±0.1 mm/y (2σ), was nearly stable from 700 CE to 1000 CE, then fell from 1000 CE and 1400 CE (P≥0.98) at a rate of 0.2±0.2 mm/y (Fig. 1A). GSL likely rose from 1400 CE to 1600 CE (P≥0.75) at 0.3±0.4 mm/y and fell from 1600 CE to 1800 CE (P≥0.86) at 0.3±0.3 mm/y. 

That's right. Contrary to what Charles wrote, overall sea level fell from a previous high 1600 years ago to the 19th century (see Figure 1 above). This is how it happened. Sea level rose a small amount between 2000 years ago and 1300 years ago at a rate of 0.1 mm a year. Then after 300 years of little change, it fell again at a rate of 0.2 mm/year. Then for a couple of centuries it rose again at a rate of 0.3 mm a year between 1400 CE to 1600 CE, and then fell from 1600 CE to 1800 CE. Over the whole period from 400 CE to the 19th century, there was a fall in sea level.

Charles continued:

From 1860 to 1900 it rose at an average rate of 0.4 mm/yr, and from 1900 to the present it has been rising at 1.4 mm/yr. 

He's wrong. This is where he got his numbers from, in the paper by Robert Kopp et al:

The average rate of GSL [global sea level] rise was 0.4±0.5 mm/y from 1860 CE to 1900 CE and 1.4±0.2 mm/y over the 20th century. 

That's right - the rise of 1.4 mm a year was for the twentieth century, not to the present. Charles can't bring himself to acknowledge that since 1993, seas have risen by an average of 3.4 mm a year.

Only one of the papers was about  pre-industrial sea level rise.  It reported that sea level varied by around ±8 cm before industrialisation, and that contrary to what Charles Clough implied, there was a marked decline in sea level between 1000 and 1400 CE.

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. 

Argument by assertion

Charles makes a lot of argument by assertion. For example, he wrote: "forecasting sea-level rise involves even more guesswork than forecasting global warming." The only evidence he provides is that tide gauge records "are less than 200 years old". Well instrumental records for surface temperature aren't much older, and only for a few locations at that. That's why scientists use other proxies to determine what happened in the past.

Charles also asserted that "Absolute sea-level measurements from satellite only began in the early 90s—too recent to establish significant trends." He is implying that estimates of future rise would be based on extrapolation of past rise. Thing is, it is known that the surface temperature is rising, and that ice is melting. Estimates of future sea level rise factor in the following:

1. expansion of water from warming and
2. additional water from melting ice.

More misinformation

Charles then says it's all too hard, and repeats his earlier misinformation, writing:

Finally, there is the problem of learning how long the oceans take to reach equilibrium once there is a change in global temperature. Temperatures have been generally rising and sea-levels with them ever since the end of the ice age thousands of years ago. 

That's wrong. Neither surface temperature nor sea level has been "generally rising". If you look at the Holocene, there was an early rise, followed by about 8,000 years of declining surface temperature. As the charts in Figure 1 above show, sea level fell overall in recent centuries and only started to rise again relatively recently. Now seas are rising faster than they have in any of the past 28 centuries. (It also raises the question of whether Charles is still a young earther, with his reference to thousands of years ago.)

When Charles writes:

But there have been numerous up-and-down oscillations in this general trend, none of which is well understood. Are we in one or more of these oscillations now?

Yes, there have been "numerous" ups and downs, though I'd not describe them as oscillations. The answer to his question is a resounding "no", of course. If Charles thinks that an ice age cometh, then you can dismiss anything he writes about climate. I can ask rhetorical questions that makes more sense than Charles' dumb question about oscillations:

Is Charles Clough knowingly deceiving WUWT readers?
Charles Clough an ice age comether?
Is Charles Clough a greenhouse effect denier?

When Charles writes, with no link and in contradiction of actual satellite altimetry:

...new satellite altimetry of absolute sea-level when carefully calibrated shows a mean rise of 0.5 mm/yr, not the modeled 1.4 mm/yr.

First, the mean sea level rise since 1993 is reported as 3.4 ±0.4 mm a year, not 0.5 mm a year and not 1.4 mm a year. I've no idea where he got his number for "modeled" sea level rise of only 1.4 mm a year.

Charles provides evidence that he's an alarmist denier or deliberate disinformer, writing:

Since atmospheric CO2 emission levels do not correlate with such changes prior to the industrial age, the upward trend in temperature and sea level will continue regardless of the political campaign to impose economy-destroying carbon asceticism on the world’s population. 

What is he talking about? There's a lot of gobbledegook about atmospheric CO2 emission levels and pre-industrial changes in something. He seems to get it right that temperature and sea level rise will continue to increase, however I don't know what he's on about with a "political campaign to impose economy-destroying carbon asceticism".

The one thing that I deduced from the article is that some deniers are so intent on harming people that they'll make up stuff. Some of them are so stupid (or think their readers are so stupid) that they'll provide links to papers that contradict what deniers claim the papers say.

From the WUWT comments

Michael Moon picked up on one of Charles Clough's wrong assertions.

May 17, 2016 at 2:24 pm
“…and new satellite altimetry of absolute sea-level when carefully calibrated shows a mean rise of 0.5 mm/yr, not the modeled 1.4 mm/yr.”
Dr. Clough,
Thanks for this fine post. I think many here would appreciate a link to your reference for the above.

Greg  wanted the same thing, but so far, and unsurprisingly, Charles has kept Mum on the matter:

May 17, 2016 at 3:32 pm
Ditto.
That is quite a surprising claim, which is not much use as a bland assertion. I would certainly be interested in the source of this figure.

ristvan seems to think that only one of the papers was wrong. He doesn't say which one, and seeing they both made similar projections that is quite curious. Perhaps Rudd Istvan is an ice age comether:

May 17, 2016 at 4:18 pm
Another paper with which they will hang themselves a decade hence. Still a long time to wait.

Russell is being irrational and just wants to proclaim all research wrong, for no reason at all:

May 17, 2016 at 4:50 pm
The lead-in of this article, on the first impression appears to legitimize its premise. I favor hard hitting, skepticism that characterizes the article and authors as utterly full of shit–because they ARE!

References and further reading

Kopp, Robert E., Andrew C. Kemp, Klaus Bittermann, Benjamin P. Horton, Jeffrey P. Donnelly, W. Roland Gehrels, Carling C. Hay, Jerry X. Mitrovica, Eric D. Morrow, and Stefan Rahmstorf. "Temperature-driven global sea-level variability in the Common Era." Proceedings of the National Academy of Sciences (2016): 201517056. doi: 10.1073/pnas.1517056113 (open access)

Mengel, Matthias, Anders Levermann, Katja Frieler, Alexander Robinson, Ben Marzeion, and Ricarda Winkelmann. "Future sea level rise constrained by observations and long-term commitment." Proceedings of the National Academy of Sciences 113, no. 10 (2016): 2597-2602. doi: 10.1073/pnas.1500515113 (open access)

Seas Are Rising at Fastest Rate in Last 28 Centuries - article by Justin Gillis at the New York Times, 22 February 2016