Thursday, May 26, 2016

HOTWHOPPER does Dave Burton's sea level claims

As promised earlier here is a reposting of a recent article written by Sou over at  In it she takes a closer look Dave Burton's statements and then clearly explains how he's manipulated facts to fabricate his lying talking points. 

Dave Burton wants to level the seas at WUWT

Over at WUWT, deniers are clutching at straws to continue to reject science in the face of all the "hottest evers". They really, really liked the last big El Nino in 1997-98, but they really, really dislike this current El Nino of 2015-16. It means they'll have to wait a while before they can start pointing to a drop in the surface temperature although Anthony Watts keeps jumping the gun and is excitedly telling his readers that a La Nina is just about here.

Here is some of what they got up to today, with a moan and lots of misdirection from a WUWT regular commenter called Dave Burton about another bane of deniers' existence - rising seas (archived here). But first, what's been happening...

TOPEX/JASON Sees 22-year Sea Level Rise

Published on Mar 9, 2016

This visualization shows total sea level change between 1992 and 2014, based on data collected from the TOPEX/Poseidon, Jason-1, and Jason-2 satellites. Blue regions are where sea level has gone down, and orange/red regions are where sea level has gone up. Since 1992, seas around the world have risen an average of nearly 3 inches. 

It's not a trick - sea level rise is accelerating

Dave Burton is complaining about a NASA web page on sea level. The chart at the top on the right hand side is from satellite readings. Remember, deniers love satellites in areas where the readings are difficult and have wide error margins, like lower tropospheric temperature. They don't like satellite readings when the error margins are smaller and the results don't suit their purpose, like sea level change. Here is the chart Dave didn't like:

NASA also showed a chart of sea level derived from tide gauge analysis from John Church and Neil White of the CSIRO, and didn't put up a big sign saying what the trend was. What Dave Burton didn't point out and maybe didn't even see, was that the chart only showed data to 2000. (I don't know why there isn't a plot using the most recent data.) Anyway, Dave probably missed seeing that because he didn't read the label in big letters, and didn't look at the x axis which was from 1870 to 2000:

So there's an entire article at WUWT all complaining that there wasn't a little sign up the top of the tide gauge data (to 2000) when there was a little sign about the satellite record (to 2016). Dave Burton's whiny WUWT article starts off with this piece of conspiracy theorising:

NASA’s tricky sea level newsletter
Anthony Watts / 6 hours ago April 7, 2016
Dave Burton writes:

Those NASA guys are tricky.

Click the “Update: Sea level change / Ocean rising at 3.42 mm per year” link in their latest Newsletter and you’ll see the big, bold “3.42 mm/yr” near the top of the web page, and two very similar-looking graphs of sea-level: one from satellites, and one from tide stations.

Since only one rate of sea-level rise is shown, the casual observer is likely to think that the same 3.42 mm/yr rate applies to both graphs. Here’s a screenshot:

Under the chart, Dave Burton says to "Look closer at the scales, and do the arithmetic". Pity he didn't take his own advice. The rate of change of the top chart is the rate of change for the period from 1993 to 2016. The rate of change of the bottom chart, or what Dave said he estimated, was for the period from "the late 1920s" to 2000. Those are different periods. Dave wrote:

Since the late 1920s it shows a slope of about 1.8 mm/yr, with no evidence of acceleration. But those tricky NASA guys scaled it to look like the slope is about the same as the first graph. It’s pretty obvious why they didn’t show a rate of sea-level rise for that graph.

Dave Burton's tricks

Dave Burton ranks highly on the conspiracy theory meter thinking NASA is out to trick deniers who don't know how to read a chart. What about the data? What tricks is Dave Burton trying to pull? :D

From the late 1920s to 2000 or so, the slope is 1.8 mm/year. From 1993 to 2016 the rise has been 3.42 mm/year. That means Dave is wrong. There is evidence of acceleration.

While deniers like to claim that the rate of sea level rise hasn't increased, if you go by what Dave Burton is saying, he's accepting there has been an acceleration of sea level rise. It used to be less than 2 mm a year and now it's up to 3.42 mm a year.

The paper by Church and White (2006) used tide gauge data through to 2001, with the data downloadable from the CSIRO website. In that paper the authors look at the data in different ways. For example, because there is a slope change, they wrote that you could: "do linear regressions on the two halves (1870– 1935 and 1936 –2001) of the record. The slopes are 0.71 ± 0.40 and 1.84 ± 0.19 mm yr 1 respectively". That 1.84 mm / year is close enough to Dave's estimate though the periods are slightly different.

The other thing is that Dave complains about adjustments to the tide gauge data. He wrote:

What’s more, the second graph is not really just from tide gauge data; it’s from tide gauge data inflated by a +0.3 mm/yr GIA “adjustment,” to subtract off the rate by which the sinking ocean floor is hypothesized to reduce sea-level rise. 

He reckons that this is wrong and that "The real rate of coastal sea-level rise from averaged tide gauge measurements is only about 1.4-1.5 mm/yr (under six inches per century), and that rate hasn’t increased since the late 1920s." He quoted from the website of some denier who referred to a NOAA tide gauge website, which reported "the absolute global sea level rise is believed to be 1.7-1.8 millimeters/year". That looks to be in need of an update. But more importantly, Dave saw fit to subtract the GIA adjustment from the NOAA data when it wasn't applied in the first place. He's a double adjuster.

There's sea level rise and there's sea level rise

There are at least two main reasons for people wanting to know about sea level rise:
  • Coastal planning and management
  • Monitoring global climate change
The thing is that for coastal planning, what people want to know is how much and how fast the sea will encroach on the coastline. They need to know the sea level relative to the local land. That will vary depending on where you are. The NASA website Dave was moaning about is for global climate change. (In case you missed it there's a big clue on the top left of the web page.) In that case the information needed is how fast are the oceans filling up? How quickly is ice melting. How quickly is the warmer water expanding? That's a different purpose and scientists need to have an indication of the change in the total volume of water in the world's oceans. That's why they allow for glacial isostatic adjustment.

Dave doesn't want to adjust the global tide or other sea level data to allow for glacial isostatic changes? What about barometric adjustments - does he approve of that? What about slippage where the tide gauge sinks or rises relative to the land surface? Does he want that adjusted for? Why doesn't he just pull a number out of the air and claim that the seas are falling? I think that probably what is happening, apart from Dave wanting to reject any and all climate science, is that he is mixing up the data and the purpose for which the data are used.

If he's concerned about the coast where he lives, then he'll need local information more than global. Different coastlines have markedly different rates of rising and sinking relative to the sea level. There's been a lot of research into what happens around the world.

On the other hand, John Church and Neil White were researching global change in their more recent 2011 paper (as in previous papers). In the introduction they explain:

Correctly estimating historical sea-level rise and representing global ocean heat uptake in climate models are both critical to projecting future climate change and its consequences. The largest uncertainty in projections of sea-level rise up to 2100 is the uncertainty in global mean sea level (GMSL) and thus improving estimates of GMSL rise (as well as regional variations in sea level) remains a high priority.

The fact that they were looking at global change, not local change, is why they allowed for glacial isostatic adjustment, and wrote:

Here, the ongoing response of the Earth to changes in surface loading following the last glacial maximum were removed from the tide-gauge records using the same estimate of glacial isostatic adjustment (GIA; Davis and Mitrovica 1996; Milne et al. 2001) as in our earlier study (Church et al. 2004). 

John Church and Neil White know what they are doing. They tested for all sorts of things and added that they even tested for the impact of the changes in dam storage, writing:

We tested the impact of correcting the tide-gauge measurements for terrestrial loading and gravitational changes resulting from dam storage (Fiedler and Conrad 2010). For the large number of tide gauges used in the period of major dam building after 1950 (mostly over 200), the impact on global mean sea level is only about 0.05 mm year−1 (smaller than the 0.2 mm year−1 quoted by Fiedler and Conrad, which is for a different less globally-distributed set of gauges). Tests of similar corrections for changes in the mass stored in glaciers and ice caps, and the Greenland and Antarctic Ice Sheets show that these effects have an even smaller impact on GMSL.

Glacial isostatic adjustment

If you're wondering about glacial isostatic adjustments, there's some information on the U Colorado sea level page. What it is is the mantle is still responding to the reduction in ice cover from around 20,000 years ago. Ice is heavy. When it melts, it means that some land surfaces pop up higher and the bottom of some oceans are falling relative to the Earth's centre. In other words, the oceans are getting bigger. If it wasn't for global warming, the sea level would be falling if there were no change in the actual volume of sea water. The CU Sea Level Research Group said in 2011 that "Including the GIA correction has the effect of increasing previous estimates of the global mean sea level rate by 0.3 mm/yr."

Meg Rosenburg submitted a video to the 2013 AGU student contest on the subject of glacial isostatic adjustment, which will give you some idea of the cause and effects:

AGU Student Video Contest: Rebound: An Earth Story 

Published on Jul 8, 2013
Submitted By: Margaret Rosenburg

Description: My submission is an education video about glacial isostatic adjustment, why we have glacial and interglacial periods, how we can reconstruct climate history, and how the Earth is responding to the retreat of the continental glaciers. I found that this topic brings together a lot of different areas of study relevant to AGU, from geophysics, to orbital mechanics, to geochemistry.

If you have the time, there are 17 videos from the Permanent Service for Mean Sea Level 80th Anniversary Workshop on Sea-Level Science, including one specifically on glacial isostatic adjustment, by Giorgio Spada.

How much has the volume of ocean water changed?

You can see the chart in Figure 1 up top to see how much the volume of water in the ocean has changed in recent years. On the CSIRO website there's a data update of Church and White (2011), which goes up to 2013 for tide gauges and 2014 for satellite (altimeter), and is plotted below. The data are available at different levels of detail. I've just plotted the annual data. The faint grey lines are the upper and lower error margins for the tide gauge data. I've added linear trend lines for different periods as shown in the legend and on the chart. (Hover over the chart to see more detail):

It's obvious from the above that the rate of sea level rise has been increasing. However the CSIRO website has a caution and a reference to a workshop. I'm not sure what it means, but I'll copy it below:

We are currently attempting to more thoroughly evaluate the methodology and to improve the reconstruction so that it better represents the variability (Legresy et al., Workshop on Global and Regional Sea Level variability and change, Mallorca, Spain, June 2015).

Here is a video of an interview with John Church, at that workshop in Spain

SLR2015 Interviews: Dr. John Church

Published on Nov 12, 2014

Dr John Church’s record in sea-level rise research, with CSIRO colleagues, the Antarctic Climate & Ecosystems Cooperative Research Centre, and international climate science agencies, has helped generate a new benchmark in understanding the science and issues of sea-level rise.

Dr Church is coordinating lead author of the Sea Level Change chapter of the IPCC Fifth Assessment Report. As the Secretary-General of the World Meteorological Organisation, Michel Jarraud, highlights in his foreword: 'The findings in this book will help set priorities for research and for observational activities over the next decade that will contribute to future assessments of the IPCC. In turn, improvements in these assessments will better inform governments, industry and society in their efforts to formulate sound mitigation an adaptation responses to rising greenhouse gas concentrations and sea level, and their economic and social consequences.'

More about sea level changes

As well as the videos I talked about earlier, there's the 2011 video with Jerry X. Mitrovica of Harvard, in which he addresses some of the false claims by fake sceptics. (He also says what many of us have found, that by investigating denier's claims, you can learn much.)

I recommend these two Mitrovica talks, fascinating and eye opening.

Postmodern Geophysics and Ice Age Climate
Published on May 14, 2014
Lecture given at Oregon State University on May 9, 2014 by Jerry X. Mitrovica


In Search of Lost Time: Ancient Eclipses, Roman Fish Tanks and the Enigma of Global Sea Level Rise

Distinctive Voices

Uploaded on Aug 17, 2010

What do ancient eclipse records kept by Babylonian, Chinese, Arabic and Greek
scholars, and fish tanks, built by wealthy Romans during100BC-100AD, contribute to our understanding of modern climate change? Dr. Jerry X. Mitrovica will describe the important role these archaeological treasures have played in the understanding of sea-level rise and how they help scientists both "fingerprint" sources of recent sea level changes and make more accurate projections of future sea levels.

Jerry X. Mitrovica, Ph.D., is a Professor of Geophysics in the Department of Earth and Planetary Sciences at Harvard University, a Fellow of the American Geophysical Union, and the Director of the Earth Systems Evolution Program of the Canadian Institute for Advanced Research. 

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