Measured sea level rise drops 30% with “pause” greater than half of RSS measurement period.
Guest essay by Larry Hamlin
A paper titled “The rate of sea-level rise” published in Nature Climate Change on March 23 by Cazenave, et al. shows that during the last decade the rate of sea level rise has declined by about 30% during the period 2003 through 2011 to about 2.4 mm/year from the rate of 3.4 mm/year in the period 1992 through 2002. The paper argues that this decrease is the result of short-term natural climate variability which it attempts to remove to reveal the “true” global warming signal with the end result being to “adjust” the lower measured sea level rate upward.
Dr. Judith Curry addresses this new paper in her April 24th post “Slowing sea level rise” where she argues that there is no convincing way to adjust out the effects of El Nino/LaNina events from the measured sea level rise record and that natural variability has dominated sea level rise during the 20th century.
The crux of her arguments are presented below with the figure shown from the UN IPCC AR5 WGI report showing that sea level rise has varied significantly since 1900 in a manner which Dr. Curry concludes demonstrates dominance by natural climate variation forces.
The slowing in the measured rate of sea level rise during the last decade has occurred while the RSS satellite measured global lower-troposphere temperature record now has more than half of its 35+ year temperature record, which began data collection in January 1979, showing no global warming whatsoever since August 1996 as demonstrated in the graph below taken from an article in Real Science addressing this “pause”.
Dr. Curry draws the following conclusions based upon these measured and perhaps interrelated outcomes by noting:
“Once again, the emerging best explanations for the ‘pause’ in global surface temperatures and the slow down in sea level rise bring into question the explanations for the rise in both in the last quarter of the 20th century. And makes the 21st century of sea level rise projections seem like unjustified arm waving.”
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Haven’t looked at this in depth, but it strikes me as passing odd that sea level rise has been decelerating if the ocean has been absorbing all the extra heat that was predicted and that we haven’t been seeing in surface/atmospheric data sets. I know, it doesn’t amount to much temperature change over the ocean, but that’s still a heck of a lot of water that’s supposed to be increased in temperature by a very small amount.
Just saying.
Dr. Curry’s point is good though.
the acidic oceans are dissolving the calcium carbonate substrate….
Colorado will have to adjust up for this
BTW…why don’t you just eliminate the first part….when sea levels were below normal
Then there’s nothing happening at all
Same thought I had – would’nt all that heat “hiding” in the oceans cause expansion, hence sea level rise? If so, any idea how much it could account for?
Last night’s Years of Living Dangerously first exploited the human misery of superstorm Sandy suggesting rising sea level could make a storm once a year. To finish the segment, they go to Christmas Island where a researcher suggests the island could be lost rising sea level. But is you look at the PSMSL website for Christmas Island sea level has actually trended lower.
[imgfit]http://www.psmsl.org/data/obtaining/rlr.monthly.plots/1371_high.png[/imgfit]
Essentional, if natural temperature veriations can cause the platue, and slowdown sea level rise, maybe they could also have caused the late 20th century warming?
Questions this brings to mind:
1) What component of sea level rate of change is tectonically / eustatically driven vs thermally driven ? (and how are you going to separate those two components objectively, let alone separate ENSO-PDO-NAO events from the thermal signal to get the AGW signal ? )
2) What’s the cross-correlation of the sea level rate of change & ocean temp / lower atmospheric temp data? The author of the original paper would infer that ocean temps / lower atmospheric temps are driving sea level rate of change – it this were the case , we should expect a very short lag (with ocean / atm temps slightly leading SL rate of change) and a high correlation coefficient. If not ==> theory busted. Has anyone seem this kind of plot?
Didn’t Willis demonstrate the same deceleration in sea level rise here about a year ago? I remember he did a bar graph of sea level rises for 10 year periods (1993-2002, 1994-2003 etc, ) using the data from http://sealevel.colorado.edu/
Hope he was cited in the paper.
strange where these articles take you,
History of the ice trade.
http://en.wikipedia.org/wiki/Ice_trade
It also makes a hash of the egregious claim that SLR is “accelerating” due to AGW, which is generally based on a tiny increase in rate, mostly seen in the still-being-adjusted satellite data, in an absurdly short data chord near the end of the data that anybody publicly posts.
I’m still waiting for someone to update:
http://en.wikipedia.org/wiki/File:Trends_in_global_average_absolute_sea_level,_1870-2008_%28US_EPA%29.png
which carefully preserves the last vestige of the claimed “acceleration” in one of the only places where the normal public can see any compendium of the data. I’m guessing that somebody is waiting for SLR to upturn again, maybe with an ENSO event, rather than honestly publishing the data to let it speak for itself without “interpretation”. I’m also waiting for the latest round of GRACE based corrections to be similarly portrayed in this figure, as I seem to recall that once gravitation and subsidence are more accurately taken into account, the satellite SLR is actually itself diminished even in the thin green line at the end. Of course satellite observations and tide gauge observations, however mismatched they might be initially, are mutually correcting in the long run, just as UAH/RSS LTT is now a hard constraint on what people can do to the global surface temperature anomaly.
I’m actually sad that the top article above doesn’t present the data through 2014 so that we can actually see the data, not a derivative of the data, through the present, not through the early-to-mid 90’s. Telling us about it doesn’t help. Showing us the data does.
I personally have a hard time seeing any hard correlation between SLR rates and ENSO events, BTW. This is a job for Willis, IMO — he seems to cut through the assertions of statistical bullshit by the simple expedient of grabbing e.g. the ENSO data, grabbing some sort of SLR compendium (warts and all) and then using R to, errr, look for correlation with an R^2 that isn’t basically zero. This process is complicated by possible lag, by the short time scale of ENSO events, by all sorts of noise, the limited length of records, confounding and obscuring stuff like uplift/subsidence, and the interesting fact that thermal expansion of water leads to an unusual breakdown of the isothermal assumption of an isostatic surface — warmer water floats, so one can actually support localized bulges of the sea level that have basically zero effect on the overall oceanic level, effects that are limited to the specific location of the warmer water (just as ice floating on water might raise the “level” of water by the height of the ice where it is floating without affecting SLR anywhere else at all).
So even though ENSO is an anomalous warming of a chunk of ocean water in a specific location, its effect on global SLR is limited to the specific region of the thermal anomaly, over the specific time the anomaly lasts. Only long term, spatially global sea surface warming can really raise SLR via thermal expansion, and of course the only other mechanism for SLR is the melting of non-seasonal land ice or the alteration of the freshwater/sea water balance on a global scale. The anomalous melting (as in an imbalance of new snowfall per year relative to deep melt, since the surfaces of these icepacks basically never reach the melting point) of the major land ice packs — Greenland and Antarctica — is almost non-existent. People make noises of a shift in the ratio of land freshwater and sea water, but I don’t think there is any compelling evidence for it. Basically, nearly all SLR observed is the ocean acting like a great big lagged thermometer that is probably the most precise and reliable direct measure of global average surface temperature in existence.
It is the lack of any compelling acceleration in SLR that is the strongest evidence that we have against the hypothesis of runaway/catastrophic anthropogenic global warming, as well as the natural vs anthropogenic fractions of such warming as has occurred. Both the SLR graph I link and the derivative of the SLR graph republished in the top article show that there is absolutely nothing remarkable about SLR rates post 1950 compared to pre-1950, where 1950 is usually given as the breakpoint year where CAGW due to CO_2 was “launched” by the advent of a steady increase in post-WWII industrialization and civilization worldwide.
This is a profound case of the inconsistency of the CAGW argument. It is so strong that it comes dangerously close to being direct evidence that the argument is unambiguously false! That’s why — IMO — there has been a more or less deliberate delay in the updating of the last “alarming” publicly published figures that the CAGW community was capable of generating. Unchanging SLR rates plus the assertion of hidden heat hiding in the oceans, taken together, suggest that we are completely missing the fundamental drivers of century scale changes in the Earth’s set point, drivers that were responsible for the LIA, the Dalton minimum, and the post-Dalton recovery. The oceans have been warming at a nearly steady rate from before CO_2 could possibly have been a factor through the present. Since we don’t know the causes of the warming or cooling pre-1950, and cannot hindcast any of the significant cooling or warming periods of the thermometric era (see figure 9.8a in AR5, which shows that CMIP5 basically collectively skates over all of the significant 20th century variations outside of the reference period), we cannot even pretend to be able to separate out natural trends from any hypothetical CO_2 linked trend.
But if SLR rates even think of flattening instead of accelerating, especially flattening on a decadal or longer time scale, this is a serious body blow to the CAGW hypothesis. The Ocean has probably been pursuing some sort of global set point, damping the entire planet’s approach to some new “equilibrium” based on the unknown factors that governed the MWP and LIA and post-LIA recovery. CO_2 may, or may not, have modulated that new set point further. But at some point it is quite possible for the ocean to reach the new set point vicinity, in which case SLR will decelerate, not accelerate. Deceleration is anathema.
rgb
According to Trenberth, Hansen and Co., ENSO should be a ‘global warming’ signal i.e. ‘global warming’ increases the frequency and intensity of (warm) El Nino events, and reduces the frequency and intensity of (cool) La Nina events.
Cazenave, et al look at the temp record, and can’t find any ‘global warming’. So they remove Trenberth and Hansen’s ‘global warming’ signal and *poof* – they find ‘global warming’ in what is left over.
Truly, ‘climate science’ is magical.
rgbatduke says:
April 28, 2014 at 11:48 am
Since the longer-term trend has been global cooling for at least the past 3000 years (arguably 5000, since the end of the Holocene Optimum), rising MSL for the past ~150 years might well reverse. As you so aptly note, the causes of decadal & centennial scale fluctuations are not known. CO2 seems not to be the control knob on them, so reversion to the mean millennial scale trend line seems likely.
Orbital mechanics appear to be a major factor on the scale of tens to hundreds of thousands of years, but are not well enough understood to predict how much longer the Holocene might last, whether 300 years, 3000 or 30,000. In any case, the current interglacial has been cooler & so far shorter than the Eemian (MIS 5) or the long, hot MIS 11. Sea level was higher in the Eemian (Scandinavia was an island, perhaps also from lowering by the weight of the big glaciation preceding it), but even with more heat for more millennia, the more vulnerable southern dome of the Greenland Ice Sheet didn’t entirely melt away then, as it may have done during MIS 11 & apparently did in MIS 19 (as shown by DNA recovered from beneath the southern dome & by climatic proxy data). The northern dome has existed for about 18 million years, but has waxed & waned.
The East Antarctic Ice Sheet, as you know, has been around for more than 34 million years, with of course some pretty big mass & area fluctuations. A study last year concluded that the West Antarctic Ice Sheet also probably formed at the Eocene/Oligocene transition:
http://phys.org/news/2013-10-west-antarctic-ice-sheet-earlier.html
@Latitude – Normal seems to be what ever they decide. Not something that is common in the history of the planet.
Damn!
He said he would do it and he did.
All hale POTUS.
Damn!
cn
I struggle really hard to accept any alleged measurement of SLR as serious – after all, it is all relative – but relative to what? an Interglacial ‘average’ – or a (just) pre-glacial ‘high’ – or perhaps a (just) post glacial ‘low’ – or perhaps some arbitrary ‘level’ invented by climate scientists or oceanographers? (I mean, we have an arbitrary avergae temp of the Earth at ’14degC’ despuite the fact it was previously ‘arbitrarily’ 15degC !!) – Can we take any of this stuff seriously when any anthropgenic signal is but a tiny smear on the backdrop of natural variability?
Good ol’ NPI again
http://virakkraft.com/NPI-sea-level-trends.png
I never understood why anybody talks about the sea level rise for the last 100 years as either supporting or refuting global warming.
Eyeballing the graphs on Wikipedia, it seems to me that the noise in the data for the past 8000 year or so is around +/- 1 meter, conservatively: http://commons.wikimedia.org/wiki/File:Holocene_Sea_Level.png
So, when I try to overlay the graph of the past hundred years or so (http://commons.wikimedia.org/wiki/File:Recent_Sea_Level_Rise.png) onto this graph in my mind, it just seems that the tiny 20 cm rise is buried in noise. It seems to me, you could have global warming and still have a sea level decline over the past hundred years, or you could have no global warming but with a rise over the past hundred years. The data is just meaningless to me.
A link to Curry’s site seems to be missing. Not that it is hard to find, but still seems appropriate.
If all those Hiroshima bombs of heat have been absorbed by the oceans, why is the sea level rise rate declining? I know. Answering that question is like wrestling a muddy pig.
http://www.osdpd.noaa.gov/ml/ocean/J2_handbook_v1-3_no_rev.pdf
OSTM/Jason-2 Products Handbook
2.3.1. Accuracy of Sea-level Measurements
Generally speaking OSTM/Jason-2 has been specified based on the Jason-1 state of the art,
including improvements in payload technology, data processing and algorithms or ancillary data
(e.g: precise orbit determination and meteorological model accuracy). The sea-surface height shall be provided with a globally averaged RMS accuracy of 3.4 cm (1 sigma), or better, assuming 1 second averages.
I tend to avoid commenting on most of these sea level posts because unlike most of the world I find the satellite sea level data to be a complete crock. If history is any indicator I will have almost no chance of turning anyone here to my point of view and I can live with that, but i would suggest that before you choose to be an epistemological mattress back for what is admittedly an amazing bit of technology, that you spend some time with the data products handbook I linked above. Try to keep a tally of the various approximations, models, adjustments and other fudge factors involved in assembling this data, bearing in mind that each of the first order “corrections” is itself based on its own ensemble of fudge factors and the logical chains extend to third and fourth orders for most of them.
With that in mind, try to recall the ubiquitous stock footage of the Southern Ocean that has been a hallmark of the wall to wall coverage of the missing Malaysian airliner and ask yourself how a satellite pinging that surface from 800 miles up could resolve its height to tenths of a millimeter, especially since in the table that provides a summary of specifications and error budget, which appears just below the paragraph I quoted above, there is a line for Significant wave height which is 10% or 0.4 m whichever is larger.
I have heard over past decade the following…..
The glaciers are melting, Antarctica and Greenland are losing mass balance, the oceans ate my global warming, the hottest decade evaaaaah, global warming hasn’t stopped etc. And now this!
I know, it doesn’t amount to much temperature change over the ocean, but that’s still a heck of a lot of water that’s supposed to be increased in temperature by a very small amount.
The point is that thermal expansion is proportional to the length of the system that is expanding. Assume that this length is (say) 1 km, or 10^6 mm. Even temperature changes that are one part in 10^5 absolute could then produce changes of several mm over 1 km. As I said in an earlier reply, that’s why the oceans are an exquisite thermometer for the Earth.
rgb
at least they didn’t try to hide the decline…
The trend lines in the RSS temperature graph have no merit whatsoever because their ends do not connect. Displaying such lines is a stain on this website, viewed with disdain by any practicing scientist including me. Anyone who knows their stuff, when encountering such sham “science” will immediately turn off to the website. Don’t do this to me.
The Cazenave, et al people are probably kicking themselves in the butt about now… they missed a big chance here. They should have subtracted to influence of the El Nino years from the previous data, which would have dropped that SLR rate to around 2.5mm/year. Addition of the El Nino correction to the data post 2000 like was done, then they would be able to claim that sea level rise is rapidly accelerating…… it is MUCH WORSE THAN WE THOUGHT could have been the headlines all around the world. Sea level rise went from 2.5 mm/yr in the 1990s to 3.3mm/yr rise in the 2000s (after corrections), an increase of 30% in a single decade.