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.”
I prefer gauge data which you can always try for whatever corrections that might seem necessary. Which is not to say that one can remove absolutely all degree of uncertainty.
Actually, it is lovely to have both. It would also be fun to have deepwater gauge measurements but alas, it is a bit difficult to create a rigid rod down to the ocean floor and not have it subject to all sorts of confounding influences from currents that bend it sideways (submerging the tip) to thermal expansion of the rod itself as surface temperatures vary, so that it out-expands the thermal expansion of the ocean due to local surface warming (lots of materials have thermal expansion coefficients as large or larger than that of water). No matter how you slice it, measuring SLR is a bitch. In one sense SLR at the coasts is what we really care about, so tide gauge measurements at the coast, whether or not they accurately reflect overall average SLR, are what matters. OTOH coastal tide gauges are subject to a range of local errors or confounding influences — uplift/subsidence of the land, silting, local warming, alteration of the tidal gap leading to the station due to construction, beach migration or storm-erosion (a BIG factor at Beaufort, for example). Satellite data is relatively global and relatively immune to most of this by simply out-sampling the confounded sites with (more) “randomly” selected ones. People don’t put tide gauges down via random site selection, or systematic grid — they put them where they live, and they live in places that are not necessarily “typical” of the (any) coast in general. And they don’t/can’t put them into the deep ocean.
But together they give us a better picture than either one alone. Sadly, the problems of isostasis and gravity and coriolis force and the non-sphericity of the globe mean that AT BEST the picture they give us is highly imperfect and imprecise.
Fortunately, until and unless the major continental-scale ice packs melt, it is pointless to be concerned about SLR. Seriously pointless. That, at least, is a simple consequence of physics, because the oceans are really, really big and take a really, really long time to substantially change their temperature. Without additional water we’re talking thousandths of a degree and millimeters/year of SLR at most, almost independent of what happens in the air or on the land surface.
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I agree: “seriously pointless”.
Unfortunately the alarmists have used this issue with much advantage and so it must be refuted. It is for this purpose thatI have an interest in the issue.
Jan Kjetil Andersen:
The U of Colo. is entirely unreliable for sea level information. NOAA data show no sea level rise for this century.
I read some time ago that it actually dropped two years in a row – I believe 2010 and 2011…
If 9000 years ago, it was 4.5 deg F warmer than today and the oceans were 2 meters higher. Then 2000mm/4.5= 444mm SLR per deg F of SLR. So, 3.2 mm per year times 100 years, a century, =320mm. 320mm/444mm = 0.72 deg F temperature rise per century. No, this can’t be that simple???