Finds sea levels have risen over the past 9 years [2002-2011] at a rate of only 1.7 mm/yr, equivalent to 6.7 inches per century, matching tide gauge data rates.
The paper corroborates the NOAA 2012 Sea Level Budget which finds sea levels have risen at only 1.1-1.3 mm/yr over the past 7 years from 2005-2012 [less than 5 inches/century], and the paper of Chambers et al finding “sea level has been rising on average by 1.7 mm/year over the last 110 years.”
From the IPCC FAR Chapter 5.5.2: Holgate and Woodworth (2004) estimated a rate of 1.7 ± 0.4 mm yr–1 sea level change averaged along the global coastline during the period 1948 to 2002, based on data from 177 stations divided into 13 regions. Church et al. (2004) (discussed further below) determined a global rise of 1.8 ± 0.3 mm yr–1 during 1950 to 2000, and Church and White (2006) determined a change of 1.7 ± 0.3 mm yr–1 for the 20th century.
The paper:
Impact of Continental Mass Change on Rate-of-Rise of Sea Level
Present-day continental mass variation as observed by space gravimetry reveals secular mass decline and accumulation. Whereas the former contributes to sea-level rise, the latter results in sea-level fall. As such, consideration of mass accumulation (rather than focussing solely on mass loss) is important for reliable overall estimates of sea-level change. Using data from the Gravity Recovery And Climate Experiment satellite mission, we quantify mass-change trends in 19 continental areas that exhibit a dominant signal. The integrated mass change within these regions is representative of the variation over the whole land areas. During the integer 9-year period of May 2002 to April 2011, GIA-adjusted mass gain and mass loss in these areas contributed, on average, to -(0.7 ± 0.4) mm/year of sea-level fall and + (1.8 ± 0.2) mm/year of sea-level rise; the net effect was + (1.1 ± 0.6) mm/year. Ice melting over Greenland, Iceland, Svalbard, the Canadian Arctic archipelago, Antarctica, Alaska and Patagonia was responsible for + (1.4±0.2) mm/year of the total balance. Hence, land-water mass accumulation compensated about 20 % of the impact of ice-melt water influx to the oceans. In order to assess the impact of geocentre motion, we converted geocentre coordinates derived from satellite laser ranging (SLR) to degree-one geopotential coefficients. We found geocentre motion to introduce small biases to mass-change and sea-level change estimates; its overall effect is + (0.1 ± 0.1) mm/year. This value, however, should be taken with care owing to questionable reliability of secular trends in SLR-derived geocentre coordinates.
A slide show on the paper is available here: Baur_GGHS2012
Reference
Baur, O., Kuhn, M. and Featherstone, W.E. 2013. Continental mass change from GRACE over 2002-2011 and its impact on sea level. Journal of Geodesy 87: 117-125.
Background
The authors write that “present-day continental mass variation as observed by space gravimetry reveals secular mass decline and accumulation,” and that “whereas the former contributes to sea-level rise, the latter results in sea-level fall.” Therefore, they state that “consideration of mass accumulation (rather than focusing solely on mass loss) is important for reliable overall estimates of sea-level change.”
What was done
Employing data derived from the Gravity Recovery And Climate Experiment – the GRACE satellite mission – Baur et al. assessed continental mass variations on a global scale, including both land-ice and land-water contributions, for 19 continental areas that exhibited significant signals. This they did for a nine-year period (2002-2011), which included “an additional 1-3 years of time-variable gravity fields over previous studies.” And to compensate for the impact of glacial isostatic adjustment (GIA), they applied the GIA model of Paulson et al. (2007).
What was learned
Over the nine years of their study, the three researchers report that the mean GIA-adjusted mass gain and mass loss in the 19 areas of their primary focus amounted to -(0.7 ± 0.4 mm/year) of sea-level fall and +(1.8 ± 0.6) mm/year of sea-level rise, for a net effect of +(1.1 ± 0.6) mm/year. Then, to obtain a figure for total sea-level change, they added the steric component of +(0.5 ± 0.5) mm/year, which was derived by Leuliette and Willis (2011), to their net result to obtain a final (geocenter neglected) result of +(1.6 ± 0.8) mm/year and a final (geocenter corrected) result of +(1.7 ± 0.8) mm/year.
What it means
The final geocenter-corrected result of Baur et al. is most heartening, as Chambers et al. (2012) indicate that “sea level has been rising on average by 1.7 mm/year over the last 110 years,” as is also suggested by the analyses of Church and White (2006) and Holgate (2007). Concomitantly, the air’s CO2 concentration has risen by close to a third. And, still, it has not impacted the rate-of-rise of global sea level!
References
Chambers, D.P, Merrifield, M.A. and Nerem, R.S. 2012. Is there a 60-year oscillation in global mean sea level? Geophysical Research Letters 39: 10.1029/2012GL052885.
Church, J.A. and White, N.J. 2006. A 20th century acceleration in global sea-level rise. Geophysical Research Letters 33: 10.1029/2005GL024826.
Holgate, S.J. 2007. On the decadal rates of sea level change during the twentieth century. Geophysical Research Letters 34: 10.1029/2006GL028492.
Paulson, A., Zhong, S. and Wahr, J. 2007. Inference of mantle viscosity from GRACE and relative sea level data. Geophysical Journal International 171: 497-508.
This essay was derived from several sources: CO2Science.org, The Hockey Schtick, and independent located content.
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This paper essentially confirms results found by other people.
A major problem in using just the 9-year period of May 2002 to April 2011 is that sea levels are affected by decadal and multidecadal climatic oscillations. And during the last 10-20 year the acceleration in SLR has normally been negative.
in my recent publications there is a extensive discussion on these topics:
Scafetta N., 2013. Multi-scale dynamical analysis (MSDA) of sea level records versus PDO, AMO, and NAO indexes. Climate Dynamics. in press. DOI: 10.1007/s00382-013-1771-3.
http://link.springer.com/article/10.1007%2Fs00382-013-1771-3
Scafetta N., 2013. Discussion on common errors in analyzing sea level accelerations, solar trends and global warming. Pattern Recognition in Physics, 1, 37–57. DOI: 10.5194/prp-1-37-2013.
http://www.pattern-recogn-phys.net/1/37/2013/prp-1-37-2013.html
Papers can be downloaded from my web-site.
Richard M says:July 3, 2013 at 7:49 am
You make some good points. I was considering wasting a post in izen asking if he had heard of land-based aquifers, which probably need recharging form all the irrigation we pull out. So his fantasy of all the rainwater running back into the oceans is moot. Speaking of aquifers, if one uses the numbers provided by the UN for the amount of water used in irrigation, which admittedly may not be good numbers, just our irrigation water, if all went to the seas, would be over 2mm/year of SL rise.
Here is a good comparison. This is an article about the island were Amelia Earhart supposedly landed nearby. The picture from the air is from 1937.
http://abcnews.go.com/US/lost-photos-reveal-clues-amelia-earhart/story?id=19472466#.UdRGeZWqc3w
Compare the photos with the most recent Google earth pictures and there is virtually no change at all.
Does the greening of the Sahel count? Now let’s go global.
Events have just overtaken your belief system. Upstream, just reported on WUWT
izen says:
July 3, 2013 at 5:47 am
@- Bill Illis
“It wouldn’t be that big of a problem if we weren’t changing our whole civilization based on these belief-driven adjustments.”
The ‘belief’, which is rather well supported by empirical observations, is that the changing climate will impose far worse changes on our whole civilisation and that the intelligent thing to do is prevent as much of the change as possible and adapt to the unavoidable damage the present changes are causing.
This is an alternative to propagating the belief that the scientific case for mitigation and adaption is a political conspiracy. With the consequent Panglossian inference that the status quo is the best of all possible worlds….
<<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>
Typical knee-jerk alarmism. What “change in climate”, pray tell? In fact, there has been none.
Jimbo says-
“10 APR 2013 Abstract
Analysis of trends in fused AVHRR and MODIS NDVI data for 1982–2006: Indication for a CO2 fertilization effect in global vegetation”
Thank you for posting this link. The pdf is available for no charge.
This is really important, because it provides a means of estimating how many people are being fed by CO2 emissions simply through fertilization. If it is included in any estimate of CO2 impacts, the result will be an overwhelming positive impact, assuming that the value of $7M to $9M per human life is used for both costs and benefits of burning fossil fuels.
Unfortunately, the people who want to stop CO2 emissions are the same ones who want global population truncated to 1 Billion or less. They count increased food production as a negative.
John Peter says:
July 3, 2013 at 5:53 am
Where does that leave the University of Colerado with their 3.2mm +/- 0.4mm per year?
http://sealevel.colorado.edu/
Maybe their various “corrections” account for their near doubling of the annual rate.
Maybe they would like to comment here. No chance.
<<<<<<<<<<<<<<<<<<<<<<<>>>>>>>>>>>>>>>>>>>>>>>
The U of Colo sea level studies are completely fanciful. They will never respond to any critique on WUWT because they would get clobbered. Better to sit quiet and rake in the public’s money.
There are various factors that alter sea level
1- thermal expansion or contraction
2- loss or gain in land based ice
3- loss or gain in land based aquifers from rainfall
As Nicola mentioned short term variations climate variation can alter any underlying trend. The recent extra rainfall seen and subsequent flooding caused the reduction in the rate of sea level rise seen in 2011/2012 as part of the 1 metre {about a yard} of water evaporated each year from the oceans was retained on the land. Most will eventually return to the oceans, but some will refill aquifers depleted by human extraction.
The thermal expansion and loss of land based ice mass can be measured with errors less than the measurement. But the balance of rainfall and aquifer retention or return to the oceans are much more uncertain and can alter the underlying rate of sea level rise significantly.
However unless there is a dramatic reversal of the thermal expansion or the negative ice-mass balance the influence of rainfall variations can only be short-term and transient. I don’t think any knowledgable oceanographer would claim that the glaciers and Greenland ice cap are suddenly going to gain mass or that the oceans will cool and contract in the next century given the energy imbalance caused by the increased CO2.
That commits human society to adapting to several feet of sea level rise by the end of the century. That MAY be a slow enough change to adapt to. But it will be a new situation that human societies have not faced in recorded history as there is good evidence, geological, archeological and astronomical, that there has never been any similar significant change in sea level in the past six thousand years.
All the great coastal cities and communities have developed over human history with a very stable sea level.
That has now changed.
“Finds sea levels have risen over the past 9 years [2002-2011] at a rate of only 1.7 mm/yr”
Oops. Bit of discrepancy here. Sea Level Research Group at University of Colorado shows 2.4 mm/yr for the same period (41% higher), AVISO 2.6 mm/yr (53% higher).
Disagreement can’t easily be ignored, as this value is well outside error bars. Are current calibration methods of satellite altimetry useless?
@paul80:
Most of the sea level rise data you see, included those cited at left, are from “altimetry” satellites. These measure the distance between themselves and the surface. The biggest wild card in these measurements is the how well the height of the orbit of these satellites is known. This height certainly isn’t known directly to mm/year accuracy or even resolution, so it must be inferred indirectly.
I have yet to find direct explanation of how this calibration process works. Indirect explanations I have seen say that the trends altimeter satellite data is compared to terrestrial tide-gauge data at specific places around the globe, and that the difference is attributed to orbital changes. These calculated orbital changes are then used to convert the raw “distance” data into “sea level” data.
However, the tide-gauges worldwide have generally show trends under 2mm/year both before and after the altimetry satellites went up. That’s why arguments that the trends used to be 1.7mm/year and are now 3.2mm per year, as put out by the IPCC (in their summaries; if you read their whole reports, they qualify this), and parroted by folks like izen, are so misleading.
The question is how well they have done this calibration process, and with what error bars they have done it. If the calibration is off by 1.5mm/year (and I think it easily could be), then these different figures are brought into line.
Check out the first link in the article. That describes an analysis by NOAA scientists to rectify three different data sets: the satellite altimetry, the GRACE gravity satellite data, and the ARGO buoy ocean thermal data. Combining these, they find a best estimate of 1.1 – 1.3 mm/year sea level rise so far this century.
izen says:
July 3, 2013 at 12:00 pm
////////////////////////
Have you seen the many Greek ports in the Med and Aegean which are now high and dry? In some places, the sea is approximately 50km from where it was at the height of the Greek and Roman Empires.
You only have to go along the Thames to see that in Tudor times and indeed in the 18th/early 19th century the river levels (the Thames is a tidal river) were much higher. In Tudor times, the Tower of London was approached via the river, but water level are now to low to permit boats to enter.
the statement “All the great coastal cities and communities have developed over human history with a very stable sea level.” does not bear scrutiny when viewed against historical and archaelogical evidence.
Hansen’s flooded West Highway along the Hudson R in 15 years prediction made in 1986 and then increased to 40 years upon expiry – man there is no end to the hubris of the faithful. The highway is ~10 feet above the river – this is the basis for his recent 20 foot rise prediction by 2100. That sucker is going to be 10 feet under! I think with the declining climate sensitivity from 4-6 down to <1, sea level (apart from the 20 feet said in anger) down from 3m to 7 inches we can soon construct an exaggeration index that might be useful.
Berényi Péter at 1:11 pm said
“Finds sea levels have risen over the past 9 years [2002-2011] at a rate of only 1.7 mm/yr”
Oops. Bit of discrepancy here. Sea Level Research Group at University of Colorado shows 2.4 mm/yr for the same period (41% higher), AVISO 2.6 mm/yr (53% higher).
Disagreement can’t easily be ignored, as this value is well outside error bars. Are current calibration methods of satellite altimetry useless?
****************
If you take the data as published at the time, “2011 rel_1”
http://sealevel.colorado.edu/files/2011_rel1/sl_ns_global.txt
and then calculate the slope from 2002 forward you will wind up with:
Slope 2002.0269 to 2011.09 yields 2.27mm/year
And since CU adds in a GIA adjustment of 0.3 mm/yr so that their sea level chart will be a proxy for ocean volume, that needs to come out, so you wind up with less than 2 mm/year. They’ve made other corrections and modifications over the years, so I expect that 1.7 mm/yr isn’t too far off the mark.
Question: As the temperatures have leveled off or dropped in the last decade, will that decrease the rate of the rise??
On balance, the effect globally on crop yields so far this year is distinctly positive (falling futures prices):
http://seekingalpha.com/article/1533362-bermuda-high-big-heat-and-floods-more-fireworks-for-some-commodities
A lot can happen in 100 years. For instance,sea levels could drop.
Interesting that the data appears to be converging at about 15 cm by 2100. I recall Dr Morner’s recent finding of 5 inches by 2100 from tidal gauge records.
I suspect projections will be revised even lower as the solar minimum really starts to kick in.
Now if someone could convince my excitable local city council that they don’t have to scare people witless and devastate our house prices with sea level hysteria, it would be nice.
Paul80 says: July 3, 2013 at 5:16 am
“Will someone explain this discrepancy? Or are these GMSL rates just plain alarmist exaggeration?”
Is there really a discrepancy at all?
Despite the headline of this post, the paper does not really make a finding about GMSL rise. It is a paper about mass gain. A part of GMSL rise is the steric (thermal/salinity) component, and here is what they say:
“In summary, at present steric sea-level change computation is subject to large uncertainty. In order to provide some numbers regarding the total sea-level change, adding the steric component of +(0.5 ± 0.5) mm/year (Leuliette and Willis 2011) to our non-steric ocean mass trends yields +(1.6 ± 0.8) mm/year (geocentre neglected) and +(1.7±0.8) mm/year (geocentre corrected).”
The “In summary” refers to a listing of some fairly divergent steric expansion results. I wouldn’t say that this statement, as phrased, is meant to be a “finding”.
But anyway it’s hard to argue that these results trump the direct satellite altimetry observations. They are created by adding together a lot of uncertain components of a budget, of which, as they say, the estimated steric component is very uncertain indeed. The component analysis is certainly interesting.
@stacase
“””””…..The sea level time series release from 2004 is over eight years old, and in that time many parts of the TOPEX and Jason-1 processing have been updated to reflect instrument and ancillary data improvements. …..”””””
news today says Jason-1 was just executed, but is going to swing in orbit for 1,000 years, just to make more space clutter.
In its 11 1/2 year life, it recorded 1.6 inches (4.0 cm) of sea level rise; well “within a few cm”, like maybe 4 cm. so between zero and 8 cm in 11 1/2 years. really useful to know that.
Thanks, Anthony for pointing this out.
stacase says:
July 3, 2013 at 1:41 pm
If you take the data as published at the time, “2011 rel_1″
http://sealevel.colorado.edu/files/2011_rel1/sl_ns_global.txt
and then calculate the slope from 2002 forward you will wind up with:
Slope 2002.0269 to 2011.09 yields 2.27mm/year
And since CU adds in a GIA adjustment of 0.3 mm/yr so that their sea level chart will be a proxy for ocean volume, that needs to come out, so you wind up with less than 2 mm/year. They’ve made other corrections and modifications over the years, so I expect that 1.7 mm/yr isn’t too far off the mark.
Well, that’s the issue with consecutive revisions being adjusted ever upward. Here are 2011_rel1 & 2013_rel4. Trend in the former one is indeed 2.27 mm/yr from (beginning of) 2002 to (beginning of) 2011, as you claim, but in the latter one it is 2.4 mm/yr from (beginning of) 2002 to (end of) 2011.
You can see retrospective adjustments done between the two releases in both textual & graphics format.
These adjustments are pretty flat (albeit noisy) up to 2002, but after that hell is getting loose.
You are of course right about the GIA adjustment of +0.3 mm/yr being added to Colorado stuff, but that’s preposterous in itself, since it has nothing to do with sea level as such. If they have meant ocean volume, they should have used that term, not another, misleading one.
Anyway, if GIA is subtracted, one is left with 1.97 mm/yr & 2.1 mm/yr in 2011_rel1 & 2013_rel4 respectively, 16% / 24% higher than this current estimate based on GRACE.
There is some splainin’ to be done indeed. Specifically, why & how later releases have made the estimate worse, not better?
This is interesting. An observational indication that the planet is starting to cool is a reversal of the polar see saw. The planet warms and cools cyclically correlating with solar magnetic cycle changes, The solar magnetic cycle activity was the highest in 8000 years for the duration of the current warming period. The solar magnetic cycle has abruptly slowed down and there are observational indications that the sun will be anomalously spotless by the end of the year.
When the planet as a whole cools, due to what causes the polar see saw, the Antarctic ice sheet warms which results in increased snow fall on the Antarctic ice sheet.
http://www.cato.org/blog/long-awaited-snowfall-increase-antarctica-now-underway
A paper to soon appear in Geophysical Research Letters give us another enticing look at recent snowfall changes in Antarctica. In “Snowfall driven mass change on the East Antarctic ice sheet,” Carmen Boening and colleagues from NASA’s Jet Propulsion Laboratory report that extreme precipitation (snowfall) events in recent years (beginning in 2009) have led to a dramatic gain in the ice mass in the coastal portions of East Antarctica amounting to about 350 Gt in total (Figure 1).
Billy Liar is confused.
I did not mean that Tide Gauges were not giving reliable data but for a locality only not for a large area or to calculate the global sea level rise accurately. They only give relative sea level changes at that gauge position.
johnmarshall says:
July 4, 2013 at 2:56 am
I’m not confused. I agree with you on the wider issue of global sea level. The point I was trying to make is that relative sea level is what’s important to you when you go to the beach or decide whether to build a house by the sea.