By Dr. Patrick Michaels from World Climate Report
Sea level rise is a topic that we frequently focus on because of all the gross environmental alterations which may result from anthropogenic greenhouse gas emissions, it is perhaps the only one which could lead to conditions unexperienced by modern societies. A swift (or accelerating) sea level rise sustained for multiple decades and/or centuries would pose challenges for many coastal locations, including major cities around the world—challenges that would have to be met in some manner to avoid inundation of valuable assets. However, as we often point out, observational evidence on the rate of sea level rise is reassuring, because the current rate of sea level rise from global warming lies far beneath the rates associated with catastrophe. While some alarmists project sea level rise of between 1 to 6 meters (3 to 20 feet) by the end of this century, currently sea level is only inching up at a rate of about 20 to 30 centimeters per hundred years (or about 7 to 11 inches of additional rise by the year 2100)—a rate some 3-4 times below the low end of the alarmist spectrum, and a whopping 20 to 30 times beneath the high end.
To get from here to catastrophe surely requires a significant acceleration in sea level. And, because disasters pay scientists handsomely, a lot of people have been looking. Here is how the Intergovernmental Panel on Climate Change (IPCC) in its Fourth Assessment Report summed up its investigation:
Global average sea level rose at an average rate of 1.8 [1.3 to 2.3] mm per year over 1961 to 2003. The rate was faster over 1993 to 2003: about 3.1 [2.4 to 3.8] mm per year. Whether the faster rate for 1993 to 2003 reflects decadal variability or an increase in the longer-term trend is unclear. There is high confidence that the rate of observed sea level rise increased from th3 19th to the 20th century, the total 20th-century rise is estimated to be 0.17 [0.12 to 0.22] m.
Since 2003—the last data assessed by the IPCC—the rate of sea level rise has slowed (Figure 1).
Figure 1. Decadal (overlapping) rates for sea level rise as determined from the satellite sea level rise observations, 1993-2011 (data available from http://sealevel.colorado.edu/).
This observation seems to tip the scale to “decadal variability” rather than an “increase in the longer-term trend” in explaining the 1993 to 2003 behavior.
But there is much more evidence that no anthropogenic global warming-related acceleration of sea level rise is taking place.
A couple of months ago, an important paper was published that examined the changing historical contribution of ground water removal (for human water needs, primarily irrigation) to global sea level. A primary finding was that this non-climate component of sea level rise was both significant and rapidly increasing, currently making up between 15 and 25 percent of the current observed rate of sea level rise. Further, the rate of ground water extraction has been increasing over time, which imparts a slight acceleration to the rate of sea level rise over the past half-century or so. Once this non-climate signal is removed, there remains no evidence for a climate-related acceleration. We covered that finding here.
Another paper has just been accepted in the journal Geophysical Research Letters that identified multidecadal cycles in the historical mean sea level observations from many ocean basins. A research team led by Don Chambers from the University of South Florida examined tide gauge records from across the globe and found oscillations with a period of about 60 years in all ocean basins except the Central/Eastern North Pacific. Chambers et al., note that a 60-yr quasi oscillation has previously been identified in other earth/climate systems including ocean circulation, global mean surface temperatures, large-scale precipitation patterns, and atmospheric pressure, among other things. Many of these cycles can be traced back hundreds of years—an indication of a natural (rather than manmade) origin.
Chambers and colleagues note that given the strong possibility for such cycles in the global sea level data, that care must be taken when attempting to identify accelerations, as they, in fact, simply be upswings in the natural oscillatory behavior. For instance, in most ocean basins, the bottom of the cycle was reached in the 1980s and an upswing has been occurring since then—precisely when the IPCC notes that the rate of sea level rise has been increasing. For this reason, Chambers et al. note:
The 60-year oscillation will, however, change our interpretation of the trends when estimated over periods less than 1-cycle of the oscillation. Although several studies have suggested the recent change in trends of global [e.g., Merrifield et al., 2009] or regional [e.g., Sallenger et al., 2012] sea level rise reflects an acceleration, this must be re-examined in light of a possible 60-year fluctuation. While technically correct that the sea level is accelerating in the sense that recent rates are higher than the long-term rate, there have been previous periods were the rate was decelerating, and the rates along the Northeast U.S. coast have what appears to be a 60-year period [Figure 4 of Sallenger et al., 2012], which is consistent with our observations of sea level variability at New York City and Baltimore. Until we understand whether the multi decadal variations in sea level reflect distinct inflexion points or a 60-year oscillation and whether there is a [Global Mean Sea Level, GMSL] signature, one should be cautious about computations of acceleration in sea level records unless they are longer than two cycles of the oscillation or at least account for the possibility of a 60-year oscillation in their model. This especially applies to interpretation of acceleration in GMSL using only the 20-year record of from satellite altimetry and to evaluations of short records of mean sea level from individual gauges. [emphasis added –eds.]
The bottom line is this: the more people look for the anticipated acceleration in the rate of sea level rise, the less evidence they seem to find in support of it. All the while, we eat into the 21st century with a rate of sea level rise not much different from that experienced during the 20th century—and one which was hardly catastrophic, readily proven by a simple look around.
References:
Chambers, D., M.A. Merrifield, and R. S. Nerem, 2012. Is there a 60-year oscillation in global mean sea level? Geophysical Research Letters, doi:1029/2012GL052885, in press.
Wada, Y., et al., 2012. Past and future contribution of global groundwater depletion to sea-level rise. Geophysical Research Letters, 39, L09402, doi:10.1029/2012GL051230.
Steve Keohane says: “…Two to three years ago, I pointed out on WUWT, that using the UN numbers for groundwater extraction for irrigation alone, that amount of water would add as much as 2mm per year to the sea level.”
I remember reading your comment, Steve. Seems you were right.
I built beaches along the Atlantic and Gulf coasts for 5 years. They are \typically built by pumping sand onto the beach from 1 to 3 miles offshore. I have a nice collection of very early Indian artifacts that were dredged from these offshore locations and pumped up onto the beach.
Groundwater removal –> decreased salinity –> increased evaporation –> increased cloud cover –> decrease in temperatures –> global cooling catastrophe
NeilT
Listen up man. The UN some years back claimed that there would be 40 million climate refugees by 2010 — due to rising sea levels indunating islands and coastal lands. Where are those refugees?? Those regions that were supposed to be indunated have actually increased in population.
Now the UN has put back the date for the 40 million climate refugees to 2020. That is only 8 years away and that are no, nada, zip, zero climate refugees so far.
Now the UN employs the greatest climate scientists in the world to make such predictions, right? So, back in the day, you must have believed that there would be 40 million climate refugees by 2010 right? How did you feel when it didn’t happen? Disappointed?? And are you looking forward to 2020 because you just know that the world is going to be aswarm with climate refugees in just 8 short years?
Alright here is your task — investigate all the diaster predictions that climate genius’ like Hansen and Gore have made in the past and then offer us clear expalanations of why they didn’t come true. Don’t talk about future predictions — talk about the past predictions that turned out to be false. Explain those away. Surely this should be an easy task. After you do that then predict the future for us.
Start with why the prediction of 40 million climate refugees by 2010 failed. Why did it fail?? Tell us, please.
Eugene WR Gallun
@JJ have you considered that the WAIS and Greenland will do for future generations.
No of course you havene’t you don’t give a second’s thought about them it’s all abot YOU and NOW.
Which is one of the dumbest things in this whole equaition. But then this site was never known for it’s nous. Belief, yes, nous? NO.
@William Howard, the natural interglacial optimum happened during the subboreal. Look it up. What is happening now is not natural. But you already knew that right? You just want to make a point against me!
But, go on, have it your way. So I’m talking rubbish and may win a WUWT prize for it. It will be a very small prize compared to the megalith WUWT is building for itself in being the prize fool of the climatic debate.
Louis Hooffstetter says: “…I have a nice collection of very early Indian artifacts that were dredged from these offshore locations and pumped up onto the beach.”
I know there’s a lot of stuff down there. I found an arrowhead in the surf, once. Much wear, but identifiable by the shape.
@NeilT
You say
Are you quite sure that you’ve really got the hang of the metric system and of its relative sizes?
1 mm/annum over 2 centuries is 200 mm = 20 cm. I just looked at my trusty school ruler to be absolutely sure and 20 cm is about 8 inches – or about the span of my hand from the end of my little finger to the end of my outstretched thumb. Try as I might I can conceive of no circumstances whatsoever where a sealevel rise of this order will ‘destroy our society’. Especially when we have two hundred years notice to make any necessary minor infrastructure changes to accommodate it.
I work in Central London. You may know that the River Thames flows through the centre of the city – indeed it is the original reason for London’s existence as a seaport. The river is tidal here and at London Bridge – the ancient heart – the tidal range is about 14 feet (4200 mm). This means that about every 6 hours and 15 minutes the river level goes up or down by that amount. We have river walls. The are about 17 feet high. This to take care of any exceptionally high tides. And we could build them 8 inches taller if needed.
An earlier correspondent nominated your remark for the dumbest thing said about GW this year. I second his idea. You really have got no idea at all.
Groundwater aquifer drawn down in Oxnard, California (Ca.) in 1950’s went so low seawater went into fresh water aquifer. It would have been a good case study of side effect on local sea level from human pattern of activity (rather than AGW). But this can’t be conclusively researched since a costly remedial 60,000 acre feet of Santa Clara River system water was engineered to re-adjust the Oxnard basin.
San Francisco, Ca. sea level may possibly also described as an artificially conserved situation . The “Bay Region” only takes 5% of it’s groundwater to provide total needed fresh water use (most comes in from Sierra mountain). If data were available from when the Bay area was both home to pre-colonial settlement(s) and compared to epoch just before Bay region stopped relying exclusively on groundwater that would be a good case study of variable side effects on local sea level from human pattern of activity (rather than AGW).
In case groundwater use seems inconsequential (in how it might relate to coastal land subsidence) try to imagine if the worldwide human coastal settlement pattern increase over the last decades is only equivalent to the current total population of Ca.. My last available data is that in 2002 Ca.(statewide, not just coastal) used 15 million acre feet of groundwater, verses only 9 million acre feet (estimated) a little over half a century earlier (1947).
Most of the tide gauge data Chambers et al use go back no farther than 1900 (often less) and end in 2003 or 2010, so the authors are properly cautious in claiming to have found a 60-year cycle that has not yet repeated twice in their data. Also they note that some older records do not support this cycle, and that records get less complete as you go farther back. And, their relatively weak cycles describe variation around the well established upward trend, not a departure from that trend.
One thing cycles clearly provide is predictions. In this case that the rate of sea level rise in the north atlantic and other basins should decrease over the next decade. Predictions based on 60-year cycles have proved spectacularly wrong about arctic ice, but perhaps they will fare better with sea level.
I heard a school boy say this the other day : “Hey I know why the Hurricanes are getting fewer and weaker, its pretty obvious really, warmer temperatures have shifted to the north pole these past few summers so it makes sense there is less heat to start and power the Hurricanes further south”…. I LOVE the logic…. How would a stroppy alarmist to that I wonder !?
NeilT says:
September 13, 2012 at 6:32 am
Neil, as I live near the Dutch border and have worked there for almost al my working life, I know something about what they have done to get no wet feet.
They have built dikes and a lot of other defenses to keep the water out. These are built to last a one-in-thousand years heavy NW storm at spring tide. That means over 10 m higher than MSL. I don’t think that an increase of 0.2 m over 200 years will worry them. If that increases a fivefold to 1 m in 200 years, they may consider to increase the heights with 1 meter… The lowest point in the Netherlands BTW is 12 meter below MSL.
The Dutch engineers have helped New Orleans with their fortifying of the dikes, with succes… And they are helping Bangladesh now who live in a similar delta…
NeilT
You are new here so can I ask that you look at the actual data instead of just repeating the things you have read that resonate with you?
Here is part 1 of my article ‘historic variations in sea levels’ which covers the Holocene to the Romans.
http://judithcurry.com/2011/07/12/historic-variations-in-sea-levels-part-1-from-the-holocene-to-romans/
Sea levels were some 20cm higher then than now, but the most important component is to factor in whether the land is rising or falling. There appears to be a cycle based around an oscillation of a metre either side of a mean average. Modern day sea level is some way from the top of the current cycle.
Tonyb
Ferdinand,
The inability (or refusal) of those worried about sea level rise to take into consideration our ability to engineer and build structures and equipment that can deal with the issue might go a long way in explaining why most engineers I know are rather skeptical about the “threat” posed by global warming.
I know that makes them “denialists” , “conspiracy theorists” and “nutters” to the AGW crowd, but what does it say about them?
tonyb says:
September 13, 2012 at 12:13 pm
You are new here so can I ask that you look at the actual data instead of just repeating the things you have read that resonate with you?
Here is part 1 of my article ‘historic variations in sea levels’ which covers the Holocene to the Romans.
The link you gave only goes to a blog post. Is there a peer-reviewed version of this article?
Yet another record that matches the plot I did of rate of change in UAH lower tropo temps
http://i45.tinypic.com/2lt1r4l.png
dT/dt and rate fo change of sea level are comparable quantities (both power related).
My plot uses 2 year gaussian filter as the longest , so it shows a bit more sub-decadal change. If we take the midpoint of his decades as the reference year, his peak is about 5 years later. The lesser thermal mass of the atmosphere will probalby account for that.
TLT hit negative rate of change in 2005 , due account needs to be taken of all the assumptions, inaccuracies and fiddle factors that do into GMSL these days. To know where the sea is by satellite, you need to know where the satellite is. To know that you need to know where the land is. To know that … well you guess how much it has moved and add another guess about how the ocean basins are deepening to make the mean sea level float somewhere above the waves.
That’s without the huge difficulty of working out where the mean level is by looking at a reflection from the _trough_ of a wave in a 2m swell without getting any systematic errors.
I take colorado’s GMLS data with a pinch of salt (sic).
Despite all that the general form is similar to TLT but with a significant residual warming. The turn-around 1995-2000 seems consistent between the two.
See, Obama does keep his promises.
REPLY: and yet in another thread you write….”Please remove the unnecessary and unhumorous reference to rioting in Libya. It’s uncalled for here.”…sorry it stays as satirical irony… be as upset as your wish. – Anthony
jonny old boy says:
September 13, 2012 at 11:54 am
Quite right! (well a reasonable explanation at anyrate!) – but seriously, this is excatly what the climate ‘team’ cannot do – i.e. look at an issue from a wide perspective and invoke logical thinking. Instead, they seem to have this unending desire to link to AGW – beats me!, but there you go……
Ironically, in places where we have altered river delta sedimentation (New Orleans, Nile delta), the rate of subsidence is much more than the rate of sea level rise, with actual consequences.
kwinterkorn says:
September 13, 2012 at 8:38 am
Where is Trenberth with a pithy phrase when we need him. The travesty is that the oceans are missing water and we cannot explain where it is. We know the glaciers and polar ice (well, the north pole, at least) are melting and the water must be somewhere. Maybe the water is hidden in the depths of the oceans.
+++++++++++++++++++++++++
Forget Trenberth, This was already published decades ago in the peer-reviewed music literature by David Byrne et al.
“There is water at the bottom of the ocean”
– Talking Heads (1981)
NeilT says:
@JJ have you considered that the WAIS and Greenland will do for future generations.
I doubt that Greenland will look very different in 200 years than it does today. If it is substantially different, I hope it is different warmer rather than different colder. If it is warmer, then my descendents might be able to live in some of the places that their Viking ancestors did ~1,000 years ago – places that I cannot live today because they are yet buried beneath great mounds of ice.
No of course you havene’t you don’t give a second’s thought about them it’s all abot YOU and NOW.
You can think about them all you want, but you don’t know jack squat about them, so the thinking that you are doing is called “imagining”. How sad it is for you that your imagination is so morose. It takes an unnatural level of defeatism to even entertain the notion that 0.75 inches of sea level rise per generation will destroy “our society”, let alone to succumb to such dystopic fantasy . Have you tried Prozac?
At any rate, you should stop worrying. MY actual descendents will be able to handle 8 inches of sea level rise over the course of ten generations. If your imaginary descendents are too crippled by their inherited personality disorders to cope, mine will likely step up and keep your disfunctional, maladaptive progeny from being swept out to sea on the crest of that 8 inch tall, super-slow-motion tsunami. No need to thank us. Its just the sort of soft hearted, considerate fellows we are.
Just plotted GMSL and UAH TLT rates of change with approx 2 year gaussian filter , shifting the air temp to 5 years later as observed above.
http://i48.tinypic.com/15666tt.png
The overlay is quite striking, if we accept the premice of a 5 year lag in the responce of the oceans They seem to be saying the same thing.
Otter says:
September 13, 2012 at 2:52 am
“One only has to step outside to see that everything is going pretty much as it always has.”
A Short History of the World’s Climate from 1800 to the Present
From 1800 to 1899, nothing much happened; the world got a little warmer, and the seas rose a little. Suddenly, in 1900, nothing much happened; nothing much had happened before, and nothing much was happening again. A distinct trend was developing. From 1901 to the present, September 13th. 2012, the trend continued, the Earth got a little warmer, and the seas rose a bit, and so nothing much happened.
Clearly, citizens of the Earth must take action to stop this worrying trend; if we do nothing, nothing much will continue to happen, and who knows what the result might be.
The rate of sea level rise has and continues to be a problem for Warmists. When you look back 10,000 years bp it’s flattening and most coral island atolls have risen with the sea.
I’m still waiting for my thermal expansion after our recent stint with global warming and the hottest decade on the record.
The US (which is only a small part of the globe unless it’s a heat wave) will soon be flooded. / sarc
http://www.bioone.org/doi/abs/10.2112/JCOASTRES-D-10-00157.1
Whatever happened to our gatekeeper? 😉
Calm down NeilT, observations trump fear and specualtion everytime.
NeilT you are getting thrashed here because your facts are not facts at all. Sea level rise has been on the same curve no matter if Co2 was high or low:
http://icecap.us/images/uploads/Sea_Level_Holgate.jpg