Yesterday, the New York Times ran an excellent cover story on sea level rise, together with two full pages inside the paper, fancy graphs and great photographs (online version here). The author, Justin Gillis, researched the piece for months, visited Greenland and talked to most of the leading scientists in the field – many of which he cites in the article. The science presented is correct and up-to-date and the story is a gripping read. That’s how science journalism should be!
What is going on in Greenland? (c) The New York Times.In the area of sea level rise, science has moved along quite a bit since the last IPCC report was published in 2007 (see for example my commentary at Nature together with that of Jason Lowe and Jonathan Gregory), and Gillis shows that most of the experts now assume a considerably higher rise until 2100 than IPCC: about one meter, potentially even more. I also had to change my position on this – only a few years ago I assumed lower values, too (see for example our book Our Threatened Oceans). By now, several US states use our projections for coastal planning (e.g. California, North Carolina) and Obama’s science adviser John Holdren shows them in his presentations.
For those interested in the projections in metric units and broken down for emission scenarios, please consult the original version. (c) The New York TimesOver the years, I’ve worked with dozens of journalists that reported on our work, but seldom was the cooperation so professional and the result so convincing as with Gillis. It is an example for how professional journalism can prove its advantage over the growing competition by blogs – few bloggers could afford such in-depth research to give a broad overview of the state-of-the-art of a particular scientific issue. This is on a completely different level than the standard quickly-cobbled-together pieces based on a press release by Science or Nature, which are so hilariously spoofed by Martin Robbins (who made me laugh out loud).
Naturally, every journalist would love to do a big story like Gillis – it’s up to the editors to grant them time and travel expenses for such a project, and then two pages of the paper. Kudos to the New York Times for making this possible even in times of tight budgets!
I saw a good example on how not to do the narrative last night, on the Weather Channel. It was a documentary from 2009 titled “Future World,” clearly crafted to be sensationally alarmist, in a time frame (2025) that would impact people alive today, but far enough in the future that people wouldn’t naturally think “that can’t happen.”
First, it purported to show possible calamities that could happen by 2025. While each of them might be likely to happen eventually (100 years?) somewhere to some degree, and improbably could happen to the extremes presented, and could in very remote circumstances happen by 2025… the idea that any of them would happen, as portrayed, by 2025, is really stretching it.
The scenarios included a dust storm that inundates Las Vegas, a desert locust plague that devastates Italy and France, a firestorm that destroys Los Angeles, and flood waters that engulf Washington, D.C.
They didn’t include the simple, obvious, and I think more likely scenario of reduced food production in the U.S. Midwest, with accompanying economic pressures and impacts on ordinary daily lives (although I don’t know that 2025 is a valid time frame for this scenario either, and I suspect it’s nowhere near it).
On top of this, the eye candy did not come close to coinciding with their comments, instead going above and beyond, to visually portray something ridiculous. For example, when talking about rising sea levels, they showed huge waves (several stories high) flooding in and swamping city blocks. They showed a map of the world with the shorelines advancing and encroaching on fully one third of the African and South American continents.
Then, to put the icing on the cake, they finished with a case of a Texas farmer involved in seeding clouds to make rain in a drought stricken area, with a voice over that implies that scientists are working hard and will come up with technology to save us from all of these events, so sorry if we scared you, you can just go back to bed now, trust in science, all is well.
Sheesh! This is exactly the sort of garbage that the deniers (rightfully) crow about. It was complete nonsense, and only serves to confuse people, and to give weight to the “They’re alarmists! Don’t listen to them!” cries of the denial crowd.
[[[
On a side note, the idea of the desert locusts extending their range into a dryer, warmer Mediterranean was interesting. In the 2004 locust outbreak, swarms reached Israel, Crete and Portugal. The danger of an impact on France/Italy was clearly exaggerated to make it feel like it was affecting Western civilization (after all, who really cares about Africa?*), but when merely considering the impact in both human lives and dollars of increased locust activity in Africa and the Middle East, it is still very frightening, and one more potential outcome of global warming that I’d never considered.
I’m unsure, however, if global warming is more likely to help (extreme rain events, warmer winters) or harm (reduced precipitation overall) desert locusts. I’ll have to do more research.
* Before anyone freaks out, “who really cares” comment was sarcasm.
]]]
Interesting random desert locust fact, pertaining only to a swarm of some unknown size (not necessarily one that could strip a European country bare, mind you) reaching Italy or France:
As I suspected (just to clarify, then no more about desert locusts, I promise):
Re Gavin’s point about DMI being based on a couple of reanalyses–I’ve pointed out to some of my “usual suspects” that if they truly think that modeling is bereft of any credibility, they really shouldn’t (for consistency) be citing DMI just because they like the answer. The only answer I’ve received so far is a protestation that (basically) they’ve heard somewhere that DMI has the best Arctic temperature data, because, well. . . just because.
Which tells me quite a lot, in a “meta” topical sort of way.
Rod B #131, huh?
J. Bob #150, don’t you feel a moral obligation to read up on a subject, especially a scientific one, before trying to pretend you know what you’re talking about?
Eh, not even close. You could start by finding out how on-board geodetic carrier-phase GPS is actually being used for satellite tracking, and how precise it is. You know, some of us have studied this stuff and applied it successfully. Just stringing together sciencey-looking words into syntactically well-formed English sentences and hoping nobody notices doesn’t make you look good.
Martin Vermeer, J. Bob …
In about 30 seconds of google searching and reading an abstract in which the author’s talk about using GPS to pin down satellite location to within 0.07m, which would appear to be a smaller number than the 1.5m proclaimed by J Bob.
Couldn’t post the link, RC sez it’s spam.
“I found an abstract” (deleted too much trying to get around the spam catcher).
#155 Martin says
“J. Bob #150, don’t you feel a moral obligation to read up on a subject, especially a scientific one, before trying to pretend you know what you’re talking about?”.
OK, Martin, here’s my reference, where’s yours?
http://www.maps-gps-info.com/gps-accuracy.html
Dan H. — BPL has a long hisotry of doing useful work regarding climate. Try these:
http://bartonpaullevenson.com/Greenhouse101.html
http://bartonpaullevenson.com/NewPlanetTemps.html
JBob – It seems a bit strange to be citing the accuracy of your “personal navigation devices” on a science site: “the bottom line is that GPS accuracy depends on the GPS technology in use.”
Don’t you think there might be a bit better technology available to science and the folks who designed, implemneted and maintain the satellite system? Investigate Relative Kinematic Positioning a bit.
Thanks, David.
dhogaza, BPL… thanks. The 0.07 m is conservative.
J. Bob, for a challenge, let’s restrict this to papers where 1) I am one of the authors, and 2) there is a free copy on the Internet — like this one. Or this one. Or this one. There are more.
Enjoy!
#155 Mark & #156 thank you, for more up to date info on GPS measurement accuracy. You say it’s 0.07m or less. Now am I to assume it’s horizontal accuracy? If that’s the case, vertical accuracy would be about 3-5 times less then the horizontal. So the resulting best GPS vertical measurements are accurate to about 0.21m, or 210mm.
#160 flxible says use RKP (0.3m), but that’s worse then carrier phase.
http://en.wikipedia.org/wiki/Global_Positioning_System#Accuracy_enhancement_and_surveying
It appears that we are talking about geological uplifting measurements in the 2mm/yr range, and the inaccuracy of the measurements is almost 100 times that. Even if the error were reduced by a factor of 10, the error would still be in the 20mm range. When I did a stint in test engineering, for orbital projects, there was a rule of thumb for measurement accuracy. That is, the measuring device had to be about 10 more accurate then what you are trying to measure. This was to reduce the RMS test error. Here we seem to have a case where the measuring instrument has an error of 10 times, or more, then the signal one is trying to measure.
Then there is the issue of past records. That is ,what was the accuracy of those GPS or Survey, measurements 5,10,20 years ago?
So unless one can have better methods of measuring “uplift”, that contribution sea level effects may have to be off the table.
J. Bob, thank you for your very clear, disappointing, but expected answer.
Re: 151, sphaerica bob
How does climate science reach newspapers?
One of the weak links is university media relations; that’s often the office which crafts press releases of recent studies. I can’t profess to know the process (I’m a lowly writing instructor), but it seems to me that if the news release about Dr. So & So’s recent study doesn’t craft a gripping lead and a good story that can accurately communicate the information, then it will just sink into the swamp of information. If you want to see these releases, just visit EurekAlert.org, sciencedaily.com, or nsf.gov/news. Many of them communicate science to other scientists reasonably effectively, but the leads often miss the boat on relevance to the average, educated person. Here’s an example:
http://manoa.hawaii.edu/news/article.php?aId=4012
Here’s the lead:
Scientists have long known that atmospheric convection in the form of hurricanes and tropical ocean thunderstorms tends to occur when sea surface temperature rises above a threshold. So how do rising ocean temperatures with global warming affect this threshold? If the threshold does not rise, it could mean more frequent hurricanes.
Several rules broken. One, the lead spans three sentences. It should be one. Two, the verbs are static: have known, affect, does (not) rise. Three, the logic is too convoluted and vocabulary too polysyllabic for the average person reading quickly. Basically, this isn’t lead material. This isn’t the main story. Sure, those were the findings, but the story is rarely the findings themselves: the story is the significance of findings, the implications, or perhaps the process of discovery. The real story is buried near the end of the article:
…the tropical atmosphere is warming at a rate that is consistent with climate model simulations…
Better lead: Researchers in Hawaii have found that changes in the way hurricanes form confirm climate models that predict global warming.
Would it have run in major papers? Probably not. But at least journalists trolling for stories might have been able to glean its significance in the time it takes to read one sentence.
J. Bob,
I finally had time to look through the Arctic data. For those stations which had long data records, high temperatures were observed in the 1930s and 1940s, and then again in the last two decades. Low were observed from the 1960s-1980s. For the four Greenland stations, two had the highest recorded temperature for the last century in 1947, the other two in 2003, while all four recorded the lowest in 1983-4.
Many people have asked about the recent change in sea level increase. The change occurred at about the same time that measurements switched from TOPEX to Jason in 2003.
http://i90.photobucket.com/albums/k247/dhm1353/Climate%20Change/CU2.png
Dear Stefan,
in post #30 I asked you:
“Can you rule out a change of only about one foot; in other words is it possible, that your non-linear extrapolation shown up there is just a wrong model?”
In post #23 you answered
“Just adding to that: the entire satellite record (starting 1993) is just one data point in the analysis of our paper. Variability on time scales shorter than 15 years or so is in my perspective not linked to global climate change but likely just “noise” – the result of various internal variability mechanisms. Let’s wait another 15 years for the next data point, then we may see something.”
This indicates, that in your own opinion there is little knowledge about the trends.
Your answer in Re #46
” I’m always a little surprised by lay people making sweeping statements like: “In fact, the sea has been rising at this rate for thousands of years.” Think about it: this would mean in the Middle Ages sea level should have been about 1.8 meters lower, in Roman times about 3.6 meters lower… Which clearly contradicts the archeological evidence, as discussed e.g. by IPCC.”
seems to indicate, that you are not willing to attribute any of the recent sea level rise to possible natural cause like the end of the little Ice Age (LIA). Probably I missunderstood this and it’s some kind of German humor..
But I would really hope, if you could comment/answer on my question.
After all the sea level rise seems to be the most important concern for humans for the global warming and your statment about the reliability for the data seems the contradict your error bars in the extrapolation.
#166 Dan H. & J. Bob
While you two are busy fondling each others notions, and romanticizing about short term variability while drinking the elixir of narrowly scoped (cherry picked) data points, the world of physics and reality is sailing away without you.
Instead, you should be looking at long term trends with attribution and the basic physics. The predictions for 1m by 2100 are looking pretty solid now. There a good chance we may have locked in 2 meters, and there is uncertainly, even a potential for SLR to be higher than 1-2m by 2100?
After the candles burn down and your dinner by the beach on the island of denial, watching the sunset of reason fade over the horizon of wishful thinking, you will find fantasy eventually replaced by the hard warm facts. What will you say then?
Economics: Balancing Economies
October Leading Edge: The Cuccinelli ‘Witch Hunt”
—
Fee & Dividend: Our best chance – Learn the Issue – Sign the Petition
A Climate Minute: Natural Cycle – Greenhouse Effect – Climate Science History – Arctic Ice Melt
John P. Reisman,
Think maybe we could take up a collection to rent J. Bob and Dan H. a room?
Maybe Max could join them for a Fun-with-Fourrier three-way.
166 Dan H. You have temperatures for the Arctic for a certain period.
Do you have Sea Surface Temperatures for the same period? Sea ice doesn’t just melt from the top down you know.
#169 Ray Ladbury
ROFLMAO
[edit – try and be constructive]
Adelady,
Do you know anyone who has sea surface temperatures for the Arctic going back to 1900? I would like to see them. I do know the US Navy took some measurements back in the 1950s in the open water over the North Pole.
[Response: Easy, around the North Pole, it will be pretty much a constant -1.8 degC (and it will stay that way until the Arctic is seasonally ice free). – gavin]
J. Bob:
No, you’re not to assume so, but obviously you did, and the reason why you did is obvious.
(it was accuracy in absolute terms, i.e. three dimensions, so the error in the vertical would be <= 0.07m, not greater as you claim.)
Thank you all for the most helpful info on GPS accuracy.
However I called professional surveyor. His info was that using Survey grade GPS equipment, there is an vertical error between 3 & 7 mm. This was confirmed from the Canadian government site:
http://www.geod.nrcan.gc.ca/products-produits/ppp_acc_e.php
So it looks like the error is about 3-5 times the resolution one is working with. Not the best situation for factoring “uplift” into sea levels.
Anyway looking at sea level data, around the US Gulf coast (no plate boundaries or glacier effects), there seems to be a fair amount of sea level changes in the early 1900’s. Wasn’t that before high levels of CO2 were around?
J Bob,
You should know that whether a 3-7 mm error is significant depends on whether it is random or systematic–and there are ways of dealing with both to achieve better resolution.
JBob@150: “If one looks at the best current GPS accuracy, it’s about 1.5 m vertically.”
JBob@158: References a link that discusses consumer recreational GPS units supporting his assertion above.
MartinVermeer@162 Links various actual studies of crustal deformation and sea level using scientific level GPS methods achieving decimal millimetre precision.
JBob@163, Apparently ignoring Martins actual science, claims “It appears that we are talking about geological uplifting measurements in the 2mm/yr range, and the inaccuracy of the measurements is almost 100 times that. Even if the error were reduced by a factor of 10, the error would still be in the 20mm range.” Therefor concluding “So unless one can have better methods of measuring “uplift”, that contribution (sic) sea level effects may have to be off the table.”
So with a hand wave, sweeps Martin off the table.
And @174, JBob prefers instead to phone a “professional surveyor”, and now believes “using Survey grade GPS equipment” (sounds important!!), there is an vertical error between 3 & 7 mm.” Which in turn he supports with a link to a Canadian Govt site that points out Precise Point Positioning with Dual-Frequency receivers achieves an accuracy of 1cm [10mm], possibly sub-cm, and his mapping-grade receivers [survey grade?] achieved no more than 20cm accuracy, and showing the information he relied on at the beginning was obviously the recreational receiver hardly capable of 1m accuracy.
So we’ve progressed from 1,500mm @150 and 158, to “the 20mm range” @163 to 3-7mm @174 with anecdotal evidence.
I’ll take Martin Vermeers science over JBobs musings any day.
#175 Ray, if a “error” is correctable, it’s not generally considered a “error”. Most of the “errors” or inaccuracies in the GPS system are corrected, or compensated for. These 3-7mm are the accuracy specs., and are assumed random errors.
#169–
I “doubt” it–oh, never mind.
Sigh. So, lay out a hundred thermometers each accurate to half a degree. How accurately can you determine temperature change in the area using all of them daily?
Now take a thousand GPS measurements of the same area, each known accurate within 5 mm. How accurately can you determine elevation change in the area using all of the measurements?
I’m making the numbers up. But I think there’s an issue of measurement accuracy with multiple observations being missed here.
For fans of learning how accurate geodetic dual frequency GPS can be, maybe take a look at the UNAVCO website (Unavco.org), or some of the current polar deployments (Polenet.org). The precision of the GPS is typically 1-2 mm in *position* in the vertical – but over three years or so of continuous data you get a better precision on the *trend* of any vertical motion.
Re: J.Bob getting seven shades beaten out of him…
The ref’s got to stop this one surely…?!
#181 Joe, I may have lost 7 shades, but there are still a lot more left.
#162 Martin, while your co-authored papers are interesting, they do not
answer what I was looking for. That is, how accurate are the “uplift” measurements relating to sea level, not only now, but in the past. While one may measure “uplift”, to mm’s accuracy now, how good was it 10, 20, or 50+ plus years ago when a significant amount of sea level data was being taken?
Prior to the current GPS system, and older laser ranging, accurate elevation measurements were hard to come by. At least on relatively flat surfaces, one could triangulate with chain, transit or even theodolites for better horizontal accuracy. Elevation in flat coastal areas was another matter. One of the best theodolites we used was the Wild Leitz T-4. That was good for measuring relative elevation just under 1 sec. of arc., in the field. So that gives one an idea of how “good” elevations were measured only ~50 years ago, when tidal data was being accumulated.
Hence, one might give greater weight to tidal measurements, where geological effects would be minimal.
Considering that the greatest concern is the sea level rise around the coastal areas, tidal measurements would be of greater importance. A global average will not really tell us much, as many areas will experience much more and others much less. Scandinavian sea level has decreased significantly in the past century (some areas >7 mm/year), whereas many areas along the eastern coast of the U.S. have experienced the largest rise (4 mm/yr). The sea level along the eastern shore of the Pacific Ocean has risen from Southern California down to Colombia, and decreased northward up to Alaska and southward to the tip of South America.
Dan, the inline response to your previous attempt at this notion should make clear why you’re not making sense here.
https://www.realclimate.org/index.php/archives/2010/11/sea-level-rise-the-new-york-times-got-the-story/comment-page-2/#comment-191123
Yes, tide gauges at places experiencing rebound from the last ice age say as long as the land keeps rising faster than the ocean they won’t be in trouble. But most places around the world where people live did not have any glaciers during the last ice age, and don’t have that temporary protection.
You know this. You looked at the map showing where the tide gauges are when you tried this assertion earlier.
There’s far more going on here than whether individual cities get wet; sea level rise doesn’t _stop_ conveniently after a short time and doesn’t reverse within millenia. It’s a one-way change for a long time all around the world.
Look at that map again. You know how to find it.
Dan H #183: “A global average will not really tell us much…”
While no one should expect a global average to tell everything, it is the starting point and principal reference for the whole discussion. For example, if a blog comment happens to mention sea level decreases of 7mm somewhere and increases of 4 mm elsewhere, the global average of of 3 mm/yr will tell you not to be misled by false balance, and show you that the 7 mm decrease is not to be expected in most places, whereas the 4 mm increase is quite typical. While readers here (most of them!) can be expected to know that context, we find false balance injected into less learned public discussions constantly, with malevolent intent and baleful result.
> J. Bob says …
> While one may measure “uplift”, to mm’s accuracy now, how good
> was it 10, 20, or 50+ plus years ago when a significant amount
> of sea level data was being taken?
Good enough. The error bars are always wider as you look at older data.
Look what’s done adding new high-precision data to the older observations–this is a very good, image-rich poster illustrating 300 years of French sea level data and how it has been incorporated into current science:
http://wcrp.ipsl.jussieu.fr/Workshops/SeaLevel/Posters/1_6_Woppelmann.pdf
Want denial sites? those rank high in the first page on ordinary Google:
http://www.google.com/search?q=sea+level+historical+record
Want the science? more science sites show up if you use Scholar:
http://scholar.google.com/scholar?q=sea+level+historical+record
Hank,
It appears that the GRACE data and tidal guage data are more in-line than previously thought. We are both indicating about 1mm.yr sea level rise.
http://www.insidescience.org/research/satellites_reveal_differences_in_sea_level_rises
http://www.agu.org/pubs/crossref/2010/2010GL044770.shtml
[Response: You are confusing the component of SLR from total water mass changes (rough 1 mm/yr from the GRL paper) with the total SLR (which includes a thermal expansion component and a small difference from residual glacial rebound) which is closer to 3mm/yr. -gavin]
#186 Hank, the link to Brest is interesting, but I have looked at it, and there are breaks in the data. However the data in the mid 1800’s to mid 1900’s is interesting. It ties into my looking at long term central & western European temperatures. These are from 14 stations that started recording priot to 1800. Included are Central England, Debilt, Berlin, Upsalla, Paris, Prague, etc.
http://www.imagenerd.com/uploads/lt-temp-1800-2008-14-9ZSv8.gif
While it’s not perfect, it’s pretty much what one has to work with, for direct temperature measurements, in those early years.
Sea level is interesting, in that it offeres a possible connection to global temperature. But sea level can be influenced by geological changes, hence the “discussion” on “uplift”, GPS accuracy, error bands and such. Anyway, in order to get away from geological & glacial changes (such as Brest), the south & east coast of the US, seemed to be a good place to start. Urban “sinking” is another issue, but off the table for now. Below are some of the longer sea level graphs from this area:
http://www.imagenerd.com/uploads/n_amer_s_e_composite_4-har7A.jpg
which I selected for analysis in the near future. That is, to see if there is any connection to global temperatures. Hopefully to form a more comprehensive view if this whole thing is another natural cycle or man’s influence.
With respect to the “denial” & “science” sites. It’s not a bad idea to go to sites, opposite one’s opinion. If your not careful, you just might learn something .
This is why I go to \Answers in Genesis\, every day …
Because I want to learn about evolutionary biology …
JBob: “With respect to the “denial” & “science” sites. It’s not a bad idea to go to sites, opposite one’s opinion.”
I can honestly say that denialist sites have never taught me a thing about climate science, just as creationist sites have never taught me anything about evolution. Such sites are an amazing (and scary) lesson in human psychology, though.
Hello there,
well it seems, that Dr. Rahmsdorf is not willing to comment my question if the non-linear extrapolations is the only possible model. A pity . .
In the meantime Austrian-climatologists opened a new blog, where they try to bring climate facts closer to a mainstream audience. So far it is only available in German, but here is a translation of a closing sentence of the “future sea level”-chapter:
http://www.zamg.ac.at/klima/Klimawandel/Klimafolgen/Meeresspiegel/Zukunft/index.php
“Recent publications of measurement data and corresponding model calculations give regarding the risk of catastrophic “Eisausbrüchen” [..= calving..] on Greenland, or a sudden “float” of the West Antarctic ice sheet is seated below the sea surface a conservative all-clear.”
Can you comment on this oppinion? After all we are talking on probably the most scary prediction for the global warming ..
LoN
LoN – The final sentence refers to “catastrophic” calving in Greenland and a “sudden” float of WAIS. I looked at your reference, but Google translate was a bit clumsy. From what I read the bulk of the item was about the large range of uncertainties in the whole field of ice and SLR.
It may be true that WAIS and Greenland won’t suddenly drop into the ocean. It is certainly true that calving rates and melt rates will increase in a warming world. And _that_ is worth being worried about.
The final sentence reassuring us that we need not be scared of an instantaneous catastrophic sea level rise is not very reassuring, it’s focusing on a fairly small risk of large SLR happening all at once. Whereas the much larger and more certain risk is of continuing and increasing rates of SLR.
#189, 190–
I have to say that, contrary to dhoghaza & Ray’s experience, that denialist sites played an important part in my learning what I have managed to pick up about climate science. Without them, I’d have known the very basic “big picture” stuff, but gone no deeper.
But with the usual memes–so thoroughly catalogued and rebutted now on Skepticalscience–to spur me with the basic question “Can this possibly be true?” I was forced to go deeper. I was forced to find out about forcings vs. feedbacks and that famous 800-year lag between rising temps and rising CO2. I was forced to find out about IR absorption and emission. About statistics. About–well, you get the idea.
And I found out that almost all denialist discourse was marked by the most elementary scholarly failure of all–the failure to do a proper literature search. (Otherwise, long-answered (originally legitimate) questions wouldn’t be continually resurrected as zombie arguments.) And that most of those arguments shared the further features of 1) internal logical incoherency, and 2) substituting rhetoric for analysis (see for examples Motl, Lord Whatsisname, and G & T.)
Oh, I learned a lot from those guys.
But I don’t need continually to repeat the lesson, thank heavens.
> #162 Martin, while your co-authored papers are interesting, they do not
> answer what I was looking for.
That’s okay J. Bob, they weren’t meant for you anyway ;-)
Yes, adding in the thermal expansion of the upper ocean layer (~0.8 mm/yr) and the deep sea estimate (~0.2 mm/yr), the SLR is about 2.0 mm/yr. Not all that different from the tidal gauge data.
Unless significant calving starts occurring in Greenland, SLR is likely to reamin in the IPCC AR$ projected range.
http://www.nature.com/nature/journal/v453/n7198/full/nature07080.html
[Response: Can I get your guarantee on that? Of course, if you were wrong that would be really bad, but if you can really promise that Greenland isn’t going start shedding mass at an increasing rate as it gets warmer against all expectation, I’ll be happy never to say anymore about it. Thanks! – gavin]
Dear Laws of Nature,
Your question to Rahmstorf was based on false premises:
1 – All models are wrong. Rahmstorf just happens to have used a model which better matches historical data than your “linear trend with about 1foot per century”.
2 – Rahmstorf’s model is not a “non-linear extrapolation”. It needs to be fed a temperature scenario in order to produce a rate of SLR. You could use it to produce a “linear trend with about 1foot per century”.
In case you don’t know what I’m talking about: Laws of Nature was implicitely referring to the dual model featured in Vermeer and Rahmstorf’s PNAS paper.
#194 Martin
Nice to hear from you again. Perhaps with you vast knowledge on geological “uplift”, it should be quite easy for you to know, and share, how accurate, “uplift” measurements were in the past 10,20 years, and before GPS systems were available. I’m sure you are well aware how this accuracy would effect station sea level measurements, as well as their long term trend line accuracy.
Can someone tell me why the GRACE “Gravity Recovery and Climate Experiment” seems to indicate a minimal rise in sea levels. Please explain in layman terms.
Thanks
Can someone explain “GRACE” and its contribution to understanding sea level rise/decline. Lay terms please.
J. Bob, thanks for the vote of confidence, but what you are asking for would be covered by a number of courses: time series analysis, geospatial statistics, satellite orbits, GPS positioning technologies and processing techniques, physical geodesy, …
I don’t want to discourage you, but this is work. You need the background. Then, you could start with Cazenave and colleagues to get up on the altimetric analysis, and perhaps Church and White, and Jevrejeva and colleagues, for the tide gauge stuff.
I am reminded of the question to Gandhi: “Sir, what do you think of Western civilization?”
;-)