Climate Central scores grade F in geography

There's a lot of it about - sea I mean. There's also a lot of reports around just now in which alarmists appear almost to be gloating over a paper in Geophysical Research Letters titled The gravitationally consistent sea-level fingerprint of future terrestrial ice loss (Spada et al . 2013), [h/t Spiel Climate.] That bastion of truth and objectivity might not be said to be gloating, but there's an element of "See - told you so!" in their article Ice Melt Means Uneven Sea Level Rise Around the World. More of that and their "grade F" later.

What that paper says (in essence) comes as no surprise to me. Sea level rise around the globe is far from even. There are many reasons for that "lumpiness", two of them being thermal expansion and gravitational effects.

We solve the sea-level equation to investigate the pattern of the gravitationally self-consistent sea-level variations (fingerprints) corresponding to modeled scenarios of future terrestrial ice melt. These were obtained from separate ice dynamics and surface mass balance models for the Greenland and Antarctic ice sheets and by a regionalized mass balance model for glaciers and ice caps. For our mid-range scenario, the ice melt component of total sea-level change attains its largest amplitude in the equatorial oceans, where we predict a cumulative sea-level rise of ~25 cm and rates of change close to 3 mm/yr from ice melt alone by 2100. According to our modeling, in low-elevation densely populated coastal zones, the gravitationally consistent sea-level variations due to continental ice loss will range between 50 and 150% of the global mean. This includes the effects of glacial-isostatic adjustment, which mostly contributes across the lateral forebulge regions in North America. While the mid range ocean-averaged elastic-gravitational sea-level variations compare with those associated with thermal expansion and ocean circulation, their combination shows a complex regional pattern, where the former component dominates in the Equatorial Pacific Ocean and the latter in the Arctic Ocean.

That mouthful is down to modelling, of course, and if you accept their estimates of ice melt, I see little wrong with their results. What I do see that's wrong, is all the alarmist pundits jumping on the bandwagon and extrapolating what the paper says about their little corner of the globe, or the "poster-children" of predicted sea-level rise, like Bangladesh, Tuvalu, etc. As my pet subject is the study of sea-level and changes thereof, I find myself often peering at maps while I sip my gin-and-tonic. Authors of articles like the one at Climate Central might find it beneficial to do the same - peering, that is, though sipping G&T would do them no harm either. Alex Kirby, their geographer in chief, says

Improved projections of the contribution of ice to sea level rise produced by Ice2sea will feed into the fifth assessment report of the Intergovernmental Panel on Climate Change. In 2007, the IPCC’s fourth report highlighted ice-sheets as the most significant remaining uncertainty in projections of sea-level rise.

The researchers found that ice melt from glaciers and from the Greenland and Antarctic ice sheets is likely to be critically important to regional sea-level change in the equatorial Pacific ocean

There the rise will be greater than the global average increase, affecting in particular western Australia, Oceania and the small atolls and islands in the region, including Hawaii. Another area which should expect an above-average increase is the east coast of South Africa and Madagascar.

The first paragraph is interesting - "will feed into the fifth assessment report of the Intergovernmental Panel on Climate Change" given that it's just undergone the review stage. Late entries anyone? However, the next paragraph states exactly what's in the abstract above; "regional sea-level change in the equatorial Pacific ocean", yet what Alex considers to be in the equatorial Pacific ocean is interesting. He thinks western Australia and Hawaii are included, and he also appears to think that the Hawaiian islands are "small islands".

Given that Honolulu is only a couple of degrees south of the Tropic of Cancer, and that only half of the western Australian coast is north of the Tropic of Capricorn, I think he's stretching the definition of "equatorial" just the teeniest bit. The biggest of the Hawaiian islands is about 250km north-south.  Still, why let a few inconvenient geographical facts stand in the way of a good story?

Perhaps he, other alarmists, and IPCC authors, might like to peruse the abstract of A synthesis of the Antarctic surface mass balance during the last 800 yrs (Frezzotti et al 2013) [h/t Greenie Watch]

Global climate models suggest that Antarctic snowfall should increase in a warming climate and mitigate rises in the sea level. Several processes affect surface mass balance (SMB), introducing large uncertainties in past, present and future ice sheet mass balance. To provide an extended perspective on the past SMB of Antarctica, we used 67 firn/ice core records to reconstruct the temporal variability in the SMB over the past 800 yr and, in greater detail, over the last 200 yr.

Our SMB reconstructions indicate that the SMB changes over most of Antarctica are statistically negligible and that the current SMB is not exceptionally high compared to the last 800 yr. High-accumulation periods have occurred in the past, specifically during the 1370s and 1610s. However, a clear increase in accumulation of more than 10% has occurred in high SMB coastal regions and over the highest part of the East Antarctic ice divide since the 1960s. To explain the differences in behaviour between the coastal/ice divide sites and the rest of Antarctica, we suggest that a higher frequency of blocking anticyclones increases the precipitation at coastal sites, leading to the advection of moist air in the highest areas, whereas blowing snow and/or erosion have significant negative impacts on the SMB at windy sites. Eight hundred years of stacked records of the SMB mimic the total solar irradiance during the 13th and 18th centuries. The link between those two variables is probably indirect and linked to a teleconnection in atmospheric circulation that forces complex feedback between the tropical Pacific and Antarctica via the generation and propagation of a large-scale atmospheric wave train.

Perhaps Spada et al should have waited a bit before publishing. Perhaps Alex should read more - an atlas maybe? Perhaps I'll have another G&T.

Missing the Point in California

We read a sad tale on the Climate Watch blog - Rising Seas Threaten California’s Coastal Past, "Higher tides and increased erosion will wipe out archaeological sites"

This site and these cultural resources — some of them a thousand years old or more — might not be around for much longer. These pieces of California’s history are in danger of disappearing as the Pacific Ocean claws at the base of this cliff. Sea level rise is accelerating the problem.

It’s not just that the tides will be higher. The cliffs are so soft, they could recede hundreds of feet back, with just a few feet of sea level rise.

So "sea level rise is accelerating the problem", and the evidence for that is...?

A tide gauge in the nearby Golden Gate has recorded eight inches of sea level rise in the past century. Scientists project it could rise three feet in the next.

That "whole eight inches" (20cm) is indisputable, the record shows it, and it's equal to the average global rise during the 20th century, but "accelerating the problem"? Mr. Newland, an archaeologist at Sonoma State University and the president of the Society for California Archaeology, seems to think so, but why, if he's so concerned about Point Reyes, is he quoting a statistic for San Francisco, when there's a gauge right on his doorstep at Point Reyes lighthouse? Perhaps this is the reason:

Source: PSMSL

... just about zero rise since 1980, clearly shown by the 5-year (61 month) moving average. This is in common with most stations from Point Reyes southward, including his quoted San Francisco. Sea level rise along this coast is a documented non-problem at the moment, and has been so for 30 years.

Source: PSMSL

I sympathise with him, but before blaming some "climate change" induced effect for what's happening, make sure you're in possession of the facts. Soft rock erodes quickly with wave action, rising sea level or not - it's part of a natural cycle, returning sediment to the sea floor to form new rock in time.

Local and city authorities are scurrying about, wringing their hands in despair, worrying about inundation of wetlands, coastal highways and houses, when sea levels along the Californian coast aren't rising, and haven't risen for around 30 years. In North Carolina, state legislators have taken a pragmatic "wait and see" approach to sea level rise and have been castigated for their common sense, The cries of "we have to act now" are nonsensical. They have to act on what's happening now, and make plans for the foreseeable future If an acceleration establishes itself, there'll be plenty of time to bring forward future plans, and formulate new ones.

In the case of Point Reyes, Mr. Newland should cite facts, not "climate-change" sound-bites to bolster his case for action. Unfortunately, this tactic is rapidly becoming the norm.

Wellington sea level rising fastest in NZ? No - more falshoods.

The New Zealand press is wetting itself, and it's not from the feet up. here's a sample from Scoop Business

Two reports released today show Wellington has the highest rate of sea-level rise in New Zealand and highlight areas in the region that are vulnerable to coastal flooding over the next 100 years.

The reports, commissioned by the Greater Wellington Regional Council (GW), look at sea-level rise and coastal flooding from storm events in the Wellington region including current trends and future scenarios based on those trends. Wave heights, wind strength, storm-tide levels, sea-level variability and large-scale storm events are all assessed.

Findings from the studies and the implications they are likely to have on the Wellington region’s coasts, communities and local authorities were presented today. 

... and another

Parts of coastal Wellington could be drowned if doomsday climate change predictions from a new study pan out over the next 100 years.

Two reports issued yesterday by Greater Wellington regional council show Wellington's sea level is the fastest rising in New Zealand - made worse by seismic rumblings causing the city to sink 1.7mm a year since 2000.

One slight problem with all of this - sea level at Wellington has barely risen at all since 1999.

Amazingly, the NIWA report Sea-level variability and trends: Wellington Region (helpfully linked from the Scoop Business report, hats off to them) actually shows just that, though the text completely ignores the fact.

The report states on page 37:

Regional subsidence, from slow-slip events, has increased the relative sea-level trend in the Wellington area since ~1997. This trend varies across the Wellington region, 

Reality check - here's the plot from 1997

Does a change from 2.44 mm/year for the entire record to 2.48 mm/year for 1997 onwards constitute an "increased sea-level trend"? I leave you to judge whether it is even worth mentioning. Moving the start year forward to 1999 reveals the tiny trend I highlighted above.

Plotting the change in annual rate from 1944 to 1980 and subsequent years to 2011 confirms it.

The rate has stabilised at almost exactly 2.5 mm/year (slightly different from that shown on the first chart above as it's calculated from annual averages, not monthly data). There is a change in the rate from 1997, but it's progressively reduced to a flat trend as the 1999-onwards "plateau" has an increasing influence.

There's an awful lot of information in that report (it's 74 pages long!) that I deem useless and confusing to any planner who wanted the "bottom line". In my opinion it's an attempt to "blind with science". Who's going to care much exactly which benchmarks were used over the life of the gauges, or precise details and dates of GPS surveys, or discussions of Arctic and Greenland melt rates? Then there's this (p57)

Relative SLR at Wellington is presently tracking towards a SLR of 0.9m by 2090s or ~1.0m by 2115 and is similar to tracking of the global-mean (relative to 1980-1999 sea levels), though based on a short sea-level average at Wellington from 2006-2011.

What? They're basing a prediction over a period of up to 103 years on a period of just six years? Note the slight uptick over the 2011 mark in the 13-month moving average on the 1999-2011 chart above. Very convenient to end their "short average". Have another look at the first (long-term) chat above. Does that look like it's heading for "~1.0 m by 2115"? This report is crap dressed up as a scientific report. It's pure bluster and alarmism, padded out with irrelevancies. They've no data to prove any such thing, and chose a very short period to give themselves the answer they want.

Making it up (2) - "Sea level 'rising fastest in SW Pacific"

Here we go again! A tranch of syndicated articles, or variation on same, which take a straightforward analysis of proxy data (which is from the past, by definition), and transpose its findings to the present or even the future. The cited paper is "Nineteenth and twentieth century sea-level changes in Tasmania and New Zealand", Gehrels et. al., though of course it takes either a site search, or a Google search to actually find an abstract, as it's just vaguely referenced, or the journal main page is given. As I've said before, this gives the distinct impression that the article authors would prefer we accept their take on it, without the benefit of reading the paper and making up our own minds. In this case, that would instantly debunk their alarmist conclusions, and in several cases, reveal that the authors either can't read and comprehend, or can but distort or even make up conclusions, effectively putting words into the mouths of the paper's authors. The abstract says

Positive deviations from linear sea-level trends represent important climate signals if they are persistent and geographically widespread. This paper documents rapid sea-level rise reconstructed from sedimentary records obtained from salt marshes in the Southwest Pacific region (Tasmania and New Zealand). A new late Holocene relative sea-level record from eastern Tasmania was dated by AMS¹⁴C (conventional, high precision and bomb-spike), ¹³⁷Cs, ²¹⁰Pb, stable Pb isotopic ratios, trace metals, pollen and charcoal analyses. Palaeosea-level positions were determined by foraminiferal analyses. Relative sea level in Tasmania was within half a metre of present sea level for much of the last 6000 yr. Between 1900 and 1950 relative sea level rose at an average rate of 4.2 ± 0.1 mm/yr. During the latter half of the 20th century the reconstructed rate of relative sea-level rise was 0.7 ± 0.6 mm/yr. Our study is consistent with a similar pattern of relative sea-level change recently reconstructed for southern New Zealand. The change in the rate of sea-level rise in the SW Pacific during the early 20th century was larger than in the North Atlantic and could suggest that northern hemisphere land-based ice was the most significant melt source for global sea-level rise.

That seems straightforward - sea level at the sample site rose at a relatively high rate (compared with the global rate) between 1900 and 1950, and a relatively low rate for the rest of the 20th century. Nothing to worry about then? Not according to several reports from "down under", whose almost identical articles, begin News.com.au (Australia):

SOUTHERN Australia and nearby Pacific nations are likely to be the most seriously affected in the world by the continuing rise in sea levels, according to new research.

... and 3 news (new Zealand

The seas around New Zealand and Australia are likely to be the most seriously affected in the world by the continuing rise in sea levels, according to research on Tasmanian swamps.

"According to research"? Apparently not, the paper abstract doesn't mention the future - remember that the paper's titled "Nineteenth and twentieth century sea-level changes in Tasmania and New Zealand". However, all the articles I've seen quote one of the authors, Patrick Moss:

"Sea levels in Tasmania remained relatively stable for much of the past 6000 years, but around 1880 they started rising drastically," said Dr Moss, who co-wrote the study in conjunction with scientists from the UK, New Zealand and Australia. 

From several reports:

Sea levels in the southwest Pacific rose at four times the average 20th-century rate between 1900 and 1950, according to the study.That was followed by a period of “relative quiet” broken by a second spike in 1990 which saw sea levels rise at a rate that defied projections.”The natural climatic factors seem to be not as apparent and anthropogenic climate change seems to be the key possible culprit,” said Moss.

and

Dr Moss said a jump in sea levels occurred after 1990.

"The rise in 1910 probably reflects the end of the little ice age, when temperatures were about one to two degrees cooler in the northern hemisphere than today," he said.

"The 1990s peak is most likely indicative of human-induced climate change."

Sounds rather like someone with an agenda - that conclusion's not in the paper. Why does he call it a "peak"? Because that's what it is, and both his sediment proxies and tide gauges in the SW Pacific generally show a decline since. The diagrams in the paper clearly show that. You have to follow the pea as the cups are moved, and analyse every word, or you might, as these web authors clearly have, assume the "jump" is still in progress. Elsewhere he says "A large ice-melt is like a fingerprint". There's that word again - if there's been a decline since the 1990s, then the "fingerprint" is rather blurred, and the "points of identity" are insufficient to identify the culprit. More to the point, what exactly was the "fingerprint" of the early 20th century rise? Here's yet another researcher putting his mouth where his paper isn't, and confirming our suspicions of his prejudice and unjustified conclusions.

What about that "lack of comprehension" I mentioned at the beginning? here's a good example from "Adelaide Now" - first the bogus prediction based on no evidence from the paper, nor its self-appointed spokesman (not the lead author), Moss

SOUTHERN Australia and nearby Pacific nations are likely to be the most seriously affected in the world by the continuing rise in sea levels, according to new research.

Then the silly error, repeated in several reports, including Planetsave (save it for whom and from what?)

Sea levels have risen approximately 20 centimetres in the South West Pacific Ocean since the end of the 19th century, a dramatic increase according to a new study released this week.

Scientists found that sea levels in Tasmania remained relatively stable for most of the previous 6,000 years but that around 1880 they started to rise dramatically. Between 1900 and 1950 the sea level rose at an average rate of 4.2 millimetres per year. The highest rates of sea level rise occurred in the 1910s with an increase of .3 to .8 millimetres per year, followed by a second peak in the 1990s.

If sea level rose 20cm since the late 19th century, and if the rate of rise between 1900 and 1950 was 4.2mm a year, which amounts to 4.2 x 50 = 210mm or 21cm, can we deduce it's fallen by 1cm since 1950?

I might add that I can see nothing like a rise of 4.2mm since 1900 for tide-gauges in the southern part of Australia, nor any "spike" in the 1910s. Perhaps I'll update this post with a few charts to illustrate that.

Where's the acceleration, dude?

We're constantly bombarded with portents of doom and gloom, and apparently, by extension "the end of civilisation as we know it". "Climate change" is accelerating, "global warming" is accelerating, sea level rise is accelerating, and (could, or may) threaten millions if not billions of people, "extreme weather events" are increasing in frequency and intensity. Of course, there's no actual evidence that these terrible events are occurring or that they will happen. They're all from model-based "projections", unjustified predictions, or just pure conjecture and general alarmism.

There's no doubt the Earth's been getting warmer in fits and starts, since the end of the last ice age. However, there's the flaw in the alarmists theories right there in that sentence - "fits and starts". The increase hasn't been on a relatively smooth upward trajectory; there's an irregular cycle built in, and no-one can explain the reasons behind the variability. Paleo-climatology has a stab at it, and there are some plausible theories, some "best-guesses", and some downright manipulation and cherry-picking of data, like Mann et. al.'s "hockey-stick". But there's no proof as to what caused the variations - there cannot be. Climatologists are looking back through a murky and distorting lens, and one which might be pointing in the wrong direction, or looking at the wrong data.

Let's look at some real data then, and see how the "x is accelerating" claims stack up. First temperature data, because most or at least may think this is the main indicator of things to come.

Latest Global Temps - UAH Satellite data to February 2012

HADCRUTt3 variance-adjusted global mean, 1979-present (Source: Wood for Trees)

I don't see much of an acceleration in either, rather a stasis, or a even a recent decline in the HADCRUT thermometer record, yet we are told "global warming has continued unabated, ar that it has accelerated. Where's the evidence for these assertions? "Habeus corpus" - "produce the body".

Variations in global mean sea level from a combination of TOPEX/Poseidon, Jason-1, and Jason-2 altimeter measurements, using 60-day and annual smoothing of 10-day average values. A glacial isostatic adjustment correction of 0.3 mm/year has been applied.
Source: Woodworth, P.L., W.R. Gehrels, and R.S. Nerem. 2011. Nineteenth and twentieth century changes in sea level. Oceanography 24(2):80–93, doi:10.5670/oceanog.2011.29

Where's the acceleration, dude?

Disconnects in Logic (6) - 34 "Is not nearly as much" as 502

Earthsky blogger Daniel Tennant relays some good news and some not-so-good news (but which does he think is "good"?)

Most sea level rise due to melting polar ice, study confirms   

Researchers report that Earth’s polar regions are losing 502 billion tons of water annually out of the total amount 536 billion tons lost annually worldwide.

Scientists published results in a February 2012 issue of Nature that reveal a detailed picture of how Earth’s glacier regions have changed over the last eight years. In previous publications, GRACE satellite data confirmed that Earth’s polar regions are the major contributors to rising sea levels. The recent publication focuses on the high mountain areas, such as the Himalayas and Andes, and shows that these ecosystems are remarkably robust: they are not losing nearly as much water to the ocean as the polar regions.

That's good news, I'd say, and an E grade for all the glaciologists and others who've been predicting the imminent demise of glaciers in "high mountain areas" for years. A little later, we're shown this graphic

Map showing the September ice extent in the Arctic in 1980, 2007, 2008, 2009, 2010, and 2011. The magenta line indicates the median September ice extent for the period 1979-2000. Image Credit: National Snow and Ice Data Center Sea Ice Index:

From simple visual evidence, if nothing else, it is clear that our polar glacier regions are depleting due to melting ice. 

Arctic report card for 2011

The "polar glacier regions", aren't shown, just the Arctic, and this is graphic data for sea ice, and has nothing to do with sea level. Sea ice has no net effect on sea level, freezing or melting. No glaciers are shown. It's certainly not clear from that graphic that "our polar glacier regions are depleting due to melting ice". Why were we given this irrelevant information and erroneous conclusion?

After this slip, band some details of how the GRACE (Gravity Recovery and Climate Experiment) satellites work, we get the "bottom line" (my bold)

Bottom line: A publication in Nature in February 2012 presents the results of an analysis of GRACE satellite data, showing that high mountain areas, such as the Himalayas and Andes, are not losing nearly as much water to the ocean as Earth's polar regions.

Shhuurely he means ice not water? If "the polar regions are losing 502 billion tons of water annually out of the total amount 536 billion tons lost annually worldwide" then how can the 32 billion tons from mountain glaciers be termed "not nearly as much" as 502 billion tons? The 32 is 6.8% of 502, or about one-fifteenth. Did he write this piece before he saw the figures? Was he disappointed when he saw them? Does his brain work logarithmically? Why did he spoil a perfectly good article with a superfluous add-on, an unsubstantiated claim, and a flawed sense of proportion (in the true sense)? Why do I get worked up about this kind of thing?

If you have any of the answers, please let him know, I'm past caring.

Australia's CSIRO - The Truth, (but not) The Whole Truth, and nothing but Cherry Picking

Bruce Mapstone, chief, CSIRO Marine and Atmospheric Research, Hobart, Tasmania (note Hobart, there's more) wrote to The Australian "Sea-level observations". February 9th, 2012

BOB Carter's references to sea level ("Scientific research drowning in a sea of alarmism", 7/2) require clarification.

Sea level observations come from measurement by satellites and, as Carter notes, a network of tide gauges around the Australian coastline operated by the Bureau of Meteorology and similar gauges internationally.

These observations show that rates of sea-level rise around Australia range from 2.6mm a year to 9.5mm a year since the early 1990s, compared with the global average rate over a similar period of about 3.2mm a year.

Variation in sea levels from region to region is to be expected, as Carter also notes, but continuing analysis indicates the dominant trend around Australia for the past 20 years is upward and above the global average.

The global average of observations is near the high end of the Inter-governmental Panel on Climate Change model projections over the same period, indicating that the range of model projections encompass changes that have occurred, and indeed that the models may be underestimating observed changes.

Lets' jump right in and have a look at the Hobart tide gauge data - right on Bruce's doorstep at CSIRO Mansions on Castray Esplanade, overlooking the harbour, and probably within sight of the gauge -


View Larger Map

(click charts to enlarge)

Hobart, Tasmania - Sea Level 1987-2010

Oh dear, things are not looking too good for Bruce's "clarification", the rate from 1987 is -0.438 mm/year (0.67 from 1962). The odd 1987 start date is due to the fact that there are large gaps and anomalous readings prior to then. The gauge was displaced several times by ship's masters who couldn't park neatly, and had to be replaced (the gauge, not the masters, but who knows?).

He was referring to an opinion piece by Bob Carter two days previously, in which he attacked a "a science-fiction prediction of a 91cm rise in sea level in the district by 2100". Carter ridiculed Lake Macquarie City Council's new coastal planning regulations, which control new developments around the lake, mandating higher floor levels to "account for sea level rise and wave action". Yet the NSW Department of Planning has said there's "uncertainty surrounding the manner in which sea level will rise", which means whatever floor levels they enforce are likely to be either inadequate or excessive. The "91" figure (notice it's not a round 90 or "almost a metre") implies an estimate accuracy of +/- 1cm. The range is given as LOW: 18 cm. MEDIUM: 55 cm. HIGH: 91 cm. So the overall spread is 1:5, yet the figures are quoted to a single cm accuracy? Over a period of 90 years? That really is "science fiction". I could stick my neck out and say 50 +/-50 centimetres, which should cover most eventualities. Of course, I could be wrong. In fact I know I'll be wrong, which is why my neck will stay in.

The regulations are based on that 91cm maximum predicted rise by 2100, and Carter says

This prediction comes from the NSW government, which in turn sourced it from a UN political body, the Intergovernmental Panel on Climate Change. As with its unnecessarily alarmist projections of global warming, the IPCC's estimate of future sea-level rise derives from speculative computer models.

He also lists what he terms "four facts"

First, that rates of sea-level change vary around the Australian coast. This means any new coastal planning regulations (if and where they are needed) should be based on the appropriate local sea-level measurements rather than a hypothetical global average.

Second, the longest east coast tide-gauge record, from Fort Denison (Sydney), records an average rate of rise over the past 100 years of about 1mm a year (10cm a century).

Third, that other tide gauges, scattered around Australia as part of the national tidal network, mostly record rates of long-term rise between about 0.5mm and 2.5mm a year with no change in behaviour in the late 20th century that might reflect a human (global warming) influence.

And, fourth, that the Sydney tide gauge, as well as other long tidal records from nearby (Fremantle, Auckland) and overseas, exhibits a slowing rate of sea-level rise over the past 40 years.

How do Carter's "facts" stack up? His first is common sense. A health service bases its policies on local , not world, nor even regional demographic statistics and forecasts. It's logical to expect local and state authorities to do the equivalent as regards local planning.

His second is indisputable (except by Bruce Mapstone and others, who just ignore it. "Post-normal" science doesn't need facts).

His third is correct if you accept his qualification of mostly, and I accept it, having analysed data from most of the 95 National Tidal Centre tide gauges (plus two privately owned) around Australia. How does it square with what Bruce Mapstone says? First note that Brucie (I feel I know him well already) doesn't actually refute what Carter wrote. In short, he can't - it's fact. Note also what Mapstone actually said - "from 2.6mm a year to 9.5mm a year since the early 1990s". "Early 1990s" is a bit vague, isn't it? Well no, it isn't, because the CSIRO have chosen to use a subset of 14 of those 97 gauges, installed and monitored by the ABSLMP project at the National Tidal Centre of the Bureau of Meteorology. In other words, they've chosen to use just one seventh of the data available to them. Cherry anyone?

The fourth is indeed fact. Data from most of the long-term records show a slowing rather than an acceleration, and most sites show a flat or declining trend since 1999. I've posted on the CSIRO's data selection bias and more recent, lower rates here.

Back to Bruce's last paragraph

The global average of observations is near the high end of the Inter-governmental Panel on Climate Change model projections over the same period, indicating that the range of model projections encompass changes that have occurred, and indeed that the models may be underestimating observed changes.

Beat that for gobbledygook - if the model "projections" didn't "encompass changes that have occurred" then they can't be much use. If the models may be underestimating "observed changes" it doesn't automatically follow that they are also underestimating future "projections". I don't know, and he doesn't know what assumptions are made in those models.

Then there's a (partial but flawed) rebuttal of Mapstone's "non-rebuttal" the following day. "Levels all at sea" from one William Kininmonth:

THE clarification on Australian sea-level observations by Bruce Mapstone (Letters, 9/2) fails to reveal all of the uncertainties relating to the data.

Australian tide gauges accurately measure the relative movements of sea level with respect to the gauges. However, the vertical movement of individual tide gauges is uncertain.

The vertical movement isn't uncertain, at least not for some of the gauges. A global network of Continuous Global Positioning System (CGPS) stations is already established, designed to monitor land movement and/or gauge movement. There are 12 around Australia, near the ABSLMP stations. Here's the current plot for Sydney - appropriately the station's in Macquarie Park!

Latest ULR GPS position time series for Sydney

A note for those who've heard of the CGPS stations used by the NTC - the stations are remote from the gauges (up to several km inland), they monitor land movement, and do not "automatically adjust" the vertical position of the gauge. That's both impractical (the gauges are of necessity firmly fixed to their supports), and undesirable. It's not only the sea that rises and falls with the pull of the sun and moon, but the Earth's crust too (crustal tide), up to about 10cm range, depending on latitude, greatest near the point nearest to the sun and/or moon. If the gauge position was kept constant relative to the GPS satellites, the gauge would be dropping relative to the land as the tide and land rose, and would register a higher reading than it should, and a lower reading as tide and land fell.

And for the last word, from a body which even Bruce might take note of, The Tasmanian Planning Commission, in its sober but a trifle "consensus science" "State of the Environment (SoE) Tasmania 2009" report is precise and factual (my bold):

Sea-level rise for Australia is only slightly less than the global average (NTC 2007; Church and White 2006) and coastal observations confirm that sea-levels have been rising since at least 1920 by approximately 1.2 mm/yr (Church et al. 2006; IPCC 2001; see also Pittock and Wratt 2001; Lambeck 2002). A common feature in many model projections is a higher than the global average sea-level rise off the southeast coast of Australia and in a band stretching across the Indian and southern Pacific oceans at about 30°–45°S (CSIRO 2009). Sea-level rise is greatest (about 3 mm/yr) in the eastern equatorial Pacific and western equatorial Indian Ocean. Observed rates of rise are smallest (about 1 mm/yr) in the western equatorial Pacific and eastern Indian Ocean, particularly the northwest coast of Australia. Two of the longest continuous Australian tide gauge records are from Fremantle in Western Australia (92 years) and Fort Denison in New South Wales (83 years) indicate that the observed rate of sea-level rise relative to the land has been 1.38 mm/yr and 0.86 mm/yr respectively (DPIWE 2004). Regional variations in the rate of sea-level rise are weaker for much of the rest of the global oceans (AGO 2003). 

They haven't got the last word, though, I have. If the CSIRO chooses to use the state-of-the-art NTC SEAFRAME gauge data for (some of) Australia, why didn't they use data from similar NTC gauges across the Pacific islands for their "Climate Change in the Pacific" reports instead of spatially coarse satellite data? Why did they choose to use (coarse) gridded HADSST2 sea surface temperature data rather than localised in-situ measurements recorded by those same gauges? You answer the question, I already know the answer.

South Pacific Sea Level to September 2011

Note: A permanent and (to be) regularly updated page has been created (see top of sidebar) located here. I've updated this page with data to December 2011.

The island sea level charts are drawn from monthly data from the South Pacific Sea Level and Climate Monitoring Project. I've included a chart for a second Fiji station, and also one at the end for a New Zealand station, Jackson Bay (South Island). Neither is part of the project, but data is provided on the website.

The high resolution SEAFRAME (Sea Level Fine Resolution Acoustic Measuring Equipment) monitoring stations comprise modern integrated housings which measure and record sea level, barometric pressure, water temperature and air temperature. Most of the stations were installed in 1992 and 1993, though a few were later. It's important to note that the effect of local land movement is eliminated from sea level data:

The Continuous Global Positioning System (CGPS) network monitors vertical movement in the earth's crust, such as subsidence or tectonic shifts, at the SEAFRAME tide gauges and adjacent land. Sea level data can then be adjusted to compensate for the earth's movement to within a millimeter, enabling the absolute sea level to be determined. 

I have voiced criticism of Australia's Bureau of Meteorology on various topics in the past, but as far as the presentation of sea level data is concerned, I rate their National Tidal Centre as the best. The page I linked to above has a table of the 12 stations in the project (and the two others I mentioned) which links to PDF plots and data tables for sea level, barometric pressure, water temperature and air temperature. The data tables in turn link to online graphical plots and text files for easy import to spreadsheets. A map links directly to the data tables. I liked that Idea so much I've pinched it for use here.

What should be evident from the plots is that any generalisation of the situation over this wide area is invalid. Apart from an almost universal downward spike during the 1997/98 ENSO event, the history and trends differ widely. It should also be clear that claims of "25 mm/year" or "no rise" since the early 1990s are also invalid.

Most of the charts are dominated by a downward "spike" in 1997/98. The level drop was due to unusually high barometric pressure during the 1997/98 ENSO ("El Niño/La Niña-Southern Oscillation") event. The correlation is well illustrated for the Marshall Islands (Majuro Atoll), so I've placed this first. Kiribati and Tuvalu have been given much attention in the news media and on the 'net recently, so they're listed next.

Readers are welcome to reproduce any of the plots - all I ask is that attribution be given, preferably with a link to this post. I haven't used thumbnails - right-click on the image and select "save image as" or whatever your browser prompts.

Level data has been converted from metres to millimetres to overcome loss of precision in Excel's trend data. Gaps in the plots indicate gaps in the original data. Note that the trend slope is monthly - multiply by 12 to get the annual value (e.g. y = 0.2269x gives 2.7228 mm/year).

Select a location from the map to view a graph of the monthly sea level statistics for that location. Click on the bottom of the blue area for the NZ station, Click on your browser's back button to return to the map.

Source: Bureau of Meteorology     

Marshall Islands

Island: Majura   Location: Uliga

Note the 1997/98 ENSO "spike" and the correspondence with the abnormally high atmospheric pressure from late 1997 to late 1998 shown in the barometric pressure plot below:

Kiribati

Island: Tarawa   Location: Betio

The trend line is pulled down by the ENSO dip from the end of 1997 to end 1998. To give an better view of the trend from 1992 to present, I replotted the chart with that data excluded:

The resulting trend is effectively zero.
A downward trend is evident from end 2001 to present:

Tuvalu

Atoll:Funafuti   Island: Fongafale

As with Kiribati, the deep ENSO dip in 1997/98 pulls the trend line down on the left; it's below the 1994/1997 average. A zero trend is evident from 1999 to present:

Papua New Guinea

Island: Manus   Location: Lombrum

Here's a clearer view of the 1999-2011 trend of 3.4 mm/year, slightly above the global average:

Solomon Islands

Island: Guadalcanal   Location: Honiara

Again the trend is pulled down on the left; the average level 1999 to present is around 750 mm, and the trend 2.1 mm/year.

Vanuatu

Island: Efate   Location: Port Vila

The big 1997/98 downward spike evident in most of the other plots is absent; instead there's a relatively steady upward trend.

Fiji

Island: Viti Levu   Location: Lautoka

Island: Viti Levu   Location: Suva

Tonga

Island: Tongatapu   Location: Nuku'alofa

Although there's a steep trend from 1993, current levels are not dissimilar to those between 2000 and 2003.

Cook Islands

Island: Rarotonga   Location: Avatiu

Levels seem to have stabilised from 2006.

Samoa

Island: Upolu   Location: Apia

The familiar ENSO dip pulls the trend down at the LHS, but there is a sharp upward "spike" from 2010.

Nauru

Island: Nauru   Location: Aiwo

Overall trend is effectively flat - levels at present similar to those in 1993. However, the trend from 2002 is downward.

Federated States of Micronesia

Island: Pohnpei   Location: Dekehtik

An overall upward trend, though little change from 2007 to present.

New Zealand

Island: South Island   Location: Jackson Bay

There seems to be little overall change from mid-1998 (after the ENSO dip) to present. A plot from 1999 confirms that: