Thursday, 29 December 2016

"Hotspot of accelerated sea-level rise on the Atlantic coast of North America" - final reality check

Last year I shredded the Sallenger et al. paper "Hotspot of accelerated sea-level rise on the Atlantic coast of North America" here. Now, with updated CGPS data from SONEL, I can finally place the headstone on its grave. South of Boston, the coast is subsiding, and subsiding at a generally increasing rate all the way south to Florida. Sandy Hook, a rather inconsequential spot, which all boat traffic in and out of New York harbour pass with barely a glance, had the honour of being one of the few sites along the NW coast with published GPS data. I say had, because SONEL has carried out a massive update of sites worldwide, adding fairly up-to-date data to many. Sandy Hook now has a downloadable record from 1995 to 2013. The record shows that the downward rate has been increasing from less than 2 mm/year in the late 1990s to over 3 mm/year in the three years 2011-2013. I've used the entire record for station SHK5, 2007-2013, which plots at -2.57 mm/year. The SONEL analysis shows -2.65 mm/year, but I've taken account of a few short-term gaps in the data; I assume they didn't. Here's the SONEL plot:

And mine:

Sandy Hook 1993-2015 (Sea-level satellite era):

The relative rate (relative to the tide-gauge/land) is 5.36 mm/year. Absolute rate (relative to the Earth/Geoid) is 2.79 mm/year. The subsidence rate is almost half the relative rate.

The SONEL plot for New York Battery Park, where both tide-gauge and GPS pillar are located:

The rate during the late 1990s was around -1 mm/year. My analysis:

The chart for New York (Battery Park) 1993-2015:

Relative rate is 3.92 mm/year; absolute rate, allowing for subsidence of 1.93 mm/year is 1.99. The "Hotspot" isn't one of sea-level rise, but one of subsidence. Sallenger et al. were also being somewhat disingenuous when they claimed that the rates of subsidence along the coast "were almost constant", and therefore didn't affect their complex analysis or results. They weren't constant when the paper was written, and the rates are generally increasing over the last 20 years; some very little, some like New York and Sandy Hook, significantly increasing. The "Hotspot" was an artefact of questionable and almost impenetrable analysis, ignoring the inconvenient past, and coastal subsidence.

Note also the obvious cycles which appeared in the record after 1970 - large and small alternating. Sallenger et al. used PSMSL annual average data, and so they wouldn't have been obvious. Take some data and torture it using complex and (to me, impenetrable) statistical techniques I imagine most sea-level experts and authors couldn't fathom, and get the answer you want. What I do know is that those techniques aren't suited to relatively small datasets, which is what you have if you use annual average data. Also PSMSL omit years from annual data, even if just one month is missing. The annual data Sallenger et al. used had quite a few years missing, shrinking their database even further.

Something else Sallenger et al. failed to mention is that a comparable rate of rise occurred before the mid-1950s. Somehow their "long-term" analysis wasn't quite that long:
Trend, in mm/year for 30-year sliding window, end year on x-axis.

The red circle marks 2009, the end year for the "Hot-spot" analysis. It's easy to see the rate of increase was much higher prior to 1953. If the whole record shows an inconvenient truth, just analyse part of it.

Tuesday, 27 December 2016

Vanuatu - something unusual and somehow encouraging

I'm busy updating spreadsheets for Pacific islands, mainly those in the Pacific Sea Level Project of the Australian National Tidal Unit - the straight-up and factual branch of the BOM. I updated Vanuatu last of all, as I'm working in alphabetical order. Here's the chart for the full record from 1993 to last month (November 2016):

The level has dropped to almost exactly what it was in 1993, from a peak in 2008-9. It seems to be a combination of SOI dropping from its high in 2009-10, a drop in sea temperature from 2008, and a rise in barometric pressure after 2011. A change of 1 hPa (=millibar) results in a change of 1cm in sea-level. Higher pressure, lower sea-level, and vice-versa. "Storm-surge" is due to low pressure (and high onshore winds) in a storm system. This is SOI to November 2016:

I'm checking on nearby (well, relatively) stations to see if there's anything remotely similar. I've already checked CGPS station data; here's that for Port Vila; the tide gauge is about 1 km away at the Cruise-ship port.

Source: SONEL

Although the red velocity analysis on the left says "Not robust", there's little change. More later maybe.

Friday, 23 December 2016

The Road to Solar - No, it's a Solar Road!

The sheer stupidity of some people is a constant source of amazement to me. Some bureaucrats and politicians (national and local) have their heads so far up their backsides they can't see the bleedin' obvious. There are quite a few stories on news sites over the last two days, about a project, a very expensive project, to install a "Solar Road". The best quote is from a "green" techno-site engadget -
A French town just installed the world's first 'solar road'
The tiny town of Tourouvre-au-Perche in Normandy, France no longer has to worry about how it will power its street lights. The Sun will handle that.
The link is to a guardian article. There are similar articles in the Daily Mail, Le Monde, and hundreds of others across the world. Street lights - they come on automatically at dusk. Dusk - when the sun has dropped below the horizon. When Solar panels aren't producing any electricity. Not one of the journalists, nor the many commenters on those pages, some of whom were critical of the relatively vast cost of the kilometre-long solar array spotted that it won't be generating any electricity when the street-lights are due to switch on. Simply amazing

Australia's "Poster Children" updated and analysed

I read a great deal of absolute rubbish on the 'net about sea-levels. Someone speaking at the American Geophysical Union meeting recently claimed that Miami was suffering more frequent flooding due to sea-level rise. Ignoring for a moment that much of Miami was already below tidal high-water before it was built, proper examination reveals that the rate of subsidence is greater than the rate of sea-level rise. At Cape Canaveral, further north, the measured rate is just over 5mm/year, but CGPS (Continuous GPS) data shows the land close to the tide gauge to be sinking at 2.8mm/year - the greater part of the rise is due to subsidence along the coast.

A couple of years ago, I read what I considered to be an outrageous claim - that the Tidal Unit (formerly National Tidal Centre) of the BOM was publishing "exaggerated data" in the ABSLMP (Australian Baseline Sea Level Monitoring Project) series. Worse, that the data was "homogenised". Well, it's impossible to "homogenise" tide-gauge data. Each gauge uses a different base-line for measurements, referred to as "Tide Gauge Zero". It's a "virtual" reference level, referenced to a physical benchmark (the TGBM or "Tide gauge Bench Mark") at the gauge site, one of a set, the remainder being on the adjacent dockside or land.

I'll relate the full story in a later post, but for now just let's say it concerned the record for Sydney, and that for Port Kembla, some 64Km to the south. Here's the full chart for Sydney, to October 2016.
Sydney 1914-2016.   Source: BOM

While the long-term rate for Sydney is 1.02 mm/year, it's easy to see that any short-term rate depends entirely on the start point. Start in 1997 or 1998, when there was a "dip" due to the 1997-8 El Niño, and you get a very high trend; start in 1990, a much lower rate. I've plotted the rate for a 20-year sliding window, using annual average data:
Rate (mm/year) for 20-year sliding window; end year on X-axis.

Port Kembla (an ABSLMP station), installed in 1991:
Port Kembla 1991-2016   Source: BOM

Sydney 1990-2016 for comparison.
Sydney 1990-2016  Source: BOM

Both together, after Port Kembla data adjusted by +58mm - the offset due to the different "Tide Gauge Zero" benchmarks.
Sydney & Port Kembla compared; 1991-2016

The claim of "homogenistation" is egrarious bullshit, invented by the morally, evidentially and statistically challenged. Put even more forcibly, it's a lie.

On to Fremantle, another source of claims and misinterpretation. The full plot first:
Fremantle, WA 1897-2016

This is the chart for Hillarys (Boat Yard), on the far side of Perth from Fremantle, to the north.
Hillarys, WA 1992-2016

Fremantle 1992-2016 for comparison:
Fremantle, WA 1992-2016

And both together, with Fremantle adjusted down by 64mm:
Hillarys/Fremantle over-plotted; Fremantle adjusted down by 64mm

Hillarys starts somewhat lower than Fremantle, but they plot together from 2002 onwards. It's easy to show such correlation between adjacent stations around Oz, even if they're several hundred Km apart. Even if it were possible to "homogenise" gauge data, the tides do a perfectly good job already.

Data is sourced from The main BOM Tidal Unit for Sydney and Fremantle, and from the AMSLMP project for Port Kembla and Hillarys.

NOTE: I've just discovered that SONEL have updated with data for many Oz stations. The CGPS pillars are often very close to tide gauges. At Hillarys they're co-located, and the latest plot shows a drop of 2.78 mm/year:
Source: SONEL

Updates include data for many of the Pacific islands, including Sceptic poster-child Tuvalu. Watch this space.

Saturday, 17 December 2016

There are none so blind....

A couple of days ago, I was chatting to a friend in our local watering hole - Yates' in High Wycombe, Buckinghamshire, UK. I'd been telling him how BBC documentaries had become un-watchable for me, mainly because of the constant and intrusive background music."Don't you watch Attenborough?" he asked "Now there's a guy knows what he's talking about."  I nearly choked on my beer, but said nothing. "It's really getting bad in the Arctic - the polar bears are becoming extinct". I asked why that was. "The ice is melting, and the bears can't catch the seals they feed on". "What do the bears eat in the summer, when there's no ice?" I asked innocently. "They live on the body fat they got in the winter, from eating seals in the winter", he replied. I followed up with a low blow - "Where are the seals in the summer?". "I don't know, on the land, I expect". I had him on the ropes - "Where are the bears in the summer?". He pondered a moment - "they must be on the land too?".

"Then what's the problem - seals on land, bears on land - bears catch seals, bears eat seals, period?". "It's not as simple as that" he parried. "Why is that?". "You're not an expert!" he said. "I don't need to be an expert, just be able to use my brain and think!", He was silent. "You'll be telling me next that penguins in the Antarctic need the ice to catch fish?", His eyes showed a glimmer of triumph - "Yes, they do!". The coup de gras from me "How do they catch fish in the summer, when there's no ice?". He was on the ropes again, and getting desperate "This argument is getting nowhere!".

He just wouldn't see that his "factual" documentaries were only telling half the story, pushing a message of starvation and extinction, climate change and global warming; in fact pushing against the truth. I didn't bother pointing out that polar bears are omnivores, and will eat anything - rotting whale carcasses, fish (yes - they can catch fish!), berries, small mammals, leaves and grass. We still chat regularly. I don't bring up any contentious subjects, and I think he's relieved I don't.

UPDATE: In case anyone thinks I'm talking out of my posterior, here's some current research debunking the idea that reduction in Arctic ice will spell doom for the iconic polar bear:

Demographic and traditional knowledge perspectives on the current status of Canadian polar bear subpopulations 
Subpopulation growth rates and the probability of decline at current harvest levels were determined for 13 subpopulations of polar bears (Ursus maritimus) that are within or shared with Canada based on mark–recapture estimates of population numbers and vital rates, and harvest statistics using population viability analyses (PVA). Aboriginal traditional ecological knowledge (TEK) on subpopulation trend agreed with the seven stable/increasing results and one of the declining results, but disagreed with PVA status of five other declining subpopulations. The decline in the Baffin Bay subpopulation appeared to be due to over-reporting of harvested numbers from outside Canada. The remaining four disputed subpopulations (Southern Beaufort Sea, Northern Beaufort Sea, Southern Hudson Bay, and Western Hudson Bay) were all incompletely mark–recapture (M-R) sampled, which may have biased their survival and subpopulation estimates. Three of the four incompletely sampled subpopulations were PVA identified as nonviable (i.e., declining even with zero harvest mortality). TEK disagreement was nonrandom with respect to M-R sampling protocols. Cluster analysis also grouped subpopulations with ambiguous demographic and harvest rate estimates separately from those with apparently reliable demographic estimates based on PVA probability of decline and unharvested subpopulation growth rate criteria. We suggest that the correspondence between TEK and scientific results can be used to improve the reliability of information on natural systems and thus improve resource management. Considering both TEK and scientific information, we suggest that the current status of Canadian polar bear subpopulations in 2013 was 12 stable/increasing and one declining (Kane Basin). We do not find support for the perspective that polar bears within or shared with Canada are currently in any sort of climate crisis. We suggest that monitoring the impacts of climate change (including sea ice decline) on polar bear subpopulations should be continued and enhanced and that adaptive management practices are warranted.
The researchers point out that:
Polar bears evolved from a common ancestor with the brown bear. The range of estimates for the age of polar bears as a species ranges from 4 million years based on deep nuclear genomic sequence data from both paternal and maternal linages (Miller et al. 2012) to 120 thousand years based on the mitochondrial genome (matrilineal) (Lindqvist et al. 2010). If polar bears have existed for the last 4 million years, they would have emerged during the mid-Pliocene approximately 1.25 million years before the onset of northern hemisphere glacial cycles (Bartoli et al. 2005). If polar bears emerged any time prior to or during the previous glacial cycle, they would have persisted through the Eemian interglacial period. During the Eemian interglacial, mean annual temperatures were 4°C warmer than the current interglacial (Holocene) for northern latitudes (Müller 2009), and some northern locations reached temperatures as high as ~7.5°C warmer than the mean temperature for the same area over the last thousand years (Dahl-Jensen et al. 2013). Both scenarios suggest that polar bears are able to mitigate impacts from sea ice decline to an extent not fully exhibited in modern times. Currently, the IPCC predicts globally averaged temperatures to warm ~2°C by 2100 and considers warming of ~4°C by 2100 to be possible although unlikely (Intergovernmental Panel on Climate Change 2013). Reduction in the heavy multiyear ice and increased productivity from a longer open water season may even enhance polar bear habitat in some areas (Stirling and Derocher 1993, 2012; Derocher et al. 2004; Rode et al. 2014). The majority of Canada's polar bears inhabit the Canadian Arctic archipelago (Obbard et al. 2010), where 5 of 13 subpopulations are currently and historically ice-free in late summer and early fall (Lunn et al. 2002; Aars et al. 2006; Obbard et al. 2010). Given the persistence of polar bears through the current and previous interglacial periods, and their ability to accommodate extended retreats onshore and based on the empirical observations of climate and sea ice change (S7), it seems unlikely that polar bears (as a species) are at risk from anthropogenic global warming. However, some subpopulations may experience diminished range, reduced productivity and subsequent decline in numbers if sea ice declines occur as predicted (Stirling and Derocher 1993, 2012; Derocher et al. 2004). While there are many projections of climate change that suggest a nearly ice-free Arctic to occur in the warmer months (i.e., September) (IPCC 2007, 2013, Durner et al. 2009; Amstrup et al. 2010; Mahlstein and Knutti 2012; Overland and Wang 2013), there are currently no global climate model (GCM) projections of climate change that suggest a totally ice-free Arctic in any season or month.
.... so there.

 I'll diversify for a moment, because I've never posted anything personal, or connected with where I live. Wycombe is a somewhat "frayed around the edges" town in the Chiltern Hills, designated an "Area of Outstanding Natural Beauty". Here's Yates' pub - well-managed, good cheap food, good beer, relaxed, friendly and hard-working staff, and a correspondingly relaxed clientèle.
Yates', Frogmore, High Wycombe

This is Wycombe High Street, a pale imitation of what it might have been if the local borough council had constrained development and preserved several much older shops and houses.
High Wycombe High Street

There's a street-market on Tuesday, Friday and Saturday. High Wycombe borough was originally "Chepping Wycombe", Chepping being a corruption of the Old English "Ceapen" meaning a town market. I can't find a pic of the whole market, but here's a colourful corner, situated centre-right in the pic above.
Wycombe market - a historical remnant of a prosperous past.

And a couple from the surrounding beechwoods and countryside.
An ancient "dyke" or boundary ditch in the beechwoods about 10 miles from Wycombe.

Bluebell carpet in the spring

Picture-postcard windmill on a windy ridge.
That'll do!

Friday, 16 December 2016

Australia's B.O.M & "Homogenisation" - they must think we're stupid

Australian scientist and blogger Jennifer Marohasy has been leading a small but vocal group campaigning for the Bureau of Meteorology to explain and defend "homogenisation" of temperature data for Australian stations. Their new, improved, value-added and of course, scientifically and mathematically sound database has, in most cases, turned a long-term static or cooling trend into a warming trend. They call it ACORN-SAT. You and I might call it GHCN/GISS outback style - if the present isn't warming to suit their meme, then by god, they'll cool the past, and "prove" local and global warming.

In most cases, the process leads to lowering past temperature data in a series of steps, supposedly corresponding to breakpoints in the series due to station moves, claimed station moves, statistical "discontinuities", or undocumented and therefore unjustified adjustments. Now this was something I could really get my teeth, and my Excel 2000 skills into. Yes, it's the 2000 version - if it ain't broke, don't spend money on a newer version.

I started several draft posts, downloaded shedloads of B.O.M. data, unadjusted GHCN/GISS data, PDF documents, bookmarked scientific literature, created new spreadsheets, chart graphics, googled for images of towns, cities, weather stations. The B.O.M. got very defensive when challenged a couple of years ago. Jennifer and her small group were tilting at a very big and huffily self-righteous windmill. The B.O.M. actually produced some documentation. What right had these upstarts to question their methodology and intent?

Then, a couple of days ago, I had an epiphany; I'd clearly missed something, something very important. The fact was, the B.O.M. has never, ever made the adjustments they'd claimed were necessary! If there's a documented station move, for example from a town out to a rural site, a small temperature change would be expected. In this case, likely to be downward because of the removal of the "urban heat-island" effect. They've identified and quantified such steps in the record at many sites. They believe an appropriate adjustment should be documented and applied, in this case an upward adjustment. The ACORN-SAT database appears not to contain any such adjustments, despite what the B.O.M. has documented, and everyone, until now, has believed.

I'd been looking at the "Station Adjustment Summary" for Amberley, Queensland. There was just one significant adjustment, forward from 1980:
2.  1 January 1980—breakpoint detected by statistical methods.
•  Night-time temperatures started to appear much cooler relative to surrounding                   stations.
•  No accessible documentation for Amberley in 1980, but a breakpoint of this size              would normally be associated with a site move.
•  Min T adjusted by -1.28 °C; no detectable impact on Max T so no adjustments made.
Adjusted by -1.28°C - wouldn't they apply an increase if temperatures "started to appear much cooler relative to surrounding stations"? You'd expect so, but that -1.28°C adjustment was correct - applied to data prior to 1980, thus leaving the "much cooler" data from 1980 onwards unchanged! The shape and trend of the resulting "homogenised" plot becomes identical to what would have resulted from a positive adjustment, but shifted down by the amount of the reversed adjustment. This is the plot of the change to average minimum temperatures for Amberley; for all my graphics, click to see a larger version, or right-click and "save as" to save them:

From the Station Adjustment Summary for Amberley.
The first thing to note is that the "difference" is positive because the author has subtracted adjusted from raw data. If you're comparing A with B, the correct way is to subtract B from A, not vice-versa. Compare 10 with 8, and the difference is 2, not -2. There's no change to raw data after 1980; if post-1980 data was "much cooler relative to surrounding stations", then it remains so. I've plotted ACORN-SAT adjusted against raw for Amberley:
Raw data series (blue) versus ACORN-SAT (red); difference (black)
The raw and adjusted series track together from 1998 rather than 1980 because a second, undocumented adjustment was made after 1996; a 2-step change. From 1980 to 2016, raw minimum trends flat. That's right - no change since 1980. The B.O.M. has what might be termed a "positive attitude" to temperature series; they like to see upward trends - flat or negative has to be "corrected".

Average annual minimum or maximum series are no good metric for measuring or tracking anything, yet they're what the Bureau uses exclusively, and to my knowledge, no other large private nor state-funded meteorological organisation does this. I'll back my up assertions in a future post. In the meantime, here's a plot of monthly average minima for 1978-1983, which spans the Bureau's "breakpoint":
Monthly average minimum temperatures
There's no "step change" evident in 1980. The dip in winter 1982 was caused by a record cold June & July. Minima generally "drifted" down after 1981 to around 1998 - which point coincides with the undocumented adjustment.

Jennifer's campaign focussed on the record for Rutherglen; the story's the same there, though more complicated:
Raw data series (blue) versus ACORN-SAT (red); difference (black)
Raw average minimum and ACORN-SAT adjusted track together (minor differences) from 1974. There's no net upward change due to the claimed adjustments in the Adjustment Summary. I've checked the other Adjustment Summaries, and a few other sites which should show adjustments. In every case, the changes resulted in raising or lowering previous temperatures, not those from the adjustment point forward. The B.O.M. isn't in  the business of correcting anomalies to create ACORN-SAT; they're in the business of changing the past to suit an agenda.