The ocean according to Renwick

Prof James Renwick

One of our favourite Kiwi climate scientists has again made alarmist climate predictions.

The predictions come from the IPCC, but I’m sure Professor James Renwick takes responsibility for repeating them (I mean, he must have satisfied himself over their accuracy). He frequently cites the IPCC’s predictions but keeps quiet when they’re wrong. For example, when they and their computer models forecast strong warming over the last 17 years instead of the lack of warming we observe.

Of sea level rise, he says: “we are expecting something like a metre of rise this century,” but adds, “the draft report said average global sea levels would rise by up to 0.97 m by 2100 but were likely to be 10 per cent higher in most of New Zealand, where the tidal range is about one metre.”

Needless fear

Prof Renwick’s expertise was earned in climatology, not coastal studies, and it could just be showing. I’m told that Renwick appears to confuse storm surge elevation probability with inundation — and thus fosters false fear of the future.

Even if he was considering an area currently below sea level, his assessment would be valid only in the unlikely event that sea level rise did actually reach the extreme level projected by the IPCC.

See, most coastal areas around New Zealand are not inundated during 1% annual exceedance probability (AEP) storm surges. That means the probability of inundation is zero — no cause for concern.

Only if sea level rises enough to actually cause inundation can we assess what the probability of inundation might be. Stands to reason.

The 0.98 metres of sea level rise by 2100 (yes, the good professor gets the number wrong, it’s not 970 mm — see page 25 of the WGI SPM) is the absolute top of the range from the IPCC. Yet Prof Renwick doesn’t tell his fellow citizens there’s another side to these “predictions”.

A low side. A mere 260 mm. They’re not at all confident which one will occur. Renwick is happy to frighten us with the high figure without even mentioning a lower one. As though there’s no question.

The top figure comes from the very highest “greenhouse gas concentration pathway” considered possible by the scare-mongers at the IPCC. There’s a set of four dreamed up for the AR5; odd that Renwick plumps for the red line that soars for the stratosphere. These are the four pathways:

IPCC Concentration Pathways

“We’re talking about what is now the high-tide line becoming the low-tide line and the beach will still go inland,” Renwick said, describing the increased risk to coastal areas as “a big deal.”

The IPCC freely admits not knowing which scenario is most likely. But we should bear in mind there’s NO EVIDENCE that these amounts of CO2 in the atmosphere will cause any harmful effects. They’re guessing. There’s no knowing whether 1200 ppm of CO2 (three times what is there now) will produce 0.52 to 0.98 m of sea-level rise, or whether 380 ppm will produce “only” 0.26 to 0.55 m.

There’s no evidence for any of that. In the SPM, the IPCC expresses “medium confidence” in all four of these guesses. Take your pick.

Experience (a wonderful thing — arises from observing the real world) tells us that mitigation measures are simple and, in the event that they are required for New Zealand, likely to be cheaper than trying to control our emissions of so-called ‘greenhouse’ gases.

His comment about NZ sea level rise does not make sense.

I wonder if he understands it?

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MagooAndyAustralisRichard C (NZ)Alexander K Recent comment authors
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Gary
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Gary

Yes he does understand it. It is called rent seeking, to get more funding, keep a good salary and get a bonus. It’s a piece of cake spouting this, some even believe it.
He will keep doing this until one day something serious will need attention, and by then the citizens will not be listening to Chicken Little stories.

Richard Treadgold
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You make him sound cynical, but I find it hard to accept that cynicism might drive senior scientists for so many years. Well, is it cynicism or something else?

Alexander K
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Alexander K

In my opinion, Renwick, like any other person who works in a large organisation, lives in a ‘bubble’ of in-group manufacture. He is not neccessarily a dishonest or cynical person, but is reflecting his own intellecual environment. This phenomenon is why so many politicians spout utter crap in areas where they are not exposed to externallly-tested and verified information.
So much for the objectivity of the well-rewarded careerist civil servant.

Richard C (NZ)
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Richard C (NZ)

>”Renwick is happy to frighten us”

In the US, the Feds go for the jugular:

‘Social Cost of Carbon Inflated by Extreme Sea Level Rise Projections’

By Patrick J. Michaels and Paul C. “Chip” Knappenberger
April 9, 2014

“We have discussed many of the problems with the SCC before, and in our last post we described how the feds have turned the idea of a “social cost” on its head. In this installment, we describe a particularly egregious fault that exists in at least one of the prominent models used by the federal government to determine the SCC: The projections of future sea-level rise (a leading driver of future climate change-related damages) from the model are much higher than even the worst-case mainstream scientific thinking on the matter. This necessarily results in an SCC determination that is higher than the best science could possibly allow.”

http://www.cato.org/blog/social-cost-carbon-inflated-extreme-sea-level-rise-projections

Richard C (NZ)
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Richard C (NZ)

[Renwick] – “we are expecting something like a metre of rise this century,”

Port of Tauranga MMSL:

http://www.psmsl.org/data/obtaining/rlr.monthly.plots/1590_high.png

A metre rise? I don’t think so.

Richard C (NZ)
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Richard C (NZ)

The nine NZ tide gauges with 21st century data from PMSL:
http://www.psmsl.org/data/obtaining/

Tauranga (Salisbury Wharf)
http://www.psmsl.org/data/obtaining/rlr.monthly.plots/1590_high.png

Napier
http://www.psmsl.org/data/obtaining/rlr.monthly.plots/1750_high.png

Wellington Harbour
http://www.psmsl.org/data/obtaining/rlr.monthly.plots/221_high.png

Dunedin (Port Chalmers)
http://www.psmsl.org/data/obtaining/rlr.monthly.plots/1643_high.png

Bluff
http://www.psmsl.org/data/obtaining/rlr.monthly.plots/213_high.png

Nelson
http://www.psmsl.org/data/obtaining/rlr.monthly.plots/787_high.png

Port Taranaki
http://www.psmsl.org/data/obtaining/rlr.monthly.plots/996_high.png

Whangarei (Marsden Point)
http://www.psmsl.org/data/obtaining/rlr.monthly.plots/1065_high.png

Chatham Island
http://www.psmsl.org/data/obtaining/rlr.monthly.plots/1920_high.png

Only Wellington and Nelson exhibit any rise this century. The other seven either flat, non-linear fluctuation, or fall. I think Prof Renwick will have to carry on “expecting” his metre rise for a while yet. Albeit a speculative non-scientific expectation apparently (call it a wild guess, or just hope).

Richard C (NZ)
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Richard C (NZ)

Note Auckland is conspicuously absent from the list of 21st C MSL data. Even so, Auckland has been a proxy for NZ MSL in studies because it’s a “long-running” dataset.

It was. Data collection ceased in May 2000 (or that forwarded to PMSL anyway). So Auckland is incapable of being indicative of NZ MSL in the 21st century. Given the disparity of trends from the nine gauges that do record 21st C MSL, projecting Auckland’s long-term 20th C trend into the 21st century and calling it a proxy for NZ is bogus.

21st century relevant indication now (in 2014 and onwards) can only be ascertained from the nine datasets above. And only then if up to date data collection continues for each of them.

Richard C (NZ)
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Richard C (NZ)

>”Note Auckland is conspicuously absent from the list of 21st C MSL data” Nevertheless, NIWA have an out-of-date (“present” is 2001) article up on their website featuring Auckland (my annotation [ ] ): ‘Sea level on the move?’ – Derek Goring, Rob Bell (2001) “A well-cited consequence of global warming [natural? or anthropogenic? or both?] is sea-level rise [but which actually varies radically region-by-region, not necessarily rise either]. What evidence is there that this is [was] happening [last century]? […] “So, what can we say about whether sea level is [was] rising or not [last century]? The graph (below right) shows the annual sea levels at Auckland from 1899 to the present [in 2001]” http://www.niwa.co.nz/sites/default/files/imagecache/PhotoGallery_ImageNodeFull/images/move5_large.jpg [We can say it was rising last century – naturally] […] In the graph, we have divided the Auckland record since 1899 into positive and negative phases of the IPO. Notice that when IPO is in its negative phase, sea level rises faster than when IPO is positive [but what is the underlying trend driver?]. The Pacific has just come out of a positive phase (from 1976 to 1998), so we can expect [not necessarily – again, what’s… Read more »

Richard C (NZ)
Guest
Richard C (NZ)

From University of Colorado (my emphasis): Why is the GMSL different than local tide gauge measurements? The global mean sea level (GMSL) we estimate is an average over the oceans (limited by the satellite inclination to ± 66 degrees latitude), and it [the satellite GMSL series] cannot be used to predict relative sea level changes along the coasts. As an average, it indicates the general state of the sea level across the oceans and not any specific location. Local tide gauges measure the sea level at a single location relative to the local land surface, a measurement referred to as “relative sea level” (RSL). Because the land surfaces are dynamic, with some locations rising (e.g., Hudson Bay due to GIA) or sinking (e.g., New Orleans due to subsidence), relative sea level changes are different across world coasts. To understand the relative sea level effects of global oceanic volume changes (as estimated by the GMSL) at a specific location, issues such as GIA, tectonic uplift, and self attraction and loading (SAL, e.g., Tamisiea et al., 2010), must also be considered. We do calibrate the altimeter sea level measurements against a network tide gauges to… Read more »

Australis
Guest
Australis

I love the way Renwick throws figures around without the slightest regard for truth for plausibility.

In the NBR, he is quoted as saying that 1-in-100 year floods would become an ANNUAL event by 2100. There’s nothing like that in the WG2 report. He just made it up as a memorable sound-bite.

Then, the same day, he is quoted in the NZ Herald as saying that 1-in-100 year floods would become a WEEKLY event by 2100. I couldn’t believe he said it and put it down as a typo. Then, the next day, there is a different quote in the Herald from a different sound-bite, but Renwick is again saying these floods would be happening weekly!

The man would say anything.

Richard Treadgold
Guest

So he wasn’t misquoted. We’ve heard him often enough giving alarmist versions of the future climate to know that’s how he really thinks. I wonder if he left NIWA because they weren’t alarmist enough for him — that only the hotbed of socialist brow-beating that VUW has become gives his world-saving aspirations full rein. But I speculate.

Andy
Guest
Andy

Breaking news is that the West Antarctica ice sheet is about to collapse and might cause catastrophic sea level rise in 200-900 years time

I hope the Christchurch and Wellington City Councils are having urgent planning meetings to discuss how to deal with this imminent threat

Magoo
Guest
Magoo

A good business opportunity for someone to blow large chunks of ice off it and either tow them to where they’re needed or store it as fresh water supplies. I can see the sales pitch already – ‘Antarctica Pure, because only the freshest will do.’

Good way to help the farming in Africa and Aussie as well.

Richard C (NZ)
Guest
Richard C (NZ)

Prof Tim Naish got all of about 5 seconds on this on TV1. I think it was a “filler” slot.

Andy
Guest
Andy

The real question is who many generations of “the children” ahead do we need to be thinking of?

Andy
Guest
Andy

Apparently, according to Dr R, each 10 cm of SLR will triple the risk of inundation events (whatever that means)

So 100cm of SLR will increase the risk by a factor of 3^10 = 59,049

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