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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16 Thoughts on “The ocean according to Renwick

  1. Gary on 08/04/2014 at 10:12 pm said:

    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.

    • 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 on 09/04/2014 at 12:15 pm said:

      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.

  2. Richard C (NZ) on 10/04/2014 at 12:01 pm said:

    >”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.”

  3. Richard C (NZ) on 10/04/2014 at 12:55 pm said:

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

    Port of Tauranga MMSL:

    A metre rise? I don’t think so.

    • Richard C (NZ) on 10/04/2014 at 4:54 pm said:

      The nine NZ tide gauges with 21st century data from PMSL:

      Tauranga (Salisbury Wharf)


      Wellington Harbour

      Dunedin (Port Chalmers)



      Port Taranaki

      Whangarei (Marsden Point)

      Chatham Island

      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) on 10/04/2014 at 6:42 pm said:

      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) on 10/04/2014 at 11:59 pm said:

      >”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]” [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 the trend driver?] sea level to rise faster [from 1998 to 2018] than it has over the last 20 years [1978 to 1998, it hasn’t for 15 of those 20 – the expectation rationale was wrong obviously]. We are already observing increased sea levels at many of our recorders [1998 to 2001]. We predict that sea level will rise more rapidly over the next 20 years or so [2001 to 2021, but it hasn’t for 13 of those 20] until the IPO switches back to its positive phase, when sea-level rise will slow again [but it has already slowed in negative phase – slower, then slower still?].

      The modern network of gauges will provide highly accurate records that will enable us to detect any [theoretical] acceleration in the underlying trend of sea level [Auckland wont, it has been defunct since May 2000] against the background of ENSO and IPO cycles. The latest sea-level projections by the Intergovernmental Panel on Climate Change (IPCC) indicate a sea-level rise of 0.3 to 0.5 m over this century [but where?], around twice that of last century [except latest science (Cazenave et al, 2014) concedes observed SL deceleration this century – so much for indication from IPCC projections].

      That means an acceleration in sea-level rise is imminent [Imminent it may have been theoretically in 2001, but evident it was not in the nine PSMSL gauges recording 21st C data for NZ] over the next decade or so [from 2001 to 2011] because of a warming world driven by the greenhouse effect [that’s the theory, but not the outcome]. However, because of the long-period natural cycles in sea level, confirmation of an acceleration in the trend may take a few decades [we’ve gone for more than one of those decades and confirmation of no continuation of the trend at all (let alone an acceleration of it) looks just as likely].

      # # #

      12 years on and any imminence of SLR acceleration has elapsed As has the relevance of the article (and the theory) in view of what has actually transpired. The article does however serve as a useful documentation of folly, although, why publicize that?

  4. Richard C (NZ) on 12/04/2014 at 12:14 pm said:

    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 discover and monitor drift in the satellite (and sometimes tide gauge) measurements. This is discussed further in the tide gauge discussion.

    GMSL is a good indicator of changes in the volume of water in the oceans due to mass influx (e.g., land ice melt) and density changes (e.g., thermal expansion), and is therefore of interest in detecting climate change.

    # # #

    A) If GMSL “cannot be used to predict relative sea level changes along the coasts”, Renwick’s (“We”, the IPCC-aligned) metre rise prediction can only be in respect to local tide gauges (9 of them at PSMSL upthread) – not GMSL.

    B) If GMSL is a “good indicator” for “detecting climate change”, what if there’s no GMSL indication consistent with Anthropogenic CC (and there isn’t)?

  5. Australis on 14/04/2014 at 10:28 pm said:

    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.

    • Andy on 14/05/2014 at 12:13 pm said:

      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

  6. 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.

  7. Andy on 13/05/2014 at 12:15 pm said:

    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 on 13/05/2014 at 5:58 pm said:

      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) on 13/05/2014 at 6:39 pm said:

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

    • Andy on 13/05/2014 at 8:25 pm said:

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

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