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Porritt’s Sea Level Rise

December 20, 2020

By Paul Homewood



In the Jonathon Porritt article in the Telegraph, which I highlighted yesterday, you may recall his claim: According to the Intergovernmental Panel on Climate Change, average sea levels will have risen by no less than a metre by 2100. That’s the best case. You probably don’t want to think too much about the worst case. That’s still 80 years away.

It is of course a common assertion designed to frighten people, and sadly it cannot be challenged in terms of accuracy because the IPCC have said as much.

But that does not mean it is correct or likely.

Since satellite monitoring started in 1992, global sea levels have officially risen at the rate of 3mm a year, with little sign of acceleration:



The recent blip above the trend line is mainly due to weak El Nino conditions last year. Current data is three months out of date, and current La Nina conditions, which tend to lead to lower sea levels, are therefore not yet reflected in the chart.


Obviously at this rate, sea levels will only rise by 240mm by 2100, not the full meter claimed.

We also know from Jevrejeva’s study in 2013 that tide gauges are in agreement with satellite data, that the sea levels rose by 3.1mm a year between 1993 and 2009 (in other words, no acceleration since 2009), and that the rate of rise since 1970 has been 1.8mm a year.





Much is always made by climate alarmists that seas are rising faster now than in the 20thC. However, as the Jevrejeva chart shows, this is a flagrantly dishonest argument. In reality, the rate of rise since 1992 is little different to the period from 1850 to 1950.

What brought the 20thC rate down was the slow down in sea level rise seen in the second half of the 20thC, a time when global temperatures were falling.

Meanwhile closer to home, sea levels have not risen at all in the last decade at North Shields.


mean trend plot 


Quite simply, the data consistently shows us that sea levels are not going to rise by a meter or more this century, despite what Jonathon Porritt might say.

  1. Patsy Lacey permalink
    December 20, 2020 11:58 am

    This morning’s puff piece in the Telegraph’s unrelenting greenwash on climate change was by Nataliya Vasilyeva. She bemoaned the fact that the “all clear” to drive on the make shift ice road bridge to Yakutsk which replaces the ferry when the ice stops it working arrives later each year shortening the ice road season. Predictably failing to present any actual data, reading between the lines it is actually an attack on Moscow’s failure to stump up £1 billion for a road bridge – but that wouldn’t have chimed with the Telegraph’s obsession with climate change

  2. Broadlands permalink
    December 20, 2020 1:23 pm

    Paul… “La Nina conditions, which tend to lead to lower sea levels.” Why should the ENSO’s sea surface temperature anomalies lead to fluctuations in sea level? The NOAA chart has seasonal ‘signals’ removed.

  3. December 20, 2020 1:42 pm

    The National Tidal and Sea level facility used to produce a UK sea level rise trends, which showed nothing much happening.

    This has recently disappeared.

    However this still remains which tell Porritt is talking nonsense!

  4. CheshireRed permalink
    December 20, 2020 1:51 pm

    Porrritt is an activist, nothing more or less. I’d trust the word of a mafia hitman before that tosser.

    • dennisambler permalink
      December 20, 2020 2:12 pm

      Just a bit:..
      “Established in 1996, Forum for the Future is now the UK’s leading sustainable development charity, with 70 staff and over 100 partner organisations including some of the world’s leading companies.

      In addition, Jonathon is Co-Director of The Prince of Wales’s Business and Sustainability Programme which runs Seminars for senior executives around the world. He is a Non-Executive Director of Wessex Water, and of Willmott Dixon Holdings. He is a Trustee of the Ashden Awards for Sustainable Energy, and is involved in the work of many NGOs and charities as Patron, Chair or Special Adviser.

      Jonathon was formerly Director of Friends of the Earth (1984-90); co-chair of the Green Party (1980-83) of which he is still a member; chairman of UNED-UK (1993-96); chairman of Sustainability South West, the South West Round Table for Sustainable Development (1999-2001); a Trustee of WWF UK (1991-2005), a member of the Board of the South West Regional Development Agency (1999-2008).”

      • John Palmer permalink
        December 20, 2020 3:37 pm

        He’s a busy little B, isn’t he!
        Mind you, he’ll likely need the incomes from all those (non) jobs if the policies he and his chums are pushing ever come to pass….

  5. wilpretty permalink
    December 20, 2020 4:13 pm

    After the 1953 sea floods in the Thames area, sea walls were raised, either 1M or 2M depending in the location.
    This was not because of the 150mm that the sea level had risen since 1880 but to deal with the danger caused by tidal surges created by storms in the North Sea.
    The last large tidal surge a few years ago was +3M and the higher sea walls were not overtopped.
    Surges caused by weather are the problem, not 2mm per year sea level rise.

  6. Burgundian permalink
    December 20, 2020 4:19 pm

    Let’s not forget the Maldives are now under water. Oh, sorry, that was the forecast for 40 years ahead that the Greens made in 1988. So far nobody there is even splashing around, let alone swimming.
    Then there’s Obama, never one to miss a chance at distorting a truth or fifteen – he was so worried about rising sea levels when he was president. Then he bought a house on the New England coast. 1.5m above sea level.

    • Graeme No.3 permalink
      December 20, 2020 6:06 pm

      I thought the forecast was by Jim Hansen at NASA in 1988 when he said that The Maldives would be underwater by 2018 (along with parts of New York incl. part of Wall St.)

    • Duker permalink
      December 20, 2020 6:15 pm

      Biden has a holiday home at Rehoboth Beach Delaware about a block from the Atlantic Ocean. It was bought after finishing his terms as VP.

  7. December 20, 2020 5:50 pm

    You’d think The Pentagon would be evacuating this place that is three feet (one metre) above sea level on average but no …. billions of dollars invested and the industrial size fuel tanks are still on the beach …. images here >

    Story here > Diego Garcia: Why This Base Is About To Get Much More Important to the U.S. Military ….

  8. Graeme No.3 permalink
    December 20, 2020 6:03 pm

    Fort Denison in Sydney Harbour has a tide gauge operating from 1914
    Maximum recorded level of 2.400 metres at 1300 hours 25/05/1974
    Minimum recorded level of -0.190 metres at 1700 hours 19/08/1982

    Mean sea level = 0.936 (Average monthly means = 0.937)
    Standard deviation of the observations = 0.4191 metres
    Claim of sea level rise of 0.65 m.m. per year
    Max. Min.
    1914 range 2.11 -0.14
    1974 range 2.40 0.00
    1982 range 1.00 0.78
    2020 range 2.13 0.10

    For other sites around Sydney see

  9. December 20, 2020 6:50 pm

    sadly it cannot be challenged in terms of accuracy because the IPCC have said as much

    Like their ‘rapidly melting’ Arctic summer sea ice accuracy? It’s been ‘rapid’ for decades according to the so-called experts, but fails to get anywhere close to vanishing. Where have the jokers kicked their can down the road to these days – 2050/2080/2100/2500? Hopeless.

  10. December 20, 2020 7:08 pm

    Porritt is wrong.

  11. yonason permalink
    December 20, 2020 7:09 pm

    Rapid extreme sea level rise = utter nonsense.

    Do rabid ignorant extremist blowhards get paid by every millimeter they claim? You know, like some kind of demented piecework?

  12. jack broughton permalink
    December 20, 2020 7:29 pm

    Fig 3 seems to catch the end of the LIA very well. Are there any reconstructions that are credible going back to the MWP or earlier?

  13. Nancy & John Hultquist permalink
    December 20, 2020 8:53 pm

    Graphs such as sea level change ought to have an overlay of something people can relate to. For example, the 1-kilogram Australian Gold Kangaroo is 75.6 mm in diameter and 13.9 mm thick.
    A 1-ounce Australian Gold Kangaroo is 32.6 mm in diameter and 2.8 mm thick.
    Search images: aud gold coin Australian
    { do not use Kangaroo }

    I did not find true size images of the edge. The above numbers are useful in that the 1-oz. coin is about as thick as the yearly rise, and the 1-kg coin is thicker than the rise shown in the first chart. That’s about 3 inches.
    An adult’s index finger is about 3 inches long. Pictures of such, in context, are easy to find – or use your own.

  14. wilpretty permalink
    December 20, 2020 9:38 pm

    I often ponder what caused the abrupt change of sea level rise in 1860.
    What ever it was, it is still happening.
    It does not correlate with CO2 atmospheric concentrations.
    It is claimed that the Little Ice Age was driven by low solar activity.
    Solar activity is said to correlate with sunspots. These do not change abruptly and do not appear to correlate directly with weather.
    CET temperature shows no abrupt changes in 1860.
    Could it be volcanism under the Antarctic ice sheet?

    • Gamecock permalink
      December 20, 2020 9:51 pm

      The volume of the ocean basin is unknown, unmeasurable, and constantly changing. Hence, attribution of sea level changes to Man is just silly. But people are making a living off it.

      • Phoenix44 permalink
        December 21, 2020 9:28 am

        There is a high negative correlation between our actual knowledge of something and the fear and alarm that is generated about that something.

        Se acid rain, ozone layer, climate change, ebola, Covid, AI.

        Those generating the fear claim its “science ” but mainly it seems to be atavistic terror of the unknown.

  15. jarlgeir permalink
    December 21, 2020 12:10 pm

    This is not true when you take a closer look at the data: «sadly it cannot be challenged in terms of accuracy because the IPCC have said as much».

    First we have the bug picture or the IPCC process, as described by Prof. Lindzen in 2018 on WUWT: «What the proponents of alarm have done is to accept the tide gauge data until 1979, but assume that the satellite data is correct after that date, and that the difference in rates constitutes ‘acceleration.’ They then assume acceleration will continue leading to large sea level rises by the end of this century. It is hard to imagine that such illogical arguments would be tolerated in other fields.»

  16. jarlgeir permalink
    December 21, 2020 12:16 pm

    Then the data, as decribed by Dr. Mörner:«Whilst NOAA gives a mean sea level rise of +2.9 ± 04 mm/yr, UC gives a means sea level rise of 3.3 ± 0.4 mm/yr. Both values are strongly affected by subjective «corrections» or «manipulation», however. Remove these improper «calibrations» and the values change to +0.45 and +0.65 mm/yr, respectively»

    All we have to worry about is a sea level rise this century of 5 to 7 centimeters.

    • Gamecock permalink
      December 21, 2020 2:40 pm

      They use decimal points to show they have a sense of humor.

      False precision fallacy.

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