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Met Office Sea Level Forecast – No Resemblance To Reality

February 11, 2014
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By Paul Homewood

 

In the Met Office report, published this week, “The Recent Storms and Floods in the UK”, there is this statement:

 

Sea level along the English Channel has already risen by about 12cm in the last 100 years. With the warming we are already committed to over the next few decades, a further 11-16cm of sea level rise is likely by 2030. This equates to 23-27cm (9-10½ inches) of total sea level rise since 1900.

 

My Garden Pond & Tallbloke have already picked up on this, and got some clarification from the Met Office’s Richard Betts, who has made it clear that the projected rise is from 1990, and not now.

That would imply a rate of rise of between 270mm and 400mm per century, between 1990 and 2030.

So what have sea levels been doing so far since 1990? We have eight tide gauge stations along the English Channel, with records back to 1990. (Dover only has data to 2010, the others are all updated to 2012). The chart below shows how sea levels have changed, according to data from the PSMSL, (Permanent Service for Mean Sea Level). All figures are in mm.

 

1990 2012 Change/Decade
Dover (To 2010) 7073 7090 8.5
Portsmouth 7026 7068 19.1
Weymouth 6949 6965 7.3
Devonport 7073 7088 6.8
Newlyn 7079 7110 14.1
Le Havre 7048 7082 15.5
Cherbourg 7057 7086 13.2
Roscoff 6952 6993 18.6
Crude Average 12.9

 

http://www.psmsl.org/data/obtaining/

 

None of the stations come anywhere near even the bottom of the Met Office’s forecast range, and the, admittedly, crude average is bang in line with the 12cm rise over the last century.

 

It is also important to take into account isostatic changes. Along the Channel, land is sinking by between about 0.5mm and 1.2mm a year. (On the English side at least!) In other words, at least a half of the observed sea level rise seems to be accounted for by this factor. Without this, we are looking at only a few inches a century.

 

image

http://www.yourclimate.org/pages/regional-adaptation-study

 

So where does all of this leave the Met Office’s forecast? According to them, there should be a sea level rise of between 82mm and 132mm in the next 18 years. In other words, 4.5mm to 7.3mm a year, which equates to a rate of 17 to 28 inches a century.

It is hard to see what could possibly lead to such a startling acceleration in the recent rate of rise.

Time for the Met Office to go back to the drawing board, methinks!

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8 Comments leave one →
  1. February 11, 2014 9:09 pm

    Comment at: http://mygardenpond.wordpress.com/2014/02/09/met-office-report-says-sea-levels-likely-to-rise-11-16-cm-by-2030/comment-page-1/#comment-378
    __________________________________________________________________

    Richard Betts on February 10, 2014 at 10:44 pm said:

    Hi Ruth

    The projected SLR of 11-16cm by 2030 for the English Channel comes from the UKCP09 projections, see this report, Table 2, columns for “High” (16.0) and “Low” (11.4) for London.

    But crucially, these numbers are relative to 1990 (the UKCP09 baseline), not 2014. This was not stated. Clearly there’s been some sea level rise since 1990, so the numbers between 2014 and 2030 would be smaller.

    Also, these numbers are for relative sea level rise, including both climate change and vertical land movement.

    So, Athelstan on Bishop Hill was right that this was part of the reason for the numbers seeming large compared to the AR5 global projections, and you were also right that there was more to it than that.

    The report has been updated, and page 2 now says:

    Sea level along the English Channel has already risen during the 20th century due to ocean warming and melting of glaciers. With the warming we are already committed to over the next few decades, a further overall 11-16cm of sea level rise is likely by 2030, relative to 1990, of which at least two-thirds will be due to the effects of climate change.

    and page 21 now says:

    Sea level along the English Channel has already risen by about 12cm during the 20th century; this is over and above the increases associated with sinking of the southern part of the UK due to isostatic adjustment from the last Ice Age. With the warming we are already committed to over the next few decades, a further overall 11-16cm of sea level rise is likely by 2030, relative to 1990, of which at least two-thirds will be due to the effects of climate change. We are very confident that sea level will continue to rise over coming decades as the planet continues to warm, and these numbers represent our current best estimate for the UK. Clearly sea level rise from whatever source has to be factored into discussions about resilience to coastal and river inundations.

    References are now included in that paragraph.

    Thanks very much for spotting this!

    Cheers

    Richard
    ___________________________________________________________

    Of course, as another commenter points out: “Over the next 16 years, I expect to age a further 40 years, relative to 1990 levels.”

  2. Billy Liar permalink
    February 11, 2014 10:21 pm

    If you take account of the isostatic adjustment for the previous 100 years, it’s worse than we thought!

    Take Newlyn, for example, isostatic adjustment for 100 years @ 1.0mm/yr = 100mm. Actual SL rise (using the 1990-2012 rate) = 141mm.

    Rise due to global warming in last 100 years = 41mm.

    This is 0.4mm/yr – and it’s suddenly going to jump to 3.5-6.3mm/yr? I don’t think so.

  3. February 11, 2014 11:42 pm

    For what it’s worth:
    According to the Sea Level Research Group, University of Colorado, the mean rate of global sea level rise is 3.2 ± 0.4 mm/yr. [Includes a “global mean glacial isostatic adjustment (GIA)” correction of 0.3 mm/yr. The GIA uncertainty is at least 50 percent.]

    See “Global Mean Sea Level Time Series (seasonal signals removed)” (Sea Level Research Group, University of Colorado. 2014_rel1, 2014-02-05), at http://sealevel.colorado.edu/

  4. Vernon E permalink
    February 14, 2014 4:30 pm

    Just been watching that genetiscist doctor with the ‘tash, who is always on TV promoting global warming scares, on Question Time yesterday (Lord Somebody) saying with a straight face that we have already experienced 20 cms of sea level rise as though it is something that happened recently. As we “in the know” recognise this rise has occurred over 200 years and is entirely commensurate with a gentle temperature rise following the little ice age. And anyway, what do we mean by “sea level rise”. We have huge tidal ranges around our coasts (10 meters or more) varying all the time between springs and neaps and these themselves varying throughout the year and over more extended cycle periods, so just what is it that’s being measured?

  5. Lawrie Ayres permalink
    February 17, 2014 10:47 am

    Why do the people of the UK pay for such erroneous forecasts and dubious data? If the CEO of a company prepared such a dodgy prospectus he would not be allowed near a company again. If you were to do away with the Met you would be in a better position than if you retain them. Sack the lot.

Trackbacks

  1. Met Office Sea Level Forecast: No Resemblance To Reality | The Global Warming Policy Foundation (GWPF)
  2. Met Offices misslyckade långtidsprognoser - Stockholmsinitiativet - Klimatupplysningen
  3. Weekly Climate and Energy News Roundup | Watts Up With That?

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