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Sea Levels In The Holocene

May 13, 2016
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By Paul Homewood

 

Post-Glacial_Sea_Level

https://en.wikipedia.org/wiki/Sea_level_rise

 

Perhaps the alarmist scare which gains most traction is that of catastrophic sea level rise. The idea that at some undefined point in the future our coastal cities will be under several meters of water.

It is, however, one that is easy to dismiss. Quite simply, we know that global climate has been much warmer than now for most of the years since the ice age ended. There was obviously a very rapid and large rise in sea levels when the ice age ended, but it is generally accepted that things stabilised around 6000 years ago. During that time, despite higher temperatures, there has been no catastrophic melt of the Greenland or Antarctic ice sheets, and no corresponding large jump in sea levels of the type currently touted.

 

Before we move on, let’s get one thing clear. It is often claimed that there has been very little change in sea levels during the last few thousand years, prior to the industrial revolution. The notoriously unreliable Wikipedia for instance quote a rise of only 0.07  mm/yr for the last 2000 years. However what they don’t mention is that there have been ups and downs during this time.

HH Lamb in his book, Climate, History and the Modern World, offers many examples of this, eg:

1) The most rapid phases [of sea level rise] were between 8000 and 5000 BC, and that the rise of general water level was effectively over by about 2000 BC, when it may have stood a metre or two higher than today.

2) The water level may have dropped by 2 metres or more between 2000 and 500 BC. What does seem certain is that there was a tendency for world sea level to rise progressively during the time of the Roman Empire, finally reaching a high stand around 400 AD comparable with, or slightly above, present.

3) The slow rise of world sea level, amounting in all probably to one metre or less, that seems to have been going on over the warmer centuries in Roman times, not only submerged the earlier harbour installations in the Mediterranean, but by 400 AD produced a notable incursion of the sea from the Wash into the English fenland, and maintained estuaries and inlets that were navigable by small craft on the continental shore of the North Sea from Flanders to Jutland.

4) The existence of pre-Norman conquest salterns – saltpans over which the tide washed and from which salt-saturated sand was taken – outside the later sea dykes on the Lincolnshire coast may point to a period of slightly lowered sea level between the late Roman and the medieval high water periods.

5) Our survey of the European scene during the warmer centuries of the Middle Ages would not be complete without mention of the things that suggest a higher stand of the sea level, which may have been rising globally during that warm time as glaciers melted .

Fig 60 [not shown] draws attention to the greater intrusions of the sea in Belgium, where Bruges was a major port, and in East Anglia where a shallow fjord with several branches led inland toward Norwich. [Bear in mind that the land here has been sinking due to isostatic forces since the ice age. If relative sea levels were as high then as now, it would mean absolute levels were higher than.]

 

 

But back to the issue of temperatures. We know from Greenland ice cores just how much warmer it has been there during most of the Holocene, yet there was no spectacular meltdown then.

 

screen-shot-2015-06-06-at-12-34-16

https://edmhdotme.wordpress.com/2015/06/01/the-holocene-context-for-anthropogenic-global-warming-2/

 

And it was not just Greenland. Glaciologists are clear that in Iceland the Little Ice Age was the coldest period for 8000years, and glaciers reached their post ice age maximum.

There is also abundant evidence from tree line and glacier studies in South America that temperatures were much higher until about 3000 years ago.

I could go on with similar evidence from New Zealand, the Rockies, California and the Alps. According to Lamb, for example, “Most – and perhaps all – of the glaciers present today in the United States Rockies south of the Canadian border are believed to have formed since 1500 BC.”

 

If global temperatures were so much higher, and for so long, back then, why do we not see the sort of sea level rise now being forecast?

 

What we do know is that there was a massive expansion of glaciers worldwide during the Little Ice Age. And, unsurprisingly, sea levels dropped.

Many studies, such as the Hofstede one below, suggest that sea levels were at a similar level to today in the Middle Ages, before falling by 300mm up to AD 1700. Lamb reckons the drop may have been even greater, up to 500mm.

It was also found that sea levels rose by about 0.2cm a year between AD 600 and AD 1200, a similar rate to today.

 

image

http://www.kwaad.net/SeaLevel-MiddleAges-LittleIceAge.html

 

 

Given the massive advance of glaciers in the LIA, it is little wonder that we have seen a recovery in sea levels since.

There is no evidence that the current rate of increase is in any way abnormal, and the history of the last few thousand years tells us that we are not going to get the inundations promised.

9 Comments leave one →
  1. Broadlands permalink
    May 13, 2016 6:55 pm

    It is certainly true that “the alarmist scare which gains most traction is that of catastrophic sea level rise.” This has been exacerbated by publications such as that by James Hansen and his team…

    “Ice melt, sea level rise and superstorms: evidence from paleoclimate data, climate modeling, and modern observations that 2 ◦C global warming is highly dangerous”

    by J. Hansen et al.

    This paper got immediate media publicity, not because of the 58 pages of technically complex science, but because of its title and the 4 pages of “implications”.

  2. May 13, 2016 7:04 pm

    interesting to read some science rather than hysteria

  3. May 13, 2016 11:03 pm

    Reblogged this on Climate Collections.

  4. Stosh permalink
    May 13, 2016 11:27 pm

    The Glo-bull warming freaks won’t be satisfied until they reinitialize the Little Ice Age so modern man can experience it’s wonders….

  5. dangeroosdave permalink
    May 14, 2016 12:17 am

    I have to come clean before these doubters. When I designed Earth, I put in a fusion core energized by great pressures of stuff, but gradually consuming carbon and dissipating heat out to the cosmos. Only a tiny bit of crust is suitable for man, but it has oxygen, water, fish, cows and almost anything one might need for many years. As stuff is consumed, the crust shrinks, we have occasional geological events and occasional regrettable disasters such as Pompeii or Krakatoa. Very regrettable. It doesn’t happen often, and I’m already working on Earth 7.0, a whole new system. Yes, we’ve had six major works, but we continue to strive toward a stable system, suitable for all. -God

  6. May 14, 2016 11:39 am

    Now just remember, in order to get his flat hockey stick handle, Michael Mann deleted the Roman and Medieval Warmings and the Little Ice Age from geologic history. You seem to have reinstated them. Did you check w/ Michael Mann? He might just sue you.

  7. JanSalie permalink
    May 14, 2016 8:35 pm

    “It was also found that sea levels rose by about 0.2mm a year between AD 600 and AD 1200, a similar rate to today”. Should that be 2 mm a year (0.2 m per century)?

  8. May 15, 2016 11:04 am

    Reblogged this on Petrossa's Blog.

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