Ian Wishart writes in Investigate Daily:
Century old map throws new doubt on climate change sea level claims
A new book on the history of New Zealand has inadvertently stirred the climate change debate by revealing a near zero sea level increase over the past century.
The book, The Great Divide, includes a 100 year old map of Cloudy Bay lagoons in New Zealand, drafted back in 1912 to show the location of 20 kilometres of canals dug with wooden spades by ancient Maori.
However, when the 1912 map is shown alongside a satellite image of the same location from Google Earth, it reveals not only the startling accuracy of the original map (drafted at a time when aerial photography did not exist) but also a stunning lack of Pacific Ocean encroachment on the narrow shoal linking the lagoons to the sea.
The shoal is comprised of rock and pebbles, making it an ideal weathervane for sea level increase as it’s less prone to erosion than shifting sands.
Even the narrowest and lowest part of the bar, marked with a black squiggle on the 1912 map, remains the same in 2012.
The Great Divide goes on sale this week, and among its revelations is confirmation that a massive comet-strike into the ocean off New Zealand’s southern coast caused a 220 metre high tsunami that may have been responsible for erasing evidence of human habitation in early New Zealand.
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This might be a good time to review my story about how easy it is to get freaked out about sea level rise.
Ian Wishart says:
April 27, 2012 at 5:03 am
Just to clear up any confusion, I was referring to aerial photography in New Zealand not being available in 1912…first aerial photo taken in 1919, and first used for cartography in 1926. See http://www.teara.govt.nz/en/modern-mapping-and-surveying/3
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Nothing personal, you just raised the hacks of some.
This no-sea-level-rise claim sounds fair enough and may well be right.
But I would normally put little faith in a record based on coastal features on an island in an area of subduction zones, transverse faulting and accompanying measured earth movements.
Given the magnitude of CAGW predictions – in the San Francisco Bay Area, an increase of 2 meters by 2100, and James Hansen and Al Gore predicting a rise of 20 feet by then – it is a red herring to quibble about whether sea level rise is accelerating a fraction of a millimeter per year. If the rate of increase doubled to 16 inches per century, which it shows no sign of doing, Pacific islands will cope very well as they have with over 400 feet of increase over the past 12,000 years since the end of the Ice Age.
Rather than producing a laundry list of factors possibly acting in some direction and magnitude or other, it is more to the point to observe and record what is instead of what may be.
The time differences have nothing to do with the N-S spreads. Germany is about half the planet east or west of NZ, take your pick.
Bill Yarber expressed doubts as to whether there has been glaciation in NZ during the last 2 million yrs or so. Even skeptics need to think before posting comments. Today the South Island of NZ contains hundreds of glaciers. The longest one is the Tasman Glacier (about 15 km or so). Areas not all that far from cloudy bay were glaciated about 20 thousand years ago during the last ice age. This includes most of Nelson Lakes National Park, which contained glaciers 15 to 20 km long. This is my MSc (Geology) thesis field area. My estimate of ice volume in the South Island at the last glacial maximum is 20,000 to 30,000 cubic kilometres. Given the elapsed time and the distance (50 km or more to big ice deposits) it is not cear whether there are residual isostatic effects at Cloudy Bay
I feel I can speak to glaciation in the South Island (to which cloudy bay is attached) with a degree of authority, having just completed a PhD incorporating glacial geomorphology and the dating of fluvioglacial deposits in North Westland (middle of the South Island). The work also incorporated dating of a flight of raised marine terraces (up to 180 m above MSL) dating back more than 100,000 years.
I would agree with Bill Y that conclusions relating to sea level change at Cloudy Bay are probably premature. Even if sea level has risen by (say) 150 mm, this is likely not sufficient to change the morphology of the Cloudy Bay coastline appreciably. It should be noted that the coastal bar at Cloudy Bay recieves an abundant supply of coarse sediment from the Wairau River. So the bar is capable of an element of regeneration.
It is also worth noting that the Cloudy Bay area is tectonically active. There was a shallow earthquake of magnitude greater than 7.0 on the Wairau (Alpine) Fault during the mid to late 1800’s. This produced a significant surface rupture near to Cloudy Bay. Clearly Cloudy Bay is inside the active Plate Boundary Zone. The area is being twisted and warped and this has been detected by precise surveying (old networks) and GPS surveys. I am not certain what this means for Cloudy Bay. Geomorpholgical evidence suggests that the adjacent Marlborough Sounds area is sinking (drowned River Valleys) so it is possible that there is little uplift at the Cloudy Bay shoreline.
Any conclusion relating to the presence or absence of sea level rise/fall at Cloudy Bay will probably need a more detailed analysis than can be accomodated in a typical blog article.
indrdev200 says:
April 26, 2012 at 9:36 pm
I was wondering where would water go from decreasing ground water level and melted ice from mountains and poles, if it is not sea, then where? May be sea water level rise is only for countries near equator like Maldives, Bangladesh etc. visit: devbahadurdongol.blogspot.com scientific analysis and answer.
Realistically, sea level rise is only for countries offering substantial discounts and freebies to visiting UN Climate delegations…