Sea level rise, earthquakes, and flying PIGs

ChristchurchT T2013

The first major study to look at the impact of sea level rise on Christchurch and Banks Peninsula following the 2010/11 earthquake sequence projects a watery future for many parts of the city and its surrounding shorelines. The image above1 shows changes in ground elevation between 2003 and 2011 in the Christchurch region. Areas in green/blue have moved upwards by half a metre – particularly noticeable to the west of the estuary – and areas in red and yellow down, in many places along the Avon and subsidiary streams by a metre or more.

The report, Effects of Sea Level Rise on Christchurch City (pdf), by consultants Tonkin & Taylor was released last week and suggests that as a minimum planners should take into account a 1m rise in sea level over the next 100 years. Combined with the elevations changes caused by the earthquakes, this would mean significant shoreline retreats, increased flooding in many areas and the loss of hundreds of hectares of land to the sea. It’s well worth digging into the report to get the full picture, and it will make uncomfortable reading for many in the city.

Tonkin & Taylor prepared their study before the IPCC’s AR5 Working Group One report was released, and so based their SLR numbers on a literature search and the Royal Society of NZ’s 2010 paper. They suggest a “plausible upper range” of 2m over the next 100 years, with the behaviour of the West Antarctic and Greenland ice sheets in a warming world “probably the largest uncertainty in sea level rise projections”.

And now the bad news…

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  1. Fig 3-4, p15 in the report. []

Waking the Giant

It’s only if we fail to grasp the enormity of the threatened impacts of climate change on the global environment that we can scoff at the notion that even volcanic eruptions and earthquakes may be triggered as a consequence of our continuing to burn fossil fuels. Not that it’s an easy consequence to appreciate, but vulcanologist Bill McGuire’s latest book Waking the Giant: How a Changing Climate Triggers Earthquakes, Tsunamis, and Volcanoes explains it with patient clarity. His book is a fascinating read in its discussion of the past and an alarming one in its analysis of future likelihoods.

The book begins with a straightforward and sobering view of the catastrophe which looms if we continue to fail to act on emissions. The signs of climate change are everywhere apparent and the prospects for the future are bleak. McGuire acknowledges the difficulties of precise prediction of what that future might hold 50 or 100 years from now and suggests that looking back on the past may be the best way to gauge what lies ahead. The main focus of his book is on ways in which Earth’s crust has responded to dramatically changing climates, but he also considers, further back, times of high levels of atmospheric carbon dioxide as possible pointers to what today’s increased greenhouse gases might forebode.

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Rebuilding on a rising tide

It’s been a shaky week in Christchurch and Canterbury. Another M6.3 shock hit the city on Monday afternoon — renewing the misery for many in the city’s eastern and seaside suburbs, but thankfully not adding to the death toll. Attention has now turned — with some force — to the question of which suburbs should be rebuilt, and an excellent feature by David Williams in last Saturday’s Press on sea level rise and its implications for the rebuilding of Christchurch should cause some pause for thought. Williams interviewed James Hansen during his visit to the city last month (shortly before I did, in fact), and uses Hansen’s views on sea level rise to kick off his discussion:

Hansen says a multi-metre sea level rise is possible this century if greenhouse gas emissions, caused by things such as coal-fired power plants, vehicle engines and agriculture, are not reduced.

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Ken Ring: he’s wrong about everything

This weekend a few of the struggling residents of earthquake-hit Christchurch have moved out of the city hoping to escape another dangerous quake, a shock foretold by Ken Ring, a New Zealand astrologer who makes a living producing “long range weather forecasts” for NZ, Australia and Ireland based on the movements of the moon. Ring claims that his moon methods predicted last September’s magnitude 7.1 Canterbury earthquake, and the M6.3 aftershock on Feb 22 that killed at least 182 people and devastated much of the central city and eastern suburbs.

But Ring’s methods don’t work. He can’t predict the weather, he can’t predict earthquakes, he is demonstrably ignorant of basic atmospheric and earth science – and yet apparently sane and rational people take him seriously. Are people simply gullible, especially those traumatised by two major quakes, the loss of lives and the incessant aftershocks? Or have the NZ and Australian media, all too happy to give Ring’s weather predictions, fishing forecasts and views on climate change air time and column inches, created an uber crank, a monster beyond their control who is now responsible for scaring thousands while callously building his book sales and brand?

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Shake your berg thing


This astonishing view of the Tasman Glacier from space, captured by NASA’s Terra satellite on March 2nd, shows the bergs in the glacial lake — the remnants of the 30 million tons of ice that broke off during the Christchurch earthquake on Feb 22nd. It’s a false colour image — red means vegetation, and the grey-browns are bare rock (and the rock debris covering the glacier itself). There’s more information at the NASA Earth Observatory. The Tasman’s near neighbour the Murchison Glacier has recently featured at Mauri Pelto’s From A Glacier’s Perspective. Both are retreating strongly.

[Update 9/3: The Earth Observatory’s latest image of the day is a stunning satellite picture of the Christchurch region, with an overlay showing shaking intensities.]

[The Chipmunks]