This article by Jim Salinger, University of Auckland; Blair Fitzharris, University of Otago, and Trevor Chinn, National Institute of Water and Atmospheric Research, was first published at The Conversation. The photo at left shows the calving face of the Tasman Glacier in Dec 2013.
A third of the permanent snow and ice of New Zealand’s Southern Alps has now disappeared, according to our new research based on National Institute of Water and Atmospheric Research aerial surveys. Since 1977, the Southern Alps’ ice volume has shrunk by 18.4 km3 or 34%, and those ice losses have been accelerating rapidly in the past 15 years.
The story of the Southern Alps’s disappearing ice has been very dramatic – and when lined up with rapid glacier retreats in many parts of the world, raises serious questions about future sea level rise and coastal climate impacts.
The Southern Alps’ total ice volume (solid line) and annual gains or losses (bars) from 1976 to 2014 in km3 of water equivalent, as calculated from the end-of-summer-snowline monitoring programme. Continue reading “New Zealand’s Southern Alps have lost a third of their ice”
In a rather reflective last post for the year at The Daily Blog today — Tomorrow is being written in New Zealand’s mountains — I ruminate on the impact warming is having on New Zealand’s largest glacier. All pictures were taken last Sunday, from a little yellow boat bobbing on the growing terminal lake. A visit to Aoraki Mt Cook to see the glaciers is something everyone should do. It’s climate change writ large, and happening on our doorstep.
Yesterday morning I climbed up the short track on the Tasman Glacier terminal moraine to the lookout, and was amazed by how much the glacier’s calving front had retreated compared with my last visit to the same spot, back in February 2008 (below – click on either picture to see a bigger version). Across the full face of the glacier there’s now a sheer cliff, where large bergs calve into the growing lake — the most recent, back in February, being rated as the largest ever.
Both pictures were taken from the same spot, but with different cameras and lenses, so a direct comparison isn’t possible, but it should be clear that the glacier front has retreated up the valley significantly over the five years. Given the dramatic scale of the landscape (those are 3,000 metre peaks up valley) it’s hard to estimate distances by eye, but recent rates of retreat have been estimated to be 400 to 800 metres per year. Glaciologist Mauri Pelto has a detailed analysis of the glacier’s recent history at his blog From A Glacier’s Perspective here.
Similar rapid rates of retreat are being seen on the nearby Mueller and Hooker glaciers, both of which have large and growing terminal lakes.
One message got home to me: rapid climate change isn’t something that happens to other people, or to other parts of the world. To see New Zealand’s largest glacier so visibly diminished in the space of a very few years brought home the reality and scale of the problem we face in a very direct manner. Sometimes we need to step away from our computers and see what’s happening with our own eyes…
Richard Alley’s book Earth: The Operators’ Manual, which I reviewed recently, was written as a companion to a PBS documentary of the same name. The documentary has recently screened in the US and is now available for viewing here. The broad themes are the same as those of the book. They’re not complicated: taking our energy from fossil fuels has caused climate change, but there are clean energy alternatives more than adequate to human needs and the sooner we move to deploy them the better.
Funded by the National Science Foundation, the documentary takes Alley to many places and countries, including New Zealand. He dwells on the human need for energy, the kind of energy demands a growing population will make, and the ultimate inability of fossil fuels, a limited resource, to meet that demand even if we could carry on burning them with impunity. But we can’t, and Alley explains why. A visit to the Franz Josef and Tasman glaciers, with some great photography, is part of what he uses to explain the real world impact of changing levels of CO2. A fascinating visit to the national ice core laboratory in Denver, Colorado demonstrates that today atmospheric CO2 is at a level not seen in cores that go back as far as 400,000 years – far above them, in fact. Then it’s back to New Zealand as, against the background of Rotorua thermal activity, Alley explains the isotopic evidence that backs up the relative volume measurements to confirm that the increased CO2 is the result of burning fossil fuels, dwarfing natural volcanic processes.
Continue reading “Alley’s documentary: upbeat and optimistic”
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.]