Totten hots up, ice shelves melting: it’s grim down south

AntarcticaCryosat2Much news in recent weeks from Antarctica, and none of it good. An Argentinian base on the tip of the Antarctic Peninsula recently reported a new high temperature record for the continent — 17.5ºC. A team of scientists has discovered that East Antarctica’s Totten Glacier — which drains a catchment that contains enough ice to raise sea levels by 3.5 metres — is vulnerable to melting caused by warm ocean water lapping underneath the ice and reaching inland1. Another group has stitched together satellite data on ice shelf thickness gathered from 1994 to 2012 and found that the ice shelves — mostly stable at the beginning of the period, are now losing mass fast2. From the abstract:

Overall, average ice-shelf volume change accelerated from negligible loss at 25 ± 64 km3 per year for 1994-2003 to rapid loss of 310 ± 74 km3 per year for 2003-2012. West Antarctic losses increased by 70% in the last decade, and earlier volume gain by East Antarctic ice shelves ceased. In the Amundsen and Bellingshausen regions, some ice shelves have lost up to 18% of their thickness in less than two decades.

The Amundsen region is home to the Pine Island Glacier, notorious for its current rapid loss of mass, and probably already past the point of no return for long term total melt. The map below shows the big picture: large red dots are ice shelves losing mass. Blue dots are shelves gaining mass.


Ice shelves are important features of the Antarctic cryosphere. They buttress the ice piled up on the land, slowing down the flow of ice into the ocean. As the shelves lose mass, the flow of ice from the centre of the continent can speed up, adding to sea level rise. There’s a very good overview of the process — and the findings of the Paulo et al paper — in this excellent Carbon Brief analysis.

The study of the Totten Glacier — one of the fastest thinning glaciers in East Antarctica — is the first to look at the detail of the sea floor and ice thickness in the area. The study finds that there are “tunnels” under the ice leading into a deep trough inland that cold convey warm water inland — the same process that has destabilised the Pine Island Glacier in West Antarctica. As the authors suggest, rather drily, “coastal processes in this area could have global consequences”.

These signs of rapid changes around the coasts of Antarctica, together with hints that large parts of the huge East Antarctic ice sheet are at risk of following West Antarctica into the sea, suggest that even if sea levels only rise by a metre by the end of this century as the IPCC projected last year, the longer term picture will be a great deal wetter than that. After all, there is the equivalent of 60 metres of sea level rise locked up in East Antarctica.

For a very good overview of the state of our understanding of what’s going on in Antarctica, I recommend a listen to VUW’s Professor Tim Naish being interviewed by Radio New Zealand National’s Kim Hill last Saturday. Naish even covers what’s happening to the sea ice down there, but a longer term study of the sea ice is getting under way, led by another VUW prof — Jim Renwick.

  1. Greenbaum JS et al, (2015), Ocean access to a cavity beneath Totten Glacier in East Antarctica, Nature Geoscience, doi:10.1038/ngeo2388 []
  2. Paolo, F.S. et al, (2015), Volume loss from Antarctic ice shelves is accelerating, Science, doi/10.1126/science.aaa0940 []

Stocker in Wellington: RSNZ to stream AR5 science workshop

Swiss climate scientist Thomas Stocker, joint chairman of the IPCC’s Working Group One, is in New Zealand for a few days, and the NZ Climate Change Centre and the Royal Society of NZ have taken the opportunity to put together a stakeholder workshop to allow Stocker and NZ lead authors to present the key findings of the recently published AR5 WG1 report. The workshop is being held tomorrow, Friday 11th, from 9am to 1pm at the RSNZ in Wellington, and is open to the public (spaces limited, register here). For the geographically challenged, the event will be web-cast live.

The workshop will open with an introduction by Richard Bedford, a council member of the RSNZ, and an overview of the IPCC process by WG1 vice-chair David Wratt. Stocker will present the key Working Group I report findings from about 9-10am. NZ’s coterie of lead authors — Dave Frame, Tim Naish, and Jim Renwick — will provide snapshots of the parts of the report they were involved with. From midday on, the Science Media Centre’s Peter Griffin will chair a “stakeholder panel” including Rod Oram, Federated Farmers vice-chair William Rolleston and Frances Sullivan from Local Government NZ to discuss how the report has been received and what it means for New Zealand.

Stocker is also being interviewed by Radio NZ National’s science correspondent Veronika Meduna, and that should be broadcast in her show next week.

Kiwiblog kobblers

New Zealand’s leading right wing blogger, National Party spinmeister and opinion poll guru David Farrar, this morning allowed himself the luxury of a rant about the New Zealand Herald‘s coverage of a new paper on sea level during the late Pliocene. In a post teasingly titled “Alarmist bullshit“, he manages to demonstrate his rudimentary grasp of the facts, misunderstands the real story behind the new research, and ends up shooting himself in the foot. Here’s David in full flow:

Anyone who thinks public policy today should be based on a forecast of what the climate might be in 5,000 years is nuts. Look at how the world has changed in just 100 years let alone hundreds or thousands. Hell in 1,000 years we may be living on Mars.

The Herald should be ashamed for saying that the projected increase could “dramatically transform” our coastal boundaries. A change over 1,000 years+ is not dramatic. It’s like saying the separation of Gondwana was dramatic.

20 metres is a lot of sea level rise. Here’s what 20 metres would mean for my nearest city, poor old quake-plagued Christchurch, courtesy of the Firetree sea level rise calculator. The central business district is under water, the new shoreline well to the west. At a rough guess, I’d say 80% of the city is flooded, and Banks Peninsula is an island once more.

I think that can be reasonably described as a dramatic transformation of the South Island coastline, even if it does take 1,000 years to happen. DPF might like to note that coping with two metres per century sea level rise is nobody’s picnic. But his misunderstanding runs deeper…

Continue reading “Kiwiblog kobblers”

We call upon the author…

I must have been asleep last week when the IPCC announced its selection of authors for the Fifth Assessment Report (AR5), due in 2013/14. As usual, NZ scientists are making a significant contribution:

  • Tim Naish is a lead author for Working Group 1 (The Physical Science Basis) chapter 5, Information from Paleoclimate Archives.
  • Jim Renwick is a lead author for WG1 Chapter 14, Climate Phenomena and their Relevance for Future Regional Climate Change.
  • David Wratt is a review editor for Chapter 14 (as is Kevin Trenberth)
  • Phil Boyd (NIWA) is a lead author for WG2 (Impacts, Adaptation and Vulnerability), Chapter 6, Ocean Systems.
  • Alistair Woodward is one of the two Coordinating Lead Authors for WG2, Chapter 11, Human Health.
  • Andy Reisinger is a Coordinating Lead Author for Chapter 25, Australasia, Paul Newton (AgResearch) and Andrew Tait (NIWA) are lead authors, and Blair Fitzharris is a Review Editor.
  • Ralph Sims is a Coordinating Lead Author for Working Group 3 (Mitigation of Climate Change), Chapter 8, on Transport.
  • Harry Clark is a lead author for WG3, Chapter 11, Agriculture, Forestry and Other Land Uses (AFOLU).
  • Complete author lists: WG1, WG2, WG3.

Congratulations to all. Now the hard work starts…

And a plug: Jim Renwick is giving a talk on climate change at the Hurunui Library (yes, the one in the heat pump ads) in Amberley on Monday, July 5th at 7-30pm. All welcome. I’ll be heckling from the cheap seats…

[Thanks to Frogblog]

[Nick Cave]