Tag: Pine Island Glacier

The PIG is flying

PIGmap.gif The Pine Island Glacier in West Antarctica is thinning four times faster than 10 years ago, a new study(*) of satellite measurements shows. Since 1994, the central portion of the glacier has thinned by as much as 90 metres, and the ice surface is currently lowering by 16 metres a year. At this rate of thinning, the glacier could disappear in 100 years, instead of the 600 years earlier estimates had suggested. The BBC report includes an excellent video, and focuses on the implications for sea level rise:

One of the authors, Professor Andrew Shepherd of Leeds University, said that the melting from the centre of the glacier would add about 3cm to global sea level.
“But the ice trapped behind it is about 20-30cm of sea level rise and as soon as we destabilise or remove the middle of the glacier we don’t know really know what’s going to happen to the ice behind it,” he told BBC News. “This is unprecedented in this area of Antarctica. We’ve known that it’s been out of balance for some time, but nothing in the natural world is lost at an accelerating exponential rate like this glacier.”

Unlike Greenland, where surface melting adds to losses caused by warming oceans, in West Antarctica it’s thought that warm ocean currents (specifically the Upper Circumpolar Deep Water, which is 3ºC warmer than surface water in the region) are being channelled in under the PIG ice shelf, helped by the large trough the glacier carved in the sea floor during previous glacial maxima. Given concerns about the stability of the West Antarctic ice sheet as the world warms and sea level rises, the words “exponential rate” sound particularly ominous…


(*) Wingham, D.J., D.W. Wallis, and A. Shepherd (2009), Spatial and temporal evolution of Pine Island Glacier thinning, 1995-2006, Geophys. Res. Lett., doi:10.1029/2009GL039126, in press.

This is hardcore

WarmWAIS.jpg The last time that atmospheric CO2 levels were as high as today, the West Antarctic Ice Sheet (WAIS) regularly retreated or collapsed, causing sea level rises of up to 7 metres according to the first analysis of the first ANDRILL core, published in Nature today. The ANDRILL (Antarctic Geological Drilling) programme, a joint effort by scientists from New Zealand, Italy, the USA and Germany, drilled a 1,280 metre core from the seabed under the Ross Ice Shelf. It’s the longest and most complete drill core recovered from Antarctica, and was made possible by drilling technology developed by a team at the Antarctic Research Centre at Victoria University of Wellington led by Alex Pyne.

Andrill.jpg

The two Nature papers [1. Obliquity-paced Pliocene West Antarctic ice sheet oscillations, Naish et al, Nature, 19 March 2009 doi:10.1038/nature07867, and Modelling West Antarctic ice sheet growth and collapse through the past five million years, Pollard and DeConto, doi:10.1038/nature07809] focus on the “warm Pliocene” between two and five million years ago when CO2 levels were around 400 ppm. This is considered a good analogue for where our climate is headed, and the consequence, according to Professor Tim Naish of VUW, joint science head of ANDRILL, is that if we reach 550 ppm CO2 and a resulting 3ºC increase in global temperature, then large parts of the WAIS could melt on timescales of the order of centuries, and be completely gone within a thousand years.

The ANDRILL core documents 38 advances and retreats of the ice sheet, and suggests that during the warm Pliocene the key driver could have been the “obliquity” cycle in the earth’s orbit around the sun — a 40,000 year tilt in the Earth’s axis towards and away from the sun that affects the length of summers at the poles. New modelling of the ice sheet[2. Pollard & DeConto] confirms the link with the obliquity cycle, and suggests that the primary mechanism is melting of the base of the ice sheet by warm oceanic waters — a process that has already started.

In other WAIS news, a British team reports on the success of their robot submarine, Autosub, which made voyages of up to 110km under the Pine Island Glacier ice shelf, recording temperature and salinity, and providing valuable data about melting at the glacier grounding line.

More coverage: Nature commentary by Phillipe Huybrechts, Science Daily, the Telegraph, AP and Reuters.

[Pulp]

Five feet high and rising!

Sea.jpg Yesterday, while dissembling, I had what I might loosely describe as a “bugger” moment. Yale’s Enviroment360 web site (which I plugged on its introduction last June) currently features an interview with Robert Bindschadler, a NASA ice expert who is working on the Pine Island and Thwaites glaciers in West Antarctica. The “bugger” moment?

e360: And in the theoretical case that Pine Island and Thwaites glaciers completely dump into the ocean – obviously it’s not going to happen in the near-future – what kind of sea level rise would they contribute to?

Bindschadler: That portion of West Antarctica, that third that flows northward primarily through those two glaciers, has the potential to raise sea level 1½ meters. That’s sort of an upper bound, a worst case. But the time scale is what really matters. Some say that we won’t see these ice shelves disappear in our lifetime – I’m not so sure. I think we might well.

e360: Are you kidding?

Bindschadler: No, no at all.

Bindschadler looks to be about my age. He reports that the ice shelf is melting from the underneath at a rate of about 50 metres per year at the grounding line. And then, a little later, just to make me spill my tea on the keyboard:

e360: I know that the IPCC was saying maybe 1 ½ feet or a half-meter of sea level rise in the 21st century. Is it your opinion that we could be looking at significantly larger sea level rise?

Bindschadler: Yeah, I think there’s sort of an unspoken consensus in my community that if you want to look at the very largest number in the IPCC report, they said 58 centimeters, so almost two feet by the end of the century. That’s way low, and it’s going to be well over a meter. We may see a meter by the middle of the century.

e360: Oh my gosh.

Bindschadler: And if this behavior that we’re seeing in Pine Island, and even Greenland continues – and we don’t see any reason why it wouldn’t continue – well, over a meter by the end of the century, I think is almost certain.

How notably prim the interviewer is. I think I might have managed something a little more Anglo Saxon. A “meter by the middle of the century” is a very long way above most people’s worst case (though not, perhaps, Hansen’s), but it makes our vulnerability to sea level rise much more of a near-term danger than a comfortable reading of AR4 might suggest. It’s a fascinating article — goes into more detail about the WA ice sheet and PIG (yes, that’s what they call it) than anything else I’ve seen in the last few years. Recommended, but not if you have beachfront property.

Meanwhile, a workshop being held at VUW in Wellington is looking at Andrill results, and finding that the WA ice sheet shows signs of repeated meltbacks over the last five million years [Stuff]:

Professor Tim Naish, director of Victoria University’s Antarctic Research Centre […] is co-science leader of the $30 million Andrill project on the ice, with Professor Ross Powell from Northern Illinois University in the United States.

“Antarctica’s ice sheets have grown and collapsed at least 40 times over the past five million years,” Prof Naish said.

“The story we are telling is around the history and behaviour of the ice sheet … as an analogue for the future,” he said.

Not good news, it seems. Expect a rush of papers covering Andrill work over the next few months.

[Johnny Cash]

Tuesday linkfest

Labour weekend means just that, chez Hot Topic. Catching up with farm work, planting the vege garden, getting a sore back – all in a weekend’s work. But climate change waits for no man, so here’s a compendium of stuff that caught my attention over the last few days.

  • Contact Energy has announced plans for a huge – 218 turbine, 650MW – wind farm called Hauauru ma raki, to be built on a remote site south of Port Waikato. NZ turbine builder Windflow Technology has announced plans for new models designed to work in India and China, and Meridian has sent wind experts to Scott Base in Antarctica to advise on building wind turbines to reduce fossil fuel requirements. According to Stuff, they think it could be easier than building in Wellington.
  • Still more on the Arctic summer: the NSIDC updates its coverage with some excellent animations, while Cryosphere Today adds an archive of maps of atmospheric conditions over the summer, and introduces a web app that allows iPhone users to monitor sea ice conditions. Another reason why I want one. Technology Review visits Greenland to meet the teams measuring the melt, and down south, satellites spot a huge berg breaking off the Pine Island Glacier.
  • On the roof of the world, the Nepali Times reports Kiwi guides describing how the disappearance of ice on the planet’s biggest mountains is changing the climbs.
  • Two more good articles from TR: Fixing the Power Grid describes how big batteries (capable of supplying 1MW+ for hours at a time) can provide back up for grid problems, and Tiny Solar Cells looks at nanowire solar cells made by a team at Harvard.
  • Carbon emissions from shipping could be as much as twice those from aviation, according to a report from Intertanko. Strong growth in trade has driven emissions to 1.2 billion tonnes oer annum. Meanwhile, the Herald reports on aviation’s attempts to be seen to be more climate friendly – and Richard Branson’s efforts to beat Air New Zealand to the first use of biofuels in jets.
  • CO2 absorption in the Atlantic has nosedived, adding to concerns that the ocean carbon sink may be reducing – leaving more of our emissions in the atmosphere [University of East Anglia].
  • Coral reef specialists have issued a call to action on the impact of climate change: “We call on all societies and governments to immediately and substantially reduce greenhouse gas emissions. Without targeted reductions, the ongoing damage to coral reefs from global warming will soon be irreversible.”
  • The Daily Telegraph [UK] is in the process of becoming enthusiastically green. Latest evidence is a nifty widget – the Telegraph Earth Pulse – which monitors climate and general environment news.
  • A dairy farm can produce as much sewage as a small town (see North & South current issue), but worms can turn it all into mellow compost according to US researchers.
  • It looks like a “three-wheeled technicolour shoehorn”, but the No More Gas will do 75 mph and has a range of 30 miles. OK for getting around town, but I’d still prefer a Tesla Roadster…
  • The financial word is getting the climate message: Deutsche Bank thinks that efforts to combat climate change will drive an investment “megatrend”, Morgan Stanley estimates that global sales of wind, solar and geothermal power and biofuels could be US$1 trillion a year by 2030, and HSBC is launching a climate change investment fund for investors who want to track companies active in the field.
  • HT tends to steer clear of dsicussing peak oil, but the Guardian [UK] covers a new report that claims that we passed peak oil last year, and that global oil production will be halved by 2030. Adds a certain piquancy to energy strategy…