Posts Tagged Climate science

Totten hots up, ice shelves melting: it’s grim down south Gareth Renowden Mar 30

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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

Leyland and Carter: the rebuttal that isn’t and the hypocrisy that is Gareth Renowden Mar 25

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CarterFlatEarth.jpgSciblogs editor Peter Griffin recently gave climate denial activists Bryan Leyland and Bob Carter a “right of reply” to my post pointing out the errors and inconsistencies in a Dominion Post op-ed penned by the pair. Griffin took this action because of vociferous complaints from Leyland, who took offence at my discussion of his expertise (non-existent) and history of campaigning against action on climate. The result is billed as a “rebuttal”, but it isn’t, as I shall demonstrate.

The Sciblogs “rebuttal” is a mishmash of a so-called “fully referenced” version (pdf) of the op-ed that Leyland says was supplied to the Dominion Post, but he and Carter also prepared a very long-winded “response” (pdf) to the debunking of their piece by David Wratt, Andy Reisinger and Jim Renwick in the DP. The latter is a real eye-opener…

Life is too short to do another point-by-point demolition1, so I’ll select a few key issues that demonstrate that although they claim to be discussing science in a scientific manner, what they are actually doing is having the equivalent of an argument in a pub — prepared to say anything if they think it will help them “win”.


It’s instructive to look at the references Leyland and Carter supplied to support their original op-ed, and use in their Sciblogs article. They include a blog post by Roy Spencer and others at µWatts and The Hockey Schtick, graphs that either don’t prove what they claim, or are scaled to make it difficult to see what’s happening, reports at right-wing web sites (Breitbart, International Business Times), and Congressional evidence given by climate denial activists. Precious little real science on display, in other words.

Worse, where they do cite real science they get the reference wrong. To support their claim that climate models have failed to project the slowdown in surface temperature trends, their Sciblogs piece cites “IPCC AR5 Chapter 9, Box 9.3.2″ supporting this sentence:

The IPCC’s 5AR states that 111 out of 114 their climate model runs failed to reproduce the actual temperature record.

No mention of which Working Group report they’re citing, but the phrase “111 out of 114″ appears in Chapter 9 (pdf) of WG1. Unfortunately, it is not in Box 9.3.2 in Chapter 9. There is no Box 9.3.2. There is a Box 9.2, and it does contain a sentence they paraphrase incorrectly:

However, an analysis of the full suite of CMIP5 historical simulations (augmented for the period 2006–2012 by RCP4.5 simulations, Section 9.3.2) reveals that 111 out of 114 realizations show a GMST trend over 1998–2012 that is higher than the entire HadCRUT4 trend ensemble (Box 9.2 Figure 1a; CMIP5 ensemble mean trend is 0.21oC per decade).

A carefully nuanced statement in a long discussion of what the IPCC refers to as “the hiatus” — and certainly not a statement about “failing to reproduce the temperature record”. Worse, if you bother to read the whole thing, you find that Leyland and Carter have been cherry-picking stuff that suits their argument, while ignoring the points that don’t. Also from Box 9.2:

There is hence very high confidence that the CMIP5 models show long-term GMST trends consistent with observations, despite the disagreement over the most recent 15-year period.

Enough of that. Time to dig a little deeper. Leyland and Carter’s “Discussion of remarks made by Wratt, Reisinger & Renwick (WRR) in the Dominion-Post on global warming” (pdf) is worth perusing, because it is a perfect illustration of their approach to the evidence. Recall for a moment that a central claim of their DP op-ed was that “the world has not experienced any significant warming over the last 18 years”. Now read this paragraph from their “discussion”:

Though the statement [that the earth is warmer than 100 years ago] is true, 100 years is too short a period of time to assess true climatic change, consisting as it does of just three climate data points.

Leyland and Carter insist that 18 years is enough to know that warming has stopped, but 100 years isn’t long enough to prove there has been real warming. The sheer intellectual hypocrisy evident here is breathtaking — and very revealing.

This isn’t a scientific debate. This isn’t how people with real expertise in climate science approach the subject. This is posturing trying to pose as academic debate. Serious scientists wouldn’t touch that style of argument with a barge pole.

Leyland and Carter are acting like defence lawyers desperate to convince a jury that their client — man-made emissions of carbon dioxide — is not guilty. They want to create an illusion of doubt to delay action, and their audience is not the climate scientists of the world, it’s the readers of the Dominion Post. Doubt is Leyland and Carter’s product, a technique honed and refined by tobacco defenders decades ago.

One final point. In my original post, I pointed out that Leyland & Carter’s stated confidence that “man-made carbon dioxide does not cause dangerous global warming and that the predictions of computer models of the climate are worthless” was not supported by 97% of climate scientists — the people with real expertise in the field.

Their response both misquotes me and attempts to hide the pea under the thimble:

“In contradiction, Mr. Renowden asserts that “the vast majority – 97% or thereabouts…would beg to differ with our statement”. This is irrelevant. Science is not concerned with consensus. It is about evidence and hypothesis testing.

What that 97% represents is the balance of evidence. The overwhelming majority of people working in the field, however you choose to measure it, think we have a big problem with atmospheric carbon. Those that don’t are a tiny minority — a crank fringe supported by fossil fuel interests — making their arguments in opinion columns instead of the peer-reviewed literature. The rest of us live in the real world. We’ll ignore their attempts to blow smoke in the face of public opinion, and get on with trying to find a solution.

  1. Leyland & Carter may be retired, with nothing better to do than promote their viewpoints, but I have grapes and truffles to nurture through to harvest, and a book to write

[This post was edited 12.31pm on 27/03/15 - Ed]

DomPost denier debacle: science has the last word Gareth Renowden Mar 10

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The Dominion Post, which blotted its editorial copybook last week by publishing a factually incorrect and highly misleading opinion piece by climate denialists, has today published a heavyweight reply by three of NZ’s top climate scientists — David Wratt, Andy Reisinger and Jim Renwick1. Headed “Human role in climate change is clear”, the article is clear about climate reality:

Human influence on the climate system is clear and growing, and impacts are evident on all continents. If left unchecked, climate change will increase the likelihood of severe, pervasive and irreversible impacts for people and ecosystems.

We do have options to reduce risks by reducing greenhouse gas emissions and adapting to some climate change, but time is running short if we want to limit changes to manageable levels. Ignoring or misconstruing the overwhelming evidence is not a responsible risk management strategy.

It’s not clear whether the DomPost plans any further response to the rubbish they printed from Bryan Leyland and Bob Carter, but the editorial team at the newspaper would do well to reflect on the approach to the subject adopted by Guardian editor Alan Rusbridger, introducing an important new series of features in that paper:

For the purposes of our coming coverage, we will assume that the scientific consensus about man-made climate change and its likely effects is overwhelming. We will leave the skeptics and deniers to waste their time challenging the science. The mainstream argument has moved on to the politics and economics.

Precisely. Rusbridger — who is retiring after 20 years as editor — wants his newspaper to do justice…

…to this huge, overshadowing, overwhelming issue of how climate change will probably, within the lifetime of our children, cause untold havoc and stress to our species.
So, in the time left to me as editor, I thought I would try to harness the Guardian’s best resources to describe what is happening and what — if we do nothing — is almost certain to occur, a future that one distinguished scientist has termed as “incompatible with any reasonable characterisation of an organised, equitable and civilised global community”.

That’s what a real newspaper does: takes on the big issues. If the Dominion Post wants to be more than a Noddy book newspaper publishing rubbish from the intellectual heirs to Big Ears, it’s high time it took a sensible approach to the climate debate, and followed Rusbridger’s lead.

Meanwhile, Bryan Leyland has posted what his web site describes as a “referenced version” of the text of the article that appeared last week. It’s available here (pdf), and is chiefly remarkable for the quality of what passes as references in crank circles. There are links to blog posts at µWatts and other climate crank sites, conspiracy-riddled pieces from extreme-right “news” services, and barely legible graphs. Where he does link to real science (on sea level rise), the underlying data doesn’t support the contentions in the article. Par for the climate crank Carterist “science” course, in other words.

  1. David Wratt is an Emeritus Climate Scientist at NIWA, an Adjunct Professor in the NZ Climate Change Research Institute at Victoria University, and a Vice Chair of Working Group 1 of the IPCC. Andy Reisinger is Deputy Director (International) of the New Zealand Agricultural Greenhouse Gas Research Centre and served as coordinating lead author in the most recent IPCC report. James Renwick is a Professor of Physical Geography at Victoria University of Wellington and served as a Lead Author on the last two IPCC Reports.

25 ways the DomPost failed its readers by publishing Leyland and Carter’s climate crap Gareth Renowden Mar 06

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The Dominion Post, the newspaper of record for New Zealand’s capital city, today gave great prominence to an opinion piece by high profile climate denialists Bob Carter and Bryan Leyland titled Hypothetical global warming: scepticism needed1. It’s a “Gish Gallop” of untruths, half-truths and misrepresentations — a piece so riddled with deliberate errors and gross misrepresentations that it beggars belief that any quality newspaper would give it space.

I will deal with the factual errors in a moment, but the DomPost‘s lack of editorial judgement extends well beyond any failure to fact check the article. Carter and Leyland’s expertise on the issue is misrepresented. The newspaper’s readers are not given a true picture of their “standing”. They are in fact paid/sponsored propagandists, way out on the crank fringes. Here’s how Carter is credited.

Professor Bob Carter is an honorary fellow of the Royal Society of NZ. His expertise is in geology and paleoclimatology — deducing past climates from geological records. He has written several books on climate change.

All of that is true2, but it is far from a full picture. In fact, Carter has been a propagandist against action on climate change since the 1990s, with a history of paid work with and for far-right wing organisations in Australia and the USA – including being paid by the notorious Heartland Institute in the US to produce shoddy pseudo-academic publications. In the right wing Australian journal Quadrant, where links to right wing organisations obviously play well, Carter’s credit runs like this:

Bob Carter is an Emeritus Fellow of the Institute of Public Affairs (IPA) and Chief Science Advisor to the International Climate Science Coalition (ICSC).

The IPA campaigns against climate action, and Carter recently starred in its Climate: Change the facts tour around Australia promoting a new propaganda pamphlet. As an adviser to the ICSC — a group attempting to promote climate denial around the world, he works to:

“…directly educate the public about what science, engineering and economics are really concluding about climate change and the downside of misguided plans (e.g., wind turbines, “carbon sequestration”, etc.) to “solve the crisis”. This includes newspaper articles, letters to the editor, radio and TV interviews, public presentations, regular postings on our, and others’, Web sites and use of all forms of popular social media.”

In other words, Carter and Leyland managed to con the DomPost into playing along with their propaganda campaign.

The DomPost credits Leyland thus:

Bryan Leyland is an engineer specialising in renewable energy. He is an accredited reviewer for the IPCC and has contributed several articles on renewable energy technologies to overseas publications.

In fact, Leyland has a long track record of activism against action to reduce carbon emissions. He was a founder member of the NZ Climate Science Coalition and a trustee of the NZ Climate Science Education Trust — formed to bring a court action against NIWA’s handling of the national temperature record. When the case was lost, the trust was folded so that Leyland and his fellow trustees could avoid paying $90,000 of court-ordered costs.

Leyland is notorious in NZ media circles for his attempts to push climate denial. It beggars belief that the DomPost did not know about his track record, and went ahead with publishing an article under his name without prominently noting his role as an activist.

As propagandists, the product that Leyland and Carter are pushing is doubt — a tactic first used by the tobacco industry, but since refined by fossil fuel interests keen to avoid emissions cuts. Leyland and Carter “win” every time a mainstream media outlet gives their views credence by giving them prominence. Newspapers do not regularly provide platforms for cranks, but that is exactly what Leyland and Carter are, as we shall see in a moment.

24 ways to be wrong about climate

Let’s be clear about this. The errors and misdirections outlined below are not mistakes. They are not reasonable constructions that an independent commentator might make when looking at the totality of the evidence. They are arguments deliberately selected to present a distorted picture of reality.

The article gets off to a bad start with this opening sentence.

1: We are constantly told that man-made carbon dioxide has caused global warming that will bring doom and disaster in a few years.

Wrong. Man-made CO2 has certainly caused global warming (IPCC, 2014), but very few people — and certainly no scientists predict doom and disaster in the near future. All bets are off for the latter half of this century, however.

2: These predictions are largely based on the output of computer models, rather than observations of what is happening in the real world.

Wrong. Paleoclimate — supposedly one of Carter’s specialities — tells us a great deal about what may happen as CO2 rises. The models are useful for giving us an idea of what might happen in the future and what we can do to affect the outcome.

3: – the world has not experienced any significant warming over the last 18 years -

Wrong. There has been some slowdown in the upwards trend of surface temperatures — the so-called “hiatus”, but no reduction in the amount of heat accumulating in the system — mainly in the oceans.

4: – more accurate satellite records -

Wrong. Satellites estimate temperature of layers of the atmosphere by using the same radiation transfer calculations as the climate models so derided by Leyland and Carter. The satellite record is interesting and useful, but cannot stand in or substitute for real temperature measurements taken at the earth’s surface.

5: – models “failed to predict this lack of warming”.

Wrong. There has been no lack of warming. Model runs are not forecasts, but when the model runs are examined, those that most closely match what’s happened over the last 15 years (such as the state of the El Niño Southern Oscillation) track recent temperatures well3.

6: We can now be confident that man-made carbon dioxide does not cause dangerous global warming and that the predictions of computer models of the climate are worthless.

Wrong. Carter and Leyland may assert their personal confidence, but that is not shared by the vast majority — 97% or thereabouts, however it is measured — of the scientists with genuine expertise in this field. To act on their say-so would be like backing a three-legged horse in the Melbourne Cup.

7: Global sea ice area is well above the 1979-2013 average.

Wrong. Over the last 35 years global sea ice area has declined by 35,000 square kilometres per year, or about -1.5% per decade. (Source)

8: In the Arctic it is close to average…

Wrong. This week’s Arctic Sea Ice News & Analysis from the NSIDC in the US reports that last month had the third lowest February ice extent in the satellite record, and suggests that there is a possibility that this year could set a new record for lowest sea ice maximum extent.

9: In the Antarctic it is at the highest level since 1979…

Wrong. The February extent of 3.58m km2 according to the NSIDC was the fourth highest summer minimum extent on record, trailing behind 2008 (3.75m km2), 2013, and 2003.

10: Once again, there is a large disparity between the computer based predictions of ever increasing loss of sea ice and reality.

Correct, but misleading. Models have consistently underestimated sea ice decline in the Arctic.

11: …rate of sea level rise has slowed…

Wrong. According to the IPCC, the rate of sea level rise has accelerated in recent decades, and is expected to increase further as warming melts land-based ice.

12: Polar bears

Still listed as endangered, and continued loss of sea ice — their preferred hunting grounds — will increase pressure on bear numbers. See this excellent recent overview for a realistic assessment of the state of the bears.

13: Coral atolls are not disappearing beneath rising oceans.

Misdirection. Coral atolls have not yet disappeared, but conditions for human habitation on a number islands — including Tuvalu — are becoming difficult, and will become impossible later in this century if sea level rise continues as expected by the experts.

14: About 15,000 years ago sea levels were rising at 3m a century and coral atolls and the Great Barrier Reef survived.

True. But there were no human populations on Pacific Islands at the time. 3m per century rise over the next century would be catastrophic for cities and populations all round the world. The “survival” of reefs would be the least of our worries.

15: Glaciers are retreating some areas and advancing in others.

Trivially true but hugely misleading, because the number of retreating glaciers far outweighs the few advancing. The World Glacier Monitoring Service estimates non-polar land ice (glaciers and ice caps) are losing mass at an increasing rate.

16: 5,000 years ago the European Alps had less ice than now and the Canadian tree line lay further north.

Misleading. That was during the Holocene optimum, when northern hemisphere regions were receiving more summer warmth than now due to Milankovitch cycles in the earth’s orbit. It tells us nothing about what will happen when the planet “catches up” with the heating effect of current atmospheric CO2 levels.

17: Historical records show that the world was warmer during the Middle Ages Warm Period.

Wrong. This is a canard, one much beloved of climate cranks, but not supported by current science. Some parts of the world may have been as warm as today, but it was not a global phenomenon.

18: Ocean acidification … the ocean is alkaline and is at no more risk of becoming acidic …

Puerile misdirection. “Acidification” is the process of becoming more acidic, and that is what is measured to be happening as CO2 dissolves into the world’s oceans. CO2 + H2O = carbonic acid. The effect on oceanic ecosystems will be huge.

19: Increased levels of carbon dioxide have boosted plant growth worldwide … modern greenhouses burn natural gas to double the CO2 concentration and hence increase production by 40%.

True, up to a point, but also a huge misdirection. Increasing CO2 will benefit some plants, some of the time, but not all. Any benefits will be offset by increasing droughts, floods and heatwaves and rapid polewards migration and distortion of ecosystems.

20: … an IPCC study shows that the frequency of droughts has hardly changed and cyclones have declined …

Misdirection. Studies show increases in rainfall extremes, heatwaves and other weather extremes, and these will increase (as will droughts) as the climate system warms.

21: The British Meteorological Office has predicted that the current lack of warming will continue until 2018 at least.

But they’re using climate models, and those can’t be trusted! The hypocrisy burns.

22: Scientists who study natural climate cycles and the effect of the sun and sunspot cycles on the climate believe that the world has — or soon will — enter a cooling cycle.

This really is crank fringe nonsense. About as credible as backing that three legged horse for a Melbourne Cup/Aintree Grand National double.

23: Most mainstream climate scientists agree that 2 degrees C extra of warming would not be harmful

Nonsense. “Most mainstream climate scientists” understand that 2 degrees of warming will cause a great deal of damage to the climate system. 2ºC is a political target, not a scientific one.

24: The obvious conclusion is that the science is not settled.

The obvious conclusion is that Carter and Leyland are desperately trying to sell “doubt at any price”. The real climate debate is not a scientific debate, or a debate about the science, it’s about how we deal with an issue which is going to shape the lives of everyone over the next few hundred years. Carter and Leyland are selling all our futures to satisfy their inflated egos — and to please the people who sponsor, support and pay for their activities.

Nothing that I write here or that is written in the Dominion Post is likely to change the views of Carter and Leyland, because they are not wedded to science and a rational assessment of climate risk. Their loyalty is to a cause, and they will be counting their DomPost article as a major triumph. The newspaper, however, faces a very big problem. Their 25th mistake.

Giving climate cranks prominence in the paper, and to allow them to misrepresent the facts in such a cavalier manner, is a gross disservice to the DomPost‘s readers, and a huge blow to the newspaper’s reputation. If the paper is really incapable of spotting nonsense when its offered to them, then what confidence can its readers have in its judgement on other matters? What can we expect next? The paper advocating in its leader column that a homeopath should be appointed minister of health?

Readers and other interested parties may wish to consider making a complaint to the editor, and if a satisfactory response is not received, pursue the matter further with the Press Council. As a bare minimum, I believe the Dominion Post should, as a matter of urgency:

  • Apologise to its readers for publishing an opinion piece so riddled with deliberate errors and misdirection.
  • Provide readers with a more accurate understanding of the activist backgrounds of Leyland and Carter.
  • Publish and give greater prominence to a rejoinder from senior scientists with genuine expertise in climate science.
  • Introduce guidelines that provide that opinion or comment pieces that make controversial or counterfactual claims are provided by authors with significant expertise in the area under discussion, or should be subject to fact-checking by people with the necessary expertise.

The Press Council’s own guidelines state that:

Material facts on which an opinion is based should be accurate.

…and that for comment and opinion pieces “requirements for a foundation of fact pertain”.

Leyland and Carter’s propaganda piece clearly falls foul of those guidelines. It is now up to the Dominion Post to address the issue and respond appropriately. It may help them if they consider the 2012 judgement by the Australian Communication and Media Authority against talkback host Alan Jones ands station 2GB, requiring them to take fact checking seriously, or the decision by the LA Times not to publish letters asserting climate change is not real:

Saying “there’s no sign humans have caused climate change” is not stating an opinion, it’s asserting a factual inaccuracy.

And factual inaccuracies should have no place in a newspaper that aspires to be a newspaper of record.

  1. On page A7 – opposite the leader. Not currently available on the web, but a scan has been posted on Twitter — see this comment below.
  2. Except perhaps for the professorship. Carter has no current academic affiliation that I know of, so I wonder why the DomPost is granting him that status? Surely he wouldn’t have misrepresented himself to the paper?
  3. See, for example, Huber and Knutti, Natural variability, radiative forcing and climate response in the recent hiatus reconciled, Nature Geoscience 7, 651–656 (2014) doi:10.1038/ngeo2228

Antarctic ice going fast: Larsen C ice shelf primed for giant calving event Gareth Renowden Mar 02

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Analysis of rift propagation using Landsat data. Background image, in which the rift is visible, is from 4 December 2014. Inset graph shows the development of rift length with respect to the 2010 tip position, and rift width at the 2010 tip position, measured from 15 Landsat images (crosses). Circles and labels on the map, and dotted red lines on the graph, show the positions of notable stages of rift development.

The Larsen C ice shelf on the east coast of the Antarctic peninsula is primed for a giant iceberg calving event, and could be heading for total collapse — similar to the fate of the Larsen B ice shelf in 2002, according to scientists monitoring the ice. A huge crack (above: hover over the picture for the full caption from the paper) is propagating northwards at an accelerating rate, and could give birth to ice islands of between 4,600 km2 and 6,400 km2 — equivalent to three or four Stewart Islands floating out to sea — according to an open access paper, Jansen et al, Newly developing rift in Larsen C Ice Shelf presents significant risk to stability1 (full pdf), published last month.

From the paper’s conclusions:

It seems inevitable that this rift will lead to a major calving event which will remove between 9 and 12 % of the ice shelf area and leave the ice front at its most retreated observed position. More significantly, our model shows that the remaining ice may be unstable. The Larsen C Ice Shelf may be following the example of its previous neighbour, Larsen B, which collapsed in 2002 following similar events.

The Larsen C ice shelf has been thinning over at least the last decade, and has shown signs of surface melting. Jansen et al developed two calving scenarios — shown below — and analysed the results with a model of the ice shelf.

 Overview of the Larsen C Ice Shelf in late 2014 showing the contemporary location of the developing rift (red line), and a selection of previous and predicted future calving fronts. Background image is MODIS Aqua, 3 December 2014. Geographic features of interest are marked (R = Revelle Inlet, FI = Francis Island, TO = Tonkin Island, TI = Trail Inlet, SI = Solberg Inlet, K = Kenyon Peninsula) and the dashed box shows the extent of Fig. 2. The highlighted flow line indicates the location of the Joerg Peninsula suture zone.

For a good overview of the current state of our knowledge of Antarctic ice melt, see The big melt: Antarctica’s retreating ice may re-shape Earth from the Associated Press, which tipped me off to the Larsen C story. Larsen C is the most northerly of the remaining major Antarctic ice sheets, and the last remnant of an ice shelf that until 1995 stretched up to the tip of the east coast of the Antarctic Peninsula. After the collapses of Larsen A and B, the glaciers feeding the shelves were observed to speed up — increasing the overall ice sheet mass loss. While the loss of the ice shelf won’t itself cause any sea level rise — because it’s already floating — the resulting speed up will increase sea levels.

  1. The Cryosphere Discuss., 9, 861–872, 2015

Blink and its gone – spectacular time-lapse of ice retreat at Fox Glacier Gareth Renowden Feb 26

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This spectacular time-lapse video1 captures the dramatic retreat of the Fox Glacier in Westland over the last year — 300 metres between January 2015 and January this year. As the ice retreats, the hillside becomes unstable and collapses down into the valley. To get a sense of the scale, you can see people watching from a safe point on the bottom right.

The rapid retreat of both Fox and its neighbour Franz Josef has led to the abandonment of guided walks on the glacier tongues. The ice is now only accessible by helicopter on to the upper reaches.

The collapse of the walls of the valley at Fox (as well as rocks and sediment transported by the ice) has caused the valley floor to rise by a metre over the last two years, as measured by Massey University scientists (see also NZ Herald). They’ve also photographed the retreat over the last decade, but the most marked loss seems to be in the last few years.

NZ’s west coast glaciers are amongst the most dynamic in the world, fed by huge snowfalls in their nevées under Mt Cook — as much as 6 metres a year in the snowfield feeding the Franz-Josef, as Mauri Pelto notes here. At the moment, ice melt in the tongues of both glaciers is outpacing the ice input above, and so the glaciers are retreating fast, but a run of years with heavy snowfalls could reverse the process — at least temporarily.

  1. Created by Victoria University of Wellington with the support of Fox Glacier Guides, Department of Conservation, Snowgrass Solutions, University of Canterbury and the Marsden Fund.

Four Revolutions in the Earth Sciences Bryan Walker Jan 28

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James Lawrence Powell is a former geology professor, college president and museum director. He is currently the executive director of the US National Physical Science Consortium. He is also an excellent communicator of science for the general reader. I reviewed two of his climate change-related books back in 2011 here and here. His latest book, Four Revolutions in the Earth Sciences: From Heresy to Truth, is wider in its scope, and places climate science alongside three other major scientific understandings which emerged in the course of the 20th century, profoundly affecting our knowledge of the planet.

Powell the geologist was familiar with the fact that great geological discoveries of the 20th century had had to struggle for decades to gain acceptance by the community of geologists. It was no easy ride for the propositions that the planet is billions of years old, that continents and sea floors move, and that meteorites crash into the earth. The opposition and the controversy his book narrates were often intense before the theories gained wide acceptance.

Powell had researched modern climate science, but was less familiar with its past history. He discovered that its early proponents had also suffered initial rejection of their theories and it was many decades before the correctness of their discoveries was acknowledged.

We are used to hearing of the fundamental contribution of Arrhenius to our understanding of the effect of atmospheric carbon dioxide on temperature. In the late 19th century he showed that atmospheric carbon dioxide alone, had its amount doubled or halved, would have caused temperature mutations of several degrees. But readers may be less aware that, following initial welcome for the theory, scientists “piled on to reject it”. It was another fifty years before scientists began to investigate greenhouse warming seriously and a further fifty before an international panel of scientists would corroborate Arrhenius’s finding.

 “A century is a long time to wait to affirm a scientific theory, especially one with the dire consequences of global warming.”

Arrhenius did not foresee those dire consequences, assuming, perhaps understandably from a Swedish perspective, that a warmer world would be more pleasant to live in. But by the late 20th century Nasa scientist James Hansen was in no doubt as to the malign consequences of warming for human society. The work of Hansen and his group dominates the latter pages of this section of Powell’s book. Hansen is respected not only for being one of the most productive modern climate scientists but also for being courageous and outspoken in his desire to warn, in every possible forum, of the dangers of global warming.

When Powell wrote his earlier books on climate change a distinguished medical friend challenged him as to why he accepted the theory. To his reply that virtually all publishing scientists accepted anthropogenic global warming his contrarian-inclined friend rejoined that scientists have been wrong before. Powell’s subsequent research into the history of 20th century climate science enabled him to see that the “scientists have been wrong before” route had already been traversed in the years immediately following Arrhenius.  For fifty years the “magisters of meteorology” favoured a debunking of Arrhenius which didn’t stand the course of time. They were wrong. As more scientists examined the data and published their findings the fundamentals became irresistible and the modern consensus emerged. This time it is right. Anthropogenic global warming has taken its place among the known facts of our planet.

The capacity of science to self-correct is in Powell’s eyes its cardinal virtue. In his book we see that process repeated four times over in the scientific revolutions he describes. What moved scientists to first reject for so long the four theories only to have later generations come to regard them as virtually self-evident? Looking back over the record it is plain, says Powell, that scientists accepted the theories when the data demanded that they do so. “To call themselves scientists they had no choice.”

But reaching this point is not necessarily straightforward. Powell comments that where science is concerned we cannot trust our common sense. In all four revolutions covered in book the discoveries are counter-intuitive.  Being able to make them is ”a triumph of human intellect, a testament to our ability to observe effects and reason back to causes”.

“I am not a scientist” is the latest mantra of denial in the US Congress, as if that statement somehow justifies a refusal to act to restrain greenhouse gas emissions or even to understand what is at stake. It’s a disgraceful evasion of intellectual and moral responsibility. One doesn’t need to be a scientist to understand the thrust of the scientific theories explained in this book, as any general reader of the book can attest.

The discovery of anthropogenic climate change may represent a triumph of human intellect, but that doesn’t put it out of reach of average human understanding. No patient reader of Powell’s book could come away confused about the scientific understandings it details, least of all  about how well established is the science of climate change. American scientists have played a prominent part in climate science. It’s hard to understand why any self-respecting American politician should continue to profess ignorance.

The wrinkled retainer returns with a Peer-reviewed Peer Gareth Renowden Jan 22

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There is much ado at Tannochbrae Manor, because the Laird has once again disproved global warming. One equation is all it takes! And an article in a new Chinese science journal with some friends, and lo!

Take away that inappropriate and misapplied equation, remove the unjustifiable tripling and the climate “crisis” vanishes.

You couldn’t make it up1. Although the Laird is a past master of self-parody, his triumphant article at WND is really something else. But enough: there is much ado at Tannochbrae Manor, because Scrotum has returned!

It’s been nearly two years since the last of my Monckton tales, and fully six since Old Scrotum first trod the boards at Hot Topic, so it’s a great pleasure to see someone else picking up the characters and beating around the bush with a pheasant in the hand and a peasant in the pocket. Izen has summoned the wrinkled retainer from retirement in order to help him express his astonishment at the chutzpah of the good Lord in writing and promoting his latest opus, which is being widely greeted with yawns — and some preliminary debunking. There will be more.

There may even be more from Scrotum. I hear rumours that the Laird’s attempts at spoken Mandarin are not going down well…

  1. No, wait a minute. You can. He has. And I might be persuaded…

Heat: 2014 breaks global temperature records, 2015 could be hotter Gareth Renowden Jan 18

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Last year was the warmest year on record for the planet, analyses by NASA and NOAA show, and it’s possible that 2015 could be warmer still. 2014 was warmer than previous record holders 2005 and 2010, and comfortably ahead of 1998. 13 of the hottest 15 years on record have all occurred since 2000. Remarkably, 2014’s warmth was achieved without much assistance from an El Niño — which boosts global temperatures and is normally a factor in record setting years, as this graphic from Skeptical Science shows:

ENSO Temps static480

For more discussion of ENSO’s impact on temperatures, see Dana Nucitelli’s article at The Guardian, and Jim Hansen et al’s discussion here. Hansen warns that more warming could be on its way:

More warming is expected in coming years and decades as a result of Earth’s large energy imbalance, more energy coming in than going out, and with the help of even a mild El Niño 2015 may be significantly warmer than 2014.

The risk of further rapid rises in global temperatures could also be increased by early signs that the Pacific Decadal Oscillation (PDO) may be shifting to its positive phase, as the Peter Hannam at the SMH pointed out late last year:

“During a positive PDO phase, you’d expect temperatures to keep climbing again as they did in the 1980s and 1990s,” Dr (Shayne) McGregor (of UNSW) said, adding that as PDOs are measured by rolling 11-year averages, it will be a while before any shift becomes clear.

In New Zealand, NIWA reports that the nationwide average temperature for 2014 was 12.8°C, 0.2°C above the 1981–2010 annual average, but that June was tied for warmest in the long term record. The MetService blog provides a good overview of regional weather here.

For further analysis and discussion, there is a lot of good coverage and supporting information available on the web. Here’s my pick of some of the best.

News coverage: New York Times (above the fold on the front page, no less), BBC, Guardian, Stuff (taking the AP coverage). Time makes the obvious point: warming continues unabated, which should give the lie to climate crank nonsense about no recent warming1.

Background analysis: the Climate Council in Australia (who created the graphic at the top of this post), a superb Bloomberg graphic, Climate Nexus, Climate Central (one and two), and for my favourite visual reminder of how warming has progressed, here’s NASA’s animation of global warming from 1880 to 2014:


  1. …but I won’t be holding my breath…

Your Life as Planet Earth Bryan Walker Jan 06

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“We can’t make sense of our future until we make sense of our past”, writes Howard Lee in his recent book Your Life as Planet Earth: A new way to understand the story of the Earth, its climate and our origins. The book demonstrates the very considerable sense that science has been able to make of our past. There are clear lessons for us as we forge our future, though whether the political leadership is able to take on board those lessons is moot.

In the first part of the book Lee provides a highly readable account of the turbulent history of the planet in the four and a half billion years of its existence. Geology, climate and the evolution of life are the recurrent themes. He measures this long history against an imagined human life spanning a century. It’s an entertaining and effective way of depicting the enormous spans of time before humans arrive on the planet. On this measure simple life starts in the teens of the centenarian’s life; oxygen arrives during the mid-life crisis; primitive plants and fungi start to colonise land in the late 70s; at 86 complex animals show up; in the 90s four-legged life evolves from fish; at 98 the dinosaurs are extinguished; homo sapiens doesn’t emerge until the 29th December in the final year. And in the few remaining minutes of that last year we have achieved a rapid rise in atmospheric carbon dioxide to levels not seen since the Pliocene, three and a half million years ago.

Our rates and quantities of carbon dioxide generation are rivalling those of the great igneous eruptions which had highly destructive effects on the climate of their times, triggering global warming, ocean anoxic events and mass extinctions. We’re making our presence felt in no uncertain manner, and Lee sees no reason to assume we can avoid the consequences which attended past rapid escalations of carbon dioxide in the atmosphere.

The second half of the book shows how scientists have discovered so much about our past.  It’s a fascinating account of the enormous range of techniques and ingenuity by which the progression of events and processes has been discovered. Plate tectonics is a stand-out in geology: “In short, it is geology’s unifying theory.” The evidence for evolution is overwhelming. It has been established in the fossil records and in the genes, anatomy and biochemistry of living things today. We have also come to understand that the evolution of life has been an integral part of the planet’s evolution.

Turning to the evidence for past climates Lee explains the numerous proxies by which past temperatures and carbon dioxide levels can be established and confirmed, along with the accompanying behaviour of the oceans. There are uncertainties of course, and there is more to be discovered, but the overall picture to date is impressive in its detail. Carbon dioxide and temperature have moved in lockstep throughout most of Earth’s history, with the gas being both a driver of and responder to warming.  The gauging of carbon dioxide levels through the climate changes of the past is, Lee emphasises, crucial to our understanding of how the planet will respond to the rising levels of today.

Lee’s survey of what has been discovered about past climates covers territory mostly familiar to readers who follow climate science, but it is marked by the completeness of its range and the writer’s ability to make complex matters clear to non-scientists. He has a light touch, but achieves admirable clarity in his explanations.

Alarm is, Lee thinks, an entirely appropriate response to scientists’ projections of Miocene-like or maybe even end-Triassic-like conditions for our grandchildren’s world and beyond. He fervently hopes for some unforeseen cooling feedback “to swoop in like a fairytale hero, saving us from destructive climate change”. But Earth’s past shows no sign of that.

The book is testimony to the high worth of the patient processes of the scientific community. The piecing together of Earth’s past is a triumph of human intelligence. It also obviously carries high import for our future as we keep raising the level of carbon dioxide by continuing to burn fossil fuels.

But if science brings understanding it takes politicians to act on scientific information, and at the end of his book Lee reflects on the complete disregard for science shown by many top political leaders. He writes of “the burden of ignorance in the upper echelons of power”. That spectacle is particularly apparent in America where Lee lives. But while I was settling to write this review I viewed for the second time Alister Barry’s documentary Hot Air screened by Maori Television. Watching the dismal progression of political and business leaders in supposedly well-educated New Zealand scrambling to evade or deny the issue of rising emissions was a depressing experience. All the more while reading yet another clear and compelling explanation of the scientific conclusions which any of those leading figures would be capable of understanding.

Lee ventures reflection on what we must do if we are to pull back from invoking the worst consequences of climate change. In this discussion I thought he surrendered too readily to the notion that decarbonisation of our energy systems within the necessary time frame is too much for us to accomplish. He appears influenced by Roger Pielke on this point. If the message from Earth’s past is allowed to finally break through into the public consciousness we may surprise ourselves by the speed with which we can move. But that’s a very big if.

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