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Posts Tagged glacier

TDB today: Tomorrow is being written in New Zealand’s mountains Gareth Renowden Dec 11

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TasmanGlacier 3

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.

TasmanGlacier 2

Easterbrook’s wrong (again) Gareth Renowden Jan 04

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Over the holiday period I’ve had a number of people point me at the latest “essay” by Don “Cooling-gate” Easterbrook — it was featured in full at µWatts, translated into German and Dutch, and made headline material for Morano: Geologist: 9,099 Of Last 10,500 Years Warmer Than 2010. I was a little surprised. I thought that recent temperatures were the warmest for at least hundreds, and probably thousands of years. But this is Easterbrook, and he’s up to his old tricks. He’s “hiding the incline” in temperatures by mangling the data from Greenland ice cores. Has he learned nothing since I last looked at his “work”? Apparently not.

Easterbrook’s argument is so flimsy and his presentation of data so dodgy that even the normally uncritical crowd at µWatts voiced grave doubts about his analysis. But there were a number of loose ends left over from my last look at Greenland ice core data, and so I took the opportunity to do a little more research. Playing fast and loose with the facts, and making schoolboy errors in the process, is not a good look for a professor emeritus. But that’s what Easterbrook’s been doing…

Easterbrook’s basic argument relies on using temperatures at the top of the Greenland ice sheet as a proxy for global temperatures. That’s a fatal flaw, before we even begin to examine his use of the ice core data. A single regional record cannot stand in for the global record — local variability will be higher than the global, plus we have evidence that Antarctic temperatures swing in the opposite direction to Arctic changes. Richard Alley discussed that in some detail at Dot Earth last year, and it’s well worth reading his comments. Easterbrook, however, is content to ignore someone who has worked in this field, and relies entirely on Greenland data to make his case.

Most of the past 10,000 [years] have been warmer than the present. Figure 4 shows temperatures from the GISP2 Greenland ice core. With the exception of a brief warm period about 8,200 years ago, the entire period from 1,500 to 10,500 years ago was significantly warmer than present.

This is Easterbrook’s Fig 4:

easterbrook_fig41.jpg

It’s a graph he’s used before, in various forms, almost certainly copied and altered from the original (click image below to see source: the NOAA web page for Richard Alley’s 2000 paper The Younger Dryas cold interval as viewed from central Greenland, though DE credits it as “Modified from Cuffy and Clow, 1997″, misspelling Kurt Cuffey’s name in the process (shades of Monckton’s Curry!)):

Easterbrook continues:

Another graph of temperatures from the Greenland ice core for the past 10,000 years is shown in Figure 5. It shows essentially the same temperatures as Cuffy and Clow (1997) but with somewhat greater detail. What both of these temperature curves show is that virtually all of the past 10,000 years has been warmer than the present.

This is his Fig 5:

easterbrook_fig5.png

Easterbrook plots the temperature data from the GISP2 core, as archived here. When I last wrote about this subject, I assumed that “present” was defined as 2000, the date of Alley’s paper on the Younger Dryas, which is given as the primary reference at the head of the data file. Easterbrook makes the same assumption explicit in his chart, defining “present” as 2000. The first data point in the file is at 95 years BP, and shown in his graph. In other words, Don presents 1905 as equivalent to the present — a point I emphasised the last time he used this data. However, we were both wrong.

One of the last comments to my “100 years of warming” post suggested that the GISP2 “present” followed a common paleoclimate convention and was actually 1950. This would make 95 years BP 1855 — a full 155 years ago, long before any other global temperature record shows any modern warming. In order to make absolutely sure of my dates, I emailed Richard Alley, and he confirmed that the GISP2 “present” is 1950, and that the most recent temperature in the GISP2 series is therefore 1855.

This is Easterbrook’s main sleight of hand. He wants to present a regional proxy for temperature from 155 years ago as somehow indicative of present global temperatures. The depths of his misunderstanding are made clear in a response he gave to a request from the German EIKE forum to clarify why he was representing 1905 (wrongly, in two senses) as the present. Here’s what he had to say:

The contention that the ice core only reaches 1905 is a complete lie (not unusual for AGW people). The top of the core is accurately dated by annual dust layers at 1987. There has been no significant warming from 1987 to the present, so the top of the core is representative of the present day climate in Greenland.

Unfortunately for Don, the first data point in the temperature series he’s relying on is not from the “top of the core”, it’s from layers dated to 1855. The reason is straightforward enough — it takes decades for snow to consolidate into ice.

And so to an interesting question. What has happened to temperatures at the top of Greenland ice sheet since 1855? When I wrote about this last year, I relied on a Mark 1 eyeball estimate based on the GISS record for Angmagssalik, but I can now do better. Jason Box is one of the most prominent scientists working on Greenland (I’ve covered his work a fair bit over the years) and he has a recent paper reconstructing Greenland temperatures for the period 1840-2007 (Box, Jason E., Lei Yang, David H. Bromwich, Le-Sheng Bai, 2009: Greenland Ice Sheet Surface Air Temperature Variability: 1840—2007. J. Climate, 22, 4029—4049. doi: 10.1175/2009JCLI2816.1). He was kind enough to supply me with a temperature reconstruction for the GRIP drilling site — 28 km from GISP2. This is what the annual average temperature record looks like (click for bigger version):

GRIPtempBox480.png

I’ve added lines showing the average temperatures for the 1850s (blue) and the last 10 years (red), and the difference between those is a warming of 1.44ºC. I’ve also added the two most recent GISP2 temperature data points (for 1847 and 1855, red crosses). It’s obvious that the GRIP site is warmer than GISP2 (at Summit Camp). The difference is estimated to be 0.9ºC on the annual average (Box, pers comm).

Let’s have ago at reconstructing Easterbrook’s Fig 5, covering the last 10,000 years of GISP2 data. It looks like this (click for bigger version):

GISP210k480.png

The GISP2 series — the red line — appears to be identical to Easterbrook’s version, proving that he can at least download a file and plot it in Excel. The bottom black line shows his 1855 “present”, and it intersects the red line in the same places as his chart. I’ve added a grey line based on the +1.44ºC quantum calculated from the GRIP temperature data, and two blue crosses, which show the GISP2 site temperatures inferred from adjusted GRIP data for 1855 and 2009.

Two things are immediately apparent. If we make allowance for local warming over the last 155 years, Easterbrook’s claim that “most of the past 10,000 [years] have been warmer than the present” is not true for central Greenland, let alone the global record. It’s also clear that there is a mismatch between the temperature reconstructions and the ice core record. The two blue crosses on the chart show the GISP site temperatures (adjusted from GRIP data) for 1855 and 2009. It’s clear there is a calibration issue between the long term proxy (based on ∂18O measurement) and recent direct measurement of temperatures on the Greenland ice sheet. How that might be resolved is an interesting question, but not directly relevant to the point at issue — which is what Don Easterbrook is trying to show. Here’s his conclusion:

So where do the 1934/1998/2010 warm years rank in the long-term list of warm years? Of the past 10,500 years, 9,100 were warmer than 1934/1998/2010. Thus, regardless of which year ( 1934, 1998, or 2010) turns out to be the warmest of the past century, that year will rank number 9,099 in the long-term list. The climate has been warming slowly since the Little Ice Age (Fig. 5), but it has quite a ways to go yet before reaching the temperature levels that persisted for nearly all of the past 10,500 years. It’s really much to do about nothing.

1855 — Easterbrook’s “present” — was not warmer than 1934, 1998 or 2010 in Greenland, let alone around the world. His claim that 9,100 out of the last 10,500 years were warmer than recent peak years is — to put it bluntly — pure bullshit, based on a misunderstanding or misrepresentation of data. He should withdraw his article, and apologise to those he has mislead. I’m confident, however, that Easterbrook will instead whinge about being attacked — which brings to mind the late, great Kenneth Williams.

The last word goes to Richard Alley, who points out that however interesting the study of past climate may be, it doesn’t help us where we’re heading:

Whether temperatures have been warmer or colder in the past is largely irrelevant to the impacts of the ongoing warming. If you don’t care about humans and the other species here, global warming may not be all that important; nature has caused warmer and colder times in the past, and life survived. But, those warmer and colder times did not come when there were almost seven billion people living as we do. The best science says that if our warming becomes large, its influences on us will be primarily negative, and the temperature of the Holocene or the Cretaceous has no bearing on that. Furthermore, the existence of warmer and colder times in the past does not remove our fingerprints from the current warming, any more than the existence of natural fires would remove an arsonist’s fingerprints from a can of flammable liquid. If anything, nature has been pushing to cool the climate over the last few decades, but warming has occurred.

[See also: MT at Only In It For The Gold. My thanks to Richard Alley and Jason Box for their rapid response to my questions.]

Clear and present danger: Lonnie Thompson on the message in the ice Bryan Walker Dec 10

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Paleoclimatologist Lonnie Thompson, distinguished university professor in the School of Earth Sciences at The Ohio State University, is well known and widely respected for his decades of work on ice caps and glaciers, especially in tropical and sub-tropical regions. In the past Thompson has let his research data and conclusions speak for him but he has this week caused something of a stir by voicing in a journal for social scientists and behaviour experts his concern at the grave risks we run in ignoring the evidence of climate change. Climate Change: The Evidence and Our Options is the title of his paper (available here) and it’s published in a special climate-change edition of The Behavior Analyst.

One hopes the paper has many readers. Its eighteen pages, a model of clarity, are highly accessible for the lay person.

Thompson opens by acknowledging that climatologists, like other scientists, tend to be a stolid group.

’We are not given to theatrical rantings about falling skies. Most of us are far more comfortable in our laboratories or gathering data in the field than we are giving interviews to journalists or speaking before Congressional committees.’

Why then, he asks, are climatologists speaking out about the dangers of global warming? Because virtually all of them are now convinced that global warming poses a clear and present danger to civilisation.

’There’s a clear pattern in the scientific evidence documenting that the earth is warming, that warming is due largely to human activity, that warming is causing important changes in climate, and that rapid and potentially catastrophic changes in the near future are very possible. This pattern emerges not, as is so often suggested, simply from computer simulations, but from the weight and balance of the empirical evidence as well.’

He explains the evidence from diverse data sources that points to relative stability in temperatures over the past 1000 years until the late twentieth century. Acknowledging that regional, seasonal and altitudinal variability can nevertheless make it difficult to convince the public and even scientists in other fields that global warming is occurring, he adds from his own area of expertise the evidence of melting ice.

The retreat of mountain glaciers is an early warning of climate change. He details the ice fields on the highest crater of Kilimanjaro which have lost 85% of their coverage since 1812. The Quelccaya ice cap in Peru, the largest tropical ice field on Earth, has lost 25% of its cover since 1978. Ice fields in the Himalayas that have long shown traces of the radioactive bomb tests in the 1950s and 1960s have since lost that signal as surface melting has removed the upper layers and thereby reduced the thickness of these glaciers. All of the glaciers in Alaska’s vast Brooks Range are retreating, as are 98 percent of those in southeastern Alaska.  And 99 percent of glaciers in the Alps, 100 percent of those in Peru and 92 percent in the Andes of Chile are likewise retreating. Some telling photographic sequences illustrate the findings. It’s a pattern repeated around the world. To glacier retreat Thompson adds the loss of polar ice and sees global warming as the only plausible explanation.

From there he moves to consideration of the natural forcers of climate change and the consensus among climatologists that the warming trend we have been experiencing for the past 100 years or so cannot be accounted for by any of the known natural forcers.

’The evidence is overwhelming that human activity is responsible for the rise in CO2, methane, and other greenhouse gas levels, and that the increase in these gases is fueling the rise in mean global temperature.’

The effects include sea level rise. He points out that if the Earth were to lose just 8% of its ice, the consequences for some coastal regions would be dramatic. The lower part of the Florida peninsula and much of Louisiana, including New Orleans, would be submerged, and low-lying cities, including London, New York, and Shanghai, would be endangered. Low-lying continental countries such as the Netherlands and Bangladesh are already battling flooding as never before and several small island states are facing imminent destruction. Other effects of warming Thompson touches on include the threats to glacier-fed fresh water sources on which populations in parts of the world depend and the increase in arid regions as the Hadley Cell expands.

Many of the models predicting future rises in temperature assume a linear rise in temperature. But in fact the rate of global temperature rise is accelerating, which is reflected in increases in the rate of ice melt, and in turn an increase in the rate of sea level rise.

’This [acceleration] means that our future may not be a steady, gradual change in the world’s climate, but an abrupt and devastating deterioration from which we cannot recover.’

At this point he discusses positive feedbacks, instancing forest fires, more dark areas opened through ice melt, and the release of CO2 and methane from melting tundra permafrost. He explains the possibility of tipping points as a result, with their ominous implications. But tipping points apart, if, as predicted, global temperature rises by another 3 degrees by the end of the century, the earth will be warmer than it has been in about 3 million years. Oceans were then about 25 metres higher than they are today.

What are our options for dealing with the crisis?  Not prevention, for global warming is already with us. We are left with three: mitigate, adapt, suffer. Mitigation is the best option, but so far the US and other large emitters have done little more than talk about its importance. Many Americans don’t even accept the reality of global warming. Disinformation campaigns have been amazingly successful. Unless appropriate steps are taken we will be left with only adaptation and suffering. And the longer the delay the more unpleasant the adaptation and the greater the suffering will be. Those with the fewest resources for adaptation will suffer most.

It’s a grim picture. The information is not new.  But it gains impetus when a leading scientist steps into the public arena and weaves his specialist contribution into the overall account in a way which leaves the reader with absolutely no doubt that the writer is convinced by the science and deeply alarmed at what it means for humanity. Like John Veron, whom I wrote about earlier this week, Thompson doesn’t allow scientific reticence to mute his message.

’Sooner or later, we will all deal with global warming. The only question is how much we will mitigate, adapt, and suffer.’

NZ glaciers holding their own (just) Gareth Renowden Nov 09

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NIWAParkPass2010.jpg

New Zealand’s glaciers just about held their own over last summer, showing a very slight gain in mass on average according to NIWA’s annual end of summer snowline survey, released today. The Park Pass glacier (above) in the Mt Aspiring National Park between the Hollyford Valley and the head of Lake Wakatipu (map) is one of the 50 index glaciers in the NIWA survey. From the press release:

’A moderate El Niño developed in the tropical Pacific in spring last year. This brought more southwesterlies, with normal to below normal temperatures through last summer and into autumn this year. The overall effect was to hold snowlines in a near steady state this year,’ says [NIWA scientist] Dr Hendrikx. The previous two years (2007—08 and 2008—09) had seen end-of-summer snowlines rise significantly as not enough snow fell to compensate for melting.

The impact of the El Niño shows as a (very) small uptick at the end of the ice mass graph, but the overall trend remains strongly downwards.

NIWAglaciermassbalance2010.gif

The full report (with lots of pictures from the aerial survey) can be downloaded from the NIWA web site. The Park Pass photo above was taken on March 6th this year on the fourth leg of NIWA’s alpine flight, and shows some spectacular icebergs in the proglacial lake. The extent of the glacier’s retreat can be seen in the Google Earth imagery at Mauri Pelto’s From A Glacier’s Perspective blog post on the nearby Donne Glacier. With a strong La Niña now influencing weather patterns in NZ, it’ll be interesting to see how the glaciers fare. I wonder if I can blag a seat on the 2011 flight? ;-)

Tropical ice land: climate change hits Peruvians Bryan Walker Sep 23

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It may not be strictly scientific, but anthropological observation like this is invaluable because in the end, people’s interpretation of the events they see around them count as much as or more than any peer-reviewed paper.’ Guardian journalist John  Vidal has been with other writers on an Oxfam-guided tour of Peru and Ecuador  to see on the ground how changing weather is affecting human development in the Andes. He’s been blogging as he goes. No doubt there will be longer and more carefully constructed articles to follow, but these reminders that already people are suffering the effects of climate change, often severely, are worth immediate attention. I agree entirely with the quote from Vidal which opens this post, and last year welcomed a number of Oxfam reports which recounted many human stories from frontiers of climate change in Bolivia, Nepal, the Pacific Islands, and elsewhere.

Vidal reports meeting Julio Hanneco, ’possibly the world’s greatest potato grower’. He grows 215 varieties of potatoes in the high Andean region of Peru.

’…folk like Julio and their extraordinary diversity of crops are critically endangered by the massive changes they observe taking place in the High Andes. When Julio was a boy, (he’s now in his 50s) a glacier was just two minutes walk from his door. Now it is a nine-hour hike away.’

In Julio’s own words:

“The seasons used to be very clear, we knew when to plant. Now we have less water. We used to get the water from the glacier. Now we have twice as many mosquitoes. We have no light from the glacier. I don’t understand what is going on. We feel very disoriented. I think that I will have no water and that will be the end of the world for us.”

Peru has more than 70% of the world’s tropical glaciers. Vidal reports most in rapid retreat, leaving behind devastated farmers and communities short of water.

In another blog post Vidal reports massive protest in the Espinar region. The Apurimac river ’is about to be hijacked’. The Peruvian government has signed a memorandum of agreement with the neighbouring province of Arequipa, to build a giant reservoir from where the water would be used to provide hydroelectric power and irrigation. But it will not benefit the people of Espinar who stand to actually lose the little water they have. The benefit will be exported to rich farmers growing food for export on the Pacific coast.

Vidal’s group found a massive strike under way in the city of Yauri. They spoke with the leader who described it as a climate change strike.

“They are condemning us to a slow death. In the future we know we will have less water. We cannot trust the rainy season any more. Every year the water levels are diminishing. Climate change and global warming indicate in the next years we will have even less. You don’t need to be clever to see climate change is affecting everything here.”

Out in the villages in the hills, whose inhabitants expressed solidarity with the striking townsfolk, the story was the same.

“Here we had snow and ice on all the hills. We don’t any more. All these lands had water but no more. Our grandparents lived very differently to us. It used to rain from October to April, and May, June and July were frosty. We used to use the snow melt water. Now we have nothing. Before we could have 300 to 400 sheep and llamas; now we have 20 to 30 and no more.”

Oxfam and a local NGO partner are working to demonstrate adaptation measures to cope better with the semi-permanent drought which now afflicts the region. There are grounds for hope that these will be effective.  But civil unrest is rife, with numerous ongoing conflicts over water.

Vidal asks ’Is this the future everywhere? Have the climate wars begun?’

[Fiery Furnaces]

Take a peek at Pukaki’s climate history Gareth Renowden Sep 12

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Irishmantreambasin.jpg

High in the Ben Ohau range to the west of Lake Pukaki in the South Island’s Mackenzie basin, the glacial moraines in the Irishman Stream Basin (Google Map) are providing important confirmation that the southern hemisphere warmed during a rapid northern hemisphere cooling event at the end of the last ice age. In a new paper in Nature, Glacier retreat in New Zealand during the Younger Dryas stadial Michael Kaplan and a team including three NZ scientists reconstruct the retreat of the glacier that used to fill the basin.

The team dated the sequence of moraines (piles of rock left by the retreating glacier) by measuring the “cosmogenic” beryllium isotope (10Be) in quartz crystals in the rocks — formed by bombardment by cosmic rays — giving a measure of how long the rocks have been exposed to the sky. By modelling the amount of ice in the valley at various moraine positions, they were able to reconstruct the glacier’s decline as the local climate warmed.

Why is this important? Because it’s another important bit of evidence in piecing together the sequence of events as the world warmed up from the last ice age — and in particular because the precise dating confirms that the Younger Dryas cold spell was not global in effect. From the abstract:

Our late-glacial glacier chronology matches climatic trends in Antarctica, Southern Ocean behaviour and variations in atmospheric CO2. The evidence points to a distinct warming of the southern mid-latitude atmosphere during the Younger Dryas and a close coupling between New Zealand’s cryosphere and southern high-latitude climate. These findings support the hypothesis that extensive winter sea ice and curtailed meridional ocean overturning in the North Atlantic led to a strong interhemispheric thermal gradient during late-glacial times, in turn leading to increased upwelling and CO2 release from the Southern Ocean, thereby triggering Southern Hemisphere warming during the northern Younger Dryas.

See also Science Daily. Ref: Kaplan et al. Glacier retreat in New Zealand during the Younger Dryas stadial. Nature (2010) vol. 467 (7312) pp. 194-197

[Edited to correct my original abysmal geography fail - wrong lake in the title]

Don’t watch that, watch this! Gareth Renowden Jun 12

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If you’ve got any interest at all in the state of the Arctic Sea Ice, resist the temptation to watch the World Cup, or the start of the All Black’s winter season, and take a look at David Barber’s talk at the International Polar Year’s Oslo Science Conference. Go to the “Web TV” page, then scroll through the videos on offer until you see Barber’s talk — On Thin Ice: The Arctic and Climate Change (or use the direct link). Barber’s a good lecturer — he gave yesterday’s (Friday) morning plenary talk at the conference — and he delivers a fascinating overview of his work on the Circumpolar Flaw Project, one of the biggest components of the 2007-8 IPY. Most interesting of all is his description of the state of the sea ice last autumn, as the icebreaker Amundsen went in search of multi-year ice in the Beaufort Sea. He gives a graphic description (involving pyjamas) of the ice breaker discovering that what the Canadian Ice Service maps were suggesting was thick multi-year ice was nothing of the sort — the Amundsen was making a comfortable 13 knots through it, not far short of its top speed of 13.7 knots. That section of his talk starts at about 20 minutes in (by the timer on the player), but it’s worth watching the whole thing. The press release for Barber’s talk is here.

There’s an enormous amount of interesting material being presented and discussed at the Oslo conference, but comments made by James Overland of the NOAA/Pacific Marine Environmental Laboratory about the mid-latitude impacts of the loss of sea ice really made me sit up and pay attention. “Cold and snowy winters will be the rule, rather than the exception,” he’s quoted as saying. Overland’s work, described in this fascinating page at PMEL, suggests that winter high pressure over the Arctic (and winter 2009-10 had the highest recorded Arctic pressures), associated with reduced sea ice cover, increases the potential for severe winters over the Eastern US, East Asia, and in late winter in Europe. This is really interesting work because it shows how Arctic change can have dramatic mid-latitude impacts, and I plan to cover it more detail to it in a future post. Don’t be surprised if Overland’s comments get the cranks all a twitter… ;-)

[Update 14/6: As predicted!]

Finally, more from the eyes in the sky over Greenland (especially for Mauri ;-) ). Here’s what the Nares Strait looked like while Barber was talking. (Click to see the full size image, and here to see what it looked like at the end of March).

Nares100612small.jpg

Temperatures are now getting above freezing, and with the snow cover melting the blue glacial ice of the Petermann Glacier tongue can be seen clearly. Ice is flowing down the Strait from the Arctic basin (look how fractured and mobile that basin ice is). I suspect, however, that there may be a temporary halt to ice export as a big lump of what could/should be thicker ice looks about to get stuck in the narrow entrance to the strait. If it’s thick multi-year ice, it could be a formidable obstacle, but if it’s “Barber ice”, it might not last long.

[Update: 15/6 -- the "big lump" is currently blocking the entrance to Nares Strait, and floes are clearly backing up behind it. However, two substantial pieces have broken off the Strait side of the "lump" and that might allow the remainder to rotate and enter the Strait. Doesn't look as though the ice was very strong...

[Madness]

It’s grim up North #2 Gareth Renowden Jun 10

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GreenlandIllulisatcrop.jpg

From NASA’s eyes in the sky, this is a view of the west coast of Greenland downloaded earlier today, looking down on the Ilulissat Icefjord — the outlet for the Jakobshavn Isbrae, the biggest outlet glacier in Greenland and the largest in the northern hemisphere. It’s the long tongue of white reaching up from right of centre to the top of the frame, where you can see the white dots of newly calved icebergs drifting out into Disko Bay (click on the picture to see the 250m/pixel original image at the MODIS site). All very interesting, of course, but I’m posting it to show the numerous large lakes of glacial meltwater that have appeared on top of the ice sheet over recent weeks. At the edge of the ice sheet, the winter snow has melted revealing the greyer ice underneath, but as you climb up the ice away from the coast you get back up into unmelted snow (bottom right). And there are lakes like this a very long way up the west coast, all primed to deliver their water down through moulins to the base of the sheet and thence out to sea, or over the surface in glacial rivers.

I hope this illustrates that there’s more to a melting Arctic than the sea ice — the rest of this post is catching up with sea ice news…

The NSIDC’s Sea Ice News June update covers the rapid decline of sea ice extent over May, but notes that it’s “still too soon to say” what will happen this summer: “although ice extent at present is relatively low, the amount of ice that survives the summer melt season will be largely determined by the wind and weather conditions over the next few months.”

A good way to monitor the melt will be to keep an eye on a new blog: Arctic Sea Ice – interesting news and data. Top post there at the moment covers the prediction for summer minimum made by Ron Lindsay and Jinlun Zhang, who work with the PIOMAS ice volume model at the Polar Science Center at the University of Washington. Lindsay’s picking (with nice animation), a September average of 4.44 +/- 0.39 million km2, his co-worker a little more.

Meanwhile a team of mad French divers have been on an expedition to the Pole, diving through thin ice and leads to capture fantastic images of the ice from the underside:

Underthepole.jpg

They’re back in France now, but I’m looking forward to seeing the completed film when it’s released. The team’s meteorologist was none other than Wayne Davidson, based in Resolute. Wayne’s a regular commenter on sea ice issues at RC and elsewhere, and has developed a system of using measurements of the sun’s disk to infer atmospheric heat content over the pole. He’s picking a low minimum, perhaps a new record.

Meanwhile over at µWatts, sea ice “expert” Steven Goddard is pontificating on prospects for the summer. Despite being repeatedly told that his preferred ice volume model is not considered accurate, notably by a commenter called Julienne (who seems knowledgeable enough to be noted ice scientist Julienne Stroeve at the NSIDC), he continues to dig himself into a hole. Here’s Goddard concluding his most recent post:

In summary:

• An ice free pole could not occur without dramatic summer warming.

• There has been almost no summer warming in the high Arctic over the last 70 years.

Goddard appears not to understand that Arctic summer temperatures don’t get much above zero degrees Celsius because all the heat’s going into melting ice. As scientists might put it, the temperature is “constrained” by the melt, and so will only show dramatic increases in summer when all the ice has gone. Here’s a handy quote, from Serreze et al (author list includes Stroeve), The emergence of surface-based Arctic amplification (The Cryosphere, 3, 11—19, 2009 www.the-cryosphere.net/3/11/2009/ [pdf]):

Arctic amplification is not prominent in summer itself, when energy is used to melt remaining sea ice and increase the sensible heat content of the upper ocean, limiting changes in surface and lower troposphere temperatures.

Watching Goddard post on sea ice is a bit like watching a slow-motion train wreck, or the progress of the ice itself. More soon, when the first SEARCH ice outlook is released.

[PS: Here's this year's North Pole webcam: still looking chilly]

Greenland ice melt spreads northwest Gareth Renowden Mar 27

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This animation shows Greenland’s ice mass loss over 2003 to 2009, estimated by combining data from NASA’s GRACE satellites with high precision GPS measurements of “rebound” in the underlying rock as the weight of ice is removed. The lightest blue shows low levels of mass loss, black the highest. From the University of Colorado press release:

“Our results show that the ice loss, which has been well documented over southern portions of Greenland, is now spreading up along the northwest coast,” said Shfaqat Abbas Khan, lead author on a paper that will appear in Geophysical Research Letters.

Khan goes on to suggest what this might imply for the future:

If this activity in northwest Greenland continues and really accelerates some of the major glaciers in the area — like the Humboldt Glacier and the Peterman Glacier — Greenland’s total ice loss could easily be increased by an additional 50 to 100 cubic kilometers (12 to 24 cubic miles) within a few years.

Another good reason to keep an eye on the Arctic this summer. Climate Progress has a very good overview of recent work on Greenland ice loss and its implications for sea level rise. Well worth a read, if not exactly comforting.

The dangerous sea Bryan Walker Mar 18

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This column was published in the Waikato Times on March 16.

The media has paid disproportionate attention to an error in the monumental 2007 report of the Intergovernmental Panel on Climate Change.  In a chapter surveying the possible future impacts of climate change on the Asian region the report included a prediction that the Himalayan glaciers could melt by 2035. The glaciers will certainly melt if we continue on our current course, but not as soon as that. This was a mistake which the IPCC has acknowledged and regretted. Not too bad in a volume of 3000 pages, but a mistake that shouldn’t have occurred and wouldn’t have if procedures had been properly applied.

Since then there have been regular media ’revelations’ claiming other errors as well. For all the fanfare with which they have been produced these have so far turned out to hinge on little more than minor technicalities. They cause much excitement in the denialist community, but they amount to nothing of consequence.

Overstatement is what the IPCC is being accused of.  But the reality is that its report is generally conservative and cautious and in one very important matter likely to have understated a real danger ahead. That is sea level rise.

The IPCC does predict sea level rise in the century ahead, somewhere between 18 and 58 centimetres, depending on how high the level of greenhouse gases is allowed to climb.  It sounds reassuringly manageable.  But this predicted rise comes only from a combination of thermal expansion of the oceans because of warmer temperatures, and the continued slow melting of glacier ice.  It assumes there will be no increase in the rate at which melting has occurred in the great ice sheets of Greenland and the Antarctic. 

Time has passed, and it is now widely accepted in scientific circles that there is reason to expect a significant acceleration in the rate at which the Greenland and Antarctica ice sheets lose mass to the sea.  The dynamics of ice movement are beginning to be better understood, and they are not reassuring.  Those massive ice sheets are seemingly not as impervious as once thought and their melting not necessarily a slow predictable linear process. Disintegration may be a more accurate word than melting. 

If the IPCC predictions are too cautious, what level of rise is now being considered likely in this century?  One metre say some.  Others say that’s still not allowing sufficiently for the acceleration likely to build, and recommend planning for a two metre rise.  James Hansen of NASA is prepared to consider five metres as a real possibility, though he doesn’t offer that as a prediction.. 

Of all the predicted impacts of climate change, sea level rise is the one that I find most unnerving.  Its effects on human populations are distressing to contemplate.  The deltaic nations such as Egypt, Vietnam, Bangladesh and Myanmar will be badly hit. Some atoll nations will disappear. Countries with large low-lying coastal plains, such as the US, China and Brazil will be faced with tremendous disruption. Some great cities will be severely threatened, including Miami, New York, Tokyo and Amsterdam. It won’t be all that straightforward in New Zealand for that matter — a one metre sea level rise would put Tamaki Drive under water for example.

And it’s not the kind of damage that can be undone.  How could we get water to return to the ice sheets?  That’s why it is so important that we stop it happening in the first place. Any suggestion that a minor error in the IPCC report has somehow put the urgency of that task into question is out of touch with reality.

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It is likely that this is the last in the series of columns I have been invited to write for the Waikato Times over the past couple of years.  The columns are directed to the general public, not Hot Topic readers, but they may have been useful here in indicating what can be written in public forums. It’s well worth anyone’s effort to get the message across in newspapers.  I often wish there were more scientists writing in that medium, though I know it can be difficult to secure a space for opinion pieces. There are always the letters to the editor, which journalists tell me are popular with readers. The company there can sometimes be embarrassing, but if you’re willing to take that risk a clear statement on climate change will receive wide attention. It has been quite depressing to see in our local paper far more letters (often muddled) from contrarians than from those who take climate change seriously.

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