Paper: ‘no clear increase in blocking’

8 January, 2014 by

US-blockingA paper, accepted for publication in Geophysical Research Letters just two days ago, challenges the warmist hypothesis that reducing ice in the Arctic is causing more blocking events resulting in more frequent instances of extreme weather. The paper, by Elizabeth Barnes, is available in PDF here.

Given the weather in the US at the moment (see previous post here), which the headbangers are using as evidence of extreme weather arising from Arctic warming, the paper shows how difficult it is to make such a link. From the abstract (my emphasis):

Observed blocking trends are diagnosed to test the hypothesis that recent Arctic warming and sea ice loss has increased the likelihood of blocking over the Northern Hemisphere. To ensure robust results, we diagnose blocking using three unique blocking identification methods from the literature, each applied to four different reanalyses. No clear hemispheric increase in blocking is found for any blocking index, and while seasonal increases and decreases are found for specific isolated regions and time periods, there is no instance where all three methods agree on a significant trend. Blocking is shown to exhibit large interannual and decadal variability, highlighting the difficulty in separating any potentially forced response from natural variability.

Of course, the paper has provoked the ire of the true believers, in particular a certain Jennifer Francis, for whom this appears to be her pet theory. She gave an interview back in August last year, when the paper was first made public, in which she questions the ‘motivation’ of the author, and labels Barnes’ approach “less than objective” and “a direct attempt to disprove [Francis’] work”.

Judith Curry expresses the views of the majority reading such comments:

So why on earth would Elizabeth Barnes be out to ‘get’ Jennifer Francis and discredit her work?  Its very hard to imagine a reason, beyond the obligation of a scientist to challenge existing findings and push forward at the knowledge frontier.

JC message to Jennifer Francis:  I’ve found that your credibility is reduced and your own motivations are questioned when you attack the motives of another scientist, particularly a young scientist without any apparent agenda beyond doing good science and advancing her academic career.  The high ground is a much better place to be, and not just in a hurricane.

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Warning: Arctic alarmism ahead

28 August, 2012 by

Warning! Alarmism ahead…

UPDATE [1.45pm AEST]: And, right on cue, the ABC (Alarmist Broadcasting Corporation) comes up trumps:

The sea ice in the Arctic Ocean has melted to its smallest point ever in a milestone that may show that worst-case forecasts on climate change are being realised, say US scientists.

They say the extent of ice observed on Sunday broke a record set in 2007 and there will likely be further melting with several weeks of northern hemisphere summer still to come. (source)

Batten down the hatches for an avalanche of alarmism relating to the impending Arctic sea ice minimum. It looks to be heading for a record low (although some measures are showing otherwise, see here), and whatever the cause, we will be swamped with links to AGW from the climate science consensus and the media.

And whilst it is at least possible that a proportion of the ice loss is attributable to warming from human emissions, the question, as always, is one of degree: how large are those effects relative to other, natural, forces?

Climate Depot details some of the other factors that may worthy of consideration, before we all leap to conclusions about the role of AGW:

  • satellite measurement began just over 30 years ago, and is too short a period to draw such confident conclusions about attribution
  • at the time satellite measurement began, Arctic ice had been growing for many years after a period of global cooling, and so a subsequent decline during a period of warming is to be expected
  • Arctic likely to have had less ice in 1930s and 40s
  • recent ice loss may be attributable to changes in ocean currents, wind or other weather-related phenomena
  • this year, a particularly severe storm caused the disintegration of a considerable area of sea ice
  • cyclical fluctuations of Arctic ice are known to have existed for millennia

I am not making any claim about the significance of any of the above, other than to say they may play a role.

But unfortunately, the AGW believers invariably insist on using Arctic sea ice levels as a crude “gotcha” to “prove” that they are right (canaries, coal mines etc), claiming absolute certainty of attribution, when in fact, as is almost always the case in these matters, it is a subtle combination of factors that lead to the present conditions.

Just another example of the extreme polarisation of the issues when the middle ground is where everyone should be focussing.

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Arctic freshening not due to sea ice melt

7 January, 2012 by

Pure fiction then, and still is now

From The Science is Settled Department. Environmental activists and climate scientists on the AGW gravy train are so desperate to keep the scare afloat that they will find evidence of climate-induced changes in our planet wherever they look.

Everything can be attributed to climate change – it is the unfalsifiable hypothesis to end all unfalsifiable hypotheses. Once our scientist finds a plausible explanation that links a particular phenomenon (freshening of the Arctic waters, for example) to a man-made cause (melting sea ice caused by global warming, for example), he/she can stop looking for any other.

Especially when the consequences are potentially so dramatic – changes in salinity are thought to affect a major ocean current, the North Atlantic Conveyor, which, if interrupted, could “flip” the climate past a “tipping point” into a new Ice Age. They even made a film about it, The Day After Tomorrow, in which the special effects team went completely overboard to create the most terrifying images of what “might” happen if you keep driving your SUV and Australia doesn’t pass the carbon tax legislation:

[tube]eCfHUQInK9o[/tube]

Faced with such a possibility, who in their right mind could possibly disagree with taking urgent and drastic action to “tackle climate change”? Once the AGW box is ticked, job done.

Except that if our scientist had behaved as a proper scientist should, he/she may have looked deeper, and found that there might be other, more likely or convincing explanations. But taking that path runs the risk of missing out on the AGW angle, which would be a disaster for PR and funding. So that job is put on hold. For a while. Until the day after tomorrow, perhaps.

At least someone was brave enough to do it, however:

A new NASA and University of Washington study allays concerns that melting Arctic sea ice could be increasing the amount of freshwater in the Arctic enough to have an impact on the global “ocean conveyor belt” that redistributes heat around our planet. 

Lead author and oceanographer Jamie Morison of the University of Washington’s Applied Physics Laboratory in Seattle, and his team, detected a previously unknown redistribution of freshwater during the past decade from the Eurasian half of the Arctic Ocean to the Canadian half. Yet despite the redistribution, they found no change in the net amount of freshwater in the Arctic that might signal a change in the conveyor belt.

The team attributes the redistribution to an eastward shift in the path of Russian runoff through the Arctic Ocean, which is tied to an increase in the strength of the Northern Hemisphere’s west-to-east atmospheric circulation, known as the Arctic Oscillation. The resulting counterclockwise winds changed the direction of ocean circulation, diverting upper-ocean freshwater from Russian rivers away from the Arctic’s Eurasian Basin, between Russia and Greenland, to the Beaufort Sea in the Canada Basin bordered by the United States and Canada. The stronger Arctic Oscillation is associated with two decades of reduced atmospheric pressure over the Russian side of the Arctic. Results of the NASA- and National Science Foundation-funded study are published Jan. 5 in the journal Nature.

…

“Changes in the volume and extent of Arctic sea ice in recent years have focused attention on melting ice,” said co-author and senior research scientist Ron Kwok of NASA’s Jet Propulsion Laboratory, Pasadena, Calif., which manages Grace for NASA. “The Grace and ICESat data allow us to now examine the impacts of widespread changes in ocean circulation.”

Kwok said on [the] whole, Arctic Ocean salinity is similar to what it was in the past, but the Eurasian Basin has become more saline, and the Canada Basin has freshened. In the Beaufort Sea, the water is the freshest it’s been in 50 years of record keeping, with only a tiny fraction of that freshwater originating from melting ice and the vast majority coming from Russian river water. 

…

“To better understand climate-related changes in sea ice and the Arctic overall, climate models need to more accurately represent the Arctic Oscillation’s low pressure and counterclockwise circulation on the Russian side of the Arctic Ocean,” Morison added. (source)

You’re saying the models aren’t perfect? Who’d have thought.

Link to Nature abstract here.

(h/t The Register)

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Wind contributing to Arctic sea ice loss

23 March, 2010 by

Arctic ice

From The Science is Settled Department: any fule kno that the Arctic is melting solely because of global warming, right? Wrong. A large part of the sea ice loss is due to changes in wind patterns, which even the Guardian acknowledges, despite putting a disclaimer at the start of the article:

[Guardian Standard Alarmist Disclaimer] New research does not question climate change is also melting ice in the Arctic, but finds wind patterns explain steep decline.

Much of the record breaking loss of ice in the Arctic ocean in recent years is down to the region’s swirling winds and is not a direct result of global warming, a new study reveals.

Ice blown out of the region by Arctic winds can explain around one-third of the steep downward trend in sea ice extent in the region since 1979, the scientists say.

The study does not question that global warming is also melting ice in the Arctic, but it could raise doubts about high-profile claims that the region has passed a climate “tipping point” that could see ice loss sharply accelerate in coming years.

The new findings also help to explain the massive loss of Arctic ice seen in the summers of 2007-08, which prompted suggestions that the summertime Arctic Ocean could be ice-free withing a decade. About half of the variation in maximum ice loss each September is down to changes in wind patterns, the study says.

Read it here.

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Don't panic! Iceberg heads for Australia!

10 December, 2009 by

Fourth from the right

Fourth from the right

Maybe we can add it to the Harbour Bridge and the Opera House as a tourist attraction! Of course, it’s all caused by “global warming” – what else?

A giant iceberg double the size of Sydney Harbour is on a slow but steady collision course with Australia, scientists have said.

The mammoth chunk of ice, which measures 12 miles long and five miles wide, was spotted floating surprisingly close to the mainland by scientists at the Australian Antarctic Division (ADD).

Known as B17B, it is currently drifting 1,000 miles from Australia’s west coast and is moving gradually north with the ocean current and prevailing wind.

Dr Neal Young, a glaciologist working for the ADD, said that if the iceberg eventually reached Australia waters, it would crash into the continental shelf causing a magnitude three to to four tremor.

However, Dr Young said the iceberg was unlikely to hit the Australian mainland. If it continued on its path north, it would eventually break up into hundreds of smaller icebergs, he said.

“As the waters warm, the iceberg will thin out, so it is not going to get to Australia, the further north it goes, the more it break up,” he said.

The smaller icebergs created when the larger berg broke up could become shipping hazards if they float closer to shore.

Dr Young said an iceberg the size of B17B had not been seen so far north since the days when 19th century clipper ships plied the trade route between Britain and Australia.

“Icebergs do come from time to time and they can be very big, but it can be a long time before we spot one – so it’s really a once-in-a-lifetime sighting.”

…

Dr Young said sightings of large icebergs could become more frequent if sea temperatures rise through global warming.

Read it here.

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UPDATED: NZ Antarctic research "debunks sceptics", claims 1.5m sea level rise

12 November, 2009 by

It will be interesting to see what the sceptic community makes of this:

New Zealand scientists say massive ice shelves are protecting Antarctica from experiencing the same rapid decline in sea ice as the Arctic.

The research team says the discovery further debunks the claims of sceptics who have pointed to the continent’s growth as evidence against global warming.

The team was led by Otago University physics researcher Andrew Mahoney, who said the eight-month study focused on a topic scientists understood little about.

Dr Mahoney said findings would help climate scientists make predictions about the future.

National Institute of Water and Atmospheric Research oceanographer Mike Williams said the research explained why Antarctic sea ice was not decreasing at a similar rate to that of the Arctic.

Figures from America’s National Snow and Ice Data Center show that Arctic sea ice shrank by about 4 per cent of 500,000 square kilometres each decade during the past 30 years. By contrast, Antarctic sea ice was not believed to have changed much in size and may have increased slightly.

However, Antarctic Research Centre director Tim Naish, who was not part of the research team, said the latest data issued in a report by Nasa indicated that the amount of Antarctic sea ice lost since 2003 could have doubled.

…

WHAT THE SCIENTISTS FOUND

  • Massive ice shelves make up half the Antarctic coastline
  • Cold water melts from these ice shelves
  • The melted water protects the ice sheets from the warming effects of climate change
  • This causes ice sheets to grow in winter, although they still melt in summer
  • This is why Antarctic sea ice has not declined as quickly as Arctic sea ice in response to global warming

Read it here.

UPDATE: Tim Naish is also in the news for predicting dramatic sea level rises:

Sea levels may rise an average of as much as 1.5m by 2100, the latest figures show.

The range indicated by several new studies is between 50cm and 150cm, said Dr Tim Naish, director of the Antarctic Research Centre at Victoria University in Wellington, New Zealand.

A glaciologist who was chief scientist on a major Antarctic drill-core project, Naish said the latest “range of plausible sea level rise” was based on observations to calculate how much water would come from polar ice sheets.

Read it here.

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