Archive for the ‘ice’ Category

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Numerical version of DMI Arctic temperature data

September 8, 2009

I am providing the DMI arctic temperature data in numerical format as a public service.  This data is available in graphical format at the DMI Centre for Ocean and Ice,  but I could not figure out a simple  way to get the numerical data that was used to make the graphs.  So I have extracted it from the graphs myself.

Here it is, for the entire set of DMI images from 1958 to the present.  You must go through a slightly convoluted procedure to use it.  First, open this word document.   Then, select all the text and copy it.  Finally, paste it into a spreadsheet.

The left column gives the day of the year.  Notice that the days are given in half day increments.  The top row shows the year, and each column represents the temperature data for the coresponding year.

You can now plot, average, and compare trends to your heart’s content.

Explanation of Data Handling

This data was acquired by copying all of the yearly graphs from DMI and writing image handling code in LabView to extract the temperature data.  The 365 days of data in each graph is distributed through 518 columns of pixels, so about 1.4 columns of pixels per day.  I decided to interpolate the data to half days.  Since leap years and non-leap years both consisted of 518 columns,  I have treated all years as 365.25 days.

All of the data suffers from the uncertainties of my extraction process.  So if anybody sees problems with the data please feel free to post your observations as comments here.

I will be showing some results of my analysis in subsequent posts.

Sample comparison:

Here is the image from DMI for the year 2008, followed by a plot of my version of the data for 2008.

DMI Arctic temperature graph for 2008

DMI Arctic temperature graph for 2008

2008 Arctic data as extracted from DMI image

2008 Arctic data as extracted from DMI image

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2 to 1 odds for Prof. David Barber

August 22, 2009

We are well into summer and the Arctic ice extent and area are taking their annual plunge.  How deep will the plunge be?  David Barber of the University of Manitoba thinks it will be very large.  Just a year ago he predicted that the the North Pole would be ice free in the summer of 2008.  National Geographic reported:

“We’re actually projecting this year that the North Pole may be free of ice for the first time [in history],” David Barber, of the University of Manitoba, told National Geographic News aboard the C.C.G.S. Amundsen, a Canadian research icebreaker.

It turned out that he was wrong. 

The 2008 summer minimum turned out to have more ice than 2007′s minimum. But he has a fallback predicton: that the Arctic Basin will be ice free, at least part of the summer, by 2015.  This is a much more profound prediction.  The North Pole is just  a dot on the map, but the Arctic Basin is 4 million square kilometers surrounding the North Pole. 

Last December I challenged Barber on this blog to wager over his 2015 prediction.  He has not taken me up on the offer.  Now I have doubled the odds for him.  One week ago (8/15/09) I sent him the following email:

Dear Prof. Barber,

I took great interest in your widely reported prediction that the Arctic Basin would see its first ice free summer in 2015. Last December I wrote a blog post in which I challenged you to a wager. That post can be seen here:

 http://climatesanity.wordpress.com/2008/12/10/arctic-sea-ice-gone-by-2015-a-challenge-to-david-barber/

 This post has been viewed thousands of times on both my website and on the sites of others who have re-posted it.

 In that post I said:

“I propose a friendly wager based on this prediction. I will bet David Barber $1000(US) that the ice covering the Arctic Basin will not be gone anytime before December 31st, 2015. The bet would involve no transfer of cash between myself or Barber, but rather, the loser will pay the sum to a charitable organization designated by the winner.

Definition of terms. The Arctic Basin is defined by the regional map at Cryosphere Today. “Gone” means the Arctic Basin sea ice area is less that 100,000 square kilometers, according to National Center for Environmental Prediction/NOAA as presented at Cryosphere Today . Charitable organizations will be agreed upon at the time the bet is initiated.

David Barber is a smart guy and evidently an expert in his field. Taking on a wager with an amateur like me should be like shooting fish in a barrel. I look forward to reaching an agreement soon.”

Perhaps you did not see that challenge online – but many other people did. I am now willing to give you two to one odds on the same wager. Are you interested?

Best Regards,
Tom Moriarty

That’s right.   I will put $2000 dollars against Professor Barber’s $1000.   It should be difficult for him to turn this down.  He can put that $2000 dollars to any good cause that he desires.  If this sum is too small, perhaps we can nogotiate something larger.  He knows how to find me.  But I haven’t had a response yet.

One more point: The Arctic Basin is about 4 million square kilometers that roughly surround the North Pole.  If the Arctic Basin were ice free, then it would be a pretty good bet that all the arctic regions south of the Arctic Basin would also be ice free.  So Barber’s bet that the Arctic Basin will be ice free at some point by 2015 is effectively like saying the entire Arctic will be ice free.    Look at the AMSR-E plots of Arctic sea ice extent below.  Anybody interested in taking my wager?

AMSR-E sea ice extent 090822

Sea Ice extent for the Entire Arctic. If the Arctic Basin becomes ice free, then it is a good bet that the entire Arctic will also be ice free.

Sea Ice extent for the Entire Arctic. Ths is a detail from the graph above. If the Arctic Basin becomes ice free, then it is a good bet that the entire Arctic will also be ice free.

Sea Ice extent for the Entire Arctic. Ths is a detail from the graph above. If the Arctic Basin becomes ice free, then it is a good bet that the entire Arctic will also be ice free.

Why am I making this bet?   Because I am concerned about climate exaggerations and the effect they have on public policy makers. It seems quite clear that David Barber was off the mark when he predicted for 2008 “this year that the North Pole may be free of ice for the first time,” because neither the Arctic Ocean, the Arctic Basin nor the North Pole were ice free in the summer of 2008.  Same with the summer of 2009, so far.  And the Arctic Basin will not be ice free by 2015 either. 

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More on Thermohaline Circulation

June 16, 2009

In a previous post “The Thermohaline Circulation Only Stops for Extreme, Unrealistic Models,” I compared the amount of fresh water used in “hosing experiment” models to drastically reduce the thermohaline circulation (THC, or Meridional Overturning Circulation, MOC) to the amount of water flowing over Niagara Falls, or flowing from all rivers into the Arctic,  or coming off of Greenland due to melting ice.

The key number was one Sverdrup, or 1 million cubic meters of fresh water per second.  One Sverdrup of fresh water artificially dumped into the Labrador sea, for 100 years would have the feared effect.  But it turns out that one Sverdrup of fresh water is 350 times the amount of water flowing over Niagara falls, and about 300 times the amount of water from melting ice that flows off of Greenland.  It was seen that there is not plausible source for this amount of extra fresh water to be dumped into the arctic.

An interesting letter that appeared in Science a year ago gives a little more perspective,  So I have reproduced it in full here:

Freshwater Forcing: Will History Repeat Itself?

IN THEIR RESEARCH ARTICLE “REDUCED North Atlantic deep water coeval with the glacial Lake Agassiz freshwater outburst” (4 January, p. 60), H. F. Kleiven et al. present compelling evidence for an abrupt deep-ocean response to the release of freshwater from glacial Lake Agassiz into the northwest Atlantic about 8400 years ago. Such data are particularly important in evaluating the response in ocean models of the Atlantic Meridional Overturning Circulation (MOC) to freshwater forcing. For this event, the freshwater forcing was likely large but short; Clarke et al. (1) estimate that the flood had a freshwater flux of 4 to 9 Sv [Sverdrups] released in 0.5 years.

In this context, we are aware of no possible mechanism that might reproduce such a forcing in response to global warming, and all available model simulations, including those with estimates of maximum Greenland Ice Sheet (GIS) melting rates, indicate that it is very unlikely that the MOC will undergo an abrupt transition during the course of the 21st century (2). Multimodel ensemble averages under Special Report on Emissions Scenario (SRES) A1B suggest a best estimate of 25 to 30% reduction in the overall MOC strength (2). In one example, 14 coupled models simulated a 100-year 0.1-Sv freshwater perturbation to the northern North Atlantic Ocean—17 times the recently estimated melt rates from the GIS [Greenland Ice Sheet]—and the MOC weakened by a multimodel mean of 30% after 100 years; none of the models simulated a shutdown (3). Another model simulated greenhouse gas levels that increased to four times preindustrial values and then remained fixed; the resulting GIS displayed a peak melting rate of about 0.1 Sv, with little effect on the MOC (4). One model simulation uses the SRES  freshwater forcing as an upper-bound estimate of potential GIS melting. In this case, the MOC weakened but subsequently recovered its strength, indicating that GIS melting would not cause abrupt climate change in the 21st century (5). Accordingly, we urge caution in drawing comparisons of the abrupt change 8400 years ago to future scenarios involving, for example, the melting of the GIS and its relevance to human societies.

PETER U. CLARK1, THOMAS L. DELWORTH2, ANDREW J. WEAVER1
1Department of Geosciences, Oregon State University, Corvallis, OR 97331, USA.
2Geophysical Fluid Dynamics Laboratory/NOAA, Princeton, NJ 08542, USA.
3School of Earth and Ocean Sciences, University of Victoria, Victoria, BC V8W 3P6, Canada.

References
1. G. K. C. Clarke, D. W. Leverington, J. T. Teller, A. S. Dyke, Quat. Sci. Rev. 23, 389 (2004).
2. G. A Meehl et al., in Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, S. Solomon et al., Eds. (Cambridge Univ. Press, New York, 2007), pp. 747–845.
3. R. J. Stouffer et al., J. Clim. 19, 1365 (2006).
4. J. K. Ridley, P. Huybrechts, J. M. Gregory, J. A. Lowe, J. Clim. 17, 3409 (2005).
5. J. H. Jungclaus, H. Haak, M. Esch, E. Roeckner, J. Marotzke, Geophys. Res. Lett. 33, 10.1029/2006GL026815 (2006).

So, the event that occurred 8400 years ago involved 4 to 9 Sverdrups of fresh water.  This is THOUSANDS of times greater than the flow of the Niagara Falls today.  It is THOUSANDS of times greater than the amount of fresh water flowing from melting Greenland ice today. It is multiples bigger than the entire fresh water budget into the Arctic.

Note that in my previous post I referred to hosing experiments that pumped up to one Sverdrup of fresh water into the oceans.   The authors of the above letter refer to hosing experiments that used only 0.1 Sverdrups – yet they still point out how gigantic this is compared to actual sources of fresh water in the Arctic today.

So, when Al Gore ominously implies that that the Greenland Ice Sheet [GIS] is going to melt down and dump enough fresh water into the Atlantic Ocean to shut down the Thermohaline Circulation, remember the works of Clarke, et.al., in the above letter: “we urge caution in drawing comparisons of the abrupt change 8400 years ago to future scenarios involving, for example, the melting of the GIS [Greenland Ice Sheet] and its relevance to human societies.”

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