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L. Hamilton
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Kwok & Rothrock (2009) "Decline in Arctic sea ice thickness from submarine and ICESat records: 1958–2008" Geophysical Research Letters doi: 10.1029/2009GL039035 [1] The decline of sea ice thickness in the Arctic Ocean from ICESat (2003–2008) is placed in the context of estimates from 42 years of submarine records (1958–2000) described by Rothrock et al. (1999, 2008). While the earlier 1999 work provides a longer historical record of the regional changes, the latter offers a more refined analysis, over a sizable portion of the Arctic Ocean supported by a much stronger and richer data set. Within the data release area (DRA) of declassified submarine sonar measurements (covering ∼38% of the Arctic Ocean), the overall mean winter thickness of 3.64 m in 1980 can be compared to a 1.89 m mean during the last winter of the ICESat record—an astonishing decrease of 1.75 m in thickness. Between 1975 and 2000, the steepest rate of decrease is −0.08 m/yr in 1990 compared to a slightly higher winter/summer rate of −0.10/−0.20 m/yr in the five-year ICESat record (2003–2008). Prior to 1997, ice extent in the DRA was >90% during the summer minimum. This can be contrasted to the gradual decrease in the early 2000s followed by an abrupt drop to <55% during the record setting minimum in 2007. This combined analysis shows a long-term trend of sea ice thinning over submarine and ICESat records that span five decades.
Toggle Commented 1 hour ago on Thinner and thinner at Arctic Sea Ice
Earlier this year a survey-based paper, "What people know," was published in a special Arctic change issue of Journal of Environmental Studies and Sciences. An author's draft of the paper can be downloaded here: The individual graphics, showing what the public believes about trends in Arctic sea ice area, can be found at these links: Fig.1: Fig.2A: Fig.2B: Fig.3:
Toggle Commented 2 days ago on Shock news! at Arctic Sea Ice
Happy to oblige Kevin. You (or anyone else) can borrow the sea ice minimum volume (through 2014) graph here: In a similar vein here is Arctic and Antarctic minimum area: And Arctic extent:
Toggle Commented 2 days ago on Shock news! at Arctic Sea Ice
Intentionally or not it reminded me I'd said OK, and ought to follow through on such things. Send me an email if you want to chat offline.
Toggle Commented 5 days ago on Shock news! at Arctic Sea Ice
Jim, I did say I'd write something new. In the meantime there's another installment of "Polar Polling" that bridges the General Social Survey (2006, 2010) and a more recent survey question about sea ice,
Toggle Commented 5 days ago on Shock news! at Arctic Sea Ice
Here is my bar-graph version of the N and S minimum sea ice area, 1979 through 2014. Feel free to borrow:
Toggle Commented 5 days ago on Shock news! at Arctic Sea Ice
With 2014 done I've updated the cycle plots of extent/area and volume by month. Sent also to Neven in case he wants these for the blog's longterm graphs page. You're welcome to borrow these for your own purposes if useful. Also, a different rendering of 0-2000m ocean heat content, updated through 2014.
Toggle Commented Jan 25, 2015 on PIOMAS January 2015 at Arctic Sea Ice
On surveys we've been asking the public whether they think late-summer Arctic sea ice area has increased, decreased or stayed about the same compared with 30 years ago. A (very brief) new paper in the Journal of Environmental Studies and Sciences plots what that looks like. Here's the key graphic: Write me if you'd like a copy of the paper.
Toggle Commented Jan 18, 2015 on Perception of the Arctic at Arctic Sea Ice
The SEARCH Sea Ice Outlook post-season report is just published, with input from the Sea Ice Prediction Network (SIPN) project:
Toggle Commented Dec 20, 2014 on In the meantime: CryoSat at Arctic Sea Ice
Our survey research on the politicization of US public science/environment perceptions, including Arctic sea ice, hit the streets last week and has been written up with key graphics by Chris Mooney at the Washington Post: The paper itself will be open access for the next month or so, you can download a copy here: I'll have more polar results to report at the AGU meetings in a couple of weeks.
A bar graph showing annual minimum PIOMAS volume, updated through 2014, can be found here:
Toggle Commented Nov 10, 2014 on PIOMAS November 2014 at Arctic Sea Ice
The Sea Level Research Group at University of Colorado has just updated their satellite-based sea level time series, through August 2014. Sea level is still rising, consistent with independent observations of ocean heat content and glacier/ice sheet attrition. A simple graph of the CU sea level series is here: The Sea Level Research Group page has details:
Toggle Commented Nov 5, 2014 on PIOMAS October 2014 at Arctic Sea Ice
FWIW I'll be presenting some new survey research, building on earlier work that Neven wrote about: The new stuff for AGU includes surveys of public knowledge & beliefs as recently as this month. It has a bland title and abstract in the program but the presentation could be spicier, "Polar facts in an age of polarization." This at a session with papers about the human impacts of Arctic Change, Monday afternoon.
Toggle Commented Oct 29, 2014 on PIOMAS October 2014 at Arctic Sea Ice
Steve, this is a great idea. I'll be there and would be happy to help with introductions to SIPN and SEARCH folks if you'd like.
Toggle Commented Oct 29, 2014 on PIOMAS October 2014 at Arctic Sea Ice
Regarding estimates of early-1970s September sea ice extent, I took a shot at this for the graph on this blog's long-term page, also here: As noted within the graph, my 1972-78 values derive from Cavalieri et al. (2003), after regression adjustment to harmonize with 1979-2013 NSIDC values based on their years of overlap (1979-2002). FWIW the Uni Bremen extent series also extended back to 1972, with values quite similar to mine, so I suspect they used the same source.
Toggle Commented Sep 9, 2014 on PIOMAS September 2014 at Arctic Sea Ice
Thanks, Jim. On my screen the images are slightly truncated at right, but click and you see the full series. Y'all are welcome to make use of these graphs if they're helpful.
Toggle Commented Aug 29, 2014 on ASI 2014 update 8: neck and neck at Arctic Sea Ice
Off topic for this thread but of wider interest, NOAA has just updated their global ocean heat and salt content data. I've updated the annual/three month graphs for 0-700 meters and 0-2000 meters
Toggle Commented Aug 29, 2014 on ASI 2014 update 8: neck and neck at Arctic Sea Ice
So, should we do an ASIB poll as a contribution to the SEARCH Sea Ice Outlook this month? Or leave well enough alone?
"Sea Ice Prediction has Easy and Difficult Years" is a sequel to our SEARCH SIO meta-analysis that came out in Geophysical Research Letters earlier this year. The sequel (an article for Witness the Arctic) looks at outcomes from two well-informed office pools that tried to predict September ice extent.
Also of possible interest -- the SIPN webcasts include results from a meta-analysis of SEARCH Sea Ice Outlook predictions from 2008-2013. Starts at 34:00 in this video of the first morning's presentations in Boulder: Neven posted about this SIO meta-analysis in March, It's published in Geophysical Research Letters, Write me if you'd like a copy of the paper.
Toggle Commented May 20, 2014 on SIPN presentation at Arctic Sea Ice
Neven did a fine job presenting the blog at this workshop; many people were intrigued. In later sessions at the workshop, I was able to share some of the blog comments that were already being posted by ASIB folks watching the webcast.
Toggle Commented May 14, 2014 on SIPN presentation at Arctic Sea Ice
I understand that today's webcast will be archived and available for later viewing. I'll post the link here when I have one.
Toggle Commented Apr 1, 2014 on Forecast me not at Arctic Sea Ice
Off topic but possibly of use to some of you: NOAA just updated their Ocean Heat Content time series, which are now complete through 2013. I drew a couple of graphs showing the full series (quarterly and annual values) from 1955 to 2013. The annual values, in particular, give a different look than NOAA's standard graphs, and tell quite a story. 0-2000 meters: 0-700 meters:
Toggle Commented Jan 21, 2014 on Looking for winter weirdness 2014 at Arctic Sea Ice
As a data analyst I am sometimes asked to 'bucket' data for marketing and management analysis, and often graph the buckets by popularity. Are big ice years getting more popular or is small ice the trend? I haven't tried it but I'd guess five buckets would do the job. Mike, can you suggest an example of what this might look like?
But returning to the topic of Neven's post, I'd like to see more data available as CSVs or something similar; there are a number of products online for which typical home computers don't have appropriate software. (It would be great, for us duffers, to be able to us non-specialist software like Excel--a lot of us will never be reasonably justified in acquiring and learning R.) Thanks, Connie, I've been thinking along csv lines too -- it should be a simple fix for most sites. Do you have particular examples in mind?