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Messages - Grubbegrabben

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1
Arctic sea ice / Re: Are 3 dimensions better than 2?
« on: April 03, 2019, 03:24:26 PM »
3 dimensions are real, 2 dimensions is just a concept, an idea, an abstract of reality.

2
The linked websites indicate that the IPCC is not ignoring ocean and cryosphere interactions for future climate change projections, and that a promising Special Report on this topic will be issued in September 2019.  Unfortunately, I strongly suspect that this special report will not address MICI risks, and will likely discount the speed and intensity of many of the coming ice-climate feedback mechanisms:

Title: "The Ocean and Cryosphere in a Changing Climate"

https://www.ipcc.ch/report/srocc/

Extract: "During its 45th Session (Guadalajara, Mexico, 28 – 31 March 2017), the IPCC Panel approved the outline of the Special Report on the Ocean and Cryosphere in a Changing Climate (SROCC). The report will be finalized in September 2019."

See also:

Title: "Decision IPCC/XLV-2. Sixth Assessment Report (AR6) Products, Outline of the Special Report on climate change and oceans and the cryosphere"

https://www.ipcc.ch/site/assets/uploads/2018/04/Decision_Outline_SR_Oceans.pdf

Extract: "Chapter 1: Framing and Context of the Report (~15 pages)
• Integrated storyline of the report, chapter narrative, chapter sequence and their linkages (including coverage of extremes and abrupt change and irreversible changes)
• Definition of ocean and cryosphere and their components
• Observing capacities, progress and limitations (e.g., time series and spatial coverage)
• Assessment methodologies, including indigenous and community knowledge, risk, including cascading risks, and applications of detection and attribution
• Role of ocean and cryosphere in the climate system, including characteristics, ocean heat content in Earth’s energy budget, key feedbacks and time scales
• Implications of climate-related ocean and cryosphere change for resources, natural systems (e.g., change and loss of habitat, extinctions), human systems (e.g., psychological, social, political, cultural and economic aspects), and vulnerability assessments, adaptation limits, and residual risks
• Solutions, including policy options and governance, and linkages of this report to relevant institutional and policy contexts (e.g., UNFCCC, Paris Agreement and SDGs, Sendai Framework)
• Treatment of vulnerabilities and marginalized areas and people (e.g., gender) in this report
• Scenarios and time frames considered in this report
• Treatment of uncertainty

Chapter 3: Polar Regions (~50 pages)
• Changes in atmospheric and ocean circulation that influence polar regions, including climate feedbacks and teleconnections and paleo perspectives
• Greenland and Antarctic ice sheets and ice shelves, Arctic and Antarctic glaciers, mass change, physics of dynamical instability and accelerated ice discharge; consequences for ocean circulation and biogeochemistry, and sea level
• Changing snow cover, freshwater ice and thawing permafrost (terrestrial and subsea); carbon flux and climate feedbacks; impacts on infrastructure and ecosystems; community- based adaptation
• Changing sea ice; effects on ocean and atmospheric circulation and climate, including teleconnections; implications for ecosystems, coastal communities, transportation and industry
• Changing polar ocean (physical, dynamical and biogeochemical properties), implications for acidification, carbon uptake and release; impacts on ecosystems and their services (e.g., fisheries); adaptation options (e.g., ecosystem-based management and habitat protection) and limits to adaptation
• Access to resources and ecological, institutional, social, economic, livelihood and cultural consequences of polar change, including issues of international cooperation
• Responses to enhance resilience

Chapter 6: Extremes, Abrupt Changes and Managing Risks (~20 pages)
• Risks of abrupt change in ocean circulation and cryosphere and potential consequences
• Extreme ENSO events and other modes of variability and their implications
• Marine heat waves and implications
• Changes in tracks, intensity, and frequency of tropical and extra-tropical storms and associated wave height
• Cascading risks (e.g., storm surge and sea level rise), irreversibility, and tipping points
• Monitoring systems for extremes, early warning and forecasting systems in the context of climate change
• Governance and policy options, risk management, including disaster risk reduction and enhancing resilience"

3
Arctic sea ice / Re: 2019 sea ice area and extent data
« on: March 17, 2019, 08:31:02 PM »
NSIDC Total Area as at 16 March 2019 (5 day trailing average)  13,113,396 km2
         
Total Area         
 13,113,396    km2      
 162,395    km2   >   2010's average.
 371,029    k   >   2018
-220,565    k   <   2000's average.
         
Total gain/loss   -10    k   loss
Peripheral Seas    15    k   gain
Central Seas__    1    k   gain
Other Seas___   -26    k   loss
         
Peripheral Seas         
Bering _______    15    k   gain
Baffin  Bay____   -1    k   loss
Greenland____   -0    k   loss
Barents ______    1    k   gain
         
CAB Seas         
Beaufort_____   -1    k   loss
CAA_________    1    k   gain
East Siberian__   -1    k   loss
Central Arctic_    1    k   gain
         
Kara_________   -4    k   loss
Laptev_______   -1    k   loss
Chukchi______    5    k   gain
         
Other Seas         
Okhotsk______   -10    k   loss
St Lawrence___   -11    k   loss
Hudson Bay___   -5    k   loss
Area LOSS 10 k, 23 k less than the 2010's average GAIN of 13 k on this day.

Other Stuff
GFS indicates that overall the Arctic temperature anomaly will gradually change from around -0.5 degrees to +3 over the next 10 days, with the additional warmth mainly from the Pacific side. 

A surprising swift switch from area gain to area loss, entirely due to losses in the Okhotsk, St Lawrence and Hudson seas. From today posting will assume the melting season is getting underway.

4
In regards to my last post, the linked reference (see also the first attached image and associated caption below, and the second image that shows the basal meltwater drainage system beneath Thwaites) provides more evidence of high geothermal flux and associated basal melt water beneath the Thwaites Glacier, both of which will threaten its future stability, and they both work to refill the recently drainage subglacial lakes beneath Thwaites:

Dustin M. Schroeder, Donald D. Blankenship, Duncan A. Young, and Enrica Quartini, (2014), "Evidence for elevated and spatially variable geothermal flux beneath the West Antarctic Ice Sheet", PNAS, doi: 10.1073/pnas.1405184111

http://www.pnas.org/content/early/2014/06/04/1405184111.abstract

http://www.pnas.org/content/suppl/2014/06/04/1405184111.DCSupplemental

Also see:
http://www.utexas.edu/news/2014/06/10/antarctic-glacier-melting/

Caption: "This map shows the locations of geothermal flow underneath Thwaites Glacier in West Antarctica that were identified with airborne ice-penetrating radar. The dark magenta triangles show where geothermal flow exceeds 150 milliwatts per square meter, and the light magenta triangles show where flow exceeds 200 milliwatts per square meter. Letters C, D and E denote high melt areas: in the western-most tributary, C; adjacent to the Crary mountains, D; and in the upper portion of the central tributaries, E. Credit: University of Texas Institute Geophysics"

5
In September 2012 the Thwaites Ice Tongue flow rate surged and continued flowing at a high rate through the end of 2012 (and this high flow rate can be associated with the surface elevation depression shown in the first image)

In this regards, the linked reference studies a subglacial draining event beneath Thwaites Glacier from June 2013 to January 2014 (see the last three attached images):

Smith et. al. (2017), "Connected subglacial lake drainage beneath Thwaites Glacier, West Antarctica", The Cryosphere, 11, 451–467, doi:10.5194/tc-11-451-2017

http://www.the-cryosphere.net/11/451/2017/tc-11-451-2017.pdf

Abstract. We present conventional and swath altimetry data from CryoSat-2, revealing a system of subglacial lakes that drained between June 2013 and January 2014 under the central part of Thwaites Glacier, West Antarctica (TWG). Much of the drainage happened in less than 6 months, with an apparent connection between three lakes spanning more than 130 km. Hydro-potential analysis of the glacier bed shows a large number of small closed basins that should trap water produced by subglacial melt, although the observed largescale motion of water suggests that water can sometimes locally move against the apparent potential gradient, at least during lake-drainage events. This shows that there are important limitations in the ability of hydro-potential maps to predict subglacial water flow. An interpretation based on a map of the melt rate suggests that lake drainages of this type should take place every 20–80 years, depending on the connectivity of the water flow at the bed. Although we observed an acceleration in the downstream part of TWG immediately before the start of the lake drainage, there is no clear connection between the drainage and any speed change of the glacier."

There is more information on the June 2013 to Jan 2014 drainage of four subglacial lakes beneath the Thwaites Glacier.  The article is entitled: "Hidden lakes drain below West Antarctica’s Thwaites Glacier".

http://www.washington.edu/news/2017/02/08/hidden-lakes-drained-under-west-antarcticas-thwaites-glacier/

Extract: "Researchers at the University of Washington and the University of Edinburgh used data from the European Space Agency’s CryoSat-2 to identify a sudden drainage of large pools below Thwaites Glacier, one of two fast-moving glaciers at the edge of the ice sheet. The study published Feb. 8 in The Cryosphere finds four interconnected lakes drained in the eight months from June 2013 and January 2014. The glacier sped up by about 10 percent during that time, showing that the glacier’s long-term movement is fairly oblivious to trickles at its underside.

Melting at the ice sheet base would refill the lakes in 20 to 80 years, Smith said. Over time meltwater gradually collects in depressions in the bedrock. When the water reaches a certain level it breaches a weak point, then flows through channels in the ice. As Thwaites Glacier thins near the coast, its surface will become steeper, Smith said, and the difference in ice pressure between inland regions and the coast may push water coastward and cause more lakes to drain."

Obviously, when these subglacial lakes have refilled by the basal meltwater drainage system, in the coming decades, Thwaites will be primed for another surge.

6
As I said that I would make a few posts (which I take to mean three posts today), I provide the following like to an article that cites research that confirms that current ice mass loss is contributing (see blue line in the attached image) to the drift of the Earth's rotational axis about the poles:

Scientists Identified Three Reasons Responsible for Earth’s Spin Axis Drift

http://www.geologyin.com/2018/09/scientists-identified-three-reasons.html

Extract: "A typical desk globe is designed to be a geometric sphere and to rotate smoothly when you spin it. Our actual planet is far less perfect—in both shape and in rotation.

Earth is not a perfect sphere. When it rotates on its spin axis—an imaginary line that passes through the North and South Poles—it drifts and wobbles. These spin-axis movements are scientifically referred to as "polar motion." Measurements for the 20th century show that the spin axis drifted about 4 inches (10 centimeters) per year. Over the course of a century, that becomes more than 11 yards (10 meters).

Using observational and model-based data spanning the entire 20th century, NASA scientists have for the first time identified three broadly-categorized processes responsible for this drift—contemporary mass loss primarily in Greenland, glacial rebound, and mantle convection.

"The traditional explanation is that one process, glacial rebound, is responsible for this motion of Earth's spin axis. But recently, many researchers have speculated that other processes could have potentially large effects on it as well," said first author Surendra Adhikari of NASA's Jet Propulsion Laboratory in Pasadena, California."

7
Arctic sea ice / Re: The 2018 melting season
« on: June 05, 2018, 09:04:33 PM »
12Z ECMWF bottoms out fairly early as well with a minimum SLP of around 970hPa. Given the different location and timing of this cyclone compared to the GAC, I think the effects will be qualitatively different and we will need to hold on any comparisons until reanalysis. However, this setup appears to be catastrophic.


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