Greenland - What Do We Know, What Is The Long Term Future And Is There Any Evidence Of A Melt Out?

[knocker]

Greenland's fastest glaciers (those with marine fronts) lose area faster in warm summers

https://t.co/h3QBOlNYOo

Edited January 28, 2016 by knocker

[knocker]

 

[Nouska]

Has this been posted elsewhere?

Early online release pdf.

http://journals.ametsoc.org/doi/pdf/10.1175/JCLI-D-15-0391.1

http://news.rutgers.edu/news/climate-change-greenland-melting-tied-shrinking-arctic-sea-ice/20160327#.Vv56TY9OI5s

[knocker]

 

[BornFromTheVoid]

The melt season is off to a roaring start for Greenland.

A message sent out on cryolist today:

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Dear all,
 
On behalf of a number of colleagues and collaborators we would like to alert you to an unusually early melt event over the Greenland ice sheet this week.
We calculate around 11.8% of the area of the ice sheet melted yesterday and according to our analysis (back to 1990, we will extend this back to 1980 shortly), this is a full month earlier over such a large area (more than 10% of the ice sheet) than has occurred previously.
 
Observations from Greenland show that for example, Kangerlussuaq measured 17.8C (only 0.2C off the record temperature measured for the whole of Greenland in April) and Summit station -6.6C, a new record for April. PROMICE station KAN_U showed a daily mean temperature of 0.5C with a maximum hourly temperature of 3.05C, most of the lower PROMICE stations recorded temperatures between 5 and 10C.
 
The culprit driving melt at this time is an interesting omega pressure pattern with a very cold north America and warm air over Greenland.
 
We have assembled some information from AWS, radiosondes and models in the attached pdf document to explain the context of this strange start to the melt season in 2016. As usual, since 2013, daily updated surface mass balance plots, and PROMICE observations as well as GRACE total mass balance can all be viewed  here (in English):
 
http://polarportal.dk/en/groenlands-indlandsis/nbsp/isens-overflade/
 
Data and model output is available for research purposes.
 
On behalf of Polar Portal scientists at DMI, DTU and GEUS,
 
Best wishes
 
Ruth Mottram

[knocker]

Streuth that's impressive. As is the WAA into Greenland

[knocker]

 

[knocker]

Atmospheric drivers of Greenland surface melt revealed by Self Organizing Maps

Quote

Recent acceleration in surface melt on the Greenland ice sheet (GrIS) has occurred concurrently with a rapidly warming Arctic and has been connected to persistent, anomalous atmospheric circulation patterns over Greenland. To identify synoptic setups favoring enhanced GrIS surface melt and their decadal changes, we develop a summer Arctic synoptic climatology by employing self organizing maps (SOM). These are applied to daily 500 hPa geopotential height fields obtained from the christmas pudding Retrospective Analysis for Research and Applications (MERRA) reanalysis, 1979-2014. Particular circulation regimes are related to meteorological conditions and GrIS surface melt estimated with outputs from the Modèle Atmosphérique Régional (MAR).

Our results demonstrate that the largest positive melt anomalies occur in concert with positive height anomalies near Greenland associated with wind, temperature and humidity patterns indicative of strong meridional transport of heat and moisture. We find an increased frequency in a 500 hPa ridge over Greenland coinciding with a 63% increase in GrIS melt between the 1979-1988 and 2005-2014 periods, with 75.0% of surface melt changes attributed to thermodynamics, 17% to dynamics, and 8.0% to a combination. We also confirm that the 2007-2012 time period has the largest dynamic forcing relative of any period, but also demonstrate that increased surface energy fluxes, temperature, and moisture separate from dynamic changes contributed more to melt even during this period. This implies that GrIS surface melt is likely to continue to increase in response to an ever warmer future Arctic, regardless of future atmospheric circulation patterns.

http://onlinelibrary.wiley.com/doi/10.1002/2015JD024550/abstract

[Gael_Force]

10 minutes ago, knocker said:

These are applied to daily 500 hPa geopotential height fields obtained from the christmas pudding Retrospective Analysis for Research and Applications (MERRA) reanalysis, 1979-2014.

That should read modern and era.

Daft set up that such should fall foul of a swear filter.

[knocker]

9 minutes ago, Gael_Force said:

That should read modern and era.

Daft set up that such should fall foul of a swear filter.

Quite. I'm afraid that has caught me out before.

[knocker]

 

[knocker]

 

[shuggee]

Greenland witnessed it's highest recorded June temp at 24ºC last week:

https://www.washingtonpost.com/news/capital-weather-gang/wp/2016/06/10/greenland-witnessed-its-highest-june-temperature-ever-recorded-on-thursday/

[Gray-Wolf]

What would be of a greater interest would be a repeat of the high extent melt we saw in 2012? At the time many folk grabbed onto the wrong end of the stick when a researcher mentioned the last time Summit showed signs of melt and folk took it as a 'cyclical even' with a 160 yr return time........ a repeat , so soon after 2012, will stop their excuse to not worry ( as it's all happened before....) about the scary changes happening on Greenland right now!!!

[knocker]

More on this

 

[knocker]

A high resolution record of Greenland mass balance

Quote

We map recent Greenland Ice Sheet elevation change at high spatial (5-km) and temporal (monthly) resolution using CryoSat-2 altimetry. After correcting for the impact of changing snowpack properties associated with unprecedented surface melting in 2012, we find good agreement (3 cm/yr bias) with airborne measurements. With the aid of regional climate and firn modelling, we compute high spatial and temporal resolution records of Greenland mass evolution, which correlate (R = 0.96) with monthly satellite gravimetry, and reveal glacier dynamic imbalance. During 2011-2014, Greenland mass loss averaged 269 ± 51 Gt/yr. Atmospherically-driven losses were widespread, with surface melt variability driving large fluctuations in the annual mass deficit. Terminus regions of five dynamically-thinning glaciers, which constitute less than 1% of Greenland's area, contributed more than 12% of the net ice loss. This high-resolution record demonstrates that mass deficits extending over small spatial and temporal scales have made a relatively large contribution to recent ice sheet imbalance.

http://onlinelibrary.wiley.com/doi/10.1002/2016GL069666/abstract

[knocker]

 

[stewfox]

Early season higher surface melt rate back to normal, annoying for some no doubt.

[knocker]

 

[knocker]

 

[knocker]

 

[stewfox]

3 hours ago, knocker said:

 

Am i reading this right

We get 350 extra G tons of snow fall but still we get -8 G tons (SMB) of ice melt over the summer season.

What was the SMB in 2012 ?

 

[knocker]

 

[knocker]

Published on Mar 22, 2017

Scientists are investigating a new "positive feedback" in Greenland's melting ice sheet - as climate warms, more microbial growth on the ice sheet is darkening ice, and hastening ice melt and sea level rise.

 

[knocker]

A tipping point in refreezing accelerates mass loss of Greenland’s glaciers and ice caps

Quote

Melting of the Greenland ice sheet (GrIS) and its peripheral glaciers and ice caps (GICs) contributes about 43% to contemporary sea level rise. While patterns of GrIS mass loss are well studied, the spatial and temporal evolution of GICs mass loss and the acting processes have remained unclear. Here we use a novel, 1 km surface mass balance product, evaluated against in situ and remote sensing data, to identify 1997 (±5 years) as a tipping point for GICs mass balance. That year marks the onset of a rapid deterioration in the capacity of the GICs firn to refreeze melangel delighter. Consequently, GICs runoff increases 65% faster than melangel delighter production, tripling the post-1997 mass loss to 36±16 Gt−1, or ∼14% of the Greenland total. In sharp contrast, the extensive inland firn of the GrIS retains most of its refreezing capacity for now, buffering 22% of the increased melangel delighter production. This underlines the very different response of the GICs and GrIS to atmospheric warming.

http://www.nature.com/articles/ncomms14730