Page 22 of 22

Re: The Greenland Thread

Unread postPosted: Fri 08 Jun 2018, 21:23:23
by Plantagenet
jawagord wrote:Looks like another big accumulation year for the Greenland Snow Mass Balance.

http://polarportal.dk/fileadmin/polarpo ... 180607.png


As the planet warms there is a tendency for more snow to fall in winter because warmer air can hold more water vapor.

However, there is also a tendency for more ablation to occur in the summer, and the data clearly shows the annual mass balance has been negative almost every year for Greenland for years now, resulting in huge losses in ice volume from this ice sheet.

Cheers!

Re: The Greenland Thread

Unread postPosted: Sat 09 Jun 2018, 08:18:24
by jawagord
Anecdotal comments don't really add much to the discussion when it so easy to find observations to the contrary. Scientist have been studying Greenland for less than 40 years that's not long enough to know how the ice sheets that have existed for millions of years behave, but generally more snow takes longer to melt!

The 2017 melt season was less intense than recent years, and was below average melt in the 1981 to 2010 reference period. Surface melting was particularly low in southeastern Greenland.In general, melting was limited to low elevations (below 1500 meters or 4900 feet) along the western and northeastern coastlines. Fewer melt days than average occurred along the Davis Strait and the interior melt pond region along the central western coast.

http://nsidc.org/greenland-today/

Re: The Greenland Thread

Unread postPosted: Sat 09 Jun 2018, 10:52:55
by dohboi
Image

Re: The Greenland Thread

Unread postPosted: Mon 11 Jun 2018, 13:23:01
by Plantagenet
jawagord wrote: more snow takes longer to melt!...


Of course. But when the climate is warming, the warmer summers are more than capable of melting "more snow."

You can see this by looking at the overall annual "mass balance" of Greenland. You can't just look at one year and you can't just look at winter snow accumulation---you also have to look at summer melting and ablation. And when you add them together, you see that Greenland is rapidly losing mass because of high summer melting. And the rate of mass loss is increasing---i.e. as it gets warmer more and more ice melts each summer and the entire Greenland Ice Sheet shrinks.

Currently Greenland is losing more than 300 Gt of ice each year through melting.

Check it out.

Image
Cheers!

Re: The Greenland Thread

Unread postPosted: Tue 12 Jun 2018, 09:25:04
by jawagord
Plantagenet wrote:
jawagord wrote: more snow takes longer to melt!...


Of course. But when the climate is warming, the warmer summers are more than capable of melting "more snow."

You can see this by looking at the overall annual "mass balance" of Greenland. You can't just look at one year and you can't just look at winter snow accumulation---you also have to look at summer melting and ablation. And when you add them together, you see that Greenland is rapidly losing mass because of high summer melting. And the rate of mass loss is increasing---i.e. as it gets warmer more and more ice melts each summer and the entire Greenland Ice Sheet shrinks.

Currently Greenland is losing more than 300 Gt of ice each year through melting.

Check it out.

Image
Cheers!


Plant I did check it out months ago, see my old posts, at current rates it will take 15,000 years for all the ice to melt. That won’t happen of course as earth will be well into the next glaciation cycle in a few 1000 years and then humans won’t be worrying about melting.

Re: The Greenland Thread

Unread postPosted: Wed 13 Jun 2018, 07:27:59
by kanon
Plant I did check it out months ago, see my old posts, at current rates it will take 15,000 years for all the ice to melt.

What happens if it rains? What is the possibility of a hurricane moving over Greenland and dropping a lot of liquid water? I suspect the chances of that type event are increasing.

Re: The Greenland Thread

Unread postPosted: Wed 13 Jun 2018, 08:19:22
by dohboi
Good point, k.

There are good reasons to expect things to go very non-linear in the not-too distant future in Greenland...lots of feedbacks. But for that very reason, rather hard to model.

Re: The Greenland Thread

Unread postPosted: Thu 14 Jun 2018, 02:59:29
by kiwichick

Re: The Greenland Thread

Unread postPosted: Thu 14 Jun 2018, 11:03:33
by dohboi
Yeah, I just saw that and posted it on the Antarctic thread.

There will be more and more 'surprises' like this going forward, that is until the fascists manage to cut off all funding for anymore studies like this, essentially gouging out our eyes just as we are flying into the outskirts of the biggest shitstorm of all time... :twisted:

Re: The Greenland Thread

Unread postPosted: Fri 13 Jul 2018, 14:14:59
by dohboi
https://www.nationalgeographic.com/envi ... greenland/

This Glacier Just Spit Out An Iceberg the Size Of Lower Manhattan

The Helheim Glacier in Greenland just lost 10 billion tons of ice--and scientists captured it on camera


https://www.hln.be/wetenschap-planeet/m ... ~acad4f17/

A 100 meter high iceberg adrift threatens the coasts of Greenland. The local authorities have already evacuated people as a precaution.

The Greenlandic police have instructed the coastal inhabitants of the island to pull away from the coast due to fears that their homes are at risk as the giant ice block breaks.

"We fear that the iceberg is calving, which would cause a flood," said chief executive Lina Daviden...


Image

Re: The Greenland Thread

Unread postPosted: Fri 13 Jul 2018, 20:20:46
by Tanada
remember, if it is 100 meters above the water line it is also 600 to 700 meters below the water line!

Re: The Greenland Thread

Unread postPosted: Wed 18 Jul 2018, 09:18:47
by dohboi
Image

Re: The Greenland Thread

Unread postPosted: Wed 18 Jul 2018, 10:15:34
by rockdoc123
The Danish Meteorological Institute is showing mass balance for Greenland for 2017-2018 well above the instrumental longer term average.
Image

Re: The Greenland Thread

Unread postPosted: Wed 18 Jul 2018, 16:53:39
by dohboi
From rock's (unlinked) source:

Image

Melt this summer has been generally above long term averages.

But of course any short-term behavior, whether last winter's or this summer's, is not very important for determining the long term trend. That is clearly shown in my large graph above.

And just to re-enforce, here's a quote emphasizing the same from the article that rd got his graphs from:

satellites measuring the ice sheet mass have observed a loss of around 200 Gt/year over the last decade

Re: The Greenland Thread

Unread postPosted: Wed 18 Jul 2018, 19:43:46
by rockdoc123
But of course any short-term behavior, whether last winter's or this summer's, is not very important for determining the long term trend. That is clearly shown in my large graph above.


the funny thing about reversal of trends is they have to start somewhere, a 2 year uptick in SMB could be the start of a trend towards increasing SMB. Greenland has seen a number of periods where it was nearly ice-free throughout the Pleistocene which means also that it has seen a number of periods where there was a switch from losses to gains for a period of time. There has been some suggestion the AMO is starting to switch to its negative phase so colder northern SST might be expected.

Re: The Greenland Thread

Unread postPosted: Wed 01 Aug 2018, 15:30:21
by dohboi
From about 50 to 80 million years ago Greenland passed over a hotspot in the Earth's mantle, and consequently it has a band of relatively high geothermal heat flux extending from its northwest corner to its southeast coast. This unexpected high geothermal heat flux implies that existing ice mass loss projections for Greenland are likely too low:

Title: "How Greenland scorched its underside"

https://www.bbc.com/news/science-environment-45031592

Extract: "From its northwest corner to its southeast coast, the world's biggest island has a band of relatively warm bedrock.

Scientists say this confirms Greenland ran over a hotspot of upwelling molten rock tens of millions of years ago as it shifted towards the Arctic."

Re: The Greenland Thread

Unread postPosted: Wed 01 Aug 2018, 17:09:30
by rockdoc123
This unexpected high geothermal heat flux implies that existing ice mass loss projections for Greenland are likely too low:


Doesn't follow, what does follow is that they have attributed all of the change in SMB at Greenland to melt. If a large part of that is instead due to basal melt as a consequence of high heat flow then the relative impact of a warming climate to negative SMB is less to this point in time.

And the interview with one of the authors is quite bizarre, he claims they had no expectation and they expected subsurface conditions to be homogeneous. Obviously, he has been living in isolation given there are numerous publications over the past two decades that talk about high heat flow beneath the Greenland ice sheet, its potential impact on melt and the fact that it could be modeled laterally knowing what the lithology of the subcrop was. Here is an example:

Fahnestock, M, et al, 2001, High geothermal heat flow, basal melt, and the origin of rapid ice flow in Central Greenland. Science, V 294, pp 2338-2341

Note that the measured heat flow was 90 mW/m2 which is about 10 mW/m2 over which it is believed basal ice will melt over large areas. In Antarctica there are large areas in West Antartica with heat flow as high as 120 mW/m2.