Sub/Alpine meadows, fires, & climate change

General discussions on hiking in Oregon and the Pacific Northwest
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rubiks
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Re: Sub/Alpine meadows, fires, & climate change

Post by rubiks » November 1st, 2022, 7:01 am

BigBear wrote:
October 31st, 2022, 10:36 am
I can't do all the work for you.
No problem, I didn't expect you to. Sea ice on average is a few meters thick. Land ice on average is a few kilometers thick. That's nearly 1000x thicker! This means that more ice is tied up in glaciers (on land) than sea ice (in the water).

I'm trying to understand your selective mention of surface coverage, which seems deliberately misleading in the context of this thread. I don't know why wouldn't mention volume or mass, both of which are a more relevant metric.
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drm
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Re: Sub/Alpine meadows, fires, & climate change

Post by drm » November 1st, 2022, 8:07 am

Climate scientists have a surprising habit: They often underplay the climate threat. In 2007 a team led by Stefan Rahmstorf compared actual observations with projections made by theoretical models for three key climate variables: atmospheric carbon dioxide, global average temperatures and sea-level rise. While the projections got CO2 levels right, they were low for real temperature and sea level rise. In 2008 Roger Pielke, Jr., found that sea-level rise was greater than forecast in two of three prior Intergovernmental Panel on Climate Change reports. In 2009 a review of hundreds of papers on climate change identified several areas where scientists had lowballed event predictions but none in which they had overstated them.
My note: these are for scientific publications. The media and non-scientist articles are not included here.

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Re: Sub/Alpine meadows, fires, & climate change

Post by BigBear » November 1st, 2022, 8:26 am

I just googled the information and looked for the first scientific source that discussed the amount of sea ice versus land ice.

Misleading facts: land ice averages a few kilometers of thickness. That doesn't even pass the sniff test. A kilometer is 6/10ths of a mile in length, so your saying that the average land ice is miles of thickness as in more than 10,000 feet thick? Seriously? You can't even bluff your way by saying it's this thick in the center of Antarctica because we have Messner's account that the center is ice-free.

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Re: Sub/Alpine meadows, fires, & climate change

Post by drm » November 1st, 2022, 8:40 am

At its thickest point the ice sheet is 4,776 meters deep. It averages 2,160 meters thick, making Antarctica the highest continent. This ice is 90 percent of all the world's ice and 70 percent of all the world's fresh water.
As to ice-free areas in Antarctica:
In Antarctica there are, in addition to mountaintops and nunataks, other natural snow- and ice-free areas often referred to as "Antarctic oases" or "dry valleys". These areas are surrounded by the Antarctic ice sheet or, in coastal areas, are situated between the ice sheet and the Antarctic ice shelves.

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retired jerry
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Re: Sub/Alpine meadows, fires, & climate change

Post by retired jerry » November 1st, 2022, 9:05 am

"My note: these are for scientific publications. The media and non-scientist articles are not included here."

yeah, scientific publications are pretty good. Like what sgyoung said.

It's the media and non scientists that exaggerate in an attempt to get more clicks or persuade people.

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Re: Sub/Alpine meadows, fires, & climate change

Post by sgyoung » November 1st, 2022, 7:03 pm

BigBear wrote:
November 1st, 2022, 8:26 am
I just googled the information and looked for the first scientific source that discussed the amount of sea ice versus land ice.

Misleading facts: land ice averages a few kilometers of thickness. That doesn't even pass the sniff test. A kilometer is 6/10ths of a mile in length, so your saying that the average land ice is miles of thickness as in more than 10,000 feet thick? Seriously? You can't even bluff your way by saying it's this thick in the center of Antarctica because we have Messner's account that the center is ice-free.
It's pretty deep though: https://www.nsf.gov/geo/opp/antarct/sci ... h%20water.

Messner's account reflects his observations of a very small slice of a very large continent, so the presence of some barren and ice free valleys isn't all that important in the grand scheme of things.

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Re: Sub/Alpine meadows, fires, & climate change

Post by rubiks » November 2nd, 2022, 8:28 am

BigBear wrote:
November 1st, 2022, 8:26 am
I just googled the information and looked for the first scientific source that discussed the amount of sea ice versus land ice.

Misleading facts: land ice averages a few kilometers of thickness. That doesn't even pass the sniff test. A kilometer is 6/10ths of a mile in length, so your saying that the average land ice is miles of thickness as in more than 10,000 feet thick? Seriously? You can't even bluff your way by saying it's this thick in the center of Antarctica because we have Messner's account that the center is ice-free.
Congratulations, BigBear, you are one of today's lucky 10,000! As drm and sgyoung pointed out, the ice in Antarctica averages 2,160 meters thick, and gets as thick as 4,776 meters. 4,776 meters is more than 15,000 feet, or almost three miles!

At the south pole proper, some of that ice is being put to good use in the form of a one cubic kilometer neutrino detector called IceCube. In college I had a professor who did research at IceCube's predecessor.

I hope you can appreciate this learning experience, and I also hope you take it as an opportunity to revisit other facts that you may have dismissed out of hand in the past. Who knows how many other cool bits of information you rejected because they failed your "sniff test", and how that might have led you to further incorrect conclusions elsewhere. I understand that some folks out there were never taught this stuff, or never sought to learn it, and that's okay. But what's not okay is to be willfully ignorant, to continue holding on to misinformation when presented with evidence to the contrary, or to spread disinformation to others.
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Water
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Re: Sub/Alpine meadows, fires, & climate change

Post by Water » November 3rd, 2022, 7:23 pm

eh, I was going to ask if anyone wanted to go burn a favorite sub-alpine meadow and hack some small trees with me now that it's really wet out but I think the moment is lost.. :lol:

really appreciate the discussion this has engendered overall.

incredible stats about the amount of ice in Greenland and Antarctica, just phenomenal to think about. Impressive to think this existed over much of North America too as (geologically) recently as 20,000 years ago.
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Re: Sub/Alpine meadows, fires, & climate change

Post by BigBear » November 4th, 2022, 5:59 am

15,000 feet of ice is even more ridiculous, if you don't include a fact that may make you one of those lucky 10,000 people. I know I was when I read the other extreme fact. Face it, 15,000 feet of ice would over all but the top 14,000 feet of Everest - that's insane. What's the sniff test I was thinking: the highest point in Antarctica is only 16,050 feet high. It would be quite the un-complishment to walk over off the ice sheet and place a boot on the summit. But, wait, all those summit photos show the mountain jutting thousands of feet above the snow and ice that surround it? So, how can both 15,000 feet of ice on land with some form of positive elevation exist with 16,050 still being the highest point? The fact I didn't know and I suspect you didn't either. I was thinking the ice flows were above sea level. I was not aware that the lowest elevation of land was in Antarctica at an insane 11,500 feet BELOW sea level. Thus, a 15,000 foot thick chunk of ice would be less than 4,000 beet above sea level which would make more sense, relative to the other topography.

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Re: Sub/Alpine meadows, fires, & climate change

Post by drm » November 4th, 2022, 7:31 am

Has it ever occurred to you to check anything online before posting? The reason the Vinson Massif sticks way above the ice is because it is near the coast, where the ice is thinner. There are some mountains in the central region that are completely covered by ice.

I could also spend some time digging more into how much the heavy ice has depressed the altitude of the land below it, and to what extent, but maybe you could take that up as an exercise. It is quite easy to measure, as something like an ice sonar can easily measure the depth. I have read that land beneath the ice is below sea level but I don't know - on average - how far.

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