What does the land under Antarctica’s ice sheet look like? • Hacker News Board

Re: What does the land under Antarctica’s ice sheet look like?

#81

Post by yencabulator » Sat, Jan 14, 2023, 4:18 PM UTC

telesilla wrote: post #41

cwmma wrote: post #28

Earlier quoted context omitted.

I mean it's what the content would look like for a long time, Scandinavia is still not done rising from the last glacial period.

Are there earthquakes or other events that are recognized on a human scale?

When my mom was a kid, the edge of my grandparent's lot used to have a rowboat tied very near it. Now the sea is about a block away.

The seismic tremors caused by the uplift are so minor that no layperson even knows about them.

Re: What does the land under Antarctica’s ice sheet look like?

#82

Post by gus_massa » Sun, Jan 15, 2023, 6:15 PM UTC

gus_massa wrote: post #80

therealdrag0 wrote: post #77

Earlier quoted context omitted.

I just read this article about it https://nautil.us/why-our-intuition-about-sea_level-rise-is-...

Let's do some back of the envelope calculation. Using data from https://en.wikipedia.org/wiki/Antarctic_ice_sheet The volume of the Antarctic Ice Sheet is 26.5 million cubic kilometres. If you use the Spherical Cow Theorem and put all that ice into an sphere, the radius is 185km https://www.wolframalpha.com/input?i=sphere+of+26.5+million+... . The gravity caused by that sphere at the surface is 0.047m/s^2 https://www…

The integral is wrong. Let's try again:

First, let's calculate the additional high. It's better to imagine the 0 is in the oposite pole, and the additional height is very similar to the old integral without the 2*pi*r https://www.wolframalpha.com/input?i=Integral+from+x+to+2000... i.e. 0.0048 * 185^2 * (1/r - 1/20000)

Now we must integrate it again, with the 2*pi*r Integral from 185 to 20000 of (0.0048 * 185^2 * (1/r-1/20000)), that is only 606km^3, so 1/80 of my previous calculation. So, fixing the last part of my comment with the new numbers:

But melting the Antarctic Ice sheet will release 24,300,000 km^3 So it's only a .0025% more. In other units, melting all the Antarctic Ice would increase the sea level like 58m (190ft). The additional effect of the gravity is less than .0004m (4mm, 1/8 inch)

Re: What does the land under Antarctica’s ice sheet look like?

#83

Post by spiralx » Mon, Jan 16, 2023, 11:48 AM UTC

nirimda wrote: post #18

seanmcdirmid wrote: post #12

Earlier quoted context omitted.

Doesn’t Antarctica technically have the largest deserts in the world?

Only because it's at the south pole. If we tilted the earth a bit, it would warm up and start raining. But if we tilted the earth a bit, Australia could probably also get wetter. As far as I understand it, the dryness of Australia, the Sahara etc are caused by the particular location from the equator, where moist air is lifted and brought to the equator and dumped there as rain. So if we pushed Australia further from…

The dryness of Australia comes from the fact that current bring cold Antarctic water up to its west coast which leads to dry winds that blow eastward, which compounds with the complete lack of any mountain ranges to serve as rain shields to leave most of the continent dry. Even the mountains in the east of the continent are barely high enough to form a rain shield, if they were even a bit smaller then the east coast would be as dry as the rest of the continent.

Moist tropical air barely reaches the very top of Australia - instead it hits places like Java, where the abundant rainfall and numerous active volcanoes provide ridiculously fertile land that currently supports 150 million people - 5x that of Australia - despite being 50 times smaller.