22 ms·

Scientists discover fossil plants beneath mile-deep Greenland ice

108 points by kvee 6y ago

deleted 6y ago
[deleted]
Proven 6y ago
Reading HN for a few years now, I was under the impression all Greenland ice had already melted
ceejayoz 6y ago
Fossil plants, which should be a little less surprising.
- rurp 6y ago
  Yeah fossil should really be included in the title for clarity.
  - dang 6y ago
    Ok, we've fossilized the title above.
- _Microft 6y ago
  I didn’t expect live plants when reading the headline. Something becoming a fossil after being buried by a mile of ice isn’t that surprising, in my opinion? Live plants would have warranted a qualifier in my opinion. Edit: but yes, you are of course right that adding ‘fossil’ would have made the headline clearer.
  - TeMPOraL 6y ago
    If the headline said "viruses" or "bacteria" instead of "plants", I'd definitely expect they meant live ones (and also that it's time to shelter-in-place even more than I already am). Given how ancient arctic pathogens are a relatively well-known popular culture meme, I also thought the headline means live plants.
    - _Microft 6y ago
      Ha, then it's just me. Though... plant-based life coming out of the cold reminds me of https://en.wikipedia.org/wiki/The_Thing_from_Another_World https://en.wikipedia.org/wiki/The_Thing_from_Another_World
  - waheoo 6y ago
    Fossils aren't plants, they're rocks. Why would anyone assume you mean rocks when you say plants?
    - simonh 6y ago
      "Scientists discover rocks beneath mile-deep Greenland ice" maybe isn't quite as catchy, or as useful in conveying relevant information.
      - darkerside 6y ago
        But it would have the advantage of being accurate. This is why they invented words like fossil.
        deleted 6y ago
        [deleted]
EGreg 6y ago
“The military mission failed, but the science team did complete important research” so they say... hmm
867-5309 6y ago
>The discovery helps confirm a new and troubling understanding that the Greenland Ice Sheet has melted entirely during recent warm periods in Earth's history -- like the one we are now creating with human-caused climate change. Earth naturally warming was a.. natural event - there is no need to label it troubling or liken it to an artificially-warmed event
- dang 6y ago
  Please don't take HN threads into classic generic flamewar topics, and definitely not with provocative one-liners, which have trollish effect if not trollish intent. https://hn.algolia.com/?query=troll%20effects%20by:dang&dateRange=all&page=0&prefix=true&sort=byDate&type=comment https://hn.algolia.com/?query=troll%20effects%20by:dang&date... Note the site guidelines on this: "Eschew flamebait. Don't introduce flamewar topics unless you have something genuinely new to say. Avoid generic tangents." https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newsguidelines.html
  - 867-5309 6y ago
    honestly, there was no intent, but I did enjoy the twisted knickers! duly noted
    - dang 6y ago
      All twisted knickers are the same and it gets old fast, especially to the bystanders (a.k.a. the rest of us) who have no stake in the titillation. So please don't. When it comes to trolling, effects matter more than intent: https://hn.algolia.com/?dateRange=all&page=0&prefix=true&sort=byDate&type=comment&query=troll%20effects%20by:dang https://hn.algolia.com/?dateRange=all&page=0&prefix=true&sor....
- animal_spirits 6y ago
  > The new study provides strong evidence that Greenland is more sensitive to climate change than previously understood -- and at risk of irreversibly melting. I think its silly to say _irreversibly_ melting. It apparently was completely ice free at one point, and then something natural caused it to freeze over. Likely it could happen again in the future
fsloth 6y ago
Melting the entire Greenland ice sheet would cause a 7.2 m sea level rise globally. So the questions will it melt and how fast are quite ... interesting.
- misja111 6y ago
  In some places it will rise, in some others not: https://www.sciencemag.org/news/2016/02/how-melting-ice-sheet-could-actually-lower-sea-level-some-places https://www.sciencemag.org/news/2016/02/how-melting-ice-shee...
  - 0xdde 6y ago
    What's the point of bringing this up? On average it is still going to be a tremendous rise.
    - TheAdamAndChe 6y ago
      It's important to mention the subtleties so we can best prepare, and so that naysayers can't point to localized sea level drops as proof that global warming is a hoax.
- LinuxBender 6y ago
  This is probably a little off topic, but it can all melt in a few hours with one decent sized asteroid. This happened before in Greenland. [1] Geologists have confirmed the impact that melted all the ice due to the existence of billions of microscopic diamonds in the crater. My question is, are we monitoring enough of space to know if a big rock is coming and what will people do? [1] - https://www.sciencemag.org/news/2018/11/massive-crater-under-greenland-s-ice-points-climate-altering-impact-time-humans https://www.sciencemag.org/news/2018/11/massive-crater-under...
  - selftest 6y ago
    If an asteroid of sufficient size were to strike Greenland, I think sea levels rising would be pretty far down the “this is definitely going to kill us all” list.
adolph 6y ago
Original work cited: https://www.pnas.org/content/118/13/e2021442118 https://www.pnas.org/content/118/13/e2021442118 Supplemental materials: https://www.pnas.org/content/pnas/suppl/2021/03/10/2021442118.DCSupplemental/pnas.2021442118.sapp.pdf https://www.pnas.org/content/pnas/suppl/2021/03/10/202144211... Abstract: Understanding the history of the Greenland Ice Sheet (GrIS) is critical for determining its sensitivity to warming and contribution to sea level; however, that history is poorly known before the last interglacial. Most knowledge comes from interpretation of marine sediment, an indirect record of past ice-sheet extent and behavior. Subglacial sediment and rock, retrieved at the base of ice cores, provide terrestrial evidence for GrIS behavior during the Pleistocene. Here, we use multiple methods to determine GrIS history from subglacial sediment at the base of the Camp Century ice core collected in 1966. This material contains a stratigraphic record of glaciation and vegetation in northwestern Greenland spanning the Pleistocene. Enriched stable isotopes of pore-ice suggest precipitation at lower elevations implying ice-sheet absence. Plant macrofossils and biomarkers in the sediment indicate that paleo-ecosystems from previous interglacial periods are preserved beneath the GrIS. Cosmogenic 26Al/10Be and luminescence data bracket the burial of the lower-most sediment between <3.2 ± 0.4 Ma and >0.7 to 1.4 Ma. In the upper-most sediment, cosmogenic 26Al/10Be data require exposure within the last 1.0 ± 0.1 My. The unique subglacial sedimentary record from Camp Century documents at least two episodes of ice-free, vegetated conditions, each followed by glaciation. The lower sediment derives from an Early Pleistocene GrIS advance. 26Al/10Be ratios in the upper-most sediment match those in subglacial bedrock from central Greenland, suggesting similar ice-cover histories across the GrIS. We conclude that the GrIS persisted through much of the Pleistocene but melted and reformed at least once since 1.1 Ma.
Rastonbury 6y ago
Why does the discovery of plants show that ice melted more recently?
- mkl 6y ago
  It's not the existence of the plants, it's the dating of the rocks' last exposure to sunlight with isotopes. The plants show it was quite a bit warmer and lasted for quite a while.

108 points by kvee 6y ago

deleted 6y ago

[deleted]

Proven 6y ago

Reading HN for a few years now, I was under the impression all Greenland ice had already melted

ceejayoz 6y ago

Fossil plants, which should be a little less surprising.

rurp 6y ago
Yeah fossil should really be included in the title for clarity.
- dang 6y ago
  Ok, we've fossilized the title above.
_Microft 6y ago
I didn’t expect live plants when reading the headline. Something becoming a fossil after being buried by a mile of ice isn’t that surprising, in my opinion? Live plants would have warranted a qualifier in my opinion. Edit: but yes, you are of course right that adding ‘fossil’ would have made the headline clearer.
- TeMPOraL 6y ago
  If the headline said "viruses" or "bacteria" instead of "plants", I'd definitely expect they meant live ones (and also that it's time to shelter-in-place even more than I already am). Given how ancient arctic pathogens are a relatively well-known popular culture meme, I also thought the headline means live plants.
  - _Microft 6y ago
    Ha, then it's just me. Though... plant-based life coming out of the cold reminds me of https://en.wikipedia.org/wiki/The_Thing_from_Another_World https://en.wikipedia.org/wiki/The_Thing_from_Another_World
- waheoo 6y ago
  Fossils aren't plants, they're rocks. Why would anyone assume you mean rocks when you say plants?
  - simonh 6y ago
    "Scientists discover rocks beneath mile-deep Greenland ice" maybe isn't quite as catchy, or as useful in conveying relevant information.
    - darkerside 6y ago
      But it would have the advantage of being accurate. This is why they invented words like fossil.
      - deleted 6y ago
        [deleted]

EGreg 6y ago

“The military mission failed, but the science team did complete important research” so they say... hmm

867-5309 6y ago

>The discovery helps confirm a new and troubling understanding that the Greenland Ice Sheet has melted entirely during recent warm periods in Earth's history -- like the one we are now creating with human-caused climate change. Earth naturally warming was a.. natural event - there is no need to label it troubling or liken it to an artificially-warmed event

dang 6y ago
Please don't take HN threads into classic generic flamewar topics, and definitely not with provocative one-liners, which have trollish effect if not trollish intent. https://hn.algolia.com/?query=troll%20effects%20by:dang&dateRange=all&page=0&prefix=true&sort=byDate&type=comment https://hn.algolia.com/?query=troll%20effects%20by:dang&date... Note the site guidelines on this: "Eschew flamebait. Don't introduce flamewar topics unless you have something genuinely new to say. Avoid generic tangents." https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newsguidelines.html
- 867-5309 6y ago
  honestly, there was no intent, but I did enjoy the twisted knickers! duly noted
  - dang 6y ago
    All twisted knickers are the same and it gets old fast, especially to the bystanders (a.k.a. the rest of us) who have no stake in the titillation. So please don't. When it comes to trolling, effects matter more than intent: https://hn.algolia.com/?dateRange=all&page=0&prefix=true&sort=byDate&type=comment&query=troll%20effects%20by:dang https://hn.algolia.com/?dateRange=all&page=0&prefix=true&sor....
animal_spirits 6y ago
> The new study provides strong evidence that Greenland is more sensitive to climate change than previously understood -- and at risk of irreversibly melting. I think its silly to say _irreversibly_ melting. It apparently was completely ice free at one point, and then something natural caused it to freeze over. Likely it could happen again in the future

fsloth 6y ago

Melting the entire Greenland ice sheet would cause a 7.2 m sea level rise globally. So the questions will it melt and how fast are quite ... interesting.

misja111 6y ago
In some places it will rise, in some others not: https://www.sciencemag.org/news/2016/02/how-melting-ice-sheet-could-actually-lower-sea-level-some-places https://www.sciencemag.org/news/2016/02/how-melting-ice-shee...
- 0xdde 6y ago
  What's the point of bringing this up? On average it is still going to be a tremendous rise.
  - TheAdamAndChe 6y ago
    It's important to mention the subtleties so we can best prepare, and so that naysayers can't point to localized sea level drops as proof that global warming is a hoax.
LinuxBender 6y ago
This is probably a little off topic, but it can all melt in a few hours with one decent sized asteroid. This happened before in Greenland. [1] Geologists have confirmed the impact that melted all the ice due to the existence of billions of microscopic diamonds in the crater. My question is, are we monitoring enough of space to know if a big rock is coming and what will people do? [1] - https://www.sciencemag.org/news/2018/11/massive-crater-under-greenland-s-ice-points-climate-altering-impact-time-humans https://www.sciencemag.org/news/2018/11/massive-crater-under...
- selftest 6y ago
  If an asteroid of sufficient size were to strike Greenland, I think sea levels rising would be pretty far down the “this is definitely going to kill us all” list.

adolph 6y ago

Original work cited: https://www.pnas.org/content/118/13/e2021442118 https://www.pnas.org/content/118/13/e2021442118 Supplemental materials: https://www.pnas.org/content/pnas/suppl/2021/03/10/2021442118.DCSupplemental/pnas.2021442118.sapp.pdf https://www.pnas.org/content/pnas/suppl/2021/03/10/202144211... Abstract: Understanding the history of the Greenland Ice Sheet (GrIS) is critical for determining its sensitivity to warming and contribution to sea level; however, that history is poorly known before the last interglacial. Most knowledge comes from interpretation of marine sediment, an indirect record of past ice-sheet extent and behavior. Subglacial sediment and rock, retrieved at the base of ice cores, provide terrestrial evidence for GrIS behavior during the Pleistocene. Here, we use multiple methods to determine GrIS history from subglacial sediment at the base of the Camp Century ice core collected in 1966. This material contains a stratigraphic record of glaciation and vegetation in northwestern Greenland spanning the Pleistocene. Enriched stable isotopes of pore-ice suggest precipitation at lower elevations implying ice-sheet absence. Plant macrofossils and biomarkers in the sediment indicate that paleo-ecosystems from previous interglacial periods are preserved beneath the GrIS. Cosmogenic 26Al/10Be and luminescence data bracket the burial of the lower-most sediment between <3.2 ± 0.4 Ma and >0.7 to 1.4 Ma. In the upper-most sediment, cosmogenic 26Al/10Be data require exposure within the last 1.0 ± 0.1 My. The unique subglacial sedimentary record from Camp Century documents at least two episodes of ice-free, vegetated conditions, each followed by glaciation. The lower sediment derives from an Early Pleistocene GrIS advance. 26Al/10Be ratios in the upper-most sediment match those in subglacial bedrock from central Greenland, suggesting similar ice-cover histories across the GrIS. We conclude that the GrIS persisted through much of the Pleistocene but melted and reformed at least once since 1.1 Ma.

Rastonbury 6y ago

Why does the discovery of plants show that ice melted more recently?

mkl 6y ago
It's not the existence of the plants, it's the dating of the rocks' last exposure to sunlight with isotopes. The plants show it was quite a bit warmer and lasted for quite a while.