Scientists discover fossil plants beneath mile-deep Greenland ice | Hacker News Reader

Scientists discover fossil plants beneath mile-deep Greenland ice

sciencedaily.com

108 pointskvee90 comments

Original work cited: https://www.pnas.org/content/118/13/e2021442118

Supplemental materials: 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.

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.

Paradoxically, Greenland's coastline is expected to see a relatively lower sea level in this scenario.

https://blogs.ei.columbia.edu/2020/02/05/greenland-rising-th...

That is 361.1 million km^2 * 7.2m = 2.6 × 10^18 liters. Or a cube of side length 137.5km of water.

In some places it will rise, in some others not: https://www.sciencemag.org/news/2016/02/how-melting-ice-shee...

What's the point of bringing this up? On average it is still going to be a tremendous rise.

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.

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...

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.

Absolutely. I believe it was estimated that asteroid was equivalent to something like 3000+ nuclear bombs all detonating at the same time.

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

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.

Fossil plants, which should be a little less surprising.

Yeah fossil should really be included in the title for clarity.

Ok, we've fossilized the title above.

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.

Fossils aren't plants, they're rocks. Why would anyone assume you mean rocks when you say plants?

"Scientists discover rocks beneath mile-deep Greenland ice" maybe isn't quite as catchy, or as useful in conveying relevant information.

But it would have the advantage of being accurate. This is why they invented words like fossil.

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.

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

“The military mission failed, but the science team did complete important research”

so they say... hmm

>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

> 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

Sure, but it seems unlikely to be reversible on human timescales, which are the ones that matter to me.

It won't melt on human timescales either. Total mass of Greenland ice = 4e15 tonnes. Upper end of predicted melt rate this century = 4e13 tonnes/century. So it could lose up to 1% of its mass this century or at the same rate, take 10,000 years to completely melt.

Those estimates can always be revised as we learn more, and melting ice sheets are not a linear process - it accelerates both as it melts and as the climate continues to warm.

You're right that it will take a long time, but wrong that we needn't worry. Even just a couple feet of sea level rise will wreak havoc in parts of the world.

We're talking about the irreversibility of the melting here, not the fact that it's melting which everyone already knows and was even happening before AGW started.

No, we were taking about the pace of melting and the impact of that. Don't move the goal posts.

It is already well known that the Earth has gone through melting and freezing cycles but we, humans, have surely created* this particular melting cycle.

The problem is not with the Earth. It is that we, humans, we likely not survive if this cycle of climate change continues.

We're at a periodic (125,000 year) temperature peak. Warming is surely a natural event. http://donath.org/Photos/TempChange.PNG

No, it's not. Stop spreading false information.

He's actually correct on both points. Just look at any source for global temperature over the past million years. Eg. Wikipedia https://en.wikipedia.org/wiki/Geologic_temperature_record

It's not that simple. The graphs you are pointing at do not include the last century, and even if - they are tracing temperature by a proxy: bentic foraminifers dO16/O18. They are organisms living in the oceans, not necessarily in equilibrium (=synchronized) with atmospheric O and a proxy for average global temperatures. They are good indicators for general trends, so to understand the range of temperatures in a given period, but for very short periods of time they are unable to provide a measure of the rate of change. +3 degrees in a million year is manageable by many species,+3° in a century it isn't.

That doesn't stop it being true. If the temperature is even higher than the million year record, we're still at a peak.

temperature is not a concern, Life can exists in a relative large range of temperatures. The problem is the speed of temperature rise, that is incompatible with the speed some species can migrate from now-hostile areas. Dinosaurs didn't died because the asteroid hit their head, but because of the abrupt climate change triggered by it. The key word is "abrupt" not "change".

"The warming" we're currently experiencing is not natural. That we're coming out of an ice age doesn't matter for the warming we've been experiencing in the last hundred years.

What's it got to do with the last 100 years? We're talking about a 100,000 year temperature cycle and Greenland's melting cycle which started before humans influenced it so it wasn't caused by humans. I think all you people replying to me think I'm a global warming denier but you can't argue with what I've said because I'm right so you're just saying random facts instead.

The assertion that no one can argue with what you've said poisons the well and isn't particularly well-suited to a discussion board. If the whole of your argument is just linking to a Wikipedia article with your arms crossed in satisfaction, I suggest visiting https://skepticalscience.com/heading-into-new-little-ice-age...

Graph is from NOAA ice core data.

What's false?

Ah yes, the overwhelming majority of scientists is in disarray over proof of the unusually fast rate of climate change with a decades long political campaign to finally make our profit-oriented societies pay some attention to the issue.

But in comes the HN smartass who definitely knows better than thousands of trained PhDs cumulating millions of man hours of research and convinces us all with a hyperlink to donath.org.

Why not destroy such sceptics (on HN or anywhere else) regarding the rate of climate change and related topics? All you have to do is demonstrate that the data presented by them & their interpretation is garbage, nonsense or whatever else you want to call it. Must surely be easier than presenting a classic logical fallacy - argument by authority and thinking that nails it.

Maybe the link is indeed total rubbish but talking about man-hours and 'trained PhD's' is irrelevant. Feynman explains nicely: https://youtu.be/EYPapE-3FRw. Science is a matter of a debate on facts versus theory not a vote-counting appeal on behalf of the supposed position of an ill-defined electorate.

I can demonstrate to someone that the Earth is round, but it'll never convince a Flat Earther.

Said skeptics have been repeatedly debunked, here and elsewhere. There's more to it than merely being right.

As an example, a sitting US Senator used "it snowed in winter" to "debunk" the idea of climate change. https://www.washingtonpost.com/news/the-fix/wp/2015/02/26/ji...

Indeed. I presented facts, he resorts to insults. Who's scientific?

Scientism dictates that the ordained technocrats have an exclusive license on what is science-y. Apparently incivility is fine when it supports the establishment consensus. Intellectual curiosity indeed.

What's "smartass" about taking the time to acquire NOAA ice core data, graphing it, and presenting it? We're at a recurring peak, that's scientifically plain.

Indeed the warming is a natural event. The glaciers melted long before humanity could make any difference.

The new bit is that we are helping it along at what is probably an unprecedented rate. So it's not about the change. It is about the rate of change.

When I was born the atmosphere had ~314 PPM of CO2. It is now north of 415PPM and going up ~2.5PPM per year. CO2 is a greenhouse gas.

Now how could that relate to us requiring over 95,000,000 barrels of oil PER DAY to run our civilization? (it is closer to 98M in 2021)

https://www.statista.com/statistics/265203/global-oil-produc....

For perspective do some back of the napkin math on the height 98,000,000 barrels of oil would be if you made a 100x100 base of barrels and stacked them vertically. Standard drums have inside dimensions of 572 millimetres (22.5 in) diameter and 851 millimetres (33.5 in) height. (remember that's per day)

We have in all probability made the time when coastal cities are flooded happen sooner and it is highly unlikely that we can improve the situation very much in the short term.

Have you looked at climate changes over the entire Cenozoic, let alone the climate record over the last 300,000 years?

We're lucky to be alive during a warm, interglacial period.

https://en.wikipedia.org/wiki/Last_Glacial_Maximum

You're spreading disinformation. Do your homework before repeating random exaggerated claims you've heard on the internet. Climate change is not predicted to exterminate humans. This melting cycle was happening before the industrial revolution and was not created by humans.

> This melting cycle was happening before the industrial revolution and was not created by humans.

If you're referring to our current predicament, it looks like you have your own homework to do.

You really can just Google this. We came out of an ice age 10,000 years ago and glaciers are still melting from then.

Why are so many commenters just making false knee-jerk claims without paying attention to well established science?

I'm a geologist and I've focused on palaeoclimatology putting an eye on the rate of climate change. I've wrote several articles on international peer-reviewed journals. I can say, basing on 20+years of study and lab/field work, that what is happening is really concerning because human emissions are summing up to natural Milankovitch cycles, altering the rate of climate change with unpredictable (since they are unprecedented) implications for food chain supply and society.

> Why are so many commenters just making false knee-jerk claims without paying attention to well established science?

I can't find any of this "well established science". Kindly link a primary source.

A primary source showing that Greenland was melting since preindustrial times? Really? No, sorry. It's not contentious at all. If you genuinely disagree, then I'll put some effort into it. Or is it something else you're asking for a source for?

EDIT: Turns out it is contentious because there are multiple cycles spanning different time periods so we're probably talking about different ones. I'm talking about the general holocene but there's also a separate human caused increased melt rate which is obviously post-industrial.

Translation of what you wrote: "I have nothing to back up my false claims, so I'll just splutter in outrage."

What you are doing here is not helpful. Yes, the Greenland ice sheet has been melting since before industrialization [1]. Yes, at current rates the ice will take 10,000 years to melt, as long as Jericho has been a city [2].

Productive responses to these claims include: Greenland's rate of melting has dramatically accelerated since industrialization and will likely continue accelerating as atmospheric carbon rises further.

and

Even losing a small percentage of the ice sheet will have devastating consequences in some regions.

These responses have a remote shot at making someone think about their position and whether it makes sense. Snarky answers where you accuse someone of ignorance over their informed claims only make you and your side look bad. I'm on your side, and I don't care for it.

[1] https://www.nationalgeographic.com/science/article/greenland...

[2] A little more tricky, sources rightly refuse to assume constant melt rate for their models. We can eyeball this, though. https://www.smithsonianmag.com/smart-news/greenlands-oldest-... gives amount of ocean rise in the last 8 years (as of 2019) as a quarter inch, and says 25 feet total ocean rise if the whole thing melted. 4 quarter in./in. * 12 in./ft * 25 ft * 8 years = ~9600 years

There are two melting cycles overlapping here. The cycle coming out of the last ice age, and the human caused warming. That latter is really stark in the velocity of change. It's not yet that stark in total magnitude, but it's also not linear with most of the change coming at the end in the future. It's looking like we may be headed for 4 degrees of average warming, which is pretty terrifying. That might just be enough to end the cycles of ice ages that's been happening for millions of years - which could be overall positive for us long term. But shorter term the disruptions to our cities, countries, and food supply is unprecedented in recorded history.

As a geologist: we are not concerned about the change, we are concerned about the rate of change. The fastest is the change, the largest number of groups of organisms will be exinct.

That's neither here nor there. Do you disagree with anything I said? Are you trying to suggest humans are likely to go extinct because of human-caused climate change? If you are, then you'll need some better evidence than appeal to your qualifications.

I'm replying exactly to your assertion "Do your homework before repeating random exaggerated claims you've heard on the internet". I did, I didn't get my qualifications searching on Wikipedia, did you? "This melting cycle was happening before the industrial revolution and was not created by humans.": the cycle existed before humans, I agree, but the velocity of temperature change has increased after humans started to burn fossil fuels and deforestate.We are increasing the rate of change.

I'm not really sure what to make of your replies. I've just been correcting some factual errors people made. You seem to agree with me but using a tone that sounds argumentative and adding some disconnected additional facts which nobody was denying and which are common knowledge. Are you engaging in an ideological fight with someone who's not present here?

> Are you engaging in an ideological fight with someone who's not present here?

Quit with the red herrings. It's fairly easy to comprehend what is being said here.

"The velocity of temperature change has increased after humans started to burn fossil fuels and deforestate. We are increasing the rate of change."

Yes that's common knowledge. So what?

I understand that you are correcting some assertions, but the way you did questioned the scientific competence of other contributors is reducing the value of the entire sentence you were replying to. You are throwing out the baby with the bath water. The key message I wanted to stress, with additional contributions to the discussion, is that we have to be concerned. If you agree with me on this I'm fine. Unfortunately however your corrections suffered the same problem of the ones you were correcting. In particular I do not agree with you on these two sentences: "Climate change is not predicted to exterminate humans." It is. It's not predicted to make Homo sapiens sapiens extinct, like you probably meant, but many humans can be exterminated by repentine climate changes (think to famine, wars, drought). "This melting cycle was happening before the industrial revolution and was not created by humans." Human-made contributions are perturbing the cyclicity, to an extent that can lead to a non-cyclical patterns.

Extinction of the species, not killing of some individuals. I thought that was clear all along. It comes from "It is that we, humans, we likely not survive".

You might just be shocked by words like "not caused by humans" and have reacted reflexively. Sometimes climate changes really aren't caused by humans.

you probably do not understand what I've wrote but it's fine, it's your right. I'm not replying to you anymore, I wrote the people that paid my education in order to study palaeoclimatology and give a educated opinion in their place when necessary. They can hopefully read my messages with a more open mind. I tried to make them constructive and informative, and I'm open to constructive questions.

You were being sealioned. You're more patient than I am.

> "Climate change is not predicted to exterminate humans." It is. It's not predicted to make Homo sapiens sapiens extinct, like you probably meant

Sorry, but the only legitimate way to interpret "climate change is predicted to exterminate humans" is as a claim that the species will go extinct.

You do not appear to be a native English speaker:

> the way you did questioned the scientific competence of other contributors is reducing the value of the entire sentence you were replying to

> you probably do not understand what I've wrote

> I wrote [?] the people that paid my education

You're probably better off not trying to do fine interpretation on English sentences.

Broadly speaking there's a long history of doomsday predictions. Credentialed members of academia or religious institutions have participated in doomsaying throughout history.

https://en.wikipedia.org/wiki/List_of_dates_predicted_for_ap...

Regardless of if the claim is or isn't being semantically backpedaled, I think historical context is important here.

>I didn't get my qualifications searching on Wikipedia, did you?

In fairness, Wikipedia's coverage would support the more alarmist narrative. Skepticism and nuance are framed as conspiracy theory.

In my reading of Wikipedia's editorial position someone who took their articles at face value would be inclined to support your tilting.

> This melting cycle was happening before the industrial revolution and was not created by humans.

"Because I, exporectomy, decree this to be so! Facts, evidence, none of these are important, compared to my opinions."

Relevant xkcd: https://xkcd.com/1732/

This puts everything in context.... Visualization is a powerful tool.

> Earth naturally warming was a.. natural event - there is no need to label it troubling or liken it to an artificially-warmed event

Natural events can still be troubling or cataclysmic.

If the Greenland ice sheet melted entirely relatively quickly, it would be extremely troubling whether it was happening for human or natural reasons.

We still have to adapt and survive any climate changes that happen, natural or not. If climate changes pose a significant risk to us, they are troubling, natural or not.

“Since some twenty feet of sea-level rise is tied up in Greenland's ice, every coastal city in the world is at risk. The new study provides the strongest evidence yet that Greenland is more fragile and sensitive to climate change than previously understood -- and at grave risk of irreversibly melting off.”

That’s troubling enough for me.

Why? At predicted climate change induced melt rate for this century, that melting will take longer than the time just about any human city has ever existed on Earth. Do the maths before you get troubled by nothing.

How long is that? From what I can recall, Jericho has been continuously inhabited for 10,000 years.

Yes, that long.

Translation of what you wrote: "I just make things up out of my imagination, because facts aren't real."

https://climate.nasa.gov/news/2940/greenlands-rapid-melt-wil...

A human accessible primer for you.

The phrase "irreversibly melting off" is troubling for me to read.

well it is irreversible - if it melts and the water flows in the ocean and mixes with the water there, there is no way to put it back. Of course if it cools down over the next few million years Greenland can grow a new glacier. But that will be a different one.

Given this article, it might be less irreversible then previously thought... but the CO2 will have to be removed from the atmosphere.

This argument is a bit like the "coal is a renewable form of energy because it eventually returns" argument. The consensus is that if the time scales required are on the order of thousands, tens of thousands, or millions of years, then it's safe to call it nonrenewable, and it is safe to call this irreversible on a human time scale.

Coal exists because microorganisms and fungi capable of breaking down lignin didn't exist then. It will never be made again on Earth.

> Earth naturally warming was a.. natural event - there is no need to label it troubling or liken it to an artificially-warmed event

So as long as a patient has the genetic markers for aggressive cancer, there is no reason we should lift a finger to give them life saving treatment? Just because people die, we shouldn't have laws for murder?

Just because a catastrophic outcome can happen naturally, does not mean that we should happily cause it to occur through artificial means or stand by and watch it happen naturally if we can avoid it.

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&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

honestly, there was no intent, but I did enjoy the twisted knickers! duly noted

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&sor....

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