7 ms·

Antarctica gained 600 Gt of ice during '09-'19 vs. a prediction of a 20k Gt loss

67 points by andreygrehov 3y ago

xwdv 3y ago
Despite this I’m sure there’s a counterintuitive reason as to why this is actually bad, far worse even than the 20k Gt loss scenario. Can anyone explain?
- Konohamaru 3y ago
  Not everything has to be bad, or a set up for something worse to happen. Sometimes, even when there is an overall line with negative m, good things can happen.
- kgwxd 3y ago
  There's already a documentary on it: "The Day After Tomorrow"
- nkozyra 3y ago
  Maybe it's not bad and the effort and concern about mitigating man's effect was actually impactful?
- rco8786 3y ago
  Man talking about starting with a conclusion and searching for the narrative.
  - justinclift 3y ago
    It kind of sounds like they were being sarcastic?
- callmeal 3y ago
  The headline overstates things. It's not a prediction of a loss, just a different way of measuring: To compare the different methods, we calculated the difference between the two numbers on all ice shelves within the study. We observed mass loss on 18 ice shelves and mass gain on 16. Overall, the steady-state assumption will overestimate ice loss on ice shelves that are advancing and underestimate ice loss on ice shelves that are retreating. The assumption also does not hold well for any irregular behaviour, such as ice shelves that have lost ice through large calving events. Our observations show that Antarctic ice shelves gained 660.6 Gt of ice mass from 2009 to 2019, whereas the steady-state approach would estimate ice loss of −20 028.1 Gt over the same period (Table 1). The steady-state prediction is an approximation and is described in the article: In the absence of an observed measurement of ice loss from iceberg calving, previous studies have used the steady-state calving approximation to estimate the volume of ice lost through calving processes (Rignot et al., 2013; Depoorter et al., 2013). This method assumes that all ice flow through a fixed flux gate, usually located near or at the last known calving front position, is lost through iceberg calving.
- defrost 3y ago
  The shelves float out over the sea .. and largely (not all) source from "main" ice mass which is much much (magnitudes) larger. The shelves (ice floating out on the fringes) "growing" can indicate more main mass flowing in from behind the shelf than is being calved and lost from the front of the shelf. ie. This could indicate greater ice mass loss and flow out from the core and accelerated Antarctica melt down. Overall this is a "bastard" problem in geophysics - to measure the South Pole ice mass "all you have to do" is measure the volume between the ice surface and the ground underneath then add in the shelves. However, large ice mass loss in an area can (and does) result in the ground underneath rising up .. and it takes a great deal of fuel and energy to fly the kinds of ice penetrating radar grids required to continuously track the ice surface and ice floor. There are other complications, but this is not as straightforward as armchair forum experts imagine.
- vba616 3y ago
  Maybe a climatologist will stop by and be interested in a fight. I am not, and cannot explain why this is "far worse". But I can explain why it's common sense to me as a random non-scientist (not a climate "doomer" or activist either) that it shouldn't change opinions about climate change in general. 1. The HN title may be deceptive - this appears to be about sea ice. A cursory look around suggests to me that conventional wisdom has been that Antarctic sea ice has not shown a trend over a few decades, while the land ice seems to be declining (and Arctic sea ice has been declining). 2. Conventional wisdom appears to be that most of the sea ice is seasonal. 600 Gt sounds like a lot in an absolute sense, but it's only 3% of 20K and minute compared to the seasonal change or the entire amount. Practically speaking, as far as I can tell, 600 Gt is equal to zero. And this would presumably be consistent with others saying that there has been no trend. 3. Finally, I've never seen anyone even try to make a case that an increasing greenhouse effect must have perfectly uniform effects. I don't think this is a matter of climatology, but of understanding what a mean or average is and that there's no uniform baseline to start from. It seems like a common sense mathematical fact to me, regardless of climatology, that if the earth warmed up by a few degrees, the temperature profile over different latitudes could become steeper or shallower. Everybody knows that the continents are not uniformly distributed, so why would you be skeptical of a difference between climate change at the poles, either? I feel like both people arguing against addressing climate change and people arguing for it tend to drift away from the idea that it is governed by global mechanisms. There are no borders stopping greenhouse gases, right? People can make dubious arguments about local problems and extreme weather that may seem weak to others, but the bottom line is that scientists observe CO2 levels as well as other things, that keep going up. And on average, until that changes, stuff will keep happening more and more. Media clickbait can't change that. I've seen submissions to HN about global emissions decelerating or hopefully levelling off, and that's where my skepticism kicks in. Emissions figures are just accounting, and accounting is fallible. As far as I know, any progress in official emissions figures is contradicted by simply measuring the atmosphere, but I would really like to know if I'm incorrect about that. It's disturbing to me to think that (a) global warming/climate change is real and proceeding unchecked with huge consequences and that (b) people who claim to be concerned are all pretending. But I haven't yet figured out an alternative to believing those things. Here is the crux of it - CO2 levels observed in Hawaii, which is physically isolated and has had observations for a long time: https://gml.noaa.gov/webdata/ccgg/trends/co2_data_mlo.png https://gml.noaa.gov/webdata/ccgg/trends/co2_data_mlo.png If there is an argument that it takes X amount of time before reduced emissions show up in that trendline, I would like to know what X is. Or how, probabilistically, it could be determined if emissions figures are likely BS. I tried asking ChatGPT (the original free version) with a nearly 200 word prompt, and it provided 4 paras of boilerplate on the topic, but entirely missed what I was asking and wasn't terribly internally consistent either.
doctor_eval 3y ago
Title is editorialising; actual title is “Change in Antarctic ice shelf area from 2009 to 2019”. From the abstract: > Our observations show that Antarctic ice shelves gained 661 Gt of ice mass over the past decade, whereas the steady-state approach would estimate substantial ice loss over the same period, demonstrating the importance of using time-variable calving flux observations to measure change.
- chrisco255 3y ago
  The title of an HN submission does not have to match the article's title. It's also not editorializing. It's a factual statement, except it should probably be revised to 661 Gt instead of the 600 Gt quoted (doesn't change substance).
  - aerojoe23 3y ago
    The ice shelves, not all of Antarctica, gained ice. I guess you could read the HN title and think, "see Antarctica must not be getting warmer if it gained ice." Where the shelves could have gained from the glaciers flowing faster off the land, and amount of ice could still have gone down.
    - postalrat 3y ago
      Well did Antarctica gain ice or are you simply speculating?
      - defrost 3y ago
        Overall Antarctica in total has steadily lost ice mass since 1990. See: Figure 8 (Shepherd et al. 2018) reproduced in link below https://www.antarcticglaciers.org/glaciers-and-climate/what-is-the-global-volume-of-land-ice-and-how-is-it-changing/ https://www.antarcticglaciers.org/glaciers-and-climate/what-...
        chrisco255 3y ago
neovialogistics 3y ago
That's a very unusual choice of start and end dates, almost as if there is an intent to misrepresent the data. Where can I find a good dataset over a wider range?
- friend_and_foe 3y ago
  https://www.researchgate.net/publication/222450369_Holocene_sea-level_change_and_ice-sheet_history_in_the_Vestfold_Hills_East_Antarctica https://www.researchgate.net/publication/222450369_Holocene_...
Flatcircle 3y ago
Somehow the temperature of the earth is now a political football so any actual facts are hijacked by people with an agenda. Intellectually, I'm scared to touch this subject because it's such a hot potato. (no pun intended)
- ajsnigrutin 3y ago
  That's why we need more raw data. Even if people argue, if it's this or that to blame, raw data is always a good thing. Adding the "good" to turn it into "good raw data" is even better. Considering the last few years of manipulations with the data about "the plague", sure, there will be arguing, but again, more data is a good thing.
  - JamisonM 3y ago
    What more raw data would you like?
    - ajsnigrutin 3y ago
      Like the article from here.. that the Antarctica gain 600Gt of ice. Some will say that global warming is a scam because of that, some may say it's just a random increase with a long-term trend of decrease due to global warming... and I just like having the data.
      - jfengel 3y ago
        This isn't raw data. The raw data is a gigantic pile of satellite measurements. This is all of that data collapsed down into a single figure via a model (itself derived from yet more data), and the scope of that figure isn't as easy to characterize as "Antarctica did X". So I'd cautioned you against the belief that you really have any data here. You have a single number, flagged for your attention by somebody who (presumably) believes that they can influence your conclusion in a particular direction. You can't really draw conclusions from data without gathering as much data as possible, and this single number is nowhere near complete. If this data strengthens your confidence that you understand the whole situation, then it is worse than having no data at all.
mrb 3y ago
Here is another way to think about these numbers: Antarctica was predicted to lose 140 cm of ice, but instead gained 4 cm. (This assumes the change of mass of ice would have been spread over the entire 14.2 million km² of the continent.)
- sn0wf1re 3y ago
  No. Antarctica did not necessarily gain ice, this study does not discuss the Antarctic ice sheets. This study is about the ice shelves (sea ice).
  - polotics 3y ago
    Seemed weird, so thank you: with all the melting going on, it would make sense more ice ends up slipping onto the sea...
  - mrb 3y ago
    Ah, thanks for the correction.
    - sn0wf1re 3y ago
      You're welcome, I too was confused at first.
oneTbrain23 3y ago
This would partially explain why sea level didnt rise up. But then again, reading the comments, seems like a lot not that happy with this piece of article. Maybe not conforming to current narrative?
- taylodl 3y ago
  Except sea levels did "rise up" as you say, faster than expected actually. This article is about the ice shelf, i.e. the ice over the sea - not the ice over land. People expected the shelf to break and go to sea, and from there currents would take it to warmer water. Turns out the shelf is able to extend further than was thought possible.
hulitu 3y ago
> Antarctica gained 600 Gt of ice during '09-'19 vs. a prediction of a 20k Gt loss Is the weighting machine calibrated ?
BasedAnon 3y ago
BOE is still going to happen this decade no matter what cope you use
_nalply 3y ago
Title: Change in Antarctic ice shelf area from 2009 to 2019

67 points by andreygrehov 3y ago

xwdv 3y ago

Despite this I’m sure there’s a counterintuitive reason as to why this is actually bad, far worse even than the 20k Gt loss scenario. Can anyone explain?

Konohamaru 3y ago
Not everything has to be bad, or a set up for something worse to happen. Sometimes, even when there is an overall line with negative m, good things can happen.
kgwxd 3y ago
There's already a documentary on it: "The Day After Tomorrow"
nkozyra 3y ago
Maybe it's not bad and the effort and concern about mitigating man's effect was actually impactful?
rco8786 3y ago
Man talking about starting with a conclusion and searching for the narrative.
- justinclift 3y ago
  It kind of sounds like they were being sarcastic?
callmeal 3y ago
The headline overstates things. It's not a prediction of a loss, just a different way of measuring: To compare the different methods, we calculated the difference between the two numbers on all ice shelves within the study. We observed mass loss on 18 ice shelves and mass gain on 16. Overall, the steady-state assumption will overestimate ice loss on ice shelves that are advancing and underestimate ice loss on ice shelves that are retreating. The assumption also does not hold well for any irregular behaviour, such as ice shelves that have lost ice through large calving events. Our observations show that Antarctic ice shelves gained 660.6 Gt of ice mass from 2009 to 2019, whereas the steady-state approach would estimate ice loss of −20 028.1 Gt over the same period (Table 1). The steady-state prediction is an approximation and is described in the article: In the absence of an observed measurement of ice loss from iceberg calving, previous studies have used the steady-state calving approximation to estimate the volume of ice lost through calving processes (Rignot et al., 2013; Depoorter et al., 2013). This method assumes that all ice flow through a fixed flux gate, usually located near or at the last known calving front position, is lost through iceberg calving.
defrost 3y ago
The shelves float out over the sea .. and largely (not all) source from "main" ice mass which is much much (magnitudes) larger. The shelves (ice floating out on the fringes) "growing" can indicate more main mass flowing in from behind the shelf than is being calved and lost from the front of the shelf. ie. This could indicate greater ice mass loss and flow out from the core and accelerated Antarctica melt down. Overall this is a "bastard" problem in geophysics - to measure the South Pole ice mass "all you have to do" is measure the volume between the ice surface and the ground underneath then add in the shelves. However, large ice mass loss in an area can (and does) result in the ground underneath rising up .. and it takes a great deal of fuel and energy to fly the kinds of ice penetrating radar grids required to continuously track the ice surface and ice floor. There are other complications, but this is not as straightforward as armchair forum experts imagine.
vba616 3y ago
Maybe a climatologist will stop by and be interested in a fight. I am not, and cannot explain why this is "far worse". But I can explain why it's common sense to me as a random non-scientist (not a climate "doomer" or activist either) that it shouldn't change opinions about climate change in general. 1. The HN title may be deceptive - this appears to be about sea ice. A cursory look around suggests to me that conventional wisdom has been that Antarctic sea ice has not shown a trend over a few decades, while the land ice seems to be declining (and Arctic sea ice has been declining). 2. Conventional wisdom appears to be that most of the sea ice is seasonal. 600 Gt sounds like a lot in an absolute sense, but it's only 3% of 20K and minute compared to the seasonal change or the entire amount. Practically speaking, as far as I can tell, 600 Gt is equal to zero. And this would presumably be consistent with others saying that there has been no trend. 3. Finally, I've never seen anyone even try to make a case that an increasing greenhouse effect must have perfectly uniform effects. I don't think this is a matter of climatology, but of understanding what a mean or average is and that there's no uniform baseline to start from. It seems like a common sense mathematical fact to me, regardless of climatology, that if the earth warmed up by a few degrees, the temperature profile over different latitudes could become steeper or shallower. Everybody knows that the continents are not uniformly distributed, so why would you be skeptical of a difference between climate change at the poles, either? I feel like both people arguing against addressing climate change and people arguing for it tend to drift away from the idea that it is governed by global mechanisms. There are no borders stopping greenhouse gases, right? People can make dubious arguments about local problems and extreme weather that may seem weak to others, but the bottom line is that scientists observe CO2 levels as well as other things, that keep going up. And on average, until that changes, stuff will keep happening more and more. Media clickbait can't change that. I've seen submissions to HN about global emissions decelerating or hopefully levelling off, and that's where my skepticism kicks in. Emissions figures are just accounting, and accounting is fallible. As far as I know, any progress in official emissions figures is contradicted by simply measuring the atmosphere, but I would really like to know if I'm incorrect about that. It's disturbing to me to think that (a) global warming/climate change is real and proceeding unchecked with huge consequences and that (b) people who claim to be concerned are all pretending. But I haven't yet figured out an alternative to believing those things. Here is the crux of it - CO2 levels observed in Hawaii, which is physically isolated and has had observations for a long time: https://gml.noaa.gov/webdata/ccgg/trends/co2_data_mlo.png https://gml.noaa.gov/webdata/ccgg/trends/co2_data_mlo.png If there is an argument that it takes X amount of time before reduced emissions show up in that trendline, I would like to know what X is. Or how, probabilistically, it could be determined if emissions figures are likely BS. I tried asking ChatGPT (the original free version) with a nearly 200 word prompt, and it provided 4 paras of boilerplate on the topic, but entirely missed what I was asking and wasn't terribly internally consistent either.

doctor_eval 3y ago

Title is editorialising; actual title is “Change in Antarctic ice shelf area from 2009 to 2019”. From the abstract: > Our observations show that Antarctic ice shelves gained 661 Gt of ice mass over the past decade, whereas the steady-state approach would estimate substantial ice loss over the same period, demonstrating the importance of using time-variable calving flux observations to measure change.

chrisco255 3y ago
The title of an HN submission does not have to match the article's title. It's also not editorializing. It's a factual statement, except it should probably be revised to 661 Gt instead of the 600 Gt quoted (doesn't change substance).
- aerojoe23 3y ago
  The ice shelves, not all of Antarctica, gained ice. I guess you could read the HN title and think, "see Antarctica must not be getting warmer if it gained ice." Where the shelves could have gained from the glaciers flowing faster off the land, and amount of ice could still have gone down.
  - postalrat 3y ago
    Well did Antarctica gain ice or are you simply speculating?
    - defrost 3y ago
      Overall Antarctica in total has steadily lost ice mass since 1990. See: Figure 8 (Shepherd et al. 2018) reproduced in link below https://www.antarcticglaciers.org/glaciers-and-climate/what-is-the-global-volume-of-land-ice-and-how-is-it-changing/ https://www.antarcticglaciers.org/glaciers-and-climate/what-...
      - chrisco255 3y ago

neovialogistics 3y ago

That's a very unusual choice of start and end dates, almost as if there is an intent to misrepresent the data. Where can I find a good dataset over a wider range?

friend_and_foe 3y ago
https://www.researchgate.net/publication/222450369_Holocene_sea-level_change_and_ice-sheet_history_in_the_Vestfold_Hills_East_Antarctica https://www.researchgate.net/publication/222450369_Holocene_...

Flatcircle 3y ago

Somehow the temperature of the earth is now a political football so any actual facts are hijacked by people with an agenda. Intellectually, I'm scared to touch this subject because it's such a hot potato. (no pun intended)

ajsnigrutin 3y ago
That's why we need more raw data. Even if people argue, if it's this or that to blame, raw data is always a good thing. Adding the "good" to turn it into "good raw data" is even better. Considering the last few years of manipulations with the data about "the plague", sure, there will be arguing, but again, more data is a good thing.
- JamisonM 3y ago
  What more raw data would you like?
  - ajsnigrutin 3y ago
    Like the article from here.. that the Antarctica gain 600Gt of ice. Some will say that global warming is a scam because of that, some may say it's just a random increase with a long-term trend of decrease due to global warming... and I just like having the data.
    - jfengel 3y ago
      This isn't raw data. The raw data is a gigantic pile of satellite measurements. This is all of that data collapsed down into a single figure via a model (itself derived from yet more data), and the scope of that figure isn't as easy to characterize as "Antarctica did X". So I'd cautioned you against the belief that you really have any data here. You have a single number, flagged for your attention by somebody who (presumably) believes that they can influence your conclusion in a particular direction. You can't really draw conclusions from data without gathering as much data as possible, and this single number is nowhere near complete. If this data strengthens your confidence that you understand the whole situation, then it is worse than having no data at all.

mrb 3y ago

Here is another way to think about these numbers: Antarctica was predicted to lose 140 cm of ice, but instead gained 4 cm. (This assumes the change of mass of ice would have been spread over the entire 14.2 million km² of the continent.)

sn0wf1re 3y ago
No. Antarctica did not necessarily gain ice, this study does not discuss the Antarctic ice sheets. This study is about the ice shelves (sea ice).
- polotics 3y ago
  Seemed weird, so thank you: with all the melting going on, it would make sense more ice ends up slipping onto the sea...
- mrb 3y ago
  Ah, thanks for the correction.
  - sn0wf1re 3y ago
    You're welcome, I too was confused at first.

oneTbrain23 3y ago

This would partially explain why sea level didnt rise up. But then again, reading the comments, seems like a lot not that happy with this piece of article. Maybe not conforming to current narrative?

taylodl 3y ago
Except sea levels did "rise up" as you say, faster than expected actually. This article is about the ice shelf, i.e. the ice over the sea - not the ice over land. People expected the shelf to break and go to sea, and from there currents would take it to warmer water. Turns out the shelf is able to extend further than was thought possible.

hulitu 3y ago

> Antarctica gained 600 Gt of ice during '09-'19 vs. a prediction of a 20k Gt loss Is the weighting machine calibrated ?

BasedAnon 3y ago

BOE is still going to happen this decade no matter what cope you use

_nalply 3y ago

Title: Change in Antarctic ice shelf area from 2009 to 2019