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Antarctic sea ice extent had been rising from 1979 (when satellite data started) to 2015. It regressed for a few years and then expanded again in 2020 and 2021

Antarctic sea ice extent had been rising from 1979 (when satellite data started) to 2015. It regressed for a few years and then expanded again in 2020 and 2021 and then regressed again. There's a lot of causes of this and there are studies looking at it going back many hundreds and thousands of years, but they aren't as accurate as satellite data. Additionally, different seas in the antarctic have had different behaviors. Some have regressed and some have expanded at different times. https://cp.copernicus.org/articles/18/1729/2022/ https://cp.copernicus.org/articles/18/1729/2022/ > ...changes in atmospheric circulation, wind stress and thermodynamic processes linked to the Southern Annular Mode (SAM) and El Niño–Southern Oscillation (ENSO) >...Thus, projections of future Antarctic sea-ice extent and the associated climate implications are highly uncertain. Steady rise then big rise and then a crash regressing to the mean. Point is - we don't know.

TravHatesMe 3y ago
Can the down voters explain themselves? I genuinely want to hear more discussion on both sides, and this commenter has provided some interesting points..
- yongjik 3y ago
  GP posted the exact same comment twice - AFAIK that's generally frowned upon. Duplicate comment: https://news.ycombinator.com/item?id=37251025 https://news.ycombinator.com/item?id=37251025
  - nemo44x 3y ago
    It’s a duplicate story. And this one raised to #1. So yeah I’m going to post this interesting information again. Nothing in response to it challenged it well. I did change the last sentence to clarify the data a bit.
scythe 3y ago
>Steady rise then big rise and then a crash regressing to the mean. Point is - we don't know. What's being observed is not a regression to the mean, it's a system under external forcing. That's hard to predict, but it doesn't justify pseudoscientific denialism. >The long-term increase in sea ice near the coast of Antarctica has been explained by a delayed response to orbital forcing and the long memory of the SO (Renssen et al., 2005). The "rise" since 1975 also has not been "steady", as can be seen clearly in the graph: https://commons.wikimedia.org/wiki/File:ClimateDashboard-Antarctic-sea-ice-summer-minimum-graph-20230307-1400px.jpg https://commons.wikimedia.org/wiki/File:ClimateDashboard-Ant...
- nemo44x 3y ago
  Data isn’t denialism. I literally posted factual observatory data. Here’s a better chart: https://www.climate.gov/media/15124 https://www.climate.gov/media/15124 Certainly recent correction but an upwards trend since 1979 (when satellite data started) and a recent large spine up followed by a more recent large spine down. There are many potential inputs to thus. Man made climate change is possibly one but not a dominate one probably.
defrost 3y ago
Focusing on the maximum sea ice extant barely captures the concern. Sea ice extent cycles from a maximum to a minimum every year. The maximum extent has been pushing outwards a bit as more of the core ice volume has melted, and the minimum extent, in recent years, has sharply (greater than five sigma drop against data since 1970s) dropped as sections of the Antarctic now see summer time ice free beaches. The minimum extent complement to your graphic (that you posted below): https://www.climate.gov/sites/default/files/styles/full_width_620_original_image/public/2023-03/ClimateDashboard-Antarctic-sea-ice-summer-minimum-graph-20230307-1400px.jpg https://www.climate.gov/sites/default/files/styles/full_widt... A lengthy discussion: Understanding climate: Antarctic sea ice extent https://www.climate.gov/news-features/understanding-climate/understanding-climate-antarctic-sea-ice-extent https://www.climate.gov/news-features/understanding-climate/...
titzer 3y ago
> Steady rise then big rise and then a crash regressing to the mean. Point is - we don't know. I don't know of any situations in statistics where a 5 sigma drop is considering "regressing to the mean".
- nemo44x 3y ago
  Suggesting even more it has little to nothing to do with man made climate change. There was a multi-sigma gain in ice shortly before after decades of steady but slow growth. Certainly man made climate change would have impacted that. A single event isn’t an indicator. Trends are. And the trend is more ice. There are many variables. And when a few things come together there are rare but large variations. Articles like this are just climate hysteria for climate doomers. So much of this has been politicized that people don’t even realize they’re reading propaganda. Yes the climate was warmed a bit over the last 40 years after decades of cooling which was preceded by a warming period. The 1930s were the warmest of the 20th century and then we saw decades of cooling. And yes carbon likely plays a role as we can model an atmosphere and see this. But it’s probably not as significant as the hundreds of other natural variables. Besides for every degree of warming in a lab you need exponentially more carbon. So it’s difficult to accelerate. Slowly move towards non-carbon energy over the next 50 years. We’ll be fine.
  - titzer 3y ago
    > And yes carbon likely plays a role as we can model an atmosphere and see this. But it’s probably not as significant as the hundreds of other natural variables. And yet, thousands of scientists who spend their entire careers on figuring this out are pretty damn sure what's driving current warming: it's greenhouse gases, primarily CO2. They use this thing called the scientific method, which includes a whole bunch of actually measuring, modeling, predicting, and checking each other's work. Forgive me if that isn't a whole lot more convincing than some offhand conversation with an unknown person on a tech news site.

TravHatesMe 3y ago

Can the down voters explain themselves? I genuinely want to hear more discussion on both sides, and this commenter has provided some interesting points..

yongjik 3y ago
GP posted the exact same comment twice - AFAIK that's generally frowned upon. Duplicate comment: https://news.ycombinator.com/item?id=37251025 https://news.ycombinator.com/item?id=37251025
- nemo44x 3y ago
  It’s a duplicate story. And this one raised to #1. So yeah I’m going to post this interesting information again. Nothing in response to it challenged it well. I did change the last sentence to clarify the data a bit.

scythe 3y ago

>Steady rise then big rise and then a crash regressing to the mean. Point is - we don't know. What's being observed is not a regression to the mean, it's a system under external forcing. That's hard to predict, but it doesn't justify pseudoscientific denialism. >The long-term increase in sea ice near the coast of Antarctica has been explained by a delayed response to orbital forcing and the long memory of the SO (Renssen et al., 2005). The "rise" since 1975 also has not been "steady", as can be seen clearly in the graph: https://commons.wikimedia.org/wiki/File:ClimateDashboard-Antarctic-sea-ice-summer-minimum-graph-20230307-1400px.jpg https://commons.wikimedia.org/wiki/File:ClimateDashboard-Ant...

nemo44x 3y ago
Data isn’t denialism. I literally posted factual observatory data. Here’s a better chart: https://www.climate.gov/media/15124 https://www.climate.gov/media/15124 Certainly recent correction but an upwards trend since 1979 (when satellite data started) and a recent large spine up followed by a more recent large spine down. There are many potential inputs to thus. Man made climate change is possibly one but not a dominate one probably.

defrost 3y ago

Focusing on the maximum sea ice extant barely captures the concern. Sea ice extent cycles from a maximum to a minimum every year. The maximum extent has been pushing outwards a bit as more of the core ice volume has melted, and the minimum extent, in recent years, has sharply (greater than five sigma drop against data since 1970s) dropped as sections of the Antarctic now see summer time ice free beaches. The minimum extent complement to your graphic (that you posted below): https://www.climate.gov/sites/default/files/styles/full_width_620_original_image/public/2023-03/ClimateDashboard-Antarctic-sea-ice-summer-minimum-graph-20230307-1400px.jpg https://www.climate.gov/sites/default/files/styles/full_widt... A lengthy discussion: Understanding climate: Antarctic sea ice extent https://www.climate.gov/news-features/understanding-climate/understanding-climate-antarctic-sea-ice-extent https://www.climate.gov/news-features/understanding-climate/...

titzer 3y ago

> Steady rise then big rise and then a crash regressing to the mean. Point is - we don't know. I don't know of any situations in statistics where a 5 sigma drop is considering "regressing to the mean".

nemo44x 3y ago
Suggesting even more it has little to nothing to do with man made climate change. There was a multi-sigma gain in ice shortly before after decades of steady but slow growth. Certainly man made climate change would have impacted that. A single event isn’t an indicator. Trends are. And the trend is more ice. There are many variables. And when a few things come together there are rare but large variations. Articles like this are just climate hysteria for climate doomers. So much of this has been politicized that people don’t even realize they’re reading propaganda. Yes the climate was warmed a bit over the last 40 years after decades of cooling which was preceded by a warming period. The 1930s were the warmest of the 20th century and then we saw decades of cooling. And yes carbon likely plays a role as we can model an atmosphere and see this. But it’s probably not as significant as the hundreds of other natural variables. Besides for every degree of warming in a lab you need exponentially more carbon. So it’s difficult to accelerate. Slowly move towards non-carbon energy over the next 50 years. We’ll be fine.
- titzer 3y ago
  > And yes carbon likely plays a role as we can model an atmosphere and see this. But it’s probably not as significant as the hundreds of other natural variables. And yet, thousands of scientists who spend their entire careers on figuring this out are pretty damn sure what's driving current warming: it's greenhouse gases, primarily CO2. They use this thing called the scientific method, which includes a whole bunch of actually measuring, modeling, predicting, and checking each other's work. Forgive me if that isn't a whole lot more convincing than some offhand conversation with an unknown person on a tech news site.