4 ms·

https://nsidc.org/arcticseaicenews/charctic-interactive-sea-ice-graph/ https://nsidc.org/arcticseaicenews/charctic-interactive-sea-... Switch to Antarctic and

https://nsidc.org/arcticseaicenews/charctic-interactive-sea-ice-graph/ https://nsidc.org/arcticseaicenews/charctic-interactive-sea-... Switch to Antarctic and make sure to click "Show All Years". Until 2023 even low years were at least slowly marginal departures overlapping with previous years. 2023 is so far off the trend it almost looks like a data error. I've never seen anything like it.

mikeyouse 3y ago
For those who don't want to play with the chart - we're apparently below the previous record by 1.5 million square kilometers of ocean with at least 15% ice compared to the record for the prior 45 years... so that's a bit concerning. https://i.imgur.com/2VgP96t.png https://i.imgur.com/2VgP96t.png
- BobbyJo 3y ago
  Also of note: the previous record that's being shattered was last year.
- reportgunner 3y ago
  I didn't want to nitpick but why is that metric "at least 15% ice per square kilometer" ? Can the 15% from four square kilometers bunch up in one square kilometer resulting in a 75% decrease of ice ?
  - mikeyouse 3y ago
    That's not how sea ice works in general - the ice is 'centered' on the continent with 100% coverage and the edges are where you need to make a judgement call on whether they are covered or not. We've established an area grid encompassing the entire antarctic and measure the extent by seeing how many grids are at least 15% ice: https://portal.nccs.nasa.gov/datashare/polar/CSIC/SH_animation.gif https://portal.nccs.nasa.gov/datashare/polar/CSIC/SH_animati... but rest assured, we also measure the total sea ice area which removes all possibility of the 'bunching' you're concerned about -- it's similarly catastrophic; Compared to the past 10 years: https://portal.nccs.nasa.gov/datashare/polar/CSIC/SH_yearly_plot.png https://portal.nccs.nasa.gov/datashare/polar/CSIC/SH_yearly_... Compared to the past 45 years with low/high/average: https://portal.nccs.nasa.gov/datashare/polar/CSIC/SH_decadal_plot.png https://portal.nccs.nasa.gov/datashare/polar/CSIC/SH_decadal...
csomar 3y ago
I am a bit confused. The start of the year looked bad but then it's better than the last couple years? (or almost the same)
- jacquesm 3y ago
  It's the Antarctic, so the ice will grow during the summer months in the Northern hemisphere because it is winter there. It started off at a record low because that's where the dashed red line left it there in the Arctic summer of 2022, and it has departed so far from the previous years that it is now completely disjoint and more than 2 million square kilometers or about 10% of the total scale of the chart behind where it normally would have been. If nothing changes (and why would it?) then it will peak at the 15th of September at 16 million square kilometers setting it up for next year with a start that is even lower. This is unbelievable. As in: I believe it but it defies the imagination, think about the quantity of ice you're talking about and try to imagine the amount of energy required to melt it. And that phase change sink is what effectively is one of the last emergency sinks for all that heat. If and when it goes all that energy will go directly into heating the ocean instead.
  - csomar 3y ago
    > It's the Antarctic, so the ice will grow during the summer months in the Northern hemisphere because it is winter there. You mean Southern, right?
    - Scarblac 3y ago
      No, ice grows now, so during summer in the north. Or winter in the south, same thing.
    - jacquesm 3y ago
      It's winter in the Antarctic right now. And summer in the North. Confusing...
jacquesm 3y ago
That's insane. Utterly depressing.

mikeyouse 3y ago

For those who don't want to play with the chart - we're apparently below the previous record by 1.5 million square kilometers of ocean with at least 15% ice compared to the record for the prior 45 years... so that's a bit concerning. https://i.imgur.com/2VgP96t.png https://i.imgur.com/2VgP96t.png

BobbyJo 3y ago
Also of note: the previous record that's being shattered was last year.
reportgunner 3y ago
I didn't want to nitpick but why is that metric "at least 15% ice per square kilometer" ? Can the 15% from four square kilometers bunch up in one square kilometer resulting in a 75% decrease of ice ?
- mikeyouse 3y ago
  That's not how sea ice works in general - the ice is 'centered' on the continent with 100% coverage and the edges are where you need to make a judgement call on whether they are covered or not. We've established an area grid encompassing the entire antarctic and measure the extent by seeing how many grids are at least 15% ice: https://portal.nccs.nasa.gov/datashare/polar/CSIC/SH_animation.gif https://portal.nccs.nasa.gov/datashare/polar/CSIC/SH_animati... but rest assured, we also measure the total sea ice area which removes all possibility of the 'bunching' you're concerned about -- it's similarly catastrophic; Compared to the past 10 years: https://portal.nccs.nasa.gov/datashare/polar/CSIC/SH_yearly_plot.png https://portal.nccs.nasa.gov/datashare/polar/CSIC/SH_yearly_... Compared to the past 45 years with low/high/average: https://portal.nccs.nasa.gov/datashare/polar/CSIC/SH_decadal_plot.png https://portal.nccs.nasa.gov/datashare/polar/CSIC/SH_decadal...

csomar 3y ago

I am a bit confused. The start of the year looked bad but then it's better than the last couple years? (or almost the same)

jacquesm 3y ago
It's the Antarctic, so the ice will grow during the summer months in the Northern hemisphere because it is winter there. It started off at a record low because that's where the dashed red line left it there in the Arctic summer of 2022, and it has departed so far from the previous years that it is now completely disjoint and more than 2 million square kilometers or about 10% of the total scale of the chart behind where it normally would have been. If nothing changes (and why would it?) then it will peak at the 15th of September at 16 million square kilometers setting it up for next year with a start that is even lower. This is unbelievable. As in: I believe it but it defies the imagination, think about the quantity of ice you're talking about and try to imagine the amount of energy required to melt it. And that phase change sink is what effectively is one of the last emergency sinks for all that heat. If and when it goes all that energy will go directly into heating the ocean instead.
- csomar 3y ago
  > It's the Antarctic, so the ice will grow during the summer months in the Northern hemisphere because it is winter there. You mean Southern, right?
  - Scarblac 3y ago
    No, ice grows now, so during summer in the north. Or winter in the south, same thing.
  - jacquesm 3y ago
    It's winter in the Antarctic right now. And summer in the North. Confusing...

jacquesm 3y ago

That's insane. Utterly depressing.