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?
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).
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.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.
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
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.