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grundar t1_j8ke9q1 wrote

Reply to comment by 9273629397759992 in New study shows Acceleration of global sea level rise imminent past 1.8℃ planetary warming by 9273629397759992

It's worth noting that this paper is actually good news, as it predicts lower global sea-level rise contributions from ice melt than previous models did; from the Abstract:
> "The combined effect is likely to decelerate global sea-level rise contributions from Antarctica relative to the uncoupled climate-forced ice-sheet model configuration."

In "Discussion" they call this out specifically for high-emission scenarios:
> "In our high-emission scenario model simulations that include parameterizations for hydrofracturing, ice-cliff instabilities, and capture sea-ice and atmospheric responses, the net impact of ice-sheet/climate feedbacks on SL rise is negative."

It looks to be a fairly marginal change, though; the projected amount of sea-level rise is still enough to be a serious problem, impacting where hundreds of millions of people currently live.

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AndyTheSane t1_j8m2doo wrote

I'm a bit dubious about this; paleogeographic studies point to large (as in around 20m) sea level rises from the kind of temperature rise we've already seen or can project in a few decades. Now, it could be a matter of timing - it might take 1000 years or so for the full ice-sheet response - but it's not exactly reassuring.

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grundar t1_j8nobbf wrote

> I'm a bit dubious about this

What exactly are you dubious about? That the paper predicts lower sea level rise than previous models, or that either way the sea level rise will be enough to have serious consequences?

Your phrasing makes it seem like you're disagreeing with me, but I don't see which part you're disagreeing with.

> Now, it could be a matter of timing - it might take 1000 years or so for the full ice-sheet response - but it's not exactly reassuring.

There's a massive difference between "20m of sea level rise in 80 years" and "20m of sea level rise in 1,000 years".

In particular, my understanding is that paleographic studies are generally of the form "temperature went up 5C and sea level went up 20m over the course of 10ky", meaning sustained temperature increase led to large sea level rise. There's not really any hope of seeing temperatures 80 years from now back to pre-industrial levels, but IPCC scenarios like SSP1-2.6 see temperature starting to fall by then, meaning it could be back to pre-industrial levels within a century or two.

As a result, if a certain amount of sea level rise requires only 80 years of sustained temperature increase of 1.5-2C, we have little hope of avoiding that. By contrast, if that amount of sea level rise requires 1,000+ years of sustained temperature increase of 1.5-2C, there's quite good odds of avoiding some, most, or potentially even virtually all of that.

In general, the known ice melt tipping points take thousands of years. I extracted a list of those tipping points from a paper previously discussed on r/science, and the timescale for 10m+ of sea level rise looks to be about 2,000 years (mainly West Antarctic ice sheet and East Antarctic subglacial basins).

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SeaUrchinSalad t1_j8osz3h wrote

If the water rises slow enough, we might get lucky and find lots of it falling on land and recharging aquifers, which would reduce the amount in the ocean and contributing to the rise. Not by much though

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3trt t1_j8piy0t wrote

That's a stretch. Most global warming models predict droughts. Sure more water will fall in places, but it's not normally where we need it for agriculture or it comes as monsoons and washes away to the ocean as quick as it came.

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SeaUrchinSalad t1_j8q9eqv wrote

Yea we need to get good at hydro geo engineering to capture those monsoons and fast

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