Shrinking freshwater availability increasing land contribution to sea level rise
43 comments
·August 3, 2025garrettdreyfus
garrettdreyfus
My reading of Figure 6 https://www.science.org/doi/10.1126/sciadv.adx0298 suggests that this study still has thermosteric effects making up the majority of sea level rise.
I also highly recommend reading up on the GRACE satellite used in this study it is amazing https://gracefo.jpl.nasa.gov/resources/50/how-grace-fo-measu...
yboris
Thank you for sharing, GRACE-FO feels to me like a brilliant design!
dang
Ok, I've put the second suggestion up there. Thanks!
(Submitted title was "Freshwater loss from land is the lead driver of sea-level rise")
ornel
Quote from the paper: "the continents are now the leading contributor (44%) to mass-driven GMSL rise". As regards to non-mass-driven rise, another article[0] states, "Ice-mass loss—predominantly from glaciers—has caused twice as much sea-level rise since 1900 as has thermal expansion". I think the findings about sea level rise are as interesting as the ones about fresh water disappearance.
garrettdreyfus
The study you cite is talking about sea level rise since 1900 which is a very different story.
The IPCC section “9.6.1.1 Global Mean Sea Level Change Budget in the Pre-satellite Era” says Since SROCC, a new ocean heat content reconstruction (Section 2.3.3.1; Zanna et al., 2019) has allowed global thermosteric sea level change to be estimated over the 20th century. As a result, the sea level budget for the 20th century can now be assessed for the first time. For the periods 1901–1990 and 1901–2018, the assessed very likely range for the sum of components is found to be consistent with the assessed very likely range of observed GMSL change (medium confidence), in agreement with Frederikse et al. (2020b; Table 9.5). This represents a major step forward in the understanding of observed GMSL change over the 20th century, which is dominated by glacier (52%) and Greenland Ice Sheet mass loss (29%) and the effect of ocean thermal expansion (32%), with a negative contribution from the LWS change (–14%). While the combined mass loss for Greenland and glaciers is consistent with SROCC, updates in the underlying datasets lead to differences in partitioning of the mass loss.”
Edit: by a different story I mean a different story from what is the leading driver of sea level rise. Sea level rise from ice melt was larger since 1900 because sea level rise in general was less fast back then and global mean temperature rise was much smaller so thermosteric sea level rise played less of a role. Thermosteric sea level rise is larger than ground water factors, both will be eclipsed by ice melt in the upcoming century.
I would note the authors pointedly do not call it the leading driver of sea level rise.
perching_aix
So let me get this straight:
- sea level is formally referred to as Global Mean Sea Level (GMSL)
- its change is segmented into two subcategories in literature(?), mass-driven (e.g. ice melting?, freshwater runoff?, freshwater water cycle stuff?) and non-mass-driven (e.g. thermal expansion?)
- freshwater loss from land was found to be at present the lead driver of the mass-driven change as per the paper (over what timeframe?)
- title says it's the primary driver for GMSL change overall, which this alone doesn't support (i.e. the title is a lie)
- @ornel (the person posting) points to another study that claims mass-driven change is the leading change, hence the title [0, this doesn't pass my smell test but i see the logic]
- you point out that that's glossing over that that other study is counting from 1900, but if one shrunk the evaluation window, the non-mass-driven causes would be the drivers now [1, this doesn't pass my smell test either, but i see the logic here as well]
The latter point then begs the question though, what is the time window in this case then, and how stable that result is? What would be an "appropriate" time window to choose, and how would one derive that?
Regarding my non-passing smell tests, imagine the following scenario for some event:
- category A: 51% of the total
- cause A1: 26% of the total
- cause A2: 25% of the total
- category B: 49% of the total
- cause B1: 27% of the total
- cause B2: 22% of the total
In this case, category A will be the lead contributor, but individually none of its contributing causes will be, addressing [0]. The causes will be ordered like so instead: B1 > A1 > A2 > B2. More elaborate variations are possible of course. For [1], you can imagine the same scenario just in reverse.
Did I get all this right?
cwillu
@dang doesn't do anything; but they're quite responsive to email.
srameshc
> New findings from studying over two decades of satellite observations reveal that the Earth’s continents have experienced unprecedented freshwater loss since 2002, driven by climate change, unsustainable groundwater use and extreme droughts.
The title captures the crux of the story
garrettdreyfus
Sorry I am referring to HN submission title not the article title
SoftTalker
So go long on desalination tech?
cubefox
Original title: "New global study shows freshwater is disappearing at alarming rates"
nabwodahs
[dead]
jfengel
Unlike climate change, this is a self correcting problem. We'll tap the last of the fresh water, and then no more sea level rise (from that source).
Problem solved, once and for all.
causal
Solutions that include mass die-off of human populations are generally considered incomplete
Ekaros
But they are effective in reducing emissions.
makeitdouble
This is an often repeated point, and many proponent of population reduction embrace it.
I think that's completely ignoring our consumption patterns. We're totally up to the challenge of burning twice the resources with only half the population.
firstworldfail
I love the first world perspective. It pretends to be erudite while being completely inhuman. As if "emissions" are something you could ever get rid of. Any excuse to avoid making their own lives more efficient or the distribution of resources more fair.
andyferris
Just like the coal, gas, oil and forests - so exactly like climate change, in fact...
(It's a problem that saturates but not a problem that self-corrects, and the saturation point is undesirable in any case)
treyd
The polar ice caps are the same way. Once we melt all the ice then the sea level rise will stop, and we can just deal with the change in lifestyle.
oh_my_goodness
I think the change in lifestyle from using up all the groundwater would be pretty severe.
micromacrofoot
personally i'm just going to evolve
Gibbon1
Considering current shitshow reaction to having to deal with smaller issues I'm not optimistic about how that's going to play out.
marcosdumay
Well, that applies to most of our habitat-change problems.
ada1981
It’s a good reminder that “climate change” will be a minor inconvenience for the rich, and an existential crisis for everyone else.
And that most of the inconvience will be needing to deploy robots to keep the poor away.
slt2021
thats what revolutionary movements are for: to organize "everyone else" and physically purge the elites that dont care about the crisis affecting regular people
giantg2
So they claim the majority of the water is ground water and also that it is due to climate change. But I thought I've seen other studies talking about how ground water is being depleted at a higher rate than it could be replaced, even using historical averages. This sounds more like a population/industrialization issue than a climate issue.
cycomanic
> So they claim the majority of the water is ground water and also that it is due to climate change. But I thought I've seen other studies talking about how ground water is being depleted at a higher rate than it could be replaced, even using historical averages. This sounds more like a population/industrialization issue than a climate issue.
I'm not sure I understand where you see a contradiction. Land areas are using groundwater faster than it can be replenished, so land is getting drier. That's according to the article (just basing of the summary not the scientific one) is driven by both overuse and drier and warmer weather. The thing is, that's a feedback loop, if it gets drier we'll be using more groundwater for irrigation. So both processes are driven by climate change.
nabwodahs
[dead]
pstuart
I think the distinction is between rainwater runoff vs aquifer depletion. They are related, and if we were collectively smarter we would do a better job of managing the runoff to help restore the aquifers.
DaveZale
in some parts of the country (US), interstate water agreements promise a certain volume of water to be delivered from one state to another, in which cases, runoff is sometimes required. Legal agreements.
I’m not sure this title is completely correct
“The researchers identified the type of water loss on land, and for the first time, found that 68% came from groundwater alone — contributing more to sea level rise than glaciers and ice caps on land.”
They are saying the leading loss of water loss is from ground water. The largest contributor to sea level rise I would guess is still thermosteric sea level rise due to the ocean becoming warmer and less dense
See ipcc https://www.ipcc.ch/report/ar6/wg1/chapter/chapter-9/
9.6.1 Global and Regional Sea Level Change in the Instrumental Era
In particular, Cross-Chapter 9.1, Figure 1 | Global Energy Inventory and Sea Level Budget. Panel b
EDIT: @dang could the submission title be changed to the article or journal article title?
“New global study shows freshwater is disappearing at alarming rates”
Or
“Unprecedented continental drying, shrinking freshwater availability, and increasing land contributions to sea level rise”