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Shrinking freshwater availability increasing land contribution to sea level rise

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Re: Shrinking freshwater availability increasing land contribution to sea level rise

#41

Post by garrettdreyfus »

perching_aix wrote: post #38
garrettdreyfus wrote: post #32

Earlier quoted context omitted.

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 centur…

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 ti…

I very much like your categories point here by the way!

Re: Shrinking freshwater availability increasing land contribution to sea level rise

#43

Post by perching_aix »

garrettdreyfus wrote: post #39
perching_aix wrote: post #38

Earlier quoted context omitted.

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 ti…

Hi, I appreciate the effort in your comment. I think upon further reflection my simpler objection is calling freshwater loss the main driver of sea level rise when the journal article and news article don’t. Also I would note this is only one study.

> I appreciate the effort in your comment.

Thanks for that! I do wish it wasn't necessary though, but I guess that's just how real life problems go.

> I think upon further reflection my simpler objection is (...)

Right, that's perfectly fine; just got curious and you seemed informed.

Editorializing the titles in general is against the guidelines here anyhow to be fair, I'm expecting it will be updated by the mods eventually: https://news.ycombinator.com/newsguidelines.html

Re: Shrinking freshwater availability increasing land contribution to sea level rise

#44

Post by dang »

garrettdreyfus wrote: post #4

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…

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")

Re: Shrinking freshwater availability increasing land contribution to sea level rise

#47

Post by cutemonster »

slt2021 wrote: post #36
ada1981 wrote: post #27

Earlier quoted context omitted.

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.

thats what revolutionary movements are for: to organize "everyone else" and physically purge the elites that dont care about the crisis affecting regular people

Nowadays the revolutionary movements listen to Twitter and go hunting immigrants instead, the elite has never been safer?

Re: Shrinking freshwater availability increasing land contribution to sea level rise

#48

Post by giantg2 »

cycomanic wrote: post #13
giantg2 wrote: post #3

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.

> 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 usi…

"is driven by both overuse and drier and warmer weather."

It wasn't that there is a contradiction. If the over use has been happening for decades, and it's at a rate faster than historical replenishment could happen anyways (before "climate change), then this would indicate that over use is the primary cause. Drier weather is a contributing factor in the pace of depletion, but in no way could be the solitary cause nor cure. Even in the article they mention the demands related to a growing population and industrial agriculture (article also mentions potential food scarcity).

Re: Shrinking freshwater availability increasing land contribution to sea level rise

#49

Post by mturmon »

garrettdreyfus wrote: post #8
garrettdreyfus wrote: post #4

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…

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...

> it is amazing

Indeed!

The GRACE measurement of mass change is one of the more revolutionary advances in Earth science remote sensing in the last few decades. It has provided a unique and completely novel view of groundwater mass change. Grace is the main reason we know so much about the massive groundwater loss in the Oglala aquifer in the US Midwest, in the Central Basin in California, and in northern India. Water well data exists but it is very sparse and idiosyncratic.

It’s also our main window into mass losses in ice sheets in high latitudes (Greenland, Antarctica). We have radar altimetry data from Antarctica, but because of glacial rebound and other effects, it’s not easy to translate height changes into mass changes. Grace measures mass change directly.

Several authors of the cited study are on the science team. It is a JPL instrument.

The original Grace pair used radio to measure separation and velocity, while the follow-up Grace-FO uses a laser. I assume the small wavelength of the laser provides a more accurate measurement. It’s possible that Grace-FO has a slightly higher spatial resolution (I’ve worked with Grace but not Grace-FO); the horizontal resolution of Grace is about 100km or about 1 degree.

From an inference perspective the measurement is very interesting. They pool about a month’s worth of observations of the distance and velocity of a pair of satellites, and do a Bayesian inversion to obtain a parameterized gravitational potential for that month. The map from gravitational potential to observation is known analytically, so it’s readily possible to get a spatial covariance for the gravitational potential, as well as the point estimate.

Re: Shrinking freshwater availability increasing land contribution to sea level rise

#50

Post by HocusLocus »

Sea level rise (#2) is a 'crisis' for absolutely no one.

I set an alarm for (#1), "Preparing for the low pressure 12ft tidal/storm surge or the 18ft tsunami that could arrive as early as tomorrow and probably will within 10 years, unless one is incredibly dumb or has never lived near the ocean."

I did not set an alarm for #2.

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