Report On Sea Level Rise And Ground Water Extraction
There is a news article from the University of Utrecht [thanks to Erik for alerting us to this!] titled
Rising sea levels attributed to global groundwater extraction
The article starts with the text
“Large-scale groundwater extraction for irrigation, drinking water or industry results in an annual rise in sea levels of approximately 0.8 mm, accounting for about one-quarter of total annual sea-level rise (3.1 mm). According to hydrologists from Utrecht University and the research institute Deltares, the rise in sea levels can be attributed to the fact that most of the groundwater extracted ultimately winds up in the sea. The hydrologists explain their findings in an article to be published in the near future in the journal Geophysical Research Letters.”
The article is based on the paper
Y. Wada, L.P.H. van Beek, C.M. van Kempen, J.W.T.M. Reckman, S. Vasak, and M.F.P. Bierkens (2010), Global depletion of groundwater resources, Geophysical Research Letters, doi:10.1029/2010GL044571, in press.
This is yet another paper that shows the interconnection among the components of the climate system. The attribution of a climate effect (in this case sea level rise) to just one cause (e.g. ocean warming and glacial melt due to positive radiative forcing from anthropogenic greenhouse gases) is too narrow of a perspective.
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What else causes this?
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Of course, extracting ground water in say, the area around San Francisco or the area around LA, lowers the level of the land, and makes it appear in those locales that sea level has risen. Witness the case of Alviso.
I agree in rough outline with TheTotalIdiot’s objections. It seems RP is being a bit too glib in his figuring. Perhaps there is an effect of the sort he’s claiming, but it would only be valid insofar as aquifers are actually being depleted, and there is evidently an upper bound on this. The amount of ocean volume increase by this cause (neglecting temperature and pressure considerations) could not exceed the amount of volume decrease in the worldwide groundwater reserve.
If he is correct and we are steadily increasing ocean volume by 8mm/yr this translates into a rather large depletion of aquifers! I hate to rally to the alarmist side, but I would suggest that this should be a matter of serious concern, if true. But I think not — or not to the degree RP’s figures suggest. Surely much of the groundwater is simply refreshed from rainfall, and some was being depleted (and refreshed) anyway, by underground runoff. In terms of the freshwater reserve, a lot of groundwater is distinguished from surface water only by being underground — there is a continuum between them. Drawing from a well near a lake is hardly different from drawing surface water from the lake. There IS some aquifer depletion in dry areas, but I expect the effect is small compared to RP’s figures.
I think protection of aquifers, in dry regions, is a serious concern and, in developing countries, alternatives to groundwater must be sought for irrigation if agriculture is to be improved (this is also true even when no aquifer is available). I thought this was a practically unsolvable problem until I looked at solar tower generation of power, which has the happy side effect of extracting H2O from the air on a large scale. So you get a steady, relatively cheap source of electricity PLUS a steady, clean source of fresh water. Imagine one of these towers outside each of thousands of small villages of Mauritania (for example). If you watch the video I link to you see that it gives a modest nightly collection of water; but this is a “small” tower. As the scale increases, the square footage of the collection area increases quadratically and so does the volume of water collected. It is naturally situated for “greenhouse” agriculture with no extra infrastructure, but with a large enough tower, H2O could be harvested for potable domestic use as well. One thing not mentioned in the video is that there is probably an extra amount of condensation on the inside of the tower itself due to adiabatic expansion…
RE: “but one to two hundred kilometers away sea levels are falling”
A bit WSW of Bangkok, along the Gulf of Siam, there used to be myriad salt evaporators set up in what used to be saline intertidal wetlands and swamps with indigenous mangrove, pickleweed, etc.
Today, the few that survive are finding it necessary to replace the old style windmill type pumps with modern ones iorder to pump the increasingly distant saline water but most simply fold or sell out to shopping mall builders. Where mangrove and pickleweed once grew now there is acacia scrub. Yeah, sea level rise … right.
“…Yeah, sea level rise … right.”
The area you speak of is tectonically active and you present no evidence that the salt ponds have not been closing due to the changing sea level rather than economics (not to mention local techtonics). Nor do you present any evidence that the sea level has actually fallen there.
http://thailand-business-news.com/news/top-stories/19335-thailands-capital-is-under-threat-of-being-underwater-within-a-century/