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.
=============================================
What else causes this?
This is a little too simplified. In my area 98% of all the water we use goes into septic systems and dry wells and percolates back into the water table. Virtually none makes it to the rivers much less the oceans.
The water taken from an aquifer is only relevant for aquifers which refill more slowly than water is being taken out, and more is being taken out than would have otherwise leaked out. A shallow well from uncapped sandstone in Florida is irrelevant, as that aquifer will be quickly refilled from rainfall. An aquifer with 10,000-year-old-water which is being emptied ten times faster than it is refilling is relevant, unless the water being taken out has reduced the outflow by the same amount. The simplest example is an aquifer which is completely sealed from the outside, as any water taken out of there will end up in the ocean and the space won’t trap replacement water.
How does that effect the ocean heat content? You’re taking water that has heat that is from the earth’s interior and adding it to the oceans, or is it the other way around? Are you diluting the heat content of the oceans by adding ground water?
Extraction of groundwater, over a long period of time, leads to local drops in ground level. Witness for example, Venice in Italy, Jakarta in Indonesia, or the famous New Orleans ie any city that allows extraction of ground water. I read a paper a number of years ago, where sea levels relative to the Australian landmass appear to be falling, but the cities with the extraction of ground water are sinking. Most of the old sea level measures are based in cities, which means by most measures, sea levels are indeed rising, in that location, but one to two hundred kilometers away sea levels are falling, with respect to the local land mass. I suspect the paper is a gross over simplification.
This is getting out of hand! Most aquifers are recharged by rivers. Where this is the case, the river itself reduces its flow to the sea if the head above the aquifer is positive. If the aquifer is not used it feeds the river. Other commenters have also pointed out that the water tied up in vegetables, livestock and drinking water use was going to get used anyway, and evapotrans and rain on land would be returned, etc. These guy’s must be Post Normal hydrologists. Old time bluesman Robert Johnson sold his soul to the devil at “The Crossroads” but at least he got to master the guitar in exchange. What do these people get out of it?
About a year ago there was an article (in Science?) which totaled up all the water held behind dams and showed that it significantly decreased sea level rise. If it ain’t one thing it’s another.
REPLY: Well without a citation, it’s just rabbett pellets – Anthony
Dave Wendt – I have to agree with you.
I did a personal test on sea level rise recently when I returned to a beach I knew very accurately as a child. ( 10) I knew all the rocks that projected out from the beach and how they related to the sea level. When I returned at low tide I found the relationship with the sea level to be exactly the same after 50 years. There was no discernible sea level rise.
The late Prof Lance Endersbee from ANU believed that the water in the aquifers has come up from the mantle below, they are not filled with rainwater seeping down.
He believed the draining of our great aquifers, especially the Great Artesian Basin in Australia was more of a threat than AGW which he had little time for.
Eli Rabett says:
September 29, 2010 at 7:36 pm
“About a year ago there was an article (in Science?) which totaled up all the water held behind dams and showed that it significantly decreased sea level rise. If it ain’t one thing it’s another.”
Eli is referring to the same article I referred to earlier today ( Curt says:
September 29, 2010 at 12:38 pm ). I now can find the report. It is:
B. F. Chao, Y. H. Wu, Y. S. Li, “Impact of Artificial Reservoir Water Impoundment on Global Sea Level”, Science, 11 April 2008, Vol 320, pp. 212-214. (behind paywall)
But Eli misses the most important aspect of the report, that the amount of impoundment has decreased significantly since the 1960s and 1970s because we are building fewer dams now. They show a very steady decline in the amount of “global sea level drop” (their term) due to impoundment from a peak of about 0.7mm/year in the 1960s, to about 0.2mm/year in the 2000s. So even if there were a recent increase in net sea level rise of 0.5mm/year since the 1960s (which the best tidal gauges do not show), it could be entirely due to this change.
Terry Miller says:
September 29, 2010 at 12:21 pm
In addition to adding water from aquifers, has anyone considered the effect of sediments transported to the sea via rivers or dust?
—
Yeah. I did a back of the envelope calculation of sealevel rise due to sediment transport, and it comes out to a couple hundredths of a mm, about .03mm. This doesn’t include land reclamation projects though.
“totaled up all the water held behind dams ”
Is that total potential water if all the dams are full to overflowing? Many dams are well drawn down.
The stupidity and shortsightedness on display here is absolutely astonishing…
“A quarter of sea level rise is due to humans pumping out groundwater and it eventually ending up in the sea. So sea level rise due to climate change is overblown, and since this aquifer water is used for drinking and irrigation, it’s an useful activity”.
And nobody ever stops for a second to think what people will drink and irrigate their crops with after the aquifers have been depleted? Which is not that far, in fact quite close, into the future in many regions
How is that possible??
Of course, it had never occurred to you that the places where aquifers aren’t depleted fast enough are also the ones where rainfall is insufficient and where people are most dependent on them. Which, BTW, includes a very large number of people and an even larger proportion of world’s agricultural production.
And if you are extracting water (and oil) from the ground, the ground often subsides a little**. So while sea levels are increasing due man’s activities, the land is also sinking.
** They used to say in UK coal mining that for every 4ft of coal taken out below, the surface sank by 1 ft.
Well, since sea level rise has dropped to around 1.3mm year since 2005, this would account for most of it. However, I wonder if they have considered how much more natural flow there would be in the river estuaries if the water wasn’t being extracted from the water table higher up the valleys.
* I meant to say “aren’t recharged fast enough” above..
I would have thought that irrigation water would, through evapotranspiration, end up back in the atmosphere to fall as rain and become ground water again. A little tenuous I would have thought especially when you think how much water would go to raise sea levels by 0.8mm. Probably more than falls as rain per day.
And this will be spun thus.
Not only are massive sea level rises due to Fossil Fuel combustion but we’re making the problem worse by our exploitation of Fossil Water.
Conclusion. We’re worse than we thought!
There is no need for spinning it, that’s exactly how it is. Climate change and Peak Fossil Water are simply different aspects of our global ecological overshoot. The latter rarely gets paid much attention so we are indeed much worse than most people think
You can extract water from air for drinking purposes. The 2010 Vancouver PNE Prize home had such a system built in.
Harvesting water from air
(AWG) Atmospheric Water Generator using solar energy
http://a2wh.com/air-extraction-water-harvest-device-A2WH-overview.html
GM says:
September 30, 2010 at 3:08 am
“[…]Climate change and Peak Fossil Water are simply different aspects of our global ecological overshoot.[…]”
Ah, a peak something.
http://en.wikipedia.org/wiki/Peak_water
and:
“Water map shows billions at risk of ‘water insecurity’
By Richard Black”
http://www.bbc.co.uk/news/science-environment-11435522
Looks like water is quickly becoming the new scare du jour. Funny, given how abundant it is.
You can also desalinate it. If you had the energy to do that. Unfortunately, the coming shortage of concentrated sources of energy is yet another aspect of our global overshoot
I wondered and posted about irrigation here a couple of years ago. The numbers from the UN for irrigation are enough for about 2mm/year, but that was all irrigation, not just groundwater. Regardless of where it comes from, center-pivot systems that spray the water add some to the atmosphere.
I suspect what anyone says re: a 3.1mm/yr. sea level rise, when the satellite only has an accuracy of some 25-35mm per pass over the ocean. Apparently, it is assumed that multiple passes will somehow reduce the error to some 10X less, but do we really know this to be the case or is it just intuitive? After all, doesn’t tidal gauge info dispute the 3.1 number, which should make the satellite data suspect, at the very least? To me, as a lay reader, SLR is more like 1.7 to 2.0, which would make extraction influence more like 40% or so. Can someone out there show me that the satellite measurement of 3.1mm is real?
From GM on September 30, 2010 at 12:44 am:
We know, yet you still keep coming back with your zero-sum, everything-is-getting-used-up-too-fast, we-are-running-out-of-everything-right-now-and-we-will-all-die-quicker-because-of-it, the-species-would-be-better-off-if-most-of-the-people-were-dead, doomy-gloomy nonsense and adding to the total.
Genus Malthusian, why can’t you just accept this is a very large planet with individual resources from sources we can tap for hundreds and thousands of years, then switch to other sources of individual resources for as long or longer, and we can also substitute one resource for another? We’re a very creative species, we will survive and prosper, with or despite you.
Since you are again failing to frighten we adults with your Peak Whatever of the day, just go past Peak Pessimism, and try something other than sounding like a little kid with a bag of candy screaming “I can’t share, it’ll be all gone and I’ll never get anymore!” We are far more at risk from an imagined resource scarcity than any real one. Is that your game, to bring about the collapse of civilization and the death of billions by panicking people into hoarding anything possible by convincing them it’ll soon be gone?
Just a thought… As sea-levels have been reportedly rising, has there been any measurable drop in salinity commensurate with the assumed influx of fresh water? I realize that any such change, even over many years, might be too small to measure.