Pumping groundwater raises sea levels?
2012-05-24 0:00

By Janet Raloff | ScienceNews.org

Two new studies flag an underreported factor in global ocean change

Pumping groundwater, some 70 percent of it to irrigate crops, has recently become a potent force in global sea-level rise, two new studies conclude.

It sounds obvious: Once brought to the surface, water will eventually run into the seas, says hydrologist Yoshihide Wada of Utrecht University in the Netherlands. But until now, most major assessments of factors affecting sea-level rise — such as those reported by the Intergovernmental Panel on Climate Change — ignored the role of groundwater extraction, he says. For instance, the IPCC has assumed that groundwater extraction would be largely balanced by river water impounded by dams.

Such an assumption was probably accurate until about 1980, says Yadu Pokhrel of Rutgers University in Piscataway, N.J. Since then, the balance has shifted, he says, and groundwater extraction is now developing into a growing force behind sea-level rise.

In recent years, sea level has been rising around 3.1 millimeters each year. Besides groundwater depletion, other major contributors include the melting of glaciers and polar ice fields, and the expansion of ocean water as it heats up. By 2003, groundwater removal was responsible for about 34 percent of that sea-level rise, Pokhrel and his colleagues report online May 20 in Nature Geoscience. They added all human water-use components to a computer program that projects climate impacts, assuming that any water demands not met by surface water came from groundwater sources.

Wada’s team also found groundwater pumping to be a bigger contributor than thought. By 2000, these researchers report online May 8 in Geophysical Research Letters, global groundwater depletion was causing sea levels to rise some 0.57 millimeters each year — around 18 percent of current annual sea-level increases and an amount of water roughly equivalent to twice as much as dams were holding back. This analysis, unlike Pokhrel’s, used globally recorded data on groundwater extraction.

This imbalance stands to only grow, Wada notes. His team adapted computer programs to, for the first time, project how humans’ water use would affect sea level through 2050. By then, the scientists calculate, reservoir impoundment would prevent about 0.1 millimeters rise in sea level, while groundwater depletion would increase sea level by more than eight times that amount.

The new studies confirm groundwater extraction as an important and growing factor in sea-level rise, says Leonard Konikow of the U.S. Geological Survey in Reston, Va. But he challenges the magnitude reported by the new studies. His own analysis, published last September in Geophysical Research Letters, pegged groundwater extraction’s impacts at only 13 percent of the recent increase.

Konikow notes that groundwater depletion must be estimated indirectly, such as by adding regional measurements of groundwater and pumping to larger-scale satellite and other data. He charges that the potentially more-simplistic techniques employed in the new papers overestimate groundwater pumping — and hence its sea level impacts.

That’s true, Pokhrel acknowledges. His and Wada’s approaches assume, for the sake of calculations, that groundwater reservoirs are infinite and affordable. Obviously, he says, that’s not true.

Wada agrees: “There are no data on global groundwater levels. So we assume in the future that there will be [sufficient] groundwater — which may not be true, in some cases, if groundwater levels become too low” or if farmers can no longer budget to tap increasingly deep sources.
“Many people think that groundwater pumping effects will be small or localized,” Pokhrel says. But the new data, he says, show that cumulatively, these withdrawals are changing sea level globally.

Article from: ScienceNews.org

New sat data shows Himalayan glaciers hardly melting at all

Glacier Meltdown: Another Scientific Scandal Involving the IPCC Climate Research Group

Amount of ice in Bering Sea reaches all-time record

Related Articles
Piers Corbyn: Delusion & Fraud: Global warming nonsense lobby to collapse (Video)
Honduran Farmers Slaughtered In Name Of Global Warming
CIA’s Global Warming Center A National Security Secret
Solar Cycles Cause Global Warming & Cooling not Humans
No apology from IPCC chief Rajendra Pachauri for glacier fallacy
Some Himalayan Glaciers Growing
Arctic freshening not due to ice melt after all, says NASA
Rise of sea levels is ’the greatest lie ever told’

Latest News from our Front Page

The Pilgrims Were Definitely Not Like Modern-Day Refugees
2015-11-27 20:01
This upcoming Thanksgiving Day is sure to offer you and your family plenty of opportunities to argue over whether America should be welcoming Syrian refugees. If you have any liberal relatives or friends coming over for your Thursday feast, they’re going to relish the chance to tell everyone that the Pilgrims were refugees too — and hope that statement decimates all ...
ISIS to France: "We will be coming. Victory has been promised to us by Allah"
2015-11-26 3:33
Homegrown French ISIS fighters have issued a chilling threat of new attacks on France just 24 hours after the terrorist group used movie footage of the Eiffel Tower's collapse in another video.  A balaclava-clad militant is seen warning 'we will be coming, we will come to crush your country' in footage posted on Twitter earlier today. It is unclear where the film ...
ISIS teenage 'poster girl' Samra Kesinovic 'beaten to death' as she tried to flee the group
2015-11-26 1:07
She appeared in social media images for the group carrying a Kalashnikov and surrounded by armed men A teenage girl who ran away from her Vienna home to join Isis in Syria has reportedly been beaten to death by the group after trying to escape. Samra Kesinovic, 17, travelled to Syria last year with her friend Sabina Selimovic, 15. The two became a ...
The Right Stuff's flagship podcast "The Daily Shoah" has been censored by Soundcloud
2015-11-25 22:56
Editor's note: The PC corporate moral police strike again. Just as Radio 3Fourteen & Red Ice Radio were censored from iTunes, The Daily Shoah was pulled from Soundcloud today. As per usual, there is a double standard, they allow any kind of anti-White material: No counter culture humor making fun of the genocidal mainstream garbage is allowed! ... From: therightstuff.biz Soundcloud took it upon ...
Merkel Welcomes A Million More: Vows To Stand By Refugee Policy Despite Security Fears
2015-11-25 21:05
Chancellor Angela Merkel vowed on Wednesday to stick to her open-door refugee policy, defying criticism at home and abroad which has intensified due to growing fears about a potential security risk after the Islamist attacks in Paris. Conservative Merkel faces splits in her right-left coalition and pressure from EU states, including France, over her insistence that Germany can cope with up ...
More News »