Pumping groundwater raises sea levels?
2012 05 24

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

NATO Exercise in Ukraine Coincided with MH-17 Shoot-down
2014 07 24
Rapid Trident was omitted from the flurry of coverage on the shoot-down MH-17. From the U.S. Army in Europe website: Rapid Trident supports interoperability among Ukraine, the United States, NATO and Partnership for Peace member nations. The exercise helps prepare participants to operate successfully in a joint, multinational, integrated environment with host-nation support from civil and governmental agencies. ...
Warning of ’imminent’ terror attack in Norway
2014 07 24
Norwegians were warned Thursday of the concrete possibility of a terror attack occurring in that country at the hands of people with connections to an extremist group in Syria. A press conference was called in Oslo, Norway on Thursday where an announcement was made of a "possible concrete threat" to national security in that country from terrorists related to an extremist ...
Judge says government can access everything in a Gmail account
2014 07 24
All your emails are belong to us. At least that’s what the latest court order from a judge in New York says. The warrant, granted on June 11, states that the government can access all the content and files contained in a Gmail account. Yes, this is a significant blow to privacy. The subject of this specific search relates to a money laundering ...
Scotland Yard Spied on Grieving Families: secret surveillance after police victim shot seven times in head ’by mistake’
2014 07 24
More terror from the ’anti-terror’ brigade. Undercover police gathered evidence on 18 grieving families By Rob Evans and Vikram Dodd | The Guardian Undercover police officers secretly gathered intelligence over two decades on 18 families fighting to get justice from the police, it was revealed on Thursday. The intelligence covering high-profile campaigns was collected between the mid-1980s and 2005, and affected grieving families ...
Air Algerie AH5017 with 116 onboard goes missing for hours, found crashed in Mali
2014 07 24
An Air Algerie flight carrying 110 passengers and six crew members has reportedly crashed in Mali after having disappeared from radar early on Thursday morning between Burkina Faso and Algeria. A French Ministry of Defense official told Fox News that the two French fighter jets located the wreckage of the plane, which had crashed in Mali. An airport official additionally confirmed ...
More News »