Groundwater greed driving sea level rises

[nebula]

Groundwater greed driving sea level rises

25 September 2011 by Michael Marshall

SLOWLY and almost imperceptibly the seas are rising, swollen by melting ice and the expansion of seawater as it warms. But there's another source of water adding to the rise: humanity's habit of pumping water from underground aquifers to the surface. Most of this water ends up in the sea.

Not many scientists even consider the effects of groundwater on sea level, says Leonard Konikow of the United States Geological Survey in Reston, Virginia. Estimates were published as far back as 1994 (Nature, DOI: 10.1038/367054a0), but without good evidence to back them up, he says. The last report of the Intergovernmental Panel on Climate Change said that changes to groundwater reserves "cannot be estimated with much confidence".

Konikow measured how much water had ended up in the oceans by looking at changes in groundwater levels in 46 well-studied aquifers, which he then extrapolated to the rest of the world. He estimates that about 4500 cubic kilometres of water was extracted from aquifers between 1900 and 2008.

That amounts to 1.26 centimetres of the overall rise in sea levels of 17 cm in the same period (Geophysical Research Letters, DOI: 10.1029/2011gl048604).

That 1.26 cm may not seem like much, but groundwater depletion has accelerated massively since 1950, particularly in the past decade. Over 1300 cubic kilometres of the groundwater was extracted between 2000 and 2008, producing 0.36 cm of the total 2.79-cm rise in that time. "I was surprised that the depletion has accelerated so much," Konikow says.

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[goldust59]

Interesting. Hadn't thought about that.

[Leonard]

Interesting. Hadn't thought about that.

If the sea levels are actually rising, then why haven't the tide depth schedules changed EVEN 1/4 INCH since they were first surveyed almost 200 years ago?

[goldust59]

Hi Leonard, that's a good question. Though I found the article interesting, I didn't necessarily agree with it. Actually, it made me wonder what the government will try to pull on us now concerning water usage.

[nebula]

If the sea levels are actually rising, then why haven't the tide depth schedules changed EVEN 1/4 INCH since they were first surveyed almost 200 years ago?

What do you mean by the tide depth schedules?

[other one]

17 centimeters is only about 3/4th of an inch

[Guest agua]

It's not only the water we're after here.

Our Great Artesian Basin is neighbours with huge amounts of coal and seam gas. I have never heard of this water raising sea levels until now. Boy... a poor old miner needs to consider so much today.

The basin, spanning 2400km from Cape York in the north to Dubbo in the south, from the Darling Downs in the east to Coober Pedy in the west, holds an estimated 64,900 gigalitres of water, or enough to fill Sydney Harbour 130,000 times.

[ayin jade]

The Colorado River (a large river in the US for those in other parts of the world) barely flows into the ocean any more. We surely dont waste ground water to the ocean either. I disagree with this article.

[Matthitjah]

The article is ridiculous on it's face. Groundwater is a renewable resource. Well's re-fill and are replenished.

So what if humans are pumping groundwater and it ends up in the oceans? It will evaporate and return to the groundwater eventually.

Sounds like more Global Warming tripe.

Peace,

Dave

[nebula]

So what if humans are pumping groundwater and it ends up in the oceans? It will evaporate and return to the groundwater eventually.

Not if the rate of uptake is greater than the rate of re-fill, which is what is happening in a lot of places.