Human Water Use Accounts For 42% of Recent Sea Level Rise

scibri writes "During the latter half of the twentieth century, global sea level rose by about 1.8 millimeters per year. The combined contribution from heating of the oceans, which makes the water expand, along with melting of ice caps and glaciers, is estimated to be 1.1 millimeters per year, which left some 0.7 millimeters per year unaccounted for. It seems that the effects of human water use on land could fill that gap. Researchers report in Nature Geoscience that land-based water storage could account for 0.77 millimeters per year, or 42%, of the observed sea-level rise between 1961 and 2003. The extraction of groundwater for irrigation and home and industrial use, with subsequent run-off to rivers and eventually to the oceans, represents the bulk of the contribution. It would be even worse if we weren't also locking up lots of water from rivers behind dams like the Hoover Dam."

sea levels rising for thousands of years

[rubycodez]

The sea levels have been rising since the last ice age, and for much of that time much faster than now. The volume of the ocean changes for many reasons. Those lands that are essentially at sea level are doomed anyway, no point in the sob stories of displaced natives as their land would be covered even without any alleged actions by man, if not now then in next few centuries. Better they move now before their population grows even bigger and more people are affected.

Re:Worse?

[Anonymous Coward]

Except no one looks back at the 20th century and remembers the great sea level disaster. The sea rose 7" over the 20th century, with zero acceleration in rate until the satellites came online, and no one noticed for 90 years. (Which obviously proves satellites cause sea level rise. )

If you continue to just use the geologically stable tide gauges (as was used before satellite data became available) the rate of sea level change hasn't changed in 100 years.

Re:Hoover dam

[blueg3]

The oceans are also much deeper than a few millimeters. Total volume isn't really meaningful here.

One millimeter across the world's oceans is about 350 cubic kilometers. So if the contents of the Hoover Dam flowed to the ocean, they would (ostensibly) raise the sea level by ~0.1 mm.

Re:Since the ice age?

[The Mighty Buzzard]

I'm pretty sure he was saying that it always continues warming from one ice age until we hit the next. Whether we melt all the ice a hundred years sooner is unimportant in both the short and long term. In the medium term you have a bunch of people pissing and moaning because they got stuck with the changing real estate rather than their great-grandkids.

The ice is going to melt. We are going to have another ice age. There's not a damned thing anyone can do about it and it's probably not going to happen in my lifetime, so why should I give a fuck?

Re:Worse?

[tompaulco]

Well... Hoover Dam doesn't have that much water behind it anymore
Having just last week spent 15 minutes flying over the lake in a commercial jetliner, I am inclined to disagree with you. In fact, it is listed as the 25th largest lake in the United states out of almost a half million lakes.

Re:Worse?

[Crosshair84]

Except that all the doom and gloom about ocean acidification is junk science.

They decrease the pH in the lab by adding sulfuric acid to the water instead of the proper method of increasing the CO2 concentration. (Since it's easier to dump in a measured amount of acid and measure with pH strips rather than rig up the equipment to measure and maintain a high-CO2 environment.) That increased CO2 makes it easier for coral and other organisms to make calcium CARBONate for their shells. Where do you think that carbon to make their shells comes from? (dissolved carbon dioxide, bicarbonate ions, carbonate ions) The carbon is what is in short supply in seawater, 441ppm calcium vs 90ppm carbon, so increasing the amount of CO2 in the oceans increases the amount of carbon, meaning coral can grow faster because the process has become more efficient because of additional carbon, more than offsetting any damage to their shells.

You also have the inconvenient fact that there are past times in Earths history where CO2 levels were 10 times higher than they are now, yet coral still grew and thrived. The pH of seawater is around pH 8.2. Pure water is pH 7.0, and clean rainwater is pH 5.6. Also, seawater is a highly buffered solution. (Translation: It can take up a huge amount of dissolved inorganic carbon without significant effect on pH.) There is not the slightest possibility that the oceans could approach the neutral pH of pure water even if all the fossil fuel in the world were burned, so all talk of ‘acid’ oceans is pointless.