Guest essay by Eric Worrall
A JPL led study has suggested construction of water reservoirs in the 1970s held back so much water from running into the sea it paused sea level rise.
Climate change: Dams played key role in limiting sea level rise
By Matt McGrathEnvironment correspondent
The construction of large-scale dams has played a surprising role in limiting rising seas, say scientists.
Over the past century, melting glaciers and the thermal expansion of sea water have driven up ocean levels.
But this new study finds that dams almost stalled the rising seas in the 1970s because of the amount of water they prevented from entering the oceans.
Without them, the annual rate of rise would have been around 12% higher.
…
Read more: https://www.bbc.com/news/science-environment-53836018
The abstract of the study;
The causes of sea-level rise since 1900
Thomas Frederikse, Felix Landerer, Lambert Caron, Surendra Adhikari, David Parkes, Vincent W. Humphrey, Sönke Dangendorf, Peter Hogarth, Laure Zanna, Lijing Cheng & Yun-Hao Wu
The rate of global-mean sea-level rise since 1900 has varied over time, but the contributing factors are still poorly understood1. Previous assessments found that the summed contributions of ice-mass loss, terrestrial water storage and thermal expansion of the ocean could not be reconciled with observed changes in global-mean sea level, implying that changes in sea level or some contributions to those changes were poorly constrained2,3. Recent improvements to observational data, our understanding of the main contributing processes to sea-level change and methods for estimating the individual contributions, mean another attempt at reconciliation is warranted. Here we present a probabilistic framework to reconstruct sea level since 1900 using independent observations and their inherent uncertainties. The sum of the contributions to sea-level change from thermal expansion of the ocean, ice-mass loss and changes in terrestrial water storage is consistent with the trends and multidecadal variability in observed sea level on both global and basin scales, which we reconstruct from tide-gauge records. Ice-mass loss—predominantly from glaciers—has caused twice as much sea-level rise since 1900 as has thermal expansion. Mass loss from glaciers and the Greenland Ice Sheet explains the high rates of global sea-level rise during the 1940s, while a sharp increase in water impoundment by artificial reservoirs is the main cause of the lower-than-average rates during the 1970s. The acceleration in sea-level rise since the 1970s is caused by the combination of thermal expansion of the ocean and increased ice-mass loss from Greenland. Our results reconcile the magnitude of observed global-mean sea-level rise since 1900 with estimates based on the underlying processes, implying that no additional processes are required to explain the observed changes in sea level since 1900.
Read more: https://www.nature.com/articles/s41586-020-2591-3
A few mm / year of sea level rise is no threat to anybody’s wellbeing. But I find it fascinating that constructing a few dam projects was apparently enough to stall this allegedly serious climate threat.
If building a few dams in the 1970s was enough to stall sea level rise, there are plenty of other gigantic water projects on the drawing board which would likely stall sea level rise for a few more decades, such as the Egyptian Qattara Depression Project, the CSIRO Three Rivers Northern Catchment Scheme, or one of the many variations of the Bradfield Scheme. China has a large area of useless wasteland which could conceivably be filled with water. Even filling these natural depressions with sea water in many cases could improve the local microclimate.
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But didn’t Tim Flannery say those dams would never fill?
I think Tim forgot the water in the dam will thermally expand as the planet heats up. Has anyone ever investigated whether thermally expanded water makes you feel less thirsty?
Surely the whole surface expands as it heats up, so the dam can hold more water
The dam can’t hold more water, and stop calling me Shirley
Good! -Very good.
And surely large areas of the surface has been “greening” up during the past decades and all that new biomass growth stores a lot of water.
I like to use thermally cooled and expanded water solids.
With a dousing of scotch whiskey.
Would someone please take away the keys to the supercomputers from these assholes? A government with limited and enumerated powers is what our Constitution tries to maintain. Now it funds children who never graduate into adulthood, playing with climate models for the rest of their lives, and who intellectually feed doomsday cult beliefs, not completely unlike failed Armageddon predictors William Miller and Harold Camping, whose failures embarrassed them and their believers alike. But at least they had enough personal integrity to make falsifiable predictions. When will CMIP models be exposed to non-vague, specific falsification testing (i.e. real science)? Because when that happens, we’ll have our next “Great Disappointment.”
+++1000
What absolute codswallop! Some people have no idea of what large numbers mean. It’s a bit like our NZ government minister Shane Jones who announced a plan to plant a billion trees in 1 year. Hurriedly backpedalled to 10 years, then by including commercial plantings, then quietly shelved when they realised they did not have enough land, or labour, or seedlings! Idiots all!
I am glad I planted my NZ citizenship tree, a Totara tree, in a park north of Upper Hutt, Wellington. My CO2 emissions, and many others, will be consumed for a 1000 years at least if it grows to maturity.
Yes, these idiots claim just about everything is caused by climate change.
But there is one effect of climate change that is beyond dispute: it drives many people completely barking mad.
Chris
Just please, no more gum trees.
So what they are saying is we should build more dams ! For once I’m in complete agreement with them. Let’s build lots more dams !!
Don’t give them any dam ideas.
At be so t Hoover would minimize sea level rise by what..< a millimeter over the course of 5 or so years that it took to fill?
Grasping at straws
At the same time the Russians were draining the Aral Sea so wouldn’t that add to sea level rise by this logic?
This was exactly my first thought too; along with the general increase in beer drinking.
Wear the badge – I’m drinking beer/wine to save the planet, hic, sorry pardon…
Let’s refill the Salton Sea until it drains on it’s own!!!
No?
Ok
Wouldn’t Death Valley make a wonderful man made lake? Imagine the vacation opportunities.
As soon as I saw….
“By Matt McGrath Environment correspondent”
I knew that it would be rubbish. He is the BBC Science correspondent with no scientific knowledge.
More misdirection.
Why does no one step back to wonder about water pumped out of the ground, trillions of gallons, which largely contribute to rain, runoff…
Do they need a paper to show this. A quick google says the total capacity of all the dams and reservoirs in the world is (say) 5440km3 = 15mm across the ocean
They say 184 mm of sea level rise 1900 – 2018 so it would have been at most 8% higher with no dams
That’s pretty close to their estimate.
The average dam levels are probably only ~50% at any given time, which is 4mm of rise and all of this is more than offset by the extraction of groundwater which runs back into the ocean, a point not noted by the author.
Great points Serge. Actually, I would suspect that the average dam across the world is a lot fuller than 50% on average, especially in wet parts of the world like Britain but your groundwater extraction point is very important but sadly not easily calculable.
Yes, ground water extraction has ADDED ~0.4mm a year for at least the last 20 years, which is 8mm alone. (Obviously depends on which source you cite though!).
What this is really about is explaining why sea levels were not rising as fast as expected according to tampered temperature records that now show warming instead of the cooling which would be consistent with no/slower sea level rise.
Oh what a tangled web…………….
This source says 0.6mm per year.
https://www.nationalgeographic.com/news/2012/6/120531-groundwater-depletion-may-accelerate-sea-level-rise/
This source says 0.8mm per year.
https://www.waterworld.com/international/article/16201939/groundwater-depletion-linked-to-rising-sea-levels
Both sources I have referenced use the same underlying research findings but they have interpreted them slightly differently. The National Geogarphic source has attempted to adjust for dam building.
As I said Bill, there’s no scientific consensus LOL. You’ll actually find higher claims and even slight negative too, for groundwater extraction effect on sea level!
Keith is talking about all dams. The article was only talking about those dams built during the 1970’s.
“Without them, the annual rate of rise would have been around 12% higher.g
So sea levels rising 9 inches per century instead of 8?
“So sea levels rising 9 inches per century instead of 8?”
Pretty much. Also if you slog through the IPCC ARs, you’ll find sea level rise budgets. They largely ignore the affect of dams because they think it’s both small and largely offset by “mining” of underground water from aquifers and by draining of wetlands.
Here are some relevant paragraphs from AR4 Section 5.5.5.3
On the other hand, impoundment of water behind dams removes water from the ocean and lowers sea level. Dams have led to a sea level drop over the past few decades of –0.5 to –0.7 mm yr–1 (Chao, 1994; Sahagian et al., 1994). Infiltration from dams and irrigation may raise the water table, storing more water. Gornitz (2001) estimated –0.33 to –0.27 mm yr–1 sea level change equivalent held by dams (not counting additional potential storage due to subsurface infiltration).
It is very difficult to provide accurate estimates of the net anthropogenic contribution, given the lack of worldwide information on each factor, although the effect caused by dams is possibly better known than other effects. According to Sahagian (2000), the sum of the above effects could be of the order of 0.05 mm yr–1 sea level rise over the past 50 years, with an uncertainty several times as large.
Let’s see. 0.05mm/yr * 100 years =5mm. 5mm/(25.4 mm/in) = 0.2 inches per century net contribution from human water use.
On the positive side. Dams — which we know how to build — usually generate a bit of hydroelectricity and promote agriculture. But using the water to refill aquifers — which we don’t know how to do — would probably be more beneficial. And in either case, it won’t matter much.
the annual rate of rise would have been around 12% higher
Why annual? They may also have said monthly, weekly, daily…
Isn’t the effect gone when the dam is filled?
Here’s the widest bit of ocean in the world and its mean sea level has FALLEN two and a half inches in the last 106 years:
http://www.bom.gov.au/ntc/IDO70000/IDO70000_60370_SLD.shtml
That’s also supported by the Pacific atolls growing in area.
So, what happened around 1970 that caused a ~0.1 in rise in sea level. 1.xxxx numbers don’t occur before, but lower level- ~0.85xx still continue to show up regularly?
It’s remarkable great long record but I suspect there was some change in calibration(electronic sensors maybe?) or other procedures in the late ’60’s.
Probably all those dams overflowing from the wet and cyclonic ’70s weather.
But these days sea levels rise and fall more from wind than they do from water.
Somebody at JPL doesn’t have any real work to do.
More Post-Modern Science. In any case, what is a “probabilistic framework”, and how does one use this to measure sea level?
They didn’t dare say “model”.
1970s and warming in the same sentence? Have they completely erased the Coming Ice Age fashion of that decade from the approved history?
My very first thought was of the ’70’s, too. Isn’t this like, “Let’s save water and put a brick in the toilet tank.” ?
First flush, all good. Additional flushes ? Is the brick standing on end or on its side ?
Once the impoundment reservoir is full, doesn’t the ‘excess’ water just flow on down to the sea ?
A brick in the tank means it takes less water to fill the tank. Which in turn means less water used per flush. There is no savings on the first tank as it is already full when you put the brick in.
Jim
You raise a point that isn’t being addressed. Reservoirs get filled with sediment (unless like at Hoover, it is taken out up stream). Therefore, many, if not most, reservoirs lose capacity for water storage over time. That is, initially, as the reservoir is being filled, less water reaches the oceans. Then, assuming constant inflow, the amount of water discharged increases annually by the volume of sediment retained behind the dam. Over decades, there should be an increase in water reaching the oceans, above what would reach the oceans in the absence of the dam. Although, evaporation from the surface of the reservoir complicates the calculations.
I think too that reservoir is not just storage for the water. Water will be used to make electricity and also to use in cities and agriculture. Every drop eventually goes to ocean. Reservoir is only a useful temporary delay for the stream to collect a storage.
Here is very little amount of water which just disappears somewhere. Same water has circulated billions of years and if there is somekind total loss why we still have water? Shouldn´t it be totally gone already?
Is it April 1st already?
Weren’t all the Glaciers growing in the 70’s? The New Ice Age scare?
The Great Global Cooling Scare of the 1970’s has been memory-holed. I remember it very well, however.
In the 1970s we were worried about global cooling. Did I miss that in the article? What are the error bars on their figures for Greenland ice mass loss?
Most published research findings are false. I bet the above mentioned study is one of those.
What complete rubbish , all water collected by dams ends up in the rivers then the Ocean.
So you flush a toilet, it goes to the sewage works, and either after purification goes to market gardens here in Adelaide , or goes back to the sea..
The produce from the garden then contain moisture which via the human body ends in the toilet.
VK5ELLMJE
So then what volume of water is held in all the world’s toilets waiting to be flushed? Did they include that amount in the calculation? Think of the world volumes tied up in beer and pop cans to say nothing of bottled water!
Try a thought experiment. If every dam in the world were to be blown up, and the water held behind the dam allowed to flow to the sea, would that water have any impact on the sea levels. If yes, then the act of capturing that water behind the dam had an influence on sea levels. Not much mind you, but an influence non the less.
I mean, seriously ? How is it that something so disconnected from reality could ever get the serious consideration being given here ? It’s not that hard to calculate the volume of water associated with a single mm of sea level rise and say ‘is it possible that this was kept back on land somewhere’ ….
Let’s refill the Caspian Sea. That’s a whole inch off sea level. Baku goes under, though.
Where’s their evidence? The tide gauge data shows no acceleration in the 1970’s. In a graph of global average sea level rise, there appears to be some starting in the mid-80’s but an examination of the plot of the longest-running data series, Battery Park, NY, shows no acceleration in the 1980’s. If there’s global acceleration it should show up everywhere, but it’s not in the Battery Park time series. In fact from the mid-70’s to the mid-90’s there is no sea level rise at Battery Park.
Then there’s this howler:
Where did they get 3.1 ± 1.4 mm per year? From the tide gauge data? Once again, it’s nowhere in the Battery Park time series. Starting in the mid-90’s sea level rise commences once again after a 20-year hiatus, but it’s essentially the same as the long-term pre-1970 trend. In the case of Battery Park that long-term trend is 2.87 mm per year, higher than the global average (measured by tide gauges) because of land subsidence.
No, the 3.1 mm number from tide gauges is data tortured to match the higher number reported by satellite data starting in 1993. Statistical massaging of the satellite telemetry consistently reports higher values than tide gauges. Of course it couldn’t be because instruments on satellites 830 miles up have a resolution of around 40mm (or more) and can’t accurately measure sea level rise with millimeter precision. No, the tide gauges must be wrong. The higher number must be right. It’s just gotta, because who cares about sub-2 mm sea level rise? So the tide gauge data beatings continue until measurements “improve” (to match the less precise satellite measurements.
About half of the battery park rise, at least in recent years, is due to land subsidence.
There’s also a quite detailed proposal to take Med water to refill the Dead Sea… something which would generate power and produce other benefits for both Israelis and Palestinians…
griff your grasp of reality is mind blowing .
You could generate a small amount of Hydro power with the water flowing down into the dead sea .What happens when the depression is full of sea water or even over half full .You wait for evaporation I suppose .
Then believing any statement from the Guardian rag on any thing resembling science .
griff yes all the water that causes floods is absorbed from the sun evaporating sea water .
Floods mean that the rivers and water ways cannot handle the flow and the rivers break their banks and vast areas are covered with water .
Excess water soon flows out to the sea and aquifers are recharged on land .
The Murray river system has for long periods never discharged to the sea as all the water has been used foe irrigation in drought times .
The world leaders have to wake up and build more dams as water grows all food on land .
Dams also reduce flooding if they are managed properly as on the Waikato River in New Zealand where flooding was almost a annual event but is now a distant memory as 8 hydro dams and a control gate at Lake Taupo holds the water back until the water in the lower reaches has dropped.
Graham
For the first time in his life, griff has actually said something that is true and useful.
People around the Dead Sea have been talking about building a pipeline to use sea water to refill the Dead Sea for a number of years. The problem is that it takes co-operation between Israel and Jordan to get it done. The Dead Sea has dropped dramatically in recent decades as much of the water that used to fill it has been taken for agricultural uses.
I don’t know if there is enough flow or drop to make a useful amount of electricity though.
The dead sea is over 1,400 feet below sea level. There is lots of potential head.
if you put 1 at the end yes, but if you put them though out the pipes length, that could make the difference in production of energy for hydro fuels
Here’s a brief reference – I hope it links to more detail.
Of course the idea is to put in water which will evaporate and contribute to various salt mining activities round the dead sea.
https://en.wikipedia.org/wiki/Mediterranean%E2%80%93Dead_Sea_Canal
and there’s this:
https://www.theguardian.com/environment/2013/aug/23/australian-floods-global-sea-level
‘Australian floods of 2010 and 2011 caused global sea level to drop’
Read that at the time and by the time I stopped laughing I had a headache. Just for reference, the change in sealevel of the Western Pacific due to the El Nino El Nina sloshing cycle is measured in feet.
Area flooded: half of Queensland, 10^6 sqkm. Area of oceans 3 10^8 sqkm. Up to 21cm rain fell, hence
210/300 = 0.7 mm sea level. Someone misplaced the decimal point somewhere.
But cheer up, because water has to evaporate before it can fall as rain the drop in sea level will occur ahead of the floods. Here we have a mechanism for accurate prediction: sea level drop => prepare for the flood. Where? That is the question, could be an interesting project to ask a grant for.
Area flooded: half of Queensland, 10^6 sqkm. Area of oceans 3 10^8 sqkm. Up to 21cm rain fell, hence 210/300 = 0.7 mm sea level drop. Someone misplaced the decimal point somewhere.
But cheer up, because water has to evaporate before it can fall as rain the drop in sea level will occur ahead of the floods. Here we have a mechanism for accurate prediction: sea level drop => prepare for the flood. Where? That is the question, could be an interesting project to ask a grant for.
Yeah and there wasn’t a drought some where else to of set that rain
Typical guardian rubbish by some dolt without a clue … I am amazed they didn’t claim all the weight on one side Australia makes it unstable and in danger of tipping over 🙂
LdB
I think that the US has the corner on the market of that kind of stupidity.
One ignorant U.S. Democrat congressman. He thought an island might tip over if too much weight was put on one side. That’s pretty ignorant.
https://www.youtube.com/watch?v=QjG958lZ1KI
Yeah – the poor guy Mr. Johnson was questioning in public testimony was looking at him as he was uncertain if he was really being asked this question seriously.
I guess my answer to LDB would be that Australia’s a lot bigger than Guam, so it’s less of a tip risk.
And speaking of the utterly brain-dead, anyone catch AOC’s plan to save the post office by having people buy a lotta stamps and have pen pals?
She came up with that after she’d ‘been thinking about for a while’.
Had to really put the ol’ skull cap on, I guess.
I swear, I listen to these people my ears start to bleed.
Most of these studies are led by an agenda to say ‘it’s worse than we thought’. So here, it’s about saying as the benefit of dams wears off, sea leve rise will accelearate. But a few years ago, we had a study saying groundwater pumping was contributing to sea level rise. That was about saying: ‘we’re making it even worse’.
But, you can argue that the manmade ‘bad news’ of groundwater pumping was offset by the ‘good news’ of dam/reservoir volumes. These are always simplistic models. The reality is that the water cycle is much more complex. Reservoir storage does not simply offset ocean water storage. It also impacts on water storage in rivers and aquifers between it and the sea.
The *UN would be angry about this one- they do not like dams. Besides, the extra weight of the water would make the land mass sink, which would cause sea levels to appear to rise.
When will people wake up that the escalation of clutching at straws insanity is end stage propaganda. They are desperately trying to avoid facing the music that the whole thing was always a scam to deprive of us of our wealth and freedom.
HT
The problem is that if the end-stage propaganda convinces enough dolts to vote for greenies, it may take decades to flush out the newly-elected incompetent incumbents. During their tenure, they may do significant damage to society.
Do they truly believe what they’re saying?
Fill the Aral sea with sea water, the Quateri depression, etc etc etc.
Dams can provide hydroelectric of course. Perhaps the solution to ‘climate change’ is renewable energy! Hahaha!
Or it could be that the late 1970s was the COLDEST period in the NH since the Little Ice Age…
… and Arctic sea ice and Arctic region surface ice were at an extreme high levels.
The amount of water behind dams will be significant to one degree or another.
What will be of greater significance is the amount of water held in deep earth aquifers. Of greater significance than that, is the amount of deep aquifer water extracted for human consumption that goes to the rivers as waste eventually.
I’m just waiting for some headbanger to tell the population of California or Saharan Africa it would be best to “leave it in the ground”
But ask the alarmists to build dams for carbon free electric and the response will be that we cannot harm the environment by flooding. So, no more nuclear and no more hydro…_