Study: 1970s Dam Construction Paused Global Warming Sea Level Rise

Hoover Dam. By Ansel Adams – This media is available in the holdings of the National Archives and Records Administration, cataloged under the National Archives Identifier (NAID) 519837., Public Domain,

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:

The abstract of the study;


The causes of sea-level rise since 1900

Thomas FrederikseFelix LandererLambert CaronSurendra AdhikariDavid ParkesVincent W. HumphreySönke DangendorfPeter HogarthLaure ZannaLijing 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:

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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August 19, 2020 10:05 pm

But didn’t Tim Flannery say those dams would never fill?

Reply to  Steve
August 19, 2020 10:30 pm

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?

Reply to  JaneHM
August 20, 2020 1:52 am

Surely the whole surface expands as it heats up, so the dam can hold more water

Bryan A
Reply to  steveta_uk
August 20, 2020 8:28 am

The dam can’t hold more water, and stop calling me Shirley

Reply to  Bryan A
August 20, 2020 8:23 pm

Good! -Very good.

Samuel C Cogar
Reply to  JaneHM
August 20, 2020 4:11 am

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.

Reply to  JaneHM
August 20, 2020 5:33 am

I like to use thermally cooled and expanded water solids.

Joel O’Bryan
Reply to  Scissor
August 20, 2020 6:35 am

With a dousing of scotch whiskey.

Mickey Reno
Reply to  JaneHM
August 20, 2020 11:04 am

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.”

Reply to  Mickey Reno
August 20, 2020 12:20 pm


Mike Lowe
August 19, 2020 10:11 pm

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!

Patrick MJD
Reply to  Mike Lowe
August 20, 2020 12:04 am

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.

Chris Wright
Reply to  Mike Lowe
August 20, 2020 3:55 am

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.

Reply to  Mike Lowe
August 20, 2020 2:56 pm

Just please, no more gum trees.

August 19, 2020 10:16 pm

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 !!

Tom in Florida
Reply to  ggm
August 20, 2020 7:36 am

Don’t give them any dam ideas.

Bryan A
August 19, 2020 10:33 pm

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

Bob boder
Reply to  Bryan A
August 20, 2020 5:18 am

At the same time the Russians were draining the Aral Sea so wouldn’t that add to sea level rise by this logic?

moderately cross of east anglia
Reply to  Bob boder
August 20, 2020 5:36 am

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…

Matthew R Epp
August 19, 2020 10:47 pm

Let’s refill the Salton Sea until it drains on it’s own!!!

Reply to  Matthew R Epp
August 20, 2020 6:32 am

Wouldn’t Death Valley make a wonderful man made lake? Imagine the vacation opportunities.

August 19, 2020 10:53 pm

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.

Reply to  JohnM
August 20, 2020 6:43 am

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…

Keith Woollard
August 19, 2020 10:55 pm

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

Serge Wright
Reply to  Eric Worrall
August 20, 2020 1:35 am

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.

Ian Magness
Reply to  Serge Wright
August 20, 2020 1:58 am

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.

Reply to  Serge Wright
August 20, 2020 2:07 am

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…………….

Bill Toland
Reply to  MrGrimNasty
August 20, 2020 2:49 am
Bill toland
Reply to  MrGrimNasty
August 20, 2020 2:53 am
Bill Toland
Reply to  MrGrimNasty
August 20, 2020 3:05 am

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.

Reply to  MrGrimNasty
August 20, 2020 5:32 am

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!

Reply to  Eric Worrall
August 20, 2020 6:33 am

Keith is talking about all dams. The article was only talking about those dams built during the 1970’s.

Reply to  Keith Woollard
August 19, 2020 11:26 pm

“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?

Don K
Reply to  Ralph Dave Westfall
August 20, 2020 2:04 am

“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

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.

Rainer Bensch
Reply to  Ralph Dave Westfall
August 20, 2020 3:34 am

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?

spangled drongo
Reply to  Ralph Dave Westfall
August 20, 2020 3:36 am

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:

That’s also supported by the Pacific atolls growing in area.

Reply to  spangled drongo
August 20, 2020 6:11 am

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.

spangled drongo
Reply to  Philo
August 20, 2020 4:45 pm

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.

Randle Dewees
Reply to  Keith Woollard
August 20, 2020 10:16 am

Somebody at JPL doesn’t have any real work to do.

August 19, 2020 10:57 pm

More Post-Modern Science. In any case, what is a “probabilistic framework”, and how does one use this to measure sea level?

Reply to  Graemethecat
August 20, 2020 2:59 pm

They didn’t dare say “model”.

The Sage
August 19, 2020 11:08 pm

1970s and warming in the same sentence? Have they completely erased the Coming Ice Age fashion of that decade from the approved history?

August 19, 2020 11:08 pm

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 ?

Reply to  Jim
August 20, 2020 6:37 am

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.

Clyde Spencer
Reply to  Jim
August 20, 2020 9:31 am

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.

Reply to  Jim
August 21, 2020 3:34 am

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?

August 19, 2020 11:11 pm

Is it April 1st already?

August 19, 2020 11:24 pm

Weren’t all the Glaciers growing in the 70’s? The New Ice Age scare?

Reply to  DavidF
August 20, 2020 2:12 am

The Great Global Cooling Scare of the 1970’s has been memory-holed. I remember it very well, however.

August 19, 2020 11:36 pm

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.

August 19, 2020 11:37 pm

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.


Ed MacAulay
Reply to  Michael
August 20, 2020 4:48 am

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!

Reply to  Michael
August 20, 2020 6:39 am

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.

August 19, 2020 11:44 pm

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’ ….

August 19, 2020 11:53 pm

Let’s refill the Caspian Sea. That’s a whole inch off sea level. Baku goes under, though.

August 20, 2020 12:03 am

The acceleration in sea-level rise since the 1970s…

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:

Our reconstructed GMSL trend of 1.1 ± 0.3 mm⋅y−1 (1σ) before 1990 falls below previous estimates, whereas our estimate of 3.1 ± 1.4 mm⋅y−1 from 1993 to 2012 is consistent with independent estimates from satellite altimetry

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.

Reply to  stinkerp
August 20, 2020 7:25 am

About half of the battery park rise, at least in recent years, is due to land subsidence.

August 20, 2020 12:22 am

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…

Reply to  griff
August 20, 2020 3:17 am

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.

Reply to  Gwan
August 20, 2020 6:44 am

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.

Reply to  MarkW
August 20, 2020 7:29 am

The dead sea is over 1,400 feet below sea level. There is lots of potential head.

Reply to  MarkW
August 20, 2020 7:31 am

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

Reply to  MarkW
August 20, 2020 8:26 am

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.

August 20, 2020 12:24 am

and there’s this:

‘Australian floods of 2010 and 2011 caused global sea level to drop’

Ed Zuiderwijk
Reply to  griff
August 20, 2020 1:58 am

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.

Ed Zuiderwijk
Reply to  griff
August 20, 2020 3:10 am

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.

Ed Zuiderwijk
Reply to  griff
August 20, 2020 3:16 am

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.

Bob boder
Reply to  Ed Zuiderwijk
August 20, 2020 5:25 am

Yeah and there wasn’t a drought some where else to of set that rain

Reply to  griff
August 20, 2020 9:11 am

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 🙂

Clyde Spencer
Reply to  LdB
August 20, 2020 9:45 am

I think that the US has the corner on the market of that kind of stupidity.

Tom Abbott
Reply to  Clyde Spencer
August 20, 2020 10:55 am

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.

Joel Snider
Reply to  Tom Abbott
August 20, 2020 12:41 pm

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.

Joel Snider
Reply to  Tom Abbott
August 20, 2020 12:46 pm

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.

August 20, 2020 12:25 am

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.

High Treason
August 20, 2020 12:43 am

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.

Clyde Spencer
Reply to  High Treason
August 20, 2020 9:50 am

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.

August 20, 2020 12:58 am

Do they truly believe what they’re saying?

Matthew Sykes
August 20, 2020 1:34 am

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!

August 20, 2020 1:41 am

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.

August 20, 2020 1:55 am

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…_

August 20, 2020 2:21 am

making use of land below sea level that one day will eventurally be breached through land movement or pressure ??? sounds a good idea, but not to just flood it, a controlled plan would be needed to get the best for our planet and mankind. their could be some great benifits from this and will no doubt be some that are not so good but the science should be able to work these out ,,,, if people can one day work together,, could be used to produce almost free electric after costs, and that could be used to make hydro fuel on a large scale, taking the need from the oil,gas and coal ind to an extent, then their’s the climate and evaporation and it’s effect on the planet’s weather system,,,, and so much more

August 20, 2020 3:04 am

It’s definitely doable to drop sea level a little with fairly small environmental impact using a variety of engineering methods. The problem is that the greens don’t want any environmental impact whatsoever.

August 20, 2020 3:10 am

The dams don’t hold the water forever. That’s the point of dams. Less what’s lost to the atmosphere via evaporation (which probably ends up in the sea eventually), once full they release water (for power production, preventing over-flow, and/or refreshing the downstream river) which reaches the sea as it would if free-flowing. My hunch is they don’t have their mass flows computed properly. Or maybe I’m missing something.

Reply to  rms
August 20, 2020 6:47 am

Once full, dams make no difference to sea levels. But while filling, they are intercepting water that would have gone into the seas.

Jim Gorman
Reply to  MarkW
August 21, 2020 6:03 am

That’s exactly what I was going to post. The initial fill might delay water reaching the ocean but that would reduce sea level rise. From that point forward, water behind the dam is either released and is basically the same amount as with no dam or it is used and some reaches the sea while the rest goes into an aquifer.

Where do these people come from? I swear these people have all grown up in a city and have never experienced real physical things in the out of doors. Their only knowledge comes from computer games. Meat is grown in the backroom of the meat counter. Vegetables and fruit appear each night in the grocery storeroom by magic.

Clyde Spencer
Reply to  Jim Gorman
August 21, 2020 10:15 am

And chocolate milk comes from brown cows.

August 20, 2020 3:14 am

These are mostly millennial authors, without wishing to denigrate their qualifications. They have been trained to the agenda, starting with a conclusion and searching for things to validate that conclusion.

One author, David Parkes, was a co-author of this paper in 2018:

“Global-mean sea-level rise (GMSLR) during the twentieth century was primarily caused by glacier and ice-sheet mass loss, thermal expansion of ocean water and changes in terrestrial water storage. Whether based on observations or results of climate models, however, the sum of estimates of each of these contributions tends to fall short of the observed GMSLR. Current estimates of the glacier contribution to GMSLR rely on the analysis of glacier inventory data, which are known to undersample the smallest glacier size classes. Here we show that from 1901 to 2015, missing and disappeared glaciers produced a sea-level equivalent (SLE) of approximately 16.7 to 48.0 millimetres.” (precisely…)

August 20, 2020 3:25 am

Idiotic conclusion

Jeff Id
August 20, 2020 3:37 am

What a joke. Sea level rise has not changed for at least 150 years and dams slowed it down. Where’s the water?

August 20, 2020 3:50 am
old white guy
August 20, 2020 4:15 am

So, the amount of water on the planet remains the same yet the level increases.

August 20, 2020 4:57 am

A better bet would be the Aral Sea which used to be the fourth largest lake in the world at around 23,000 square miles but lost around 90% of its area due to water being diverted from incoming rivers for irrigation projects, mainly cotton.
The government of Kazakhstan is now trying to restore the lake.

Reply to  StephenP
August 20, 2020 6:25 am

I think doing this is good, and refilling aquifers that have been used for agriculture. On problem though is that the greenies don’t like diverting some flow from rivers to do this. I don’t understand as so much fresh water wasted flowing to ocean from rivers.

August 20, 2020 5:27 am

1970s Dam Construction Paused Global Warming Sea Level Rise

If building a few dams in the 1970s was enough to stall sea level rise…

Then we need a mass building programme of swimming pools.

August 20, 2020 6:30 am

While I don’t doubt that the new dams had an impact on global sea level rise, I suspect the cool temperatures of the 70’s had a much bigger impact.

August 20, 2020 6:42 am

It’s probably also causing the melting of glaciers and increase in global temperature. All that extra water surface changes the effective land use of an area.

August 20, 2020 6:50 am

Presumably, all of these dams are above sea level.
They have taken a lot of water from sea level and placed it above sea level.
Has anyone calculated how many micro-seconds this has slowed the earth’s rotation by?

Reply to  MarkW
August 20, 2020 9:18 am

NASA has calculated that the Three Gorges dam slows the Earth’s rotation by a mind boggling 0.06 microseconds, which is six hundredths of a millionth of a second. So all of the dams on the planet would maybe cause a slowing of a few microseconds. Don’t rush to change your clocks as it hardly even affects the leap seconds we need to adjust to keep things in ‘time’ with natural processes.

Tom Abbott
Reply to  Earthling2
August 20, 2020 11:04 am

I was reading an article yesterday about the flooding currently going on around the Three Gorges dam and the article said China hadn’t seen this much rain since the 1940’s.

Next thing you know, the Alarmists will start claiming China is experiencing unprecedented flooding and Human-caused Climate change is the reason why, but we will just have to refer them to the 1940’s. Nothing to see here.

August 20, 2020 6:57 am

If the world population increased by 4.2 billion people from 1970 to 2020, and the average person is 60% water, I wonder how many new dams worth of water are walking around on the planet today?

Maybe the UN can mandate making more babies to slow the sea level rise. For the common good, of course.

Somebody contact Al Gore and Greta. They need to get busy.

August 20, 2020 7:26 am

Did the paper compensate for pumping out ground water ?

Tom in Florida
August 20, 2020 7:38 am

August 20, 2020 8:11 am

“The rate of global-mean sea-level rise since 1900 has varied over time, but the contributing factors are still poorly understood”

Heresy! Everyone knows the science is settled and we’re all doomed to drown. I trust these deniers and spreaders of fake news have been kicked off Facebook and Twitter.

Phillip Britton
August 20, 2020 8:16 am

Has anyone done a more comprehensive study of the global climate/weather impacts of all these man-made reservoirs? I recall Roger Pielke Sr. co-authored a 2011 study which found evidence of micro climate changes near some large reservoirs.

Fg mike
August 20, 2020 8:44 am

So we need to build bigger toilets to hold more water and prevent sea level rise?

August 20, 2020 8:44 am

Greenland ice sheet lost a record 1m tonnes of ice per minute in 2019

Climate-driven loss is likely to be the worst for centuries, and is pushing up sea levels

Reply to  griff
August 20, 2020 2:23 pm
Reply to  griff
August 20, 2020 3:24 pm

Greenland ice loss..LOL… more puerile meaningless bluster from griffool, the climate change denier.

SMB is average this year, and the tiny losses due to the partial recovery from the 1970s COLD era are meaningless

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Greenland ice area is still way above what they have been for most of the last 10,000 years

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Get an education griffool, so you don’t continue to make an baboon’s a*se of yourself.

Ulric Lyons
August 20, 2020 9:13 am

The 1970’s had the strongest solar wind conditions of the space age. That drove a colder AMO, which cools the Arctic, increases low cloud cover, and slows continental glacier retreat. Since 1995 the reverse has occurred, with weaker solar wind driving a warmer AMO, and which is why the sea level is normally higher during centennial solar minima.

J Mac
August 20, 2020 9:14 am

Ummm… Griffter,
The climate-driven ice sheet loss has been ‘worst’ since about 13,000 years ago, when naturally (and thankfully!) the climate started warming and mile thick glaciers spanning the northern USA and Canada began to melt. All natural climate change… and continuing today, naturally. The Null Hypothesis holds!

Have a rainbow day!

August 20, 2020 11:48 am

At the same time, lots of parking lots, roads, houses were built and lots of forests got cleared to make more farmland. All that makes rainfall just go downriver, instead of staying in the aquifer for a month or seven.

On the other hand, much more farmland needs irrigations, so much that some rivers run dry. Add swimming pools and lawns and evaporation…

So many variables, but sure, the Graudian picks one and cries ‘Wolf’

Reply to  lb
August 20, 2020 12:04 pm

Sorry, the Beeb, not the Graudian

August 20, 2020 1:15 pm

I wonder how many millimeters of sea level rise could be mitigated by completing the Auburn Dam-

It would certainly help mitigate black outs in the foothills.

August 20, 2020 2:33 pm

“The rate of global-mean sea-level rise since 1900 has varied over time, but the contributing factors are still poorly understood”

As if the world didn’t exist before 1900. Way to cherry pick. Why not start with the end of the last glaciation?

Nicholas McGinley
August 20, 2020 2:55 pm

“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.”

12% is “almost stalled”?
What a bunch of malarkey.
12% is 12%.
Less than one eighth.
How does reducing the rate of rise by one eighth mean it was “almost stalled”?

August 20, 2020 4:51 pm

I don’t think they ever actually saw an ocean. They need to take a ride on a freighter across the Pacific to get some respect for the size of the thing.

Gunga Din
August 20, 2020 5:19 pm

It cost a lot of money to build a dam. They aren’t built without a reason.
They are built so the water is available to use and/or prevent flooding. (By “to use” I’m including hydro and recreational use.)
The water used from what is pooled behind it does not disappear.
It is mostly returned to the rivers via wastewater plants, transpiration if used for irrigation, etc.
Again, the water doesn’t disappear. It will still end up in the oceans where some will evaporate and again fall as rain or snow.

Gary Remington
August 20, 2020 6:42 pm

What impact do shingled roofs, sidewalks and paved roads have on sea level? Millions of acres of material designed to shed water which often are complimented by sewers and storm drains, that empty into the oceans.
How much water by dint of human activity is ushered via the most direct path to the oceans where it would have otherwise been absorbed by the soil and sequestered in a pond, lake or aquifer?

August 21, 2020 5:07 am

Since when is a 12% reduction a “pause”? Reducing 3mm of sea level rise by 12% would still mean 2.97 mm of sea level rise. Who publishes this crap?

Clyde Spencer
Reply to  Pachygrapsus
August 21, 2020 10:21 am

It is published by those shackled to the “Publish or Perish” job requirement. It is the quantity of publications, not the quality, that governs raises.

Michael Zorn
August 21, 2020 10:27 am

Let’s just do a little calculation. Take the area of the world’s oceans. Assume a 1″ (OK, 3 cm) depth, and work out the volume of that sheet. (Scientific notation is encouraged.) now compare that to the volume of water behind dams. I haven’t done that yet, but I’m betting there’s a big difference.

Leon Earren
August 22, 2020 12:11 am

Why should there be any sea level rise since the meteor that caused the extinction of the dinosaurs? The amount of water on this planet has remained constant since the seas were formed 3 1/2 billion years ago. Have you all overlooked the fact that these dams you are talking about are on land, all of which are on tectonic plates, which in turn, float of the earth’s mantle which in turn is made up of molten rock.
Archimedes principle applies here. When an object is wholly or partially immersed in water the weight of water displaced equals the weight of the object. If this were not true ships would not float to their designed water mark. The principle would still apply to any liquids.
Try a little experiment. Fill a jug with ice then top it up to the brim with water. You should notice that about 1/5th of the ice will protrude above the rim of the jug. Now let the ice melt and see how much water spills over the side of the jug. This test should show you that the claim by climate changers of catastrophic sea level changed by melting of ice is totally false.
If the sea raises in one place it must rise by the same amount in another place. Water is incompressible. We do of course have tides, storm surges and the effects of the spinning earth which causes water depths to increase on the eastern side of continents and not so on the western side. Also aren’t most of these claims of sea level changes, if not all, the result of tectonic movements or gravitational pull or the earth’s momentum? Certainly not by atmospheric activities – heat rises, carbon absorbs heat, not generate it.
When Captain John Hunter of HMS Serius came to Australia in 1788 with the First Fleet, he carried out a complete survey of Sydney and environs. He determined the sea level of the maximum spring tide and put a mark on a rock at Fort Denison which became the base datum line (BDM) for measuring all heights in the Sydney region. As far as I can ascertain there has been no adjustment to this line.

August 25, 2020 12:45 am

The Amazon river has a fifth of the worlds fresh water flowing out of it and the mouth is a hundred miles wide. Tell me again how many dams are on it?
I can’t believe how stupid some in the world are and what they will believe. Anything to try and push the agenda. I can understand the Three Gorges dam having some affect and even the Hoover Dam but the rest would be like a flee on a dog. It might be interesting to see if any dams break in China with their latest edict.

Leon Warren
Reply to  mikebartnz
August 25, 2020 1:41 am

Just as well we have a sense of humor. The bully’s of this world love to spook everyone with the boogeyman, this one being climate change, nee global warming, nee global cooling. When the Snowy River scheme, a huge irrigation project on the border of New South Wales and Victoria, states of Australia, was built there was no discernable change in the tides around the coast of Australia. Within the same time we built Hume Reservoir, Burrenjuck Dam, Warragamba Dam, and the great Lake Argyle in Northern Territory and we still got no tidal increase and there have been a lot of similar dams building going on around the world in other countries.

Reply to  Leon Warren
August 25, 2020 3:55 am

My uncle made the pumps for the Snowy River scheme and my father who was about 5ft 10in could walk through them without ducking. They must have pushed a hell lot of water through.

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