Increasing Arctic freshwater is driven by climate change

UNIVERSITY OF COLORADO AT BOULDER

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IMAGE: NARES STRAIT, BETWEEN GREENLAND AND CANADA, AS SEEN FROM SPACE. view more CREDIT: MODIS LAND RAPID RESPONSE TEAM, NASA GSFC

New, first-of-its-kind research from the University of Colorado Boulder shows that climate change is driving increasing amounts of freshwater in the Arctic Ocean. Within the next few decades, this will lead to increased freshwater moving into the North Atlantic Ocean, which could disrupt ocean currents and affect temperatures in northern Europe.

The paper, published July 27, 2020 in Geophysical Research Letters, examined the unexplained increase in Arctic freshwater over the past two decades and what these trends could mean for the future.

“We hear a lot about changes in the Arctic with respect to temperature, how ecosystems and animals are going to be affected,” said Rory Laiho, co-author and PhD student in atmospheric and oceanic sciences. “But this particular study gives an added perspective on what’s happening physically to the ocean itself, which then can have important implications for ocean circulation and climate.”

Since the 1990s, the Arctic Ocean has seen a 10% increase in its freshwater. That’s 2,400 cubic miles (10,000 cubic kilometers), the same amount it would take to cover the entire U.S. with 3 feet of water.

The salinity in the ocean isn’t the same everywhere, and the Arctic Ocean’s surface waters are already some of the freshest in the world due to large amounts of river runoff.

This freshwater is what makes sea ice possible: it keeps cold water at the surface, instead of allowing this denser liquid to sink below less dense, warm water. In this way, the Arctic Ocean is much different than other oceans. But as more freshwater exits the Arctic, this same stabilizing mechanism could disrupt the ocean currents in the North Atlantic that moderate winter temperatures in Europe.

Such disruptions have happened before, during the “great salinity anomalies” of the 1970s and 80s. But these were temporary events. If too much cold freshwater from the Arctic continuously flows into the North Atlantic, the ocean turnover could be disrupted more permanently.

Ironically, this would mitigate the impacts of global warming during winter in northern Europe for a while. But disrupting the ocean currents could have negative effects for climate long-term and on the North Atlantic’s ecosystems.

A signal in the noise

The main mission of the research for Alexandra Jahn, lead author of the new study and assistant professor in the Department of Atmospheric and Oceanic Sciences and the Institute of Arctic and Alpine Research, and her graduate student, Laiho, was to differentiate between natural variability cycles in Arctic freshwater amounts and climate change’s impact. They examined the results from an ensemble of models run from 1920 to 2100.

“When we look at all the simulations together, we can see if they all do the same thing. If so, then that’s due to a forced response,” said Jahn. “If those changes are big enough so they could not occur without increasing greenhouse gases in the model simulations, that’s what we call the emergence of a clear climate change signal. And here we see such clear climate change signals for the Arctic freshwater during the current decade.”

Their results showed that Nares Strait, which runs between Greenland and Canada and is the most northern gateway between the Arctic and more southern oceans–will be the first place to see a freshwater export increase attributable to climate change in the next decade. Other straits farther south and east, including Davis and Fram straits, will be next to show this signal.

The researchers also ran the models through different emissions scenarios to see if these changes will be affected by humans’ emissions choices in the next few decades. They looked at the “business as usual” (over 4 degrees Celsius warming by the end of the century) scenario and what would happen if humans limited warming to 2 degrees Celsius, the upper end of IPCC (Intergovernmental Panel on Climate Change) targets for this century.

They found that the change in freshwater in the Arctic Ocean and the amounts moving through the northern straits were unaffected since they will be subject to an increase in freshwater before the 2040s–and the decisions made globally in the next few decades will not influence them, as these climatic changes are already in motion. But in the second half of this century, the two scenarios diverged, and increases in freshwater amounts were seen in more places in the high-warming scenario than in the low-warming scenario.

“What this work is showing us is that we’re probably already experiencing the first of these changes, we just can’t tell from the direct observations yet,” Jahn said.

All water from the Arctic Ocean eventually ends up in the North Atlantic. But timing is everything. Being able to predict the timing of the emergence of climate change signals will allow scientists to monitor upcoming changes in real time, and better understand how changes in the Arctic Ocean can impact climate worldwide.

“It fills a gap in our current understanding, and helps us ask new questions about what physically is happening in the Arctic,” said Jahn.

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From EurekAlert!

57 thoughts on “Increasing Arctic freshwater is driven by climate change

      • They examined the results from an ensemble of models run from 1920 to 2100. ….”we just can’t tell from the direct observations yet,” Jahn said.

        Has your model been validated against real data? Has it made a successful prediction ( about the future ) ?

        ?

        I thought not.

        Come back when you have something better than “we just can’t tell”. ie observations or a model validated by successful prediction of future change.

        Arctic Ocean’s surface waters are already some of the freshest in the world

        Ah, so it not “fresh water” it’s freshER water. What we have apparently is ocean freshification crisis. WE MUST ACT NOW !!

    • Look at all that open water in it and north of Greenland and Ellesmere Island!

      Griffinator! Where ya been, buddy? Good to hear from ya. A bit of advice, best not be walkin’ on the ocean there north of Greenland & Ellesmere Island right now, eh? Wait a couple months for that.

    • Good work Griff. As you may have noticed, every summer about 10 million km² of sea ice melts in the Arctic**. It’s now August, so what, actually would you expect to see in Nares Strait on August 1st?

      The answer is ………… Open Water!!

      **And the same 10 million km² freezes again the following winter!! Isn’t Nature wonderful?

  1. “…helps us ask new questions about what physically is happening in the Arctic.”

    How about actually answering some of the older ones?

  2. –Ironically, this would mitigate the impacts of global warming during winter in northern Europe for a while. But disrupting the ocean currents could have negative effects for climate long-term and on the North Atlantic’s ecosystems.–
    Or said differently cause Europe to be colder.
    Also could causes less deep cold water to leave arctic.
    Which means entire ocean cools less, and fits my definition of global warming.
    But rather than fresh water leaving arctic, it could freeze easier, and one gets more polar sea ice.
    Or not be exiting the arctic, and not global warming- just colder Europe.
    And then Europeans finally get what they want, not warmer, in Europe, but colder in Europe.
    Why Europeans imagine their current average of about 9 C, is too warm and want 8 C or colder- I have no idea.

    How much is “for awhile”, decades?
    Decades of more winter heating bills?
    And less snow, maybe.
    But more froze lakes to skate on.

  3. “They examined the results from an ensemble of models run from 1920 to 2100.”

    Hmm, right. That sounds legit.

  4. “Such disruptions have happened before, during the “great salinity anomalies” of the 1970s and 80s. But these were temporary events. If too much cold freshwater from the Arctic continuously flows into the North Atlantic, the ocean turnover could be disrupted more permanently.”

    Well obviously there was less freshwater flowing into the Arctic in the 1970-1980’s for the Arctic Ocean to be more saline. The dog is the AMO, the tail is the Arctic Ocean. When the solar wind is stronger, as in the early-mid 1970’s and mid 1980’s, the AMO shifts colder and freshwater runoff into the Arctic declines. And when the solar wind is weaker the AMO shifts warmer, like from 1995, and the freshwater runoff increases. This inverse relationship can be seen operating at seasonal scales so there is very little lag. Plus there is a feedback from El Nino events driving major AMO warm pulses with a roughly an 8 month lag, and El Nino conditions normally increase during centennial solar minima.

    https://www.linkedin.com/pulse/association-between-sunspot-cycles-amo-ulric-lyons/

  5. Models on top of assumptions, and then they say “we’re probably already experiencing the first of these changes, we just can’t tell from the direct observations yet.” When you summarize your report by saying “probably” and “can’t tell”, you are signaling science has been left behind somewhere (but you’re in the mainstream of your peers). Northern Europe lives a fairly good life-style based on ocean current-imported heat, and, sure, someday it could not work out so well.

    • Observation is the first step of science.
      To assume observations will come later after your tests to prove a predetermined hypothesis is laughable.

      • Stephen W. their first step was assumptions. They assumed that a few years data of freshwater in the Arctic was unusual and ran with it. Please don’t lecture me about science.

      • By the way, Stephen W, when I managed a Research Group I visited the Center For The Study Of Earth From Space, an internal part of the University of Colorado at Boulder. The lead scientist there greatly assisted our research efforts into utilizing the Spectral Angle Mapper Algorithim, part of the ENVI image processing system, in our application of Supervised Classification. Further application of this technique has made millions for me personally. I mention this to say I don’t have any natural bias against the University of Colorado at Boulder, just against the tendency to include assumptions in scientific studies.

  6. Didn’t I see this premise in some disaster movie somewhere?
    Resulted in New York being covered in half a mile of ice?

  7. Doesn’t more fresh water in the Arctic imply a more frozen Arctic? because saline water is denser so fresh water floats on top of the ocean, and the freezing point of fresh water is above that of saline.

    • That might explain why the Kronprins Hakken, class I icebreaker Norwegian Arctic research ship encountered 3 meter ice when the DMI ice maps for the Arctic (or should I say model?) said the ice would only be 0.5 metre thick. They also found thick one year ice, which according to the DMI model does not exist.

      Only 3 years before the DMI had changed their model towards thinner ice because they believed it was over-estimating. I have heard of no reaction from them to the Hakkon fiasco.

  8. Can someone help out a simple minded person. I thought that fresh water would freeze at 0C but salt water at -4C. surely if there was fresh water the ice levels would increase as it would freeze earlier and melt later?

    What am i missing please?

    • Andy in Epsom
      Q.1. Do horses still race around the wrong way in Epsom or the same way they do in America?
      A. 1. Fresh water reaches max density at 4ºC and then for some mysterious reason the molecules regroup to less density and rise to the surface to freeze at 0ºC. ..which explains why your pond ice is on the surface and not the bottom like e.g. a bowl of melted candle wax.
      2. Salt water density increases with salinity and simultanously lowers its freezing point. I’m not sure how low the freezing point can be reduced by increasing salinity, but it must be well below -4ºC or they wouldn’t waste time throwing salt all over the roads in freezing weather.
      When sea water (30-35,000 ppm disolved solids ( mostly NaCl ) freezes it sheds salt increasing the salinity and hence its density while the ice so formed is fresh water and floats. The cold dense brine solution sinks to drive the thermo-haline ocean circulation while the fresh water ice floats around in search of the Titanic…. oops! sorry
      That’s all I know hope it helps.
      Cheers
      Mike

      • I think salt melt ice down to ~-17c then stops working
        In calgary at -30 the salt just acts like sand on top of the ice
        Which is why they use a mixture of sand and salt

  9. “They examined the results from an ensemble of models run from 1920 to 2100.

    “When we look at all the simulations together, we can see if they all do the same thing.”

    Models all the way down. Where are the field observations over a long period of time that can be used to validate the model outputs? Out of the “ensembles” of models, which one most closely matches reality? How can you tell if you don’t validate the model?

  10. Day after Tomorrow.
    If the Gulf stream collapses… and it can.
    I was surprised to know that Siberia had never been under a glacier during the last ice age.
    Just Europe and North America were covered by the km-thick ice shields!
    Altai – where the aryan originated – was a wonderful place at that time.

  11. Yet again, a Climate “Science” paper which treats the output of a speculative, unverified computer model as actual empirical data.

    This is a travesty of real Science.

    • I am with you on that.. or may have a question:

      If I understand
      ” the “business as usual” (over 4 degrees Celsius warming by the end of the century) scenario”
      correctly, they take the fact that the Arctic is currently warming faster than the average of the planet and extrapolate proportional towards the global 2°C anthropogenic warming by 2100 or so..
      (I am guessing the argument is “we are seeing half of what we expect by then right now, so double the observed arctic warming as a guesstimate”)

      Well, my question is, if there is a good paper/article or anything, which excludes this more than average warming to come from a different effect like ocean cycles or the sun..
      The extra Antarctic warming seems to be correlated to the IPO, I could make a guess that there is a similar influence in the Arctic and “business as usual” would less than average warming in the future as the cyclic warming seems near a peak at the moment.

  12. “Ironically, this would mitigate the impacts of global warming during winter in northern Europe for a while.”

    Palm meets face. Now the concept of negative feedback (this one didn’t seem to operate when the Laurentide ice sheet melted) is mere irony to the cult.

  13. “What this work is showing us is that we’re probably already experiencing the first of these changes UFO’s are real, we just can’t tell from the direct observations yet,”

    This statement is just as true as the original.

    (actually, the revised statement may be more true, if recent government commitment to declassify information is followed.)

  14. “And here we see such clear climate change signals for the Arctic freshwater during the current decade.”
    Such …. that. I guess we’re supposed to fill in the “that” part. I’ll start.
    “And here we see such clear climate change signals for the Arctic freshwater during the current decade that we require way more funding to figure out what they actually are.”

  15. They are selling old science as new. All of this was told by Wally Broecker in the late 90s-early 00s, and was the basis for the 2004 movie “The day after tomorrow.”

    The hypothesis goes that if you add enough fresh water to the North Atlantic you disrupt and could even shut down the Atlantic Meridional Overturning Circulation of which the Gulf Stream is part. But the hypothesis is likely wrong. There is no good evidence that it has happened in the past and the climate of Europe is not as dependent on the Gulf Stream as traditionally thought. It is certainly controversial stuff.

    • How do you explain Dansgaard-Oeschger events without the AMOC? (And without mentioning the word “solar” 🙂

  16. That might explain why the Kronprins Hakken, class I icebreaker Norwegian Arctic research ship encountered 3 meter ice when the DMI ice maps for the Arctic (or should I say model?) said the ice would only be 0.5 metre thick. They also found thick one year ice, which according to the DMI model does not exist.

    Only 3 years before the DMI had changed their model towards thinner ice because they believed it was over-estimating. I have heard of no reaction from them to the Hakkon fiasco.

  17. “When we look at all the simulations together, we can see if they all do the same thing. If so, then that’s due to a forced response,”

    Ah, NO!
    It’s due to the programming of your models. I.e the assumptions, guesses and further ‘secret sauce’ in your models are the same (or at least similar). It says nothing on wether the model is correct and certainly nothing about a ‘forced response’.
    Any computer model outcome is solely dependent on How it is programmed. Computers don’t think for you, at best they do what you tell them to do (and only if your program is correctly coded). And when observations don’t agree with your model, your model is wrong!

    This whole article seems to be yet more circular reasoning.

    Best,
    Willem

  18. “When we look at all the simulations together, we can see if they all do the same thing. If so, then that’s due to a forced response,” said Jahn.

    Or they all contain the same wrong assumption.
    I gave up at that point.

  19. LOL. The increasing melt is clearly due to the AMO, which is at peak of its ~60 year cycle.

    Indeed I suspect the melt is part of the forcing for the cycle since it is linked to the thermohaline cycle. Mann has a 2005 paper on it. It makes logical sense that increased melt produces a lower salinity, which is then moved through the slow abyssal currents right around the globe. The velocity of the abyssal currents fits pretty well with the ~60 year period of the thermohaline cycle at about 3 cm/s.

    • Bruce
      Exactly. The gulf stream and downwelling of cold saline water in the Norwegian Sea, the chief source of north Atlantic cold deep water, both reinforce eachother in a positive feedback. By themselves they would cause runaway increase in the Gulf Stream. But in climate nothing is runaway, sooner or later a positive feedback excurson is curteiled by something else. In the north Atlantic the something else is freshwater input inhibiting the downwelling. This indeed causes intermittency of the gulf stream and the AMO (which is not always 60 years in duration but varies from cycle to cycle).

  20. “This freshwater is what makes sea ice possible: it keeps cold water at the surface, instead of allowing this denser liquid to sink below less dense, warm water. In this way, the Arctic Ocean is much different than other oceans. ”
    How? this make no sense. Fresh water has a density of about 1.00g/cm3. Seawater has a density of 1.03 g/cm3 and this suggests that the fresh water will accumulate as a layer on top of the seawater. Of course this will eventually mix with the seawater but the combination will still have a lower density than the “pure” seawater, no matter what its salinity.
    Also fresh water freezes at 0oC while seawater freezes at about -2oC. So the correct explanation is that

    “This fresh water is what makes sea ice possible: it keeps a layer of fresh low density water at the surface that also has a lower freezing point than then dense saline water beneath. This fresh water freezes first when the ambient temperature drops forming the sea ice.”

    One must have some doubts about the reliability of the claims of this report when the authors make such a fundamental error in their explanation.

  21. This paper starts well by noting rising Arctic fresh water input over several decades and proposing two alternative explanations: anthropogenic climate warming or natural multidecadal oceanic oscillation. They’re actually (claiming to be) sticking to the real scientific method by testing against a null hypothesis – although they wouldn’t call it that.

    However it then continues badly by choosing to “test” the hypotheses by using a climate computer model (yay!) which has been built around the assumption of CO2 driven warming. And what does it find? CO2 driven warming of course.

    They’ve tested the computer model, not the oceans or climate.

  22. This freshwater is what makes sea ice possible: it keeps cold water at the surface, instead of allowing this denser liquid to sink below less dense, warm water

    So more fresh water runoff means less sea-ice loss! Good news?

    Of course, when you work for the Bad News Factory, good news is not permitted, so they just skirt around the implications of what they are saying. The message must prevail.

  23. “The main mission of the research for Alexandra Jahn,

    and her graduate student, Laiho, was to differentiate between natural variability cycles in Arctic freshwater amounts and climate change’s impact. They examined the results from an ensemble of models run from 1920 to 2100.

    “When we look at all the simulations together, we can see if they all do the same thing. If so, then that’s due to a forced response,”

    “The researchers also ran the models through different emissions scenarios to see if these changes will be affected by humans’ emissions choices in the next few decades. They looked at the “business as usual” (over 4 degrees Celsius warming by the end of the century) scenario and what would happen if humans limited warming to 2 degrees Celsius, the upper end of IPCC (Intergovernmental Panel on Climate Change) targets for this century.”

    Sharing self gratification delusional fantasies are so hard…
    Armchair researchers publicizing their simulations as if they are reality.
    Pathetic.

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