A benefit to ‘climate change’ – less dead zones in the ocean

From the University of Washington

Ocean’s most oxygen-deprived zones to shrink under climate change

As the complex story of climate change unfolds, many of the endings are grim. But there are exceptions. Predictions that the lowest-oxygen environments in the ocean would get worse may not come to pass. Instead, University of Washington research shows climate change, as it weakens the trade winds, could shrink the size of these extreme low-oxygen waters.

“The tropics should actually get better oxygenated as the climate warms up,” said Curtis Deutsch, a UW associate professor of oceanography. He is lead author of the study published Aug. 8 in Science.

Warmer water contains less gas, so climate change is expected to reduce oxygen levels worldwide. Observations show this is already taking place in many places. Declines during the past 20 years in the tropical low-oxygen zones, the lowest-oxygen waters on the planet, had led to a 2008 study proposing that these zones would also get worse over time.

Tropical regions are usually associated with an abundance of life, but they have some of the most inhospitable places for ocean dwellers. The oxygen minimum zones off Mexico and Peru have oxygen levels already too low to support most animals (so, unlike in other low-oxygen zones, here there’s no risk of killing fish).

But when those levels drop even further, a particular group of bacteria, which can use nitrogen instead of oxygen as a source of energy, thrive. Nitrogen is an essential and very scarce nutrient for marine plants. When oxygen levels get low enough for that particular group of bacteria to take over, significant amounts of the ocean’s fertilizer get deep-sixed to the bottom of the tropical ocean.

The new paper shows that water flowing into the tropics is indeed likely to get lower in oxygen, decreasing the initial oxygen supply. But demand will also shift under climate change. Specifically, as the trade winds weaken, the whole sequence of events that feeds this bacterial food chain will slow down, and the low-oxygen zone will shrink.

“If we want to understand how biological and chemical aspects of the ocean will change in the future, we really have to pay a lot of attention to what happens with the winds,” Deutsch said. “The winds can lead to conclusions that are exactly the opposite of what you’d expect.”

Trade winds from the west cause deep water to percolate up along western coasts, bringing nutrients up from the deep sea. These nutrients feed marine plants, which feed marine animals, which decompose to feed bacteria that use up the remaining oxygen. As trade winds weaken, less nutrient-rich water percolates up from the deep. Fewer plants grow at the surface. Finally, fewer oxygen-gobbling bacteria can survive.

Deutsch is a climate modeler who studies tropical ocean circulation. He learned of sediment cores, collected off Mexico by co-authors William Berelson at the University of Southern California and Alexander van Geen at Columbia University, that showed a puzzling longer-term trend. The authors worked together to interpret the samples. Results show that for most of the time since 1850 the population of these nitrogen-eating bacteria has been going down, coincident with warming oceans and weakening trade winds. This implies that the local oxygen levels, for which few direct measurements exist, have been rising.

“I find it an interesting question for understanding the way the ocean functions on climatic or geologic timescales,” Deutsch said.

Most climate models predict that trade winds will continue to weaken in the future, shrinking the oxygen-minimum zones in the Pacific Ocean off the coasts of Mexico, Chile and Peru, and in the Indian Ocean off western Australia.

Decreasing oxygen in the wider ocean is still a major concern, Deutsch said, as are overfishing, ocean acidification and warming water temperatures. “This study shows that what happens to the winds, which is sometimes overlooked, is really important for predicting how the oceans will respond to climate change,” Deutsch said.

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The research was funded by the National Science Foundation, the Gordon and Betty Moore Foundation, the U.S. Geological Survey and the Lamont-Doherty Earth Observatory. Other co-authors are Tom Weber, a research scientist at the UW; Robert Thunell at the University of South Carolina; Caitlin Terms at the University of Southern California; James McManus at the University of Akron; John Crusius at the U.S. Geological Survey; Taka Ito at the Georgia Institute of Technology; Timothy Baumgartner and Vicente Ferreira at Mexico’s Autonomous University of Baja California; and Jacob Mey at the City University of New York.

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38 thoughts on “A benefit to ‘climate change’ – less dead zones in the ocean

  1. “could”….”likely”….”should”….Words that are just climate model-driven rubbish and conjecture.

    “The winds can lead to conclusions that are exactly the opposite of what you’d expect.”….only if you entered into the experiment with a preconceived conclusion in your head.

  2. From above:

    Instead, University of Washington research shows climate change, as it weakens the trade winds, could shrink the size of these extreme low-oxygen waters.

    From four days ago here:

    New research has found rapid warming of the Atlantic Ocean, likely caused by global warming, has turbocharged Pacific Equatorial trade winds. Currently the winds are at a level never before seen on observed records, which extend back to the 1860s.

    Global warming weakens trade winds. Global warming ‘turbocharges’ trade winds.

    Good thing the science is settled.

  3. No, not with more mandates for corn ethanol in your gas tank and the fertilizers to carry out that mandate. Call it the Iowa Caucus dead zone.

  4. “If we want to understand how biological and chemical aspects of the ocean will change in the future, we really have to pay a lot of attention to what happens with the winds,” Deutsch said.

    “The winds can lead to conclusions that are exactly the opposite of what you’d expect.”

    Perhaps Caption Bright Light would like to look at Algae bloom from Iron and Ag. runoffs?

    Wind has little to do with the chemistry.

  5. JJ@11:53am
    says all that needs to be said concerning this paper and its dubious assumptions.
    Looks like the two sets of clowns will have to turbo charge their respective climate models and duel it out.

  6. Latitude says:
    August 7, 2014 at 11:47 am

    see the Black Sea studies but, I agree, they have nothing to do with reality ; )

  7. Opinions wanted please!

    Would it be safe to say this is yet another climate feedback mechanism?

  8. Every day I read see another study about what’s going to happen “as the climate warms up”. That’s wonderful but it leaves me wondering what will happen if/when the climate actually cools down. I guess there’s no funding available for that question.

  9. Think of it as a REALLY big WIN for anaerobic bacteria !!!

    That’s the thing I hate about warministas – always with the negative waves !!

    “Why don’t you knock it off with them negative waves? Why don’t you dig how beautiful it is out here? Why don’t you say something righteous and hopeful for a change?” Oddball in Kelly’s Heroes

  10. First we are told “Warmer water contains less gas, so climate change is expected to reduce oxygen levels worldwide. Observations show this is already taking place in many places”.

    So presumably that applies to CO2 as well.

    And yet further down we find references to ocean acidification presumably caused by more dissolved CO2…

  11. John…he is saying the dead spots will shrink…because the oceans will stratify more

    has nothing to do with the “Black Sea Studies”…….

    The idiots don’t realize nitrification, denitrification, ammonification, sulfur reduction, etc etc don’t care, and will keep on keeping on…….

  12. NASA Climate Scientist Explains 15-Year ‘Global Warming Hiatus’:

    http://washington.cbslocal.com/2014/08/06/nasa-climate-scientist-explains-15-year-global-warming-hiatus/

    According to NASA and Climate Scientist Norman Loeb:

    _The world is warming but the warming is also on hiatus at the same time (which of this words doesn’t mean what he thinks it means — “warming” or “hiatus?).
    _Warming is happening at half the rate it previously was. (Wait, is it on hiatus, or is it warming?)

    _Money quote: “For average climate records, 30 years is like one data point,” said Loeb, reiterating that while the Earth is warming more slowly, it is still warming. “It’s really forcing us to look at our models and observations and ask questions.”

  13. Get real !

    All of the worlds great sport fishing waters, are in the tropics. The hotter the water, the better the fishing.

    I’ve been fishing the Sea of Cortez, for over 45 years, and we always go in the hottest summer months, when the place is crawling with fish.

    Well it was, until the gummint let some churls install yellowfin tuna raising pens in La Paz Bay.

    Now they are netting the entire sea of Cortez to get food for those tuna. That’s killing the whole sea, and all the Baja population. No bait, no fish, no gringo fishermen, no hotel bookings no income for Baja.

    Hey dummies ! YFT can run down baitfish better than you can, when they are free to swim the oceans.

  14. Resourceguy says:
    August 7, 2014 at 12:08 pm
    No, not with more mandates for corn ethanol in your gas tank and the fertilizers to carry out that mandate. Call it the Iowa Caucus dead zone.

    …bingo. so with less winds to move them around (and dilute) the dead zone in the Gulf won’t be as large geographically but more, uhm, dead-er.

  15. The press release reads, “Trade winds from the west cause deep water to percolate up along western coasts, bringing nutrients up from the deep sea. These nutrients feed marine plants, which feed marine animals, which decompose to feed bacteria that use up the remaining oxygen. As trade winds weaken, less nutrient-rich water percolates up from the deep. Fewer plants grow at the surface. Finally, fewer oxygen-gobbling bacteria can survive.”

    Winds out of the west are called westerlies, not trade winds. And the trade winds have strengthened, not weakened, over the past 30 years as we’ve transitioned from El Nino dominance to La Nina dominance.

    So take the model study and throw it away.

  16. Resourceguy is correct. When we use 40,000,000 acres in the US to grow corn(the most fertilizer/nitrogen intensive crop) for ethanol, the runoff from this is more important by several orders of magnitude than any effects from climate.

    With exceptions……… during droughts it doesn’t rain much and there isn’t much runoff. Droughts have a tendency to occur more frequently for the worlds biggest grain producer (US Midwest) from global cooling and La Nina’s.

    However, the US Cornbelt went a record 24 straight years from 1988 to 2012 without a widespread severe drought……..best growing conditions ever for over 2 decades and several beneficial El Nino’s. The 2011 La Nina, played a major role in the S.Plains drought, that expanded northeast into the Cornbelt in 2012.

    http://onlinelibrary.wiley.com/doi/10.1029/2012GL053055/abstract

    The one type of weather that does increase with global warming is rainfall……sometimes excessive which increases runoff. This would in fact increase dead zones from agricultural runoff.
    The amount of the planet experiencing drought, has slightly decreased over the last 3 decades

    El Nino’s and La Nina’s occur naturally and their effects on weather/climate are natural.

  17. Climate change = less dead zones in the oceans.
    Climate change claims = more brain dead zones in Washington DC and the grants they fund.

  18. “Results show that for most of the time since 1850 the population of these nitrogen-eating bacteria has been going down, coincident with warming oceans and weakening trade winds.”

    .
    Please excuse the ignorance but I thought the trade winds had strengthened with AGW?

    Or something.

  19. Bob Tisdale says:
    August 7, 2014 at 1:29 pm

    Yet more evidence of the PDO shift from warm water predominating off North America from 1977 to c. 2006 toward cool water in the past decade or so:

    http://www.sciencedirect.com/science/article/pii/S1040618213000621

    Although the latest NOAA map at the top of the post “El Niño is just not paying attention to climate models – looks like a bust” seems to show still a lot of warm water off the Pacific NW coast.

    In comments of other posts on this blog, a number of readers asked for your opinion as to the ultimate cause of decadal, centennial and millennial scale climatic fluctuations during the Holocene, with respect especially to Pacific and Atlantic oscillations.

  20. Deutsch said: “The winds can lead you to conclusions that are exactly the opposite of what you expect”
    There is a fine irony to this statement, coming from one who shows that hr thinks that trade winds blow from west to east, or so the press rralease reports.

    My motto: do science by press release, then be judged by press release.

  21. So, more life in the oceans.

    Wonder how much plant food carbon pollution *that* will take out of the atmosphere…

  22. Other studies have shown just the opposite. In Gutierrez et al (2009) Rapid reorganization in ocean biogeochemistry off Peru towards the end of the Little Ice Age” Biogeosciences, 6, 835–848. They show that since the end of the Little Ice Age, warming increased trade winds which increased upwelling. Upwelling allows greater photosynthesis and ocean productivity as nutrients are brought from the dark abyss into the sunlight (photic zone). However increased productivity results in more bodies that decay and deplete oxygen.

    The alarmists often claim oceans will lose oxygen because the upper layers warm and stratify. (Just the of Trenberth’s arguments that heat surface waters are driven into the depths.) However these oxygen dead zones are not a function of oxygen diffusing from the surface but from biological decay that increases when productivity at the sunlit surfaces increase.

    Indeed their observation is true that increased upwelling is connected to increased dead zones. However they falsely suggest that warming will cause the trade winds to slow down and decrease upwelling. Historically that has not been the case. Gutierrez et al (2009) show less upwelling during the Little Ice Age. The trade winds vacillate depending on the Walker circulation which is governed by El Nino events. The modelers have done a poor job of capturing El Nino events and every time the winds slow down or speed up they blindly attribute global warming. Vecchi 2006 claimed slowing trade winds were evidence of global warming. But as the Pacific Decadal Oscillation switched to its negative phase and more La Ninas intensified the Walker Circulation, they claimed global warming increases the faster trade winds now observed. They are clueless “day traders” blindly grabbing on to every trend.

  23. sturgishooper says:
    August 7, 2014 at 1:59 pm

    Bob Tisdale says:
    August 7, 2014 at 1:29 pm

    To reply to my own question, here’s another paper supporting the view that the ultimate “driver” behind longer-term fluctuations in the ENSO is tropical insolation, which IMO ought not to surprise anyone. Wonder if you concur in the importance of insolation as a “forcing” of climatic changes in frequency and amplitude to the weather events of the ENSO.

    http://geology.gsapubs.org/content/38/1/43.short

    Postglacial changes in El Niño and La Niña behavior

    Matthew C. Makou1,*, Timothy I. Eglinton2, Delia W. Oppo1 and Konrad A. Hughen2

    Paleoclimate reconstructions suggest distinctive changes in the El Niño–Southern Oscillation (ENSO), the dominant mode of tropical climate variability, over the last glacial cycle and throughout the Holocene. However, to the best of our knowledge, no studies provide parallel reconstructions of warm (El Niño) and cold (La Niña) phase variability, thus precluding distinction between variations in ENSO activity and the mean state of the tropical Pacific. Here we provide the first such records, generated using molecular organic geochemical proxies in a sediment core from the Peru margin region. The opposing influences of El Niño and La Niña on coastal upwelling and phytoplankton community structure produce distinct sedimentary sterol records describing the evolution of each ENSO phase. We document changes in surface ocean productivity on the Peru margin over the past 16 ka that indicate enhanced La Niña–like conditions alone during deglaciation, but concomitant increases in both El Niño and La Niña activity during the past 2 ka. We propose that the preponderance of La Niña–like conditions prior to 11.5 ka reflects the influence of waning glacial boundary conditions. By contrast, warm and cold phase covariability during the late Holocene suggests centennial-scale changes in ENSO activity, rather than the Pacific mean state, driven by tropical insolation.

    jim Steele says:
    August 7, 2014 at 2:27 pm

    The same study IMO supports your view on biological productivity and upwelling, but on the time frame going back to before the end of the last glacial, ie 16 kya.

  24. “They are clueless “day traders” blindly grabbing on to every trend.”

    excellent Jim….

  25. Fewer?? Perhaps the number of zones is unchanged, but each zone is “less dead”….

  26. This will be seized upon by the delay/deny/misdirect factory. These vultures will forget important points illustrated in the research paper, however:

    a. scientists can and do freely publish occasional “good” news about AGW, without losing their grants, without fear. b. the research assumes the existence and increases of AGW c. the reduced oxygen poor zones are limited, and the authors speak of the dangers of oxygen depletion in the wider ocean as well as the dangers of warmer and more acidified waters.

  27. Charlie Martin says:
    August 7, 2014 at 11:36 am

    Er, “fewer”.

    I’m sorry, I just can’t stop myself from editing.

    Had the same impulse, but the meaning could be, “Dead zones will become less dead”, which is consistent with the post. It’s a matter of degree, not number.

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