New study identifies thermometer for global ocean

Posted: January 4, 2018 by oldbrew in atmosphere, Ocean dynamics, research, Temperature

Thermometer with Fahrenheit and Celsius units [image credit: Stilfehler at Wikipedia]

Geoscientist Jeff Severinghaus said: “Our precision is about 0.2 ºC (0.4 ºF) now, and the warming of the past 50 years is only about 0.1 ºC,” adding that advanced equipment can provide more precise measurements, allowing scientists to use this technique to track the current warming trend in the world’s oceans, reports Quite modest recent warming then?

There’s a new way to measure the average temperature of the ocean thanks to researchers at Scripps Institution of Oceanography at the University of California San Diego.

In an article published in the Jan. 4, 2018, issue of the journal Nature, geoscientist Jeff Severinghaus and colleagues at Scripps Oceanography and institutions in Switzerland and Japan detailed their ground-breaking approach.

Determining changes in the average temperature of the entire world’s ocean has proven to be a nearly impossible task due to the distribution of different water masses. Each layer of water can have drastically different temperatures, so determining the average over the entirety of the ocean’s surface and depths presents a challenge.

Severinghaus and colleagues were able to bypass these obstacles by determining the value indirectly. Instead of measuring water temperature, they determined the ratio of noble gases in the atmosphere, which are in direct relation to the ocean’s temperature.

“This method is a radically new way to measure change in total ocean heat,” said Severinghaus. “It takes advantage of the fact that the atmosphere is well-mixed, so a single measurement anywhere in the world can give you the answer.”

In the study, the scientists measured values of the noble gases argon, krypton, and xenon in air bubbles captured inside ice in Antarctica. As the oceans warm, krypton and xenon are released into the atmosphere in known quantities. The ratio of these gases in the atmosphere therefore allows for the calculation of average global ocean temperature.

Measurements were taken from ice samples collected during the West Antarctic Ice Sheet (WAIS) Divide coring project, of which Severinghaus is a leader. Over the course of six field seasons in Antarctica, a drill removed ice in cylindrical samples 3.7 meters (just under 9 feet) in length. The final sample was taken at a depth of 3,405 meters (over 11,000 feet) in 2011. This record spans nearly 100,000 years and the age of the layers can be determined to within 50 years.

Earth’s atmosphere mixes on a scale of weeks to months, so a measurement of these air bubbles gives what is essentially a global average. For this study, scientists focused on samples 8,000 to 22,000 years old, and collected data in increments averaging 250 years in resolution.

New insights into the glaciation cycles that occurred on Earth long before humans began affecting the temperature of the atmosphere and oceans are now possible using the technique of measuring noble gas quantities.

The study determined that the average global ocean temperature at the peak of the most recent ice age was 0.9 ºC (33.6 ºF). The modern ocean’s average temperature is 3.5 ºC (38.3 ºF). The incremental measurements between these data points provide an understanding of the global climate never before possible.

Continued here.

  1. oldbrew says:

    From the abstract of the study:
    We find that the mean global ocean temperature is closely correlated with Antarctic temperature and has no lead or lag with atmospheric CO2, thereby confirming the important role of Southern Hemisphere climate in global climate trends.

  2. Can anyone comment on how snow as it becomes firn and then glacial ice, in such a manner that the ice cores are represent to us the composition of the atmosphere in which the snow formed?

    All noble gases are soluble in both water and ice, but they differ in their solubilty in water and differ in their solubility in ice.

    Each noble gas also differs in solubility in H2O as liquid and H2O as ice. This has been confirmed in the lab and in lakes capped with a layer of ice.

    Noble Gases in Seawater as Tracers for Physical and Biogeochemical Ocean Processes
    Rachel H. R. Stanley and William J. Jenkins, 2013

    That is part of the problem in determining to what extent a glacial core can be used to determine the composition of atmospheres:

    There is another aspect to this problem. Snow not only contains dissolved gases within the crystal lattice, the snow physically entrains gases between the branches of the crystal lattice.

    I would like to believe that the researchers have done the lab work with snow that would resolve my reservations about their methodology. I can suspend disbelief while reading the account of their work, but then I am niggled by the same questions I have had about CO2 in snow, firn and ice cores.

    This research appears very impressive. Should I trust that the research team has done the lab work on the transition of snow to ice core?

  3. ivan says:

    This research appears very impressive. Should I trust that the research team has done the lab work on the transition of snow to ice core?

    The thing you need to consider is that very little actual physical lab testing of the basics of anything to do with climate change is undertaken.

    It appears that they don’t have the time to go all the way back to the basics but rely on building on the work of others. If that previous work is wrong there is no way the derivative work can be correct hence the complete mess we have with the so called ‘climate science’ we have today.

  4. The Badger says:

    Even if you can test several cubic metres of sea water in a lab at different temperatures to determine a temperature/noble gas relationship then to extrapolate that to the oceans of the world seems not just a stretch too far but actually scientifically ridiculous.
    Noble gas concentration vs temperature might be valid for a single lump of water at a fixed temperature but you are not going to get the same physical relationship when the water varies in temperature over parts of its surface AND in time.
    If water at temperature T1 has associated atmospheric gas concentration C1 and at T2 its C2 then how can adding C1+C2 be equated to T1+T2 if you have 2 lumps of water at different temperatures? That would only be anywhere near valid if you have perfect linear relationships of all the physical processes involved.
    Anyone who knows anything about these knows that is nonsense, in fact it would be impossible.

  5. oldbrew says:

    New Study Shows Past Research On Rising Ocean Temps Built On Faulty Science

    Ocean temperatures have risen only 0.1 degree Celsius over the last five decades, according to a landmark study some scientists argue could change the way researchers measure the ocean’s temperature levels.

    Each layer of water in the ocean has vastly different temperatures, so determining the average temperature is nearly impossible without glossing over important data. Researchers at the University of California, San Diego decided on a different model – they measured the ratio of noble gases in the atmosphere, which are in direct relation to the ocean’s temperature.

  6. p.g.sharrow says:

    Somehow I am of the opinion that their ocean temperature proxy is only valid for the first 300 feet of ocean. That is about the depth that surface events affect the ocean waters…pg

  7. Steve Borodin says:

    7 meters is 12.14 feet.

    [reply] sorry, nowhere near. But the ‘3.7 meters (just under 9 feet)’ in the report is also wrong, maybe they meant 2.7

  8. E.M.Smith says:

    It looks to me like the strong corelation with antarctic temperatures is due to the antarctic temps determining nobel gas stripping more so than the temp 100 meters under tropical Pacific Ocean surface…

    IMHO, more proof of method required…

  9. tom0mason says:

    Given “Geoscientist Jeff Severinghaus said: “Our precision is about 0.2 ºC (0.4 ºF) now, and the warming of the past 50 years is only about 0.1 ºC,” “
    ANY idea that the oceans (all oceans!?) are consistently warming is pure superstitious superposition. Warming? Cooling? It is unknown given the limitation of the equipment and the size of the task.