Ships’ emissions create measurable regional change in clouds

This satellite image was taken January 16, 2018, off the coast of Europe. Pollution from ships creates lines of clouds that can stretch hundreds of miles. The narrower ends of the clouds are youngest, while the broader, wavier ends are older. Credit NASA Earth Observatory

This satellite image was taken January 16, 2018, off the coast of Europe. Pollution from ships creates lines of clouds that can stretch hundreds of miles. The narrower ends of the clouds are youngest, while the broader, wavier ends are older. Credit NASA Earth Observatory

A container ship leaves a trail of white clouds in its wake that can linger in the air for hours. This puffy line is not just exhaust from the engine, but a change in the clouds that’s caused by small airborne particles of pollution.

New research led by the University of Washington is the first to measure this phenomenon’s effect over years and at a regional scale. Satellite data over a shipping lane in the south Atlantic show that the ships modify clouds to block an additional 2 Watts of solar energy, on average, from reaching each square meter of ocean surface near the shipping lane.

The result implies that globally, cloud changes caused by particles from all forms of industrial pollution block 1 Watt of solar energy per square meter of Earth’s surface, masking almost a third of the present-day warming from greenhouse gases. The open-access study was published March 24 in AGU Advances, a journal of the American Geophysical Union.

“In climate models, if you simulate the world with sulfur emissions from shipping, and you simulate the world without these emissions, there is a pretty sizable cooling effect from changes in the model clouds due to shipping,” said first author Michael Diamond, a UW doctoral student in atmospheric sciences. “But because there’s so much natural variability it’s been hard to see this effect in observations of the real world.”

The new study uses observations from 2003 to 2015 in spring, the cloudiest season, over the shipping route between Europe and South Africa. This path is also part of a popular open-ocean shipping route between Europe and Asia.

Small particles in exhaust from burning fossil fuels creates “seeds” on which water vapor in the air can condense into cloud droplets. More particles of airborne sulfate or other material leads to clouds with more small droplets, compared to the same amount of water condensed into fewer, bigger droplets. This makes the clouds brighter, or more reflective.

Past attempts to measure this effect from ships had focused on places where the wind blows across the shipping lane, in order to compare the “clean” area upwind with the “polluted” area downstream. But in this study researchers focused on an area that had previously been excluded: a place where the wind blows along the shipping lane, keeping pollution concentrated in that small area.

The study analyzed cloud properties detected over 12 years by the MODIS instrument on NASA satellites and the amount of reflected sunlight at the top of the atmosphere from the CERES group of satellite instruments. The authors compared cloud properties inside the shipping route with an estimate of what those cloud properties would have been in the absence of shipping based on statistics from nearby, unpolluted areas.

“The difference inside the shipping lane is small enough that we need about six years of data to confirm that it is real,” said co-author Hannah Director, a UW doctoral student in statistics. “However, if this small change occurred worldwide, it would be enough to affect global temperatures.”

Once they could measure the ship emissions’ effect on solar radiation, the researchers used that number to estimate how much cloud brightening from all industrial pollution has affected the climate overall.

Averaged globally, they found changes in low clouds due to pollution from all sources block 1 Watt per square meter of solar energy — compared to the roughly 3 Watts per square meter trapped today by the greenhouse gases also emitted by industrial activities. In other words, without the cooling effect of pollution-seeded clouds, Earth might have already warmed by 1.5 degrees Celsius (2.7 F), a change that the Intergovernmental Panel on Climate Change projects would have significant societal impacts. (For comparison, today the Earth is estimated to have warmed by approximately 1 C (1.8 F) since the late 1800s.)

“I think the biggest contribution of this study is our ability to generalize, to calculate a global assessment of the overall impact of sulfate pollution on low clouds,” said co-author Rob Wood, a UW professor of atmospheric sciences.

The results also have implications for one possible mechanism of deliberate climate intervention. They suggest that strategies to temporarily slow global warming by spraying salt particles to make low-level marine clouds more reflective, known as marine cloud brightening, might be effective. But they also imply these changes could take years to be easily observed.

“What this study doesn’t tell us at all is: Is marine cloud brightening a good idea? Should we do it? There’s a lot more research that needs to go into that, including from the social sciences and humanities,” Diamond said. “It does tell us that these effects are possible — and on a more cautionary note, that these effects might be difficult to confidently detect.”

###

Other co-authors are Ryan Eastman, a UW research scientist in atmospheric sciences, and Anna Possner at Goethe University in Frankfurt. The research was funded by NASA and the National Science Foundation.

From EurekAlert!

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76 thoughts on “Ships’ emissions create measurable regional change in clouds

  1. This is somewhat like the vapor trails left by jet aircraft. I’m guessing the clouds created by ships are quite a bit lower than those created by aircraft.

    Given that clouds have a cooling effect by day and a warming effect by night, what’s the net effect? This link doesn’t seem to give a clear answer.

    • commieBob
      March 24, 2020 at 2:14 pm

      The other point to consider is just what % of the Earth’s surface is covered by these things…surely it is absolutely miniscule in the bigger picture.

      • After 911 it’s said that the absence of vapor trails caused measurable changes in the weather.

        In 2004, NASA scientist Patrick Minnis wrote that “increased cirrus coverage, attributable to air traffic, could account for nearly all of the warming observed over the United States for nearly 20 years starting in 1975.” link

        • New research led by the University of Washington is the first to measure this phenomenon’s effect over years and at a regional scale. Satellite data over a shipping lane in the south Atlantic show that the ships modify clouds to block an additional 2 Watts of solar energy, on average, from reaching each square meter of ocean surface near the shipping lane.

          Soooo
          This would also block and mask natural warming prior to CO2’s purported influence on current weather

        • commieBob, ……. apparently you overlooked the part about ….. “could account for”.

          Kinda like, …… iffen a toad had wings, ….. it “could account for” ….. no bumping butt on ground.

          • Real scientists give error bars or something like that. An example of one who expresses absolute certainty would be Dr. Mann, inventor of the fraudulent hockey stick.

            Anyway, if vapor trails could account for all the warming since 1975, that’s a big deal. It provides an alternative to the CO2 global thermostat theory (CO2GT).

            In a sane world, you’d evaluate both theories and, if neither could be refuted, you’d treat the issue with caution. In the real world, on the other hand …

      • The MAIN point to consider is, we would be in deep do-do, if these container ships did not deliver their cargos all over the world.

        Ship fuel is very dirty, has lots of particulates for water vapor to condense on.
        Aviation fuel is also very dirty, also has lots of particulates.

        After 9/11, no planes were flying, there were no contrails, skies were blue.

        • @ willem post

          After 9/11, no planes were flying, there were no contrails, skies were blue.

          Willem, …… early mornings and late afternoons is the best time to view jet aircraft “contrails” because they are pretty much invisible during other hours during the day.

          Sunshine has to reflect off the bottom to be visible from the surface.

  2. The albedo effect is a two edge sword. Of course they reflect (a minuscule amount of) sunlight back into space and off the planet at wavelengths that CO2 cannot intercept. Yet they also redirect infrared back down to the earth (& more so at night) effectively balancing out their albedo effect.

    The same has also been observed with aircraft contrails, and this effect was documented in the 4 day period after 9/11 when planes were grounded all over the world!

    Conclusion: Ship tracks and contrails are non-starters in the climate change equation!

    • These aerosols don’t affect how much water vapor is in the atmosphere so there should be little if any impact on how much IR is blocked by it.
      On the other hand by causing it to condense there would be an impact on how much light is able to penetrate the cloud layer.

    • “& more so at night”

      Huh? The amount of IR the atmosphere sends toward the Earth is based on the temperature of the atmosphere, not on whether it is day or night.

      Nor is all the IR radiated back toward the Earth absorbed by the Earth permanently. If that IR does heat the Earth then the Earth will radiate at a faster rate toward space. What does happen at night is that the IR from the atmosphere slows down the rate the Earth can cool (i.e. the total amount of IR it can emit over time) so nighttime temperatures remain higher than would normally be expected.

      That’s why an increasing average global temperature is so misleading. Far too many people think that an increasing average means daytime temperatures are going up and up. They all failed 8th grade math – an average can go up from minimums going up just as easily as maximums going up.

      It’s why the average global temp going up is such a good thing – it lengthens growing seasons and it spurs more crop growth at night (i.e. more food). As the Earth greens from higher nighttime temperatures it also means the Earth is sinking more carbon!

      • Tim: In the absence of intervening GHGs, clouds, shiptracks, and contrails, Radiational Cooling would send more IR into space through a transparent atmosphere at night. The reason I say “…more so at night…” is that there is lack of incoming solar wattage to offset it.

        I agree with your last paragraph if you add “and plants are releasing more Oxygen.” to the last sentence!

      • @ Tim Gorman

        ….. so nighttime temperatures remain higher than would normally be expected.

        Tim, …….. only if the atmosphere contains a lot of H2O vapor.

  3. … show that the ships modify clouds to block an additional 2 Watts of solar energy, on average, from reaching each square meter of ocean surface near the shipping lane.

    So what exactly was the point if the recent change maritime law to force ships to use more expensive and valuable “low sulphur” fuel instead of bunker oil?

    They actually KNOW that this will cause the more of the global warming they are always screaming is an “existential climate emergency”.

    now just wait until they ban air travel as well , reduce all those lower stratosphere cloud formation nucleii and we can see another 0.5 deg C of warming. They can then pretend that their climate models were right all along !!

    • “So what exactly was the point …”

      They’re grasping at straws to try and explain why the warming they expect to see is not occurring since it’s about 2 W/m^2 forcing they think all of mankind’s CO2 emissions throughout history are now causing and this is enough incremental reflection to offset it.

    • Greg,

      According to Oregon’s DEQ, the port of Portland has been Portland’s #1 polluter for decades. That’s why the requirement to upgrade port equipment and ships to cleaner burning fuel. People were blaming cars, pickups and trucks for the smog when in reality it was the port.

  4. ” Is marine cloud brightening a good idea? Should we do it? ”

    So we stop using cheap bunker oil to make less cloud, then start spraying “salt” into the atmosphere to achieve the opposite result, at great expense.

    hey, this is a real twofer. We pay twice to maintain the existing global cooling. Pay twoferfukall.

    You can not fault their ingenuity to waste money twice and stay in exactly the same place. That requires the skills of a circus acrobat.

  5. “This puffy line is not just exhaust from the engine, but a change in the clouds that’s caused by small airborne particles of pollution.”

    Evaporation for the ocean will create largely a similar amount of clouds. Sure, there might be some nuclei in the exhaust that helps condensation, but the exhaust itself is already a water saturated condition, which facilitates condensation. So, what’s their problem? Global warming will be canceled by shipping?

    • Yes, let’s burn more fossil fuels for ships and by extension airplanes to offset the global warming caused by other uses of fossil fuels. Problem solved and everybody’s happy (except for those that thought this was a good excuse to impose centralized control).

      • Think of a large container ship as equivalent to ~thirty 777 aircraft in terms of pounds of fuel burned per unit distance. One container ship could produce a whopper of a con trail.
        (This was a quick back-of-the-virtual-envelope calculation without calculating H2O production between bunker fuel and jet fuel)

  6. 1) It’s not ‘pollution’ causing the clouds, but the water vapor from combustion. It’s bad enough they want to call the CO2 emissions pollution, but now the water vapor is also pollution?

    2) How can they know that as the consequence of those clouds, other clouds don’t need to form for the planet to be in a balance? Surely, the reduced solar energy evaporates less ocean water to feed other clouds.

  7. But in this study researchers focused on an area that had previously been excluded: a place where the wind blows along the shipping lane, keeping pollution concentrated in that small area.

    “WOW”, ….. that means the wind and the ships are moving at the same speed.

    But that can’t be cause the picture shows there are cross-winds to the ship’s movement.

    “HA”, ……. contrails from airplane??

    • This just doesn’t pass the sniff test. My measurement puts those trails at over 500km, so the ship has been traveling more than 10 hours since the beginning of the trail. Is it really going to stay that compact and self-contained in 10 hours? I think not

      • You are right about the sniff test, Keith.
        The trail down the centre of the photo must be from about 45 N to about 35 N, or around 10 degrees of latitude. This equates to 600 sea miles. Container ships travel at around 20 Kts, taking about a day and a bit to cover this distance. Tankers and Bulkers, which are much more numerous, will steam at around 12 Kts, taking over 2 days to cover this distance. And the “trail” stays in place all that time without being distorted by different wind speeds etc? I think not.
        Also, the picture is of winter over the N. Atlantic. It would be interesting to see the weather synoptic for that area at that time, and this should be available in an archive somewhere.
        Finally, there will have been many many more vessels going through this area at that time than the score or so here. For example there seem to be none making a passage between the Mediterranean and the Panama Canal.

        Look for some other reason.

      • That’s exactly what I was thinking – there’s no way that can be from slow moving container ships. Airplanes, yes.

  8. The study assumes that the impact of pollutants on clouds has been constant since the beginning of the industrial revolution.
    In reality since the 70’s the total amount of such pollution has been dramatically reduced.

    This means that instead of a cooling factor, during the time period of interest, aerosols have been a warming factor.

    • I agree. If this study can be extrapolated, then the major push to remove particulates and other “real” pollution since the 50s might account for a part of the current warming!

  9. “It does tell us that these effects (marine cloud brightening) are possible — and on a more cautionary note, that these effects might be difficult to confidently detect.”
    So at some, probably considerable, expense and after a lot of intergovernmental squabbling salt particles will be blasted into the air, but with no confidence that it will have any observable effect except on the accelerated rusting of marine and coastal structures . In what kind of world does that make sense?

  10. Maximum allowed sulphur level in bunkers oil for shios without scrubbers was reduced from 3.5 percent to 0.5 percent from January 1st 2020.

    That is a sevenfold decrease! If the article is right, we should see a warming now.

  11. “There’s a lot more research that needs to go into that, including from the social sciences and humanities,” Diamond said.
    What could the social sciences and humanities
    add ?
    I suppose a sociology professor could paint a picture of clouds for them.

  12. How do they resolve solar radiation less than 1 W/m2 and end up with this value as a sum? Typical total uncertainties for global pyranometers using thermopiles are about 5%, at best.

    Let me guess–models.

  13. I’m sure they scoured the archives to get the picture in the article. Like contrails from jets, the atmospheric conditions have to be just right to form the clouds. I think this would only apply to shipping lanes in certain areas of the world where you have water vapor and enough cold air to condense it. Not too viable in the tropics I would guess, nor in the high Arctic where the air is very dry.

    2 watts for each square meter in the shipping lanes? I would like to see the math and assumptions on this one. How many days would you get “ship contrails” and where in the world does this apply.

  14. Since when was Europe next to the South Atlantic?
    There are few trails leading to Europe shown here; most seem to be heading to……..Greenland??

  15. Of course, with IMO2020, you no longer burn high sulfur bunker or have to scrub the sulfur out of the exhaust if you do, so perhaps it is now moot.

  16. Contrails from ships…

    Since when do ships leave contrails over that distance?
    What speed are those container ships trucking along at? 200 to 300 nautical miles per hours?

    Bogus. At the speeds container ships move at, those ‘contrails’ would be far dispersed by winds that run counter to or perpendicular to the ship’s direction.

    • What makes you think that there is always strong winds over the ocean?
      Pictures of contrails being made by ships have been available from satellites for decades.

      • MarkW:
        Where did I state “strong”?
        Nor did I make any reference to fake.

        Winds at 10-15 MPH (nautical miles) are considered moderate and sweep along at 100-150 miles every ten hours.

        “4-6 Light Breeze
        7-10 Gentle Breeze
        11-15 Moderate Breeze
        16-21 Fresh Breeze
        22-27 strong Breeze”

        Strong winds, i.e. 22 MPH and higher mean the winds carry the supposed ship soot 220 nautical miles (253 miles) over ten hours.
        Prevailing winds are usually not zephyrs.

        The research authors state:

        ““I think the biggest contribution of this study is our ability to generalize, to calculate a global assessment of the overall impact of sulfate pollution on low clouds,” said co-author Rob Wood, a UW professor of atmospheric sciences.”

        Key words, “low clouds”. Low clouds are at 6,000 feet and higher.
        The fastest container ships run above 30 KPH (knots per hour), most run in the low 20 KPH. And when they’re saving fuel, run at less than 20 KPH.

        According to these alleged researchers, sulfate particles from the ships cause contrails to form in the low clouds.
        A claim that ignores the surface direction of winds and all possible atmospheric layers that might be in motion towards different directions.

        Plus their claim ignores the prevailing westerlies north of Gibraltar pictured to the SE. That is; the prevailing westerlies at 6,000 feet.

        Slow moving ship very close to the Earth’s surface, emits sulfates that climb straight through multiple cross currents to form contrails in low clouds…

        Their claims are in the realm of “want to buy the Brooklyn Bridge?”.

        Then buried in their article, but there nonetheless:

        “In climate models, if you simulate the world with sulfur emissions from shipping, and you simulate the world without these emissions, there is a pretty sizable cooling effect from changes in the model clouds due to shipping,” said first author Michael Diamond, a UW doctoral student in atmospheric sciences. “But because there’s so much natural variability it’s been hard to see this effect in observations of the real world.”

        The new study uses observations from 2003 to 2015 in spring, the cloudiest season, over the shipping route between Europe and South Africa. This path is also part of a popular open-ocean shipping route between Europe and Asia.”

        Modeling and gross assumption that the contrails identified are ships, not airplanes.

        Looks to me they are trying develop excuses for their failed climate models.
        Next on their ‘contrail forming exhaust’ will be tractors, diesel trucks, tanks, etc…

        https://external-content.duckduckgo.com/iu/?u=http%3A%2F%2Fwww.physicalgeography.net%2Ffundamentals%2Fimages%2Fuppercirculation.jpg&f=1&nofb=1

        https://www.weather.gov/source/zhu/ZHU_Training_Page/winds/Wx_Terms/Flight_Environment.htm

        https://sciencing.com/types-prevailing-winds-12325257.html

  17. Wouldn’t cosmic particles have similar cloud-chamber effect?
    Or is this a super-cooled water / particles interaction in unseen before low altitude cloud systems?

    Or…

    I don’t know the maritime terminology, yet, don’t ships also leave a “wake turbulence” in their trail ?
    And wouldn’t that turbulence trail, since we’re speaking of clouds, a.k.a. water vapor, modify the local evaporation pattern allowing more molecules to escape the liquid as vapor? And create false politically correct pollution positives?

  18. “In climate models, if you simulate the world with sulfur emissions from shipping, and you simulate the world without these emissions, there is a pretty sizable cooling effect from changes in the model clouds due to shipping…But because there’s so much natural variability it’s been hard to see this effect in observations of the real world…”

    Sizable effectt in models but hard to see in real world observations. Imagine that.

  19. There’s another possible reason why co-morbidity is so high in the deaths in Italy.
    The hospitals are swamped so doctors have to decide who to put on ventilators. Obviously they choose the people with the greatest chances of survival. People with pre-existing conditions are literally being denied treatment. Sometimes treatment for those conditions is stopped as well – for instance in UK a lot of chemotherapy is being suspended.

    Hence the need to slow the spread so that the amount of equipment and trained medics can be increated to meet the demand.

  20. ” Small particles in exhaust from burning fossil fuels creates “seeds” on which water vapor in the air can condense into cloud droplets. ”

    Why is this then not true for the skies over cities ?

  21. What about the fact that a ship’s passage churns up the water, bringing cold water to the surface? Would there be condensation of warm humid air?

  22. They have just destroyed the main argument against Henrik Svensmark’s GCR theory. Svensmark shows that increased GCRs result in increased numbers of cloud-forming particles. The main argument against has been that there are so many particles (aerosols) already that a few more won’t make any difference. This study shows that a few more do make a difference. Score one more to Henrik Svensmark.

  23. Is LNG a good option for all ships then very clean and economical.

    Cruise liners were converting I think there will be conversion capacity to burn so as to say.

  24. Maybe it’s not just the ship’s engine exhaust?

    Look behind any large ship and you see a churning wake that throws up a lot of water vapor and water droplets … throwing a lot of water vapor into the air behind the vessel that then condenses into a cloud trail. In the process, it is moving a lot of heat from the ocean into the air … speeding the cooling of the water.

    I’m reminded of some old articles (cannot find links) hypothesizing the global temperature drops during WW1 and WW2 might be linked to the surge in naval activity.

  25. What about the swath of oily soot that every bunker-fueled ship lays on surface of the ocean? But that would be a non-CO2 warming effect that no planetary savior wants to find.

  26. So presumably all the factories burning the cheapest coal available would have lowered the temperature. Say from mid nineteenth centuary-1950s when they began to clean up their act. If that’s right, then some of the recent warming would have been due to cleaner power rather than GHGs.

  27. I thought most modern container and tanker vessels are diesel powered (or LNG), with the number of HFO/bunker oil fuelled ships gradually diminishing. Any merchant seamen around able to confirm this?

  28. Shipping rules have recently changed to require Ultra Low Sulfer Diesel Fuels. My bet is that that will reduce the clouds allowing more sunlight to reach the oceans. That will result in MORE warming and it will have absolutely nothiing to do with CO2. Alarmists will use this positive news on pollution to be spun as a negative that CO2 is causing warming. If you want warming, simply allow more sunlight to reach the oceans, it is that easy and has nothing to do with CO2.

  29. BTW, fewer jets flying has also cleared the skies, so more sunlight is already reaching the oceans. Expect more warming, and it has nothing to do with CO2.

  30. But because there’s so much natural variability it’s been hard to see this effect in observations of the real world

    That says it all, about climate science in general. Emphasis on the “real world”

  31. More contrails sciencism. No comparison to coal or oil-fired, low temp steam shipping. No cost-benefit comparison to wind powered logistics. Don’t eat yellow journalism.

  32. A container ship leaves a trail of white clouds in its wake that can linger in the air for hours. This puffy line is not just exhaust from the engine, but a change in the clouds that’s caused by small airborne particles of pollution.

    It is difficult to take an article as a serious scientific report when the author telegraphs their bias so clearly by using the word “pollution”. Forests also cause cloud formation by similar such “pollutants” normally emitted by vegetation.

    To be fair, I realise the article later puts the words “pollution” and “clean” in quotation marks, and it is not immediately obvious what words were actually used by the UW researchers themselves. But the abandonment of journalistic integrity has already happened before most readers get that far into the article, and the people writing such pieces know it well. Most of the damage to science reporting is done in the headline and first sentence.

  33. I live overlooking Subic Bay, PI. Container ships in and out of here all the time. I’ve never seen a line of clouds following them. Must be a northern latitude deal. BTW, the virus has had the effect of emptying the port. Not a ship in sight.

    • I note credit for the “photo” is as follows: ” Credit NASA Earth Observatory ”

      This does not seem to be one of the NOAA operational GOES satellites. We need more detail on the provenance of this so-called image, was it even “visible” light (as opposed IR or WV wavelengths) that is being depicted? Is it a time-lapse in nature? IOW, trails behind the ships dissipated some minutes later BUT the image illustrates a 3 or 6 or 12 hour period?

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