Climate impact of clouds made from airplane contrails may triple by 2050
From the EUROPEAN GEOSCIENCES UNION
In the right conditions, airplane contrails can linger in the sky as contrail cirrus – ice clouds that can trap heat inside the Earth’s atmosphere. Their climate impact has been largely neglected in global schemes to offset aviation emissions, even though contrail cirrus have contributed more to warming the atmosphere than all CO2 emitted by aircraft since the start of aviation. A new study published in the European Geosciences Union (EGU) journal Atmospheric Chemistry and Physics has found that, due to air traffic activity, the climate impact of contrail cirrus will be even more significant in the future, tripling by 2050.
Contrail cirrus change global cloudiness, which creates an imbalance in the Earth’s radiation budget – called ‘radiative forcing’ – that results in warming of the planet. The larger this radiative forcing, the more significant the climate impact. In 2005, air traffic made up about 5% of all anthropogenic radiative forcing, with contrail cirrus being the largest contributor to aviation’s climate impact.
“It is important to recognise the significant impact of non-CO2 emissions, such as contrail cirrus, on climate and to take those effects into consideration when setting up emission trading systems or schemes like the Corsia agreement,”
…says Lisa Bock, a researcher at DLR, the German Aerospace Center, and lead-author of the new study. Corsia, the UN’s scheme to offset air traffic carbon emissions from 2020, ignores the non-CO2 climate impacts of aviation.
But the new Atmospheric Chemistry and Physics study shows these non-CO2 climate impacts cannot be neglected. Bock and her colleague Ulrike Burkhardt estimate that contrail cirrus radiative forcing will be 3 times larger in 2050 than in 2006. This increase is predicted to be faster than the rise in CO2 radiative forcing since expected fuel efficiency measures will reduce CO2 emissions.
CREDIT Bock and Burkhardt, Atmos. Chem. Phys., 2019
The increase in contrail cirrus radiative forcing is due to air traffic growth, expected to be 4 times larger in 2050 compared to 2006 levels, and a slight shift of flight routes to higher altitudes, which favours the formation of contrails in the tropics. The impact on climate due to contrail cirrus will be stronger over Northern America and Europe, the busiest air traffic areas on the globe, but will also significantly increase in Asia.
“Contrail cirrus’ main impact is that of warming the higher atmosphere at air traffic levels and changing natural cloudiness. How large their impact is on surface temperature and possibly on precipitation due to the cloud modifications is unclear,” says Burkhardt. Bock adds: “There are still some uncertainties regarding the overall climate impact of contrail cirrus and in particular their impact on surface temperatures because contrail cirrus themselves and their effects on the surface are ongoing topics of research. But it’s clear they warm the atmosphere.”
Cleaner aircraft emissions would solve part of the problem highlighted in the study. Reducing the number of soot particles emitted by aircraft engines decreases the number of ice crystals in contrails, which in turn reduces the climate impact of contrail cirrus. However, “larger reductions than the projected 50% decrease in soot number emissions are needed,” says Burkhardt. She adds that even 90% reductions would likely not be enough to limit the climate impact of contrail cirrus to 2006 levels.
Another often discussed mitigation method is rerouting flights to avoid regions particularly sensitive to the effects of contrail formation. But Bock and Burkhardt caution about applying measures to reduce the climate impact of short-lived contrail cirrus that could result in increases in long-lived CO2 emissions, in particular given the uncertainties in estimating the climate impact of contrail cirrus. They say that measures to reduce soot emissions would be preferable to minimise the overall radiative forcing of future air traffic since they do not involve an increase of CO2 emissions.
“This would enable international aviation to effectively support measures to achieve the Paris climate goals,” Burkhardt concludes.
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The publication is in Atmospheric Chemistry and Physics – link to the paper
Some thoughts:
- This is a model output, so take it with a grain of salt.
- They seem to only consider the Long Wave IR to space reflectivity for contrails as being the big forcing component, yet there’s a big reflectivity factor for incoming solar radiation too. And, that’s got to be considered. If contrails were only reflective one way (from the surface looking up) we’d not be able to take photographs like this one from space:
NOTE: Any discussion of “chemtrails” in this comment thread will be immediately deleted. -Anthony
Be in awe of contemporary politicalized science! Observe how a little judiciously applied ignorance (i.e., ignoring the reflected radiation of the Sun) turns what was observed, modeled and measured on its head: namely, that more clouds cause a cooler climate.
And more: the authors Lisa Bock and Ulrike Burkhardt’s future research funding will be positively affected by the impact factor of 5,5 (of the magazine), they will therefore receive more state funding for their break-through research, and publish more articles like this.
Peer review? Gimme a break – it is their colleagues with equivalent interests who reviewed the article.
Contrails contribute to pretty sunsets:
Library.photoslibrary/resources/proxies/derivatives/4e/00/4e32/8Tc4PrFXSHOwKNmLX67NVg_thumb_4e32.jpg
[According to the article]”Another often discussed mitigation method is rerouting flights to avoid regions particularly sensitive to the effects of contrail formation.”
Airplane contrails only form when there are light winds at the plane’s altitude in an otherwise clear sky (usually near the center of an anticyclone), otherwise the water droplets from the plane’s exhaust are scattered by the wind before they can form clouds.
Re-routing flights away from zones of clear sky and light winds would force them into areas with strong winds. Planes sometimes ride the jet stream if it produces a tailwind over the planned route, but flight planners usually try to avoid strong headwinds or crosswinds which would increase airspeed and fuel consumption (and water and CO2 emissions) for the same ground speed.
Ask any pilot whether he would prefer flying through turbulence and/or storms, or straight across an area of clear skies and light winds, and the pilot will choose the clear area every time. It’s safer, and it saves time and fuel.
When I was a toddler growing up here in Perth, Western Australia, during the 1960s, I recall looking in awe at the jet contrails that would occasionally be visible in the sky. There weren’t many jets up there compared to nowadays.
Since the 1960s, I pretty well never see jet contrails. In fact, it’s been decades since I saw a contrail over Perth, no matter the month so I assume air temperature isn’t contributing. Whenever I’ve traveled to the east of Australia, same thing. However, when I’ve traveled to the northern hemisphere, and from what I constantly see on American and European television footage, the sky is frequently zig-zagged with contrails. A quick search of the web confirms that many other people have observed that contrails hardly ever happen in Australia but are abundant in the northern hemisphere.
Maybe jets fly at lower altitudes over Australia because of the lack of tall mountains. The reason for our lack of contrails has long puzzled me. Whatever, their absence suggests Australian temperature trends aren’t influenced by contrails – although they are influenced by some very dubious homogenising techniques typified by ACORN 2.
If I understand correctly this paper is saying that the greenhouse gas water vapor that is already present in the airplanes flight path, when changed to ice crystals, causes a radiative forcing increase. What is the calculated direct or immediate radiative forcing difference?
“There’s a new fear of flying: You’re more likely to die from exposure to toxic pollutants in plane exhaust than in a plane crash, a new study suggests.
In recent years, airplane crashes have killed about a thousand people annually, whereas plane emissions kill about ten thousand people each year, researchers say.”
https://news.nationalgeographic.com/news/2010/10/101005-planes-pollution-deaths-science-environment/
Contrail cirrus change global cloudiness, which creates an imbalance in the Earth’s radiation budget – called ‘radiative forcing’ – that results in warming of the planet.
No. The imbalance clouds cause is called ALBEDO.
It cools the planet.
This fraudulent idiocy is not even aimed at scientists.
It’s aimed over their heads at the uneducated and gullible general public.
So now, clouds cause warming even in summer?
Let’s hope for some blue skies so we can cool off from this heat-wave! (Sarc.)
Phil Salmon, Don’t forget that clouds can act like a blanket at night .
Anthony Watts / 5 days ago June 27, 2019
From the EUROPEAN GEOSCIENCES UNION
Jet contrails will likely affect climate by 2050.
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Since Jet contrails are produced by Earth’s inheritant fuels here’s no change to Earth’s energy budget.
So what changes every day is Weather.
Not climate.