Climate impact of clouds made from airplane contrails may triple by 2050
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.
Contrail cirrus radiative forcing for future air traffic (DOI: 10.5194/acp-19-8163-2019)
(Score: 4, Funny) by Alfred on Friday June 28 2019, @07:33PM
(Score: 1, Insightful) by Anonymous Coward on Friday June 28 2019, @07:34PM (2 children)
My theory is that kids have been huffing chemtrain dust in the woods as part of satanic rituals which is making them grow horns.
(Score: 1, Touché) by Anonymous Coward on Friday June 28 2019, @07:45PM (1 child)
Um, I don't think that's what they mean by "being horny".
(Score: 0) by Anonymous Coward on Friday June 28 2019, @09:52PM
https://www.washingtonpost.com/opinions/2019/06/21/kids-growing-horns-their-heads-dont-panic/?noredirect=on&utm_term=.3f105b198b3d [washingtonpost.com]
(Score: 4, Insightful) by Barenflimski on Friday June 28 2019, @08:17PM (8 children)
For years I've read that overall, contrails reduce the temperature by reflecting energy back into space.
The only study that I had seen here at Penn State [psu.edu], talks specifically about how daytime temperatures were depressed by 5-6 degrees Fahrenheit while the night-time temperatures were increased with these Cirrus clouds created by contrails. The study was done using data from the only 3 days there was no air traffic in the US, after the 9/11/2001 attacks.
I do not see on this study where they came up with the data that shows the contrails themselves (not including CO2) increase warming of the planet, though I would love to know. For now I'll be forced to believe that depending on the research team, both must be right.
(Score: 2) by Entropy on Friday June 28 2019, @08:49PM (1 child)
Doesn't fit the global warming(tm) FUD. You're clearly a racist/terrorist/child diddler.
(Score: 1, Funny) by Anonymous Coward on Friday June 28 2019, @08:52PM
And your brain has reached max entropy while still being considered "alive."
(Score: 2) by Snow on Friday June 28 2019, @08:55PM
I was under that same understanding...
(Score: 4, Interesting) by AthanasiusKircher on Friday June 28 2019, @11:27PM (1 child)
Just a clarification: that link says that the daily SWING of temperatures was reduced by 5-6 degrees F, not the daily high temp. Presumably the highs were lowered by 2-3 degrees and the loss were raised by 2-3 degrees. Not a very big effect, but still interesting.
I would imagine the overall long-term heating effect comes from the fact that water vapor is one of the most substantial greenhouse gases in the atmosphere. Increasing the quantity of it will hold heat in and prevent thermal radiation to space. Yes, it also can help reflect heat a bit in clouds, but once the heat gets in, water vapor will keep it bouncing back down to the ground, so anything that adds significant quantities of water vapor to the atmosphere will contribute to greenhouse effects.
(Score: 3, Interesting) by bradley13 on Saturday June 29 2019, @05:35AM
As I understand it, it isn't so much the visible contrails, but rather the water vapor released by burning fuel is acting as a greenhouse gas, and producing the warming. Water vapor is a potent greenhouse gas.
The thing is, as with so many of these models, they don't seem to consider negative feedback. If the atmosphere were subject to runaway effects based on either CO2 or water, it would have already run away. If you release more water into the atmosphere, all that's going to happen (in anything beyond the short term) is that it will condense and rain out.
The entire AGW argument is based on positive feedback: CO2 (which is a very minor greenhouse gas) raises the atmospheric temperature, which therefore allows more water vapor to remain in the atmosphere, which raises the temperature, which allows more water vapor... That isn't how things work. Failure to account for negative feedback is the reason why all of the long-term climate models keep missing their predictions [duckduckgo.com].
Which is not to say that dumping piles of CO2 into the atmosphere is a good idea. We only have the one atmosphere, and carrying out uncontrolled experiments on it is not a great idea. But the continuous alarmism (of which TFA is just the latest example) is tiresome, and imho gets in the way of doing actual, good science.
Everyone is somebody else's weirdo.
(Score: 2) by edIII on Saturday June 29 2019, @01:57AM (1 child)
This just doesn't make sense though at scale. I'm not seeing criss-crossing contrails covering the sky during the day. Size wise isn't this like a super thin hair being stretched out over a lake?
Meaning, a very tiny percentage of the sky (.01%) surely is what they're talking about right? That much difference in cloud cover can register on the scales of climate change? Compared to a cow "fart" how bad is it?
There must be a lot more contrails then I think, or the effect is exaggerated.
Technically, lunchtime is at any moment. It's just a wave function.
(Score: 1) by Sabriel on Saturday June 29 2019, @06:01AM
"In the right conditions, airplane contrails can linger in the sky as contrail cirrus—ice clouds"
Atmospheric water vapour can more easily condense in the presence of a catalyst (such as existing water droplets, ice crystals or dust, all of which are much more common at low altitudes). Clouds form when this effect is propagated across an area.
Aircraft contrails can sometimes trigger this cascade effect. Thus the name "contrail cirrus" - cirrus (high-altitude) clouds created by contrails.
So it's not the contrails themselves that directly impact climate, it's the resulting clouds that can form around them (which would otherwise not have happened).
(Score: 1, Informative) by Anonymous Coward on Saturday June 29 2019, @04:28AM
Their projections show a difference of ~ 50 mW/m2 due to contrails. Since insolation is >1.3 kW/m2, the change, taking their most extreme view, is 0.004%. Applying that to a global average of near enough to 300K leads to a temperature change of 0.011 degrees.
They say that the effect will triple by 2050. Three times nothing is still nothing.
(Score: 0) by Anonymous Coward on Saturday June 29 2019, @02:06AM (2 children)
When there are no contrails, sunlight makes it all the way down and heats the surface instead of the atmosphere.
When contrails are in the sky, although they absorb the sun's heat, they also shade the ground slightly and prevent the surface from heating up a little.
So either the ground warms up, or the atmosphere warms up.
I think the net temperature effect contrails have on the planet be close to zero.
(Score: 0) by Anonymous Coward on Saturday June 29 2019, @03:24AM
Why do you hate Al Gore?
(Score: 0) by Anonymous Coward on Saturday June 29 2019, @04:03AM
(Score: 1) by ChrisMaple on Saturday June 29 2019, @04:20AM
Three times zero is zero.
(Score: 2) by Bot on Sunday June 30 2019, @12:35AM
> contrail cirrus—ice clouds
fairly sure it's not ice.
Have you ever noticed some iridescent reflections after the trails have expanded into that milky cloud? it happens, not often, but only with chemtrails. never with clouds. In fact the iridescent reflections from the clouds, the rainbow, is completely different, larger and on the other side wrt the sun.
Now you could argue that the clouds are made of water, while these 'ice clouds' are made of ice. Sure, but the refraction index of ice is almost like water's, so I reject the objection.
Needless to say, I never noticed this phenomenon in the 70s and 80s, even if living 20 miles from an airport.
Account abandoned.