Airplane contrails are a tricky, and surprising, contributor to global warming

[Admin]

Commercial airplanes have made strides in reducing carbon emissions, but it turns out the exhaust clouds trailing behind them can have long-term impacts on the environment.

Airplane contrails are a tricky, and surprising, contributor to global warming : Read more

 

[COLGeek]

Not surprising at all. Post 9/11, when aircraft were grounded/severely limited, there were noticeable/measurable changes tracked then.

 

[Unclear Engineer]

It would have been nice if the article had described how contrails increase temperatures on the surface.

There seem to be a lot of competing effects, but clouds have generally been described as causing cooling on the surface by reflecting incoming solar radiation (sunlight) back into space without changing its wavelengths. Of course, they can also capture heat radiated from the earth's surface towards space and reradiate it back to the surface. We generally think of cloudy days as cooler than average and cloudy nights as warmer than average for those reasons.

Also, particulates in the stratosphere have been proposed to decrease global warming, but usually something like sulfuric acid, not carbon particles.

And, CO2 in the upper atmosphere has been modeled to decrease upper atmospheric temperatures, mostly due to CO2 migration there from the air below, not from jet contrails.

So, this article does not really do anything to explain how the net effect of contrails warms the planet's surface air. But, it needs to provide some explanation to attain credibility. With all of the doom-and-gloom biases in science reporting in the media these days, it needs to seem to make scientific sense to the lay person to have any effect on thinking in the general population.

And, including a "global warming" video that does not even mention the phenomena discussed in the article just makes it seem more likely to be propaganda than new scientific discovery.

If you want credibility, don't preach - do explain.

 

[Classical Motion]

“As a result, these thin cloud streaks have a greater impact on global warming than that of carbon emissions from combustion of jet fuel, according to the study.”

That’s quite a statement. How low do we need to fly so that only the combustion carbon emitted goes to global warming?

What’s the combustion/contrail ratio at 20,000 ft? Where’s the least of both?

Pilots will need faster response times for in flight control problems. Less drop time.

 

[John Topham]

It would have been nice if the article had described how contrails increase temperatures on the surface.

There seem to be a lot of competing effects, but clouds have generally been described as causing cooling on the surface by reflecting incoming solar radiation (sunlight) back into space without changing its wavelengths. Of course, they can also capture heat radiated from the earth's surface towards space and reradiate it back to the surface. We generally think of cloudy days as cooler than average and cloudy nights as warmer than average for those reasons.

Also, particulates in the stratosphere have been proposed to decrease global warming, but usually something like sulfuric acid, not carbon particles.

And, CO2 in the upper atmosphere has been modeled to decrease upper atmospheric temperatures, mostly due to CO2 migration there from the air below, not from jet contrails.

So, this article does not really do anything to explain how the net effect of contrails warms the planet's surface air. But, it needs to provide some explanation to attain credibility. With all of the doom-and-gloom biases in science reporting in the media these days, it needs to seem to make scientific sense to the lay person to have any effect on thinking in the general population.

And, including a "global warming" video that does not even mention the phenomena discussed in the article just makes it seem more likely to be propaganda than new scientific discovery.

If you want credibility, don't preach - do explain.

The heating effects occur mostly at night when there is no sunlight to reflect.

 

[Unclear Engineer]

I understand the individual effects, as already stated in my previous post.

The question remains why the net effect is heating, rather than cooling.

And, for that matter, what is the uncertainty in the calculations of the individual effects that are somewhat canceling each other? What level of certainty does that leave that the net effect is heating rather than cooling?

To explain my last question, if one parameter is 5 +/- 1 and another parameter that is subtracted from it is 4 +/- 1 the result looks like 1, but it could also be anything from 6 - 3 = 3 to 4 -5 = -1, with various probabilities for the numbers between. So, the question becomes what is the probability that the difference is greater than 0? How does that come out for the atmospheric temperature change calculation for contrails? (Also note that uncertainty calculations for model results are notoriously underestimated by nearly all modelers.)

 

[John Topham]

I understand the individual effects, as already stated in my previous post.

The question remains why the net effect is heating, rather than cooling.

And, for that matter, what is the uncertainty in the calculations of the individual effects that are somewhat canceling each other? What level of certainty does that leave that the net effect is heating rather than cooling?

To explain my last question, if one parameter is 5 +/- 1 and another parameter that is subtracted from it is 4 +/- 1 the result looks like 1, but it could also be anything from 6 - 3 = 3 to 4 -5 = -1, with various probabilities for the numbers between. So, the question becomes what is the probability that the difference is greater than 0? How does that come out for the atmospheric temperature change calculation for contrails? (Also note that uncertainty calculations for model results are notoriously underestimated by nearly all modelers.)

This was my source. I am assuming that their reasoning and references are accurate. I don't have the time to follow all the links to be sure.

How Airplane Contrails Are Helping Make the Planet Warmer​

By Fred Pearce • July 18, 2019

 

[Unclear Engineer]

Thanks for the title. I searched and found the link: https://e360.yale.edu/features/how-airplane-contrails-are-helping-make-the-planet-warmer .

The article is clear that it states that the heat trapping effect over-night exceeds the heat reflecting effect during the day. But, it doesn't provide anything about how certain that conclusion is, mathematically.

It does say "There are certainly uncertainties in the measurement of the climate impact of contrails," but does not say anything more about uncertainty. It quotes a government bureaucrat as saying "William Raillant-Clark, said it could only change tack 'on the basis of a technical/scientific consensus, which currently does not exist. There are no commonly accepted numbers' for the climate impact of contrails." It then criticizes that statement with "“Uncertainty is being used as an excuse to remain inactive,” by the International Civil Aviation Organization, a United Nations agency that has been coordinating the industry’s response to the climate emergency,

Trying to click on links in the article gave me "This site can't be reached" errors, so basically dead ends unless I search for each title to see if there is still something on the Web. Some links are not even titles, such as "retrospective studies", which links to https://www.aviationsystemsdivision.arc.nasa.gov/publications/2010/Sridhar_DASC2010_final.pdf , which is no longer available.

So, as reported, I can only file this as an opinion by a writer who is not even a researcher: "Fred Pearce is a freelance author and journalist based in the U.K. He is a contributing writer for Yale Environment 360 and is the author of numerous books, including The Land Grabbers, Earth Then and Now: Amazing Images of Our Changing World, and The Climate Files: The Battle for the Truth About Global Warming."

Maybe not an unbiased source?

As we often discuss at a professional level on another forum, government policy development does need to consider the uncertainties in the parameters that it is considering affecting. Those uncertainties are often so large that it is not clear whether any policy option has net positive or net negative effects. And, to make matters even more complicated, sometimes the benefits accrue to a different sub-population than the disbenefits harm, so there is an equity issue on top of the uncertainty issues.

This article does discuss 3 options for reducing the warming effects of contrails, but also discusses how they might not be net-beneficial. So, it seems somewhat hypocritical to criticize the government for not taking action to solve this problem - if it really is one.

 

[John Topham]

Thanks for the title. I searched and found the link: https://e360.yale.edu/features/how-airplane-contrails-are-helping-make-the-planet-warmer .

The article is clear that it states that the heat trapping effect over-night exceeds the heat reflecting effect during the day. But, it doesn't provide anything about how certain that conclusion is, mathematically.

It does say "There are certainly uncertainties in the measurement of the climate impact of contrails," but does not say anything more about uncertainty. It quotes a government bureaucrat as saying "William Raillant-Clark, said it could only change tack 'on the basis of a technical/scientific consensus, which currently does not exist. There are no commonly accepted numbers' for the climate impact of contrails." It then criticizes that statement with "“Uncertainty is being used as an excuse to remain inactive,” by the International Civil Aviation Organization, a United Nations agency that has been coordinating the industry’s response to the climate emergency,

Trying to click on links in the article gave me "This site can't be reached" errors, so basically dead ends unless I search for each title to see if there is still something on the Web. Some links are not even titles, such as "retrospective studies", which links to https://www.aviationsystemsdivision.arc.nasa.gov/publications/2010/Sridhar_DASC2010_final.pdf , which is no longer available.

So, as reported, I can only file this as an opinion by a writer who is not even a researcher: "Fred Pearce is a freelance author and journalist based in the U.K. He is a contributing writer for Yale Environment 360 and is the author of numerous books, including The Land Grabbers, Earth Then and Now: Amazing Images of Our Changing World, and The Climate Files: The Battle for the Truth About Global Warming."

Maybe not an unbiased source?

As we often discuss at a professional level on another forum, government policy development does need to consider the uncertainties in the parameters that it is considering affecting. Those uncertainties are often so large that it is not clear whether any policy option has net positive or net negative effects. And, to make matters even more complicated, sometimes the benefits accrue to a different sub-population than the disbenefits harm, so there is an equity issue on top of the uncertainty issues.

This article does discuss 3 options for reducing the warming effects of contrails, but also discusses how they might not be net-beneficial. So, it seems somewhat hypocritical to criticize the government for not taking action to solve this problem - if it really is one.

 

[John Topham]

After I wrote my reply I found this: https://www.sciencedirect.com/science/article/pii/S1352231020305689?via=ihub

 

[Unclear Engineer]

Thanks for that link, too. I will need to get some time to look through it.

2 things jumped out of the abstract for me:

1. "The best estimates of the ERFs from aviation aerosol-cloud interactions for soot and sulfate remain undetermined."

and

2. "The formation and emission of sulfate aerosol yields a negative (cooling) term."

I note that #2 was not discussed in the subject article on this Space.com forum.

Which gets me to wondering if the aviation industry will think of adding sulfur to their aviation fuel to try for net zero warming effects. I'm not a fan of adding a lot of sulfur dioxide to the upper atmosphere, because it will eventually get to the lower atmosphere and the hydrosphere, adding to the acidification of our waters.

 

[John Topham]

Thanks for that link, too. I will need to get some time to look through it.

2 things jumped out of the abstract for me:

1. "The best estimates of the ERFs from aviation aerosol-cloud interactions for soot and sulfate remain undetermined."

and

2. "The formation and emission of sulfate aerosol yields a negative (cooling) term."

I note that #2 was not discussed in the subject article on this Space.com forum.

Which gets me to wondering if the aviation industry will think of adding sulfur to their aviation fuel to try for net zero warming effects. I'm not a fan of adding a lot of sulfur dioxide to the upper atmosphere, because it will eventually get to the lower atmosphere and the hydrosphere, adding to the acidification of our waters.

The idea of using aerosols for geoengineering comes to the media's attention every few years. I can see two problems with this. The first is getting international agreement. Some countries might think that results would cause harm to their country. The second is that the effects are temporary. To maintain the effect, you have to keep adding more aerosols.

As far as I can tell, the biggest problem with aviation is that it is too convenient. If you look at fuel used per passenger kilometre, there is some overlap with cars and trucks, but when people fly they go further and contribute more to global warming. Electric aviation, e-fuels and bio-fuels are coming but they are still a decade (?) away.

 

[Unclear Engineer]

I am going to disagree on flying being "too convenient", considering how inconvenient it has become for me. I take a train up the U.S. east coast (electric most of the way) rather than drive or fly. But, to get from the east coast to the west coast, airplanes are the only option unless you really plan to take the trip itself for enjoyment.

Also need to consider that trains need infrastructure, which also releases CO2 (and other stuff) to produce and maintain. And highways require a lot of concrete. Concrete production makes a lot of CO2, at least the way we do it now. There has been some effort to make it differently to avoid some of that. See https://www.scientificamerican.com/article/solving-cements-massive-carbon-problem/ .

It would be a major effort to calculate the total emissions for a variety of future transportation policy options when you include everything, not just the fuel used.

And, it gets into other social issues, such as "work-from-home", so disbenefits to productivity, quality, innovation, etc. become points of contention, too.

It would be nice if people could live near where they work, and do meetings at larger distances mostly on the Internet. But, with housing costs and mortgage costs in their current states, people are loath to move their residences, even if they have to change jobs and commute longer distances. I have even seen reassignments to distant locations used to effectively "fire" employees that could not be overtly fired.

Real life is terribly complicated these days.

 

[Helio]

Though water vapor is a major greenhouse gas, I wonder hydrogen would be an effective alternative as an aviation fuel for these higher altitude jets?

 

[Unclear Engineer]

It would probably need to be liquid hydrogen for long-distance flights, and that is a problem. Remember the early Centaur explosions? It is a whole different level of fueling care needed to put that ultra cold, ultra leaky stuff into a flight vehicle, compared to kerosene jet fuel. And, it needs to "boil off" during delays. Plus, hydrogen burns with a clear flame where it leaks and finds an ignition source. I have seen hydrogen fires with IR technology that just don't seem to be there to the naked eye. So, hydrogen in an airport scares me.

 

[John Topham]

I am going to disagree on flying being "too convenient", considering how inconvenient it has become for me. I take a train up the U.S. east coast (electric most of the way) rather than drive or fly. But, to get from the east coast to the west coast, airplanes are the only option unless you really plan to take the trip itself for enjoyment.

Also need to consider that trains need infrastructure, which also releases CO2 (and other stuff) to produce and maintain. And highways require a lot of concrete. Concrete production makes a lot of CO2, at least the way we do it now. There has been some effort to make it differently to avoid some of that. See https://www.scientificamerican.com/article/solving-cements-massive-carbon-problem/ .

It would be a major effort to calculate the total emissions for a variety of future transportation policy options when you include everything, not just the fuel used.

And, it gets into other social issues, such as "work-from-home", so disbenefits to productivity, quality, innovation, etc. become points of contention, too.

It would be nice if people could live near where they work, and do meetings at larger distances mostly on the Internet. But, with housing costs and mortgage costs in their current states, people are loath to move their residences, even if they have to change jobs and commute longer distances. I have even seen reassignments to distant locations used to effectively "fire" employees that could not be overtly fired.

Real life is terribly complicated these days.

In a way you made my point when you said "to get from the east coast to the west coast, airplanes are the only option unless you really plan to take the trip itself for enjoyment". If flying wasn't an option then people probably travel to some place closer. You might argue that people need to travel for family visits or business but again people choose their place of residence differently.

I want to revise my previous statement that the "biggest" problem with aviation is that it is too convenient. After digesting information on contrails, I'm now of the opinion that contrails are an equal problem to convenience. If I understand the science correctly, then the effect of all the CO2 in the atmosphere that is currently attributable to aviation (100 years of emissions) is less than 1/2 of the effect of the contrails that currently exist. It's confusing because if we stopped flying today, then effect of the contrails would disappear within 24 hours, but the effect of CO2 would continue for decades. If we switch to e-fuels or bio-fuels then we solve the CO2 problem but the contrail problem would still exist. Electric aviation holds promise but it will be limited to short haul flights.

 

[Unclear Engineer]

The effects of contrails really don't "go away within a few hours" if you consider the heat that has been deposited on the surface and in the oceans. If there has been years of heat build-up from contrails, then that will take a long time to radiate back to space from anything that is not very close to the surface. So, whatever heat has already mixed into the deep ocean will take many years to go back into space. And, it will heat the land and air on the way out. If there really is a net heat input, then it is cumulative. Stopping the instantaneous effect does not immediately erase the cumulative effect.

But, if we are talking about atmospheric weather effects, stopping the contrails effect would be quickly felt in air temperature, humidity, etc. Not in sea level, though.

 

[John Topham]

The effects of contrails really don't "go away within a few hours" if you consider the heat that has been deposited on the surface and in the oceans. If there has been years of heat build-up from contrails, then that will take a long time to radiate back to space from anything that is not very close to the surface. So, whatever heat has already mixed into the deep ocean will take many years to go back into space. And, it will heat the land and air on the way out. If there really is a net heat input, then it is cumulative. Stopping the instantaneous effect does not immediately erase the cumulative effect.

But, if we are talking about atmospheric weather effects, stopping the contrails effect would be quickly felt in air temperature, humidity, etc. Not in sea level, though.

I was referring to the heating effects but thanks for the other part. I've been wondering about cumulative heat (or whatever the scientific term is). When the planet heats up, it will radiate more heat back out into space but I'm sure that it's more complex then just the temperature difference. If you have any links on this topic then I'd like to read them.

The topic is of interest to me because of the link below. On Sunday, I encountered two very different opinions about it. One of big factors has to do with the SO2 in dirty fossil fuels. The SO2 has been reflecting heat back into space. Some people think the contribution to our current average global temperature from fossil fuels is smaller than other sources because this effect. As we clean-up fossil fuels, we are also potentially removing some this reflectivity and speeding up climate change.

Radware Bot Manager Captcha

 

[John Topham]

I was referring to the heating effects but thanks for the other part. I've been wondering about cumulative heat (or whatever the scientific term is). When the planet heats up, it will radiate more heat back out into space but I'm sure that it's more complex then just the temperature difference. If you have any links on this topic then I'd like to read them.

The topic is of interest to me because of the link below. On Sunday, I encountered two very different opinions about it. One of big factors has to do with the SO2 in dirty fossil fuels. The SO2 has been reflecting heat back into space. Some people think the contribution to our current average global temperature from fossil fuels is smaller than other sources because this effect. As we clean-up fossil fuels, we are also potentially removing some this reflectivity and speeding up climate change.

Radware Bot Manager Captcha

The effects of contrails really don't "go away within a few hours" if you consider the heat that has been deposited on the surface and in the oceans. If there has been years of heat build-up from contrails, then that will take a long time to radiate back to space from anything that is not very close to the surface. So, whatever heat has already mixed into the deep ocean will take many years to go back into space. And, it will heat the land and air on the way out. If there really is a net heat input, then it is cumulative. Stopping the instantaneous effect does not immediately erase the cumulative effect.

But, if we are talking about atmospheric weather effects, stopping the contrails effect would be quickly felt in air temperature, humidity, etc. Not in sea level, though.

I don't know if you saw my previous reply. It had a completely unrelated link. The reply has since been edited with the correct link.

 

[Unclear Engineer]

Not so sure I want to click on a link that says "Radware Bot Manager Captcha"

 

[John Topham]

Not so sure I want to click on a link that says "Radware Bot Manager Captcha"

 

[John Topham]

Try searching for this instead:
Increased transparency in accounting conventions
could benefit climate policy

 

[Classical Motion]

Today's future belongs to those who can generate the most power. There is a run coming on electrical generation, and it won't be green.