American Airlines demonstrated contrail-reducing technology | Hacker News Reader

American Airlines demonstrated contrail-reducing technology

qz.com

30 pointsdonohoe44 comments

"not putting carbon into the atmosphere" != "removing carbon from the atmosphere"

Comparing the "cost" of not putting carbon into the atmosphere with the cost of taking it out is incredibly misleading and irresponsible and it leads to the kind of logic of "I was totally about to burn this entire forest down but instead I decided not to, look at how much emissions I've saved!".

Putting that trap aside, according to a calculator I found via Google[1], if this were made mandatory for all passengers then it seems like it would increase the one-way cost of JFK -> LHR by about $10 which seems pretty reasonable. I imagine short-haul flights might become more expensive, but that might encourage more people to consider other means of transport.

[1]: https://co2.myclimate.org/en/portfolios?calculation_id=65175...

This article is not about carbon at all so I'm not sure why you are bringing that up.

From the article:

> Marc Shapiro, the head of contrails at Breakthrough Energy, calls reducing contrails the “highest-leverage climate opportunity that we know of,” the equivalent of removing carbon from the atmosphere at a cost of 10 dollars per ton or less. ...

> It’s not yet clear how this service will be deployed commercially. Google and Breakthrough view it as research underlying their commitments to reducing carbon footprints.

With effective governance and regulation this kind of measure could be part of addressing climate change in a more cost effective way. In the absence of that bad ideas and even good ideas can fail.

> "not putting carbon into the atmosphere" != "removing carbon from the atmosphere"

That’s not what they claim. Their claim is that the effect on global warming of creating X fewer contrails equals that of putting Y amount of CO2 less into the atmosphere (our main concern isn’t having so much CO2 in the atmosphere, it’s its effect on temperatures)

Unfortunately they also produce Z amount of extra CO2 and don’t know yet whether the effects of X compensate for Y and Z combined.

I may be wrong, but I think user 22c may be trying to point out that we put an amount, W, of CO2 into the air by making the collective decision to fly so many planes in the first place.

More specifically I was talking about equating contrail reduction with removing carbon from the atmosphere, which the article does when it says

> Marc Shapiro, the head of contrails at Breakthrough Energy, calls reducing contrails [...] the equivalent of removing carbon from the atmosphere at a cost of 10 dollars per ton or less

Contrail reduction and carbon sequestration aren't the same thing and it's not fair to equate them on cost.

Its not about carbon. Its about removing contrails (made of water vapor) that warm the atmosphere. Removing the contrails would have a cooling effect that is "equivalent" to removing carbon.

After the events of 9/11, the skies were empty for a few days

> During the three-day commercial flight hiatus, when the artificial clouds known as contrails all but disappeared, the variations in high and low temperatures increased by 1.1 degrees Celsius (2 degrees Fahrenheit) each day, said meteorological researchers.

https://globalnews.ca/news/2934513/empty-skies-after-911-set...

https://edition.cnn.com/2002/TECH/science/08/07/contrails.cl...

https://acp.copernicus.org/articles/21/9405/2021/#Ch1.S3.SS3

Similar research during COVID flight reductions.

I really have to wonder where this outweighs the effects of the extra CO2 added to the atmosphere (article says it increases fuel usage by 2%, but that's likely to be an ideal case) in the long term.

CO2's problems aren't merely global warming. More CO2 also affects our brains and makes us tired, contributes to ocean acidification, and countless other things. This alone might not be enough to completely destroy the world, but as with anything, one industry finds a way to greenwash and then you have a snowballing effect of every company rushing to implement those same ideas and causing more harm than good. Producing more CO2 to prevent a tiny bit of sunlight/heat retention could be one of those things.

Are there studies showing a causal link between global atmospheric CO2 and feelings of tiredness?

https://www.hsph.harvard.edu/healthybuildings/2021/09/09/imp...

CO2 affects cognition all around.

We also found effects of CO2 (a proxy for ventilation) on cognitive function. For every 500ppm increase, we saw response times 1.4-1.8% slower, and 2.1-2.4% lower throughput.

Which is why you open a window: Atmospheric CO2 is at around 410ppm. And rising, yes, by around 2-3ppm/a. So I suppose it's making us around 0.02% slower per year, going by those figures.

We need to curtail emissions, but not because atmospheric CO2 is affecting cognition.

So, assuming a straight line backwards, we have gotten 1% slower since 1970?

Doesn't sound great.

Edit: to prove my slowness I typo'd a zero into the number. It's 1%, not 10%.

It's not a straight line, no. In 1970 it was around 320ppm, so not quite 100ppm less than today as opposed to 100-150ppm. So 0.3% slower, again if you take those performance numbers at face value which you probably should both, because they are the result of experiments that take place at levels of 1000ppm and beyond and it's unclear if they even apply to lower levels.

https://www.statista.com/statistics/1091926/atmospheric-conc...

Today’s 422ppm (https://www.co2.earth/daily-co2) assumes you’re outside in a remote area with a light breeze to constantly get fresh air. Even just a city has higher levels and normal office space is sitting at 800ppm or so. A meeting room can break 1500ppm depending on occupants and ventilation, which is one of the reasons meetings suck and packed meetings suck more.

Thus a meeting where the PPM was ~1200ppm in 1970 with the same number of people in the same room in 2023 should be ~1300ppm.

Yeah, we're talking atmospheric CO2, hence: outside. I'm aware that indoor CO2 is higher, I've quoted the study.

I was pointing out that outdoor CO2 ppm vary significantly, and we are at ~420ppm not 410ppm which was quoted earlier.

Also, outdoor ppm increases indoor ppm which is within the range being studied so talking about cognitive decline from ongoing carbon emissions is supported.

Counterpoint: https://onlinelibrary.wiley.com/doi/pdf/10.1111/ina.12939

> Impairment of cognitive performance is not expected from exposure to 20 000 ppm CO2, neither as direct effect on central nervous system function nor as a distraction related to perception of health effects.

The study you’re linking is discussing the combined effects of CO2 and PM2.5; likely it’s the particulate matter that’s the issue rather than the CO2.

CO2 is generally used as a proxy for IAQ as in the link you posted. I strongly suspect it's another factor than just CO2, for example reduced O2 levels, or VOCs and particulates. I'm sceptical that usual levels of CO2 have a noticeable impact on metabolism.

> in the long term

In the long term added CO2 outweighs. In the long term added water vapor has no effect, yet any carbon fuel extracted from the ground has a forever effect. The carbon in that fuel is never going back into the ground.

The forest burns and releases carbon, a few years later the forest regrows and reabsorbs the carbon. A drop of oil is brought out of the ground, a million years later that drop of oil goes back into the ground.

> These clouds trap heat in the Earth’s atmosphere

Wait, that's the problem with them? Naïvely I would think on an average day they are absolutely dwarfed by actual (by which I suppose I mean natural) clouds? Even without but especially accounting for longevity, the contrail evaporating vs. the cloud sitting there all day.

What am I missing, or how big of a contributor actually is it? Or is it just 'well we're a bit stuck on jet fuel, what else can we do' even if the impact is minimal?

TFA calls it 'low-hanging fruit' and 'the equivalent of removing carbon from the atmosphere at a cost of 10 dollars per ton or less' - fair enough, but I suppose I'm thinking how sweet is the fruit; equivalent of removing how much carbon at that cost? (It also says aviation accounts for 3.5% of warming, but not how much of that is contrails.)

To be a bit pithy/facetious about it: I can go and turn off some light bulbs right now, 'the equivalent of removing carbon from the atmosphere at a cost of nothing per tonne'. But I can't do very much of it!

I remember some research that found the initial contrails were not in themselves significant but that they could seed cloud formation which was.

https://www.weather.gov/fgz/CloudsContrails

There was a significant impact on the weather in the week following 9/11. This was documented and studied by NASA. In some areas we saw this again during Covid lockdowns.

This is also a topic I mention here from time to time, knowing it will get down voted into oblivion. Even HN suffers from group think on certain things.

You can't just focus on CO2 when water is a far more powerful greenhouse gas, and we've seen contrails have large short term effects on the weather.

I think the problem might be that in the wrong hands the issue is used to muddy rather than enhance the discussion. Generally the problem with focusing on water as "a greenhouse gas" is that there is limited scope for doing anything about it. Indeed, it's likely part of various feedback systems so acts as a confounder rather than an independent variable.

Of course we should consider the impact of dumping lots of high altitude water into the atmosphere, but we should primarily consider the impact of dumping lots of co2 and methane since those are a much bigger slice of the anthropogenic delta.

>> but we should primarily consider the impact of dumping lots of co2 and methane since those are a much bigger slice of the anthropogenic delta.

Honestly, I doubt it. I've seen the effects of stopping air travel with my own eyes. What if it really is the dominant driver, and all the CO2 fighting is for nothing? What if? And the reason we can't do anything about the water vapor is.... the economy and convenience. What if that's the case?

The article says this:

> Last year, the Intergovernmental Panel on Climate Change (IPCC) estimated that contrails represent about 35% of the aviation industry’s contribution to global warming.

Is it gonna be like with ships? When they lowered emissions but it only made things worse xD

That strategy seems to be useful only for flights in the afternoon/evening (depending on how long the contrails persist) and night to avoid trapping radiation back to space. But during the day contrails should reflect back to the sun. Optimize routing to create them (only early during the day, so they disappear before it gets dark).

It's hard to find hard statements on this, but it appears to me that even during the day, the net effect of contrails is warming rather than cooling.

E.g. https://phys.org/news/2022-12-airlines-contrails-environment...

A small percentage of flights are happening at night, but those are creating the most contrails," Chen said. "And that's the worst time for it to happen."

Even contrails during the day are bad, though clouds may be acting to block some sunlight from reaching the surface, Chen said.

How can $10 per ton of carbon abatement, be the biggest leverage when there's things that save or make money?

> when there's things that save or make money

What examples are there of carbon removal/abatement that are net profitable, and aren't already fully saturated?

insulation for houses and heat pumps instead of burning gas or space heaters, public transport, other YIMBY efforts (denser and cheaper cities, less commute, more people can move to where they want), green steel efforts, SMR nuclear.

basically anything where a big commitment (eg. ordering hundreds of billions of the greenish version) can move the needle permanently, the downstream effects are enormous

"head of contrails". What a job title

I bet that one has the conspiracy nuts going.

Well, we went from gosh what conspiracy theory idea you have about contrails that totally do not exist to every airline should do this because the scientist that works for Bill Gates at Breakthrough Energy says is the highest-leverage climate opportunity that we know of so not only these were happening but we're pushing to do a lot more, really really fast.

Uuuh you're sorta failing to mention that the common conspiracy theories are that they contain population controlling chemicals. Seems less like a really fast change and more like completely unrelated things

Where's your tin-foil hat[1]?

Obviously the Communists figured out how to use the CIA mind control chemicals in contrails against us. So, they've got to be stopped, either the Communists or the contrails, but it's easier to stop the contrails. Environmental benefits is just a cover story. PS, that extra fuel they say they'll need has the next gen mind control chemicals, that the Communists can't use, but these will be invisible.

[1] You do have one made of actual tin-foil don't you? Aluminum foil hats don't actually work for anything other than fashion. Have you tried to get rolled tin lately --- there's a reason it's hard to find.

https://www.stopabductions.com/

Reminds me of the story of the commercial pilot who had a new flight attendant (doing her first flight) come over to the flight deck and started explaining the airplane controls to her to make conversation. Except the pilot had previously put a label saying "chemtrails" on a random switch and then told her that they activate that switch when they receive a signal from the government.

> The key is avoiding humid “ice supersaturated regions” of the atmosphere where long-lasting contrails can form.

I hope they can still occasionally do a few daytime contrails over land - it's like they're scratching the sky, it's nice to see.

Official site: https://sites.research.google/contrails/

Great. By increasing CO2 emissions and using a lot of compute they reduce global warming (maybe)

""world's cheapest way to fight global warming""

That is fan boy headline if I ever saw one.

The cheapest way to fight global warming resulting from air travel is .. dont fly.

Only a fraction of airline travel is absolutely vitally necessary.

We want walkable cities that dont require a car. We should create solutions so flying is no longer necessary.

Like recycling, walking or riding a bike, improving housing to use less energy, eating less meat, and all the other common and cheap ways to reduce emissions. We need a culture change where travelling to faraway place for fun (vacation) is no longer desired.

Remote work, and families living closer together would do a lot.

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