[crazygringo]

I'm so confused. This article is explaining that eliminating contrails would have a significant effect on warming.

But contrails are just the tiniest, tiniest fraction of the sky somewhere and only last over a given area for a few minutes generally. Like, sure, if you live next to a busy airport maybe you see them more often, but that's balanced out by the 99.9% of sky not next to a busy airport. Plus the many days that they just don't show up at all, because they depend on certain weather conditions.

I mean, this just doesn't pass the smell test.

But Wikipedia has an entire section [1] full of citations. But then... it sounds like maybe a lot of them aren't credible or suggest that it's not a problem? E.g.:

> However, follow-up studies found that a natural change in cloud cover can more than explain these findings. The authors of a 2008 study wrote, "The variations in high cloud cover, including contrails and contrail-induced cirrus clouds, contribute weakly to the changes in the diurnal temperature range, which is governed primarily by lower altitude clouds, winds, and humidity."

> Then, the global response to the 2020 coronavirus pandemic led to a reduction in global air traffic of nearly 70% relative to 2019. Thus, it provided an extended opportunity to study the impact of contrails on regional and global temperature. Multiple studies found "no significant response of diurnal surface air temperature range" as the result of contrail changes, and either "no net significant global ERF" (effective radiative forcing) or a very small warming effect.

So it sounds like this theoretical contrail warming problem possibly doesn't exist? I find it strange the article doesn't even acknowledge any discussion over whether it's actually a problem in the first place.

[1] https://en.wikipedia.org/wiki/Contrail#Impacts_on_climate

[dingaling]

> But contrails are just the tiniest > tiniest fraction of the sky somewhere

Initially yes, but as a contrail diffuses it acts like a seed for wider cirrus cloud formation.

During COVID lockdown, researchers at Universität Leipzig found that the reduction of air travel correspondingly reduced cirrus formation by 9% in the area studied.

[Theodores]

Check out satellite images and look at the clouds closely. Or, better still, try and predict rain just from the images. Chances are that you will be predicting a lot more rain or 'overcast days' than what you will get.

I am based in the UK and there are clear flight paths, for example, the big airport is west of London (Heathrow) and a lot of planes fly west to the 'New World'. A typical route will be over the Bristol Channel, which is over water rather than land. If you look at the satellite imagery in the different wavelengths then you will see the whole Bristol Channel 'clouded' with what can only be contrails.

If you are old enough then you might be able to remember 9/11 and the skies in the aftermath, when no planes were flying for quite a few days. The pandemic gave us a glimpse of this too, however, we were shutting down a lot else then.

To summarise, we are pissing in the pool big time with this aviation lark. I appreciate that you can't see it, but I don't think anyone that is heavily car dependent actually will. It is a 'wood for the trees' thing, and, if you are always around cars, trucks and planes, you are in the pool of piss and just not seeing it or smelling it.

You can see this filth if you get out of town, climb a hill and look back. If it is a clear day with a big sky and no wind, then you should be able to see the filthy air above the town, and that isn't from people riding bicycles.

What we have done with cars is to make them more efficient. Nobody is rolling coal any more, well, maybe in South Carolina, but everything was 'rolling coal' with added lead until relatively recent times. There might not be clumps of soot the size of snowflakes in the air, what happens now is that the car dependent person has a vehicle that burns the same amount of fuel as before, but the particle sizes that come out the back are extremely small, so small that you can't see them. But you can see them if you happen to be using a satellite to do so, or if you do get ten miles out of town on a clear day, and look at it properly.

I live in Scotland where we have had an interesting history with air quality. We have a network of paths that are made from former railway lines and canals that take you a long way from cars. There are stretches where you are riding through nothing but flowers for mile after mile. You can also unlock extra adventure levels to find networks of roads that don't exist on Google Maps that are closed to cars but definitely open to bicycles. However, eventually, some big road will need to be crossed or there will be a road running parallel to the trail. Then the magic ends.

What amazes me is how you can get used to the wonderful smells of the truly clean air to then be utterly appalled at how toxic the air is anywhere within a mile of a car. But, inside a car,the air always smells good, right? It is not as if you get tired from carbon monoxide poisoning on longer journeys, is it?

So, does any of this matter? Not if you are young with no health problems. Just suck in the air wherever there is an abundance of vehicles. You will never know what good air is or why it matters. Besides, we all need cars and trucks to get food on our tables, so there is no escaping and it would be hypocritical to do so.

Or you can opt out, to never fly and never drive. I chose this as a challenge and, so far, no regrets. I haven't been on a plane for three decades yet I seem to know more about the world than most frequent fliers. As for not getting into a car, there are occasions such as funerals where I will get a lift, and yes, I do get the occasional item delivered to my door, but everything else? Bicycle, or electric train, powered by wind farms. It seems to me that you can only really assess the problem if you aren't part of it.

Regarding contrails, they have been a conspiracy theorist talking point for as long as the internet has been around. What is pernicious about conspiracy stories is that there is always a small grain of truth in there. All of these hydrocarbons we burn - all of them - are toxic to life and cancer causing. Conspiracy theorists have egged the pudding on this, but who wins from this? Well, it means that anyone with a preference for genuinely clean air, buzzing with bees and wonderful smells from plants, can be branded a crazy person because they must be, right?