TIL contrails are a legitimate concern and have environmental impact!
this post was submitted on 15 Aug 2023
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Same here, and I'm a bit confused since it was recently discovered that clouds formed due to ship sulfur pollution were helpful to reduce warming, and reducing the sulfur pollution actually caused heating.
Why do those clouds cool the planet while contrails heat it? Is it just the difference in altitude, having the clouds higher up for some reason acting more insulating?
It’s exactly as you said—different clouds have different effects on the climate. Some warm things, some cool things.
It’s more complicated than this, but the way I learned in school was that all clouds reflect sunlight, but they can also block some IR from leaving the earth. Low clouds absorb IR from the surface but re-emit it at a similar level to the ground because they are a similar temperature. In this case the reflective effect dominates, so most low clouds have a cooling effect. But high clouds are very cold—this means they absorb the same IR from the surface but emit far less into space, keeping the planet warmer. This dominates the reflective influence, so high clouds can warm the climate.
Clouds at night are particularly warming, since they don’t reflect sunlight. For this reason, redeye flights have a greater warming effect than other flights. Supersonic jets and other very high flying aircraft can also be extra harmful.
My uneducated guess - That article mentions the high sulphur content causing them to be reflective. If those weren't there, the sun would be hitting the dark water and being absorbed instead of reflected. Contrails are just water and so probably absorb more energy instead of reflecting.
y tho
just put everything on rails, or at least as much as humanely possible
transatlantic railroad
WaterLev©™® trains powered by Big Hydro
But that would hurt oil industry profits, and you know they can't have that.
Because executives have to get from coast to coast NOW, they are very important have have to be in the same room as other executives while they tank the possibility that you can ever retire.
As the airline industry pushes and waits for more sustainable fuels and alternative power engines, many major carriers have shifted focus to the emerging field of studying contrails, once considered an innocent byproduct of water vapor at high altitudes. But those whispy clouds are actually a significant environmental detriment because they hold heat in the atmosphere that would otherwise escape. [...]
The initial trial tested 70 flights, modifying flight paths to try to avoid conditions with altitudes, weather and humidity where they thought contrails were most likely to form. They were able to cut down on contrail coverage by about 54%, based on Google's satellite imagery. But those flights had to use about 2% more fuel to gain the results.
So does a 54% reduction in trails offset the 2% higher carbon emissions?
Probably hard to measure as the contrails stay in the atmosphere for hours and the CO2 stays there for what, hundreds or thousands of years?