When we talk about airplanes and their influence on climate and the environment, the first thing that comes to our mind is greenhouse gases and carbon dioxide in particular. It probably has something to do with the campaign of airline companies to make people pay for carbon offset as part of their tickets. This is just my speculation.
But in any case, it turns out, greenhouse gases are not the only byproduct of flying, which accelerates climate change.
Scientists from the German Institute of Atmospheric Physics calculated that the non-CO2 warming effects from aviation can in fact triple in the coming 30 years.
The team led by Ulrike Burkhardt took into account not only air traffic, but also the location and altitude of the flights. In their opinion, the trail of soot and fumes, which airplanes leave behind them, could be detrimental when it happens at high altitudes.
The scientific back up of this statement comes down to the following. The higher the altitude of the flight, the more likely it is that the water vapor condenses onto these soot particles. In turns, these freeze and form cirrus clouds. The clouds then act as a block preventing the heat radiated by the Earth to escape. Yes, they also act as a barrier that blocks incoming radiation from the sun, but on average cirrus clouds have a net warming effect.
To put this into numbers, the team reported the following results.
The warming effect, which is caused by these clouds, is about to increase from 50 milliwatts per square metre of the earth’s surface in 2006 to 160 mW/m2 by 2050. When compared to what CO2 emissions from aviation will do, the rise will be from 24 mW/m2 in 2006 to 84 mW/m2 by 2050.
Of course, the aviation industry can do something about this. If they decide to impose policies and restrictions, improve fuel efficiency and reduce pollution from engines, it could not be all too bad. The scientific models gave a slightly more optimistic outlook. The warming from contrails drops down to 140 mW/m2 and the warming from CO2 to 60 mW/m2, all by 2050.
Well, it seems the team is not so negative about the whole thing. That is despite the fact that they say their models could actually be underestimating the effect of contrails by 70%. The silver lining- cirrus clouds and contrails use up all available water at high altitudes, and therefore prevent normal cloud formation. If this is really the case, we can see a small drop in the above numbers.
I do not see how the current measures that are in place are going to help counteract these effects. There are a few policies and plans- for example the international scheme Corsia, which aims to reduce emissions from aviation. However, it is so loosely applied and formulated, that many actually use it to cut short on taxes and measures. Something has to change, and someone has to take responsibility. Unfortunately the topic of who that should be is comfortably avoided.
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