Bill Z. has pointed out a new remarkable story in the media based on an article in Nature Climate Change,
The influence of AB on CD is nonzero for virtually all pairs AB and CD – except that the influences of most random things on most other random things are so tiny that no sensible person would ever talk about the influence. The topic of the Karnauskas et al. paper is clearly an example of these ludicrously small influences.
Karkauskas et al. decide that the flights could be up to 1% slower, due to some influence of global warming on jet streams and upper-level wind circulation patterns. The extra wind the aircraft need to overcome will increase the annual fuel expenses by $3 billion and exacerbate the global warming problems by increasing the carbon emissions. You don't need to read the Nature Climate Change or media articles because they don't contain anything that goes beyond the comments in this paragraph.
Let's believe that the CO2 really influences the wind patterns so substantially that the accumulated effect of CO2 over a few decades makes a 1% difference to the fuel consumption by the aircraft. I don't really believe that the impact could be this high – almost all remarkable claims like that boil down to the authors' manual "erasure" of all terms of one sign (they only consider the terms of the sign they like) – but let's ignore all this skepticism.
The main question is: assuming that the 1% influence is right, does it matter?
The global oil production is increasing towards 100 million barrels a day. That's 36.5 billion barrels per year. Multiply it by the current oil price around $55 and you will get about $2 trillion per year.
The world oil producers sell oil worth about $2 trillion per year (slightly over 2% of the world's GDP of $80 trillion or so). If the price doubled, and the price was almost doubled just a year ago, it would be $4 trillion per year.
Now, those folks have calculated that due to their influence of the "global warming" on air travel, a difference that is being accumulated from a trend over many decades, the fuel consumption by the airlines increases by $3 billion per year. This is clearly just 0.15% of the total price of the oil produced, sold, and bought over the same period (one year).
So the "worrisome" increase of the fuel consumption by air travel is equivalent to the change of the oil price by 0.15%. Now, everyone who follows the oil price knows that the price dropped by 50% or so within a year. Just yesterday, within minutes after the Iran deal was announced, the price dropped by 2%.
The change of oil price by 0.15% is equivalent to what normally takes place in the markets during several seconds. The carbon dioxide emissions have to be emitted for many and many decades to match the natural market fluctuations that normally take several seconds to materialize. Why would you talk about a 0.15% change of the oil price at all? If you are buying or selling actual barrels (and not some leveraged papers that only "stand for" the actual oil), the effect is absolutely unmeasurable. This effect is 300 times smaller than the natural change of the oil price during the recent year. As I said, the ratio is almost certainly greater than 300 because the influence of the greenhouse effect on the wind patterns is almost certainly heavily overestimated.
Whatever the exact magnitude of the effect is, one thing is clear: Everyone who talks about this unmeasurably tiny effect is crazy. For example, I am batšit crazy because I am writing this damn blog post at all – and wasting 5 minutes that could have been used more effectively. But to post a similar unhinged rant in a branch of the Nature Magazine is just absolutely unbelievable.
Even if you compare the hypothetical changes of the fuel consumption to the fuel costs of the airlines themselves (and forget about all oil consumed outside airlines), it's very small. Airlines buy about 1/30 of the world's oil so the ratio 300 changes to 10. The hypothetical CO2-induced changes to the upper-layer wind patterns increase (or decrease, they can't be quite sure about the sign – except that the alarmists always automatically assume that the sign of all these effects is "bad" even though about 50% of them are bound to be "good") the fuel costs per year may increase by 10% – but that's only if you consider the effect of the greenhouse effect accumulated over many decades.
The increase of the greenhouse effect per year is smaller – of order 0.1%. So even from the viewpoint of the airlines' budgets, the hypothetical "global warming" that is added each year and that hypothetically modifies the wind patterns has the same effect as the change of the oil price by 0.1% in every year. Again, this is clearly impossible to incorporate in the airlines' financial planning because the oil price will change by dozens of percent (100+ times more intensely) each year for totally different reasons.
If the greenhouse effect over the next decade, 2015-2025, combines to a 1% increase of the airlines' fuel costs, the increased price will be transferred on the passengers. But it will still be absolutely impossible to disentangle this 1% change from the changes coming from different airplanes, different routes, different number of passengers and weight of the cargo – and especially politically and technologically driven changes of the oil price and the general inflation rate.
The effect the Nature Climate Change article discusses is clearly zero for absolutely all practical purposes – and for a great majority of the impractical purposes, too. People who write these papers are despicable corrupt pseudointellectuals, stinky garbage of the Academia. The purpose of all this pseudoscientific activity is to suggest that the effects of CO2 on our lives through the climate matters even though it demonstrably and obviously doesn't.