Aviation uses so much energy, it’s gotta be this or stop flying.
Flying is the most fossil fuel intensive thing regular people interact with, so we naturally assume it's the biggest energy user there is.
Last I heard the number was around 2% of all CO₂ emissions.
But most people disregard this on the basis of cost (in reality it costs a little more upfront but saves money in the long term) or outdated conditionings that buildings need to breath naturally and should not be airtight.
Net emissions. Planes burning fuel synthesised from electrolysed water and atmospheric CO2 is a closed carbon loop.
[1]: https://www.carbonbrief.org/explainer-challenge-tackling-avi... [2]: https://www.sciencealert.com/ipcc-report-2018-easy-things-yo...
The number I heard most recently was 3% and growing, but generally, I think I agree with you. It is something we will have to tackle, but there is higher priority, relatively low hanging fruit that will have a much bigger impact.
The problem with aviation is that it is hard to store energy for the actual planes. Since everything on a plane must be light, then the energy per weight (i.e., energy density) is crucial, and fossil fuels thus far have unparalleled energy density.
So the solution is to make some kind of fuel that is similar to fossil fuels but is carbon neutral. What Rolls Royce is suggesting is that their nuclear plants will be perfect to power the factories that make this green fuel. But of course that is not true. Any grid connected generator can power these factories including renewables that are already much cheaper and safer than nuclear.
> Maritime transport accounts for 3.5% to 4% of all climate change emissions, primarily carbon dioxide.
Aviation is about half that, but there is a lot less aviation, so we need to consider that. If we are saying "efficient" as a comparison, yes ships are. But that's not really the issue about climate change. The issue is that we have too much green house gasses in our atmosphere and are not slowing down (side bar: with sequestration the argument is that greenhouse gasses aren't inherently bad, but the levels are. So as long as net is zero or negative, who cares -- there is more nuance to this than suggested here). The issue is that we have to transport stuff. Sorry, but we can't live our current life unless we transport stuff globally. Doing otherwise would require drastic shift, which is needed, but come at a great cost. So do we solve it technologically or socially (I for one don't have faith in the social solution, but would love to be surprised). So the three ways we have of getting stuff across oceans (if we include Musk for entertainment value) are (in order of emissions): Shipping, Aviation, big fucking rockets (this isn't a linear scale and one of these dwarfs all the others).
The issue is that we need to be at 0 or negative emissions (i.e. sequestering carbon). The short end of that argument is that US and EU combined is about 25% of global emissions and I don't know if we can trust other countries to be as aggressive as we are. (So obviously in favor of sequestration. What's the worst that can happen? We go too far and have to operate a few coal plants to balance out? LOL)
The conversation is frequently a distracting one. We talk about energy, cars, and plastic straws. That accounts for <50% of a first world's carbon emissions, which energy needs are growing btw (keeping current levels of emissions is a difficult challenge alone!). Unless we have a serious conversation about this, we're never going to get to 0 emissions by 2100 (forget 2050, we've already given up on that. We're not willing to have a nuanced discussion about the issues and instead pretending paper vs plastic straws are an actual issue).
[0] https://en.wikipedia.org/wiki/Environmental_impact_of_shippi...