The aviation industry (Letters, 29 June) says innovation will allow continued growth in a zero-carbon world. It may be right, but it needs to provide more than PR proof points as evidence. The industry’s long-term plans predict 3% annual growth and estimates an annual efficiency improvement of 1.5% from design and operations. It proposes the use of biofuels and other low-emissions technology to cover the rest.
In the spirit of the late David MacKay, it is straightforward to carry out a back-of-the-envelope calculation of what this would need. At current productivity levels of biofuels, this would require a land area of over six times that of the UK, or most of Indonesia, to supply aviation in a net-zero 2050. The scale of the challenge is immense, and all industry sectors must innovate to rapidly decarbonise. But they should not simply assume that success will allow growth to continue unchecked. Each sector should provide a detailed, quantified and open decarbonisation plan for assessment by the Intergovernmental Panel on Climate Change, and be honest about the risks to their business. If they can’t innovate to decarbonise in line with IPCC requirements while respecting other planetary boundaries (such as wildlife habitat preservation), they will need to diversify or contract.
Investors need to look carefully at these long-term risks to avoid being exposed to stranded assets such as underused airports or grounded aeroplanes. The aviation industry might not be in climate denial, but it must avoid using techo-hubris to lock itself into climate delay.
Prof Chris Preist
Faculty of engineering, University of Bristol
• The claim that aviation contributes only 2% of global carbon emissions ignores the effect of the radiative forcing effect of emissions in the upper atmosphere. This means aviation greenhouse gas output is two to four times as damaging as the same amount at ground level. We are asked to be reassured by a claimed reduction of 3.5% in aviation’s emissions in the past 12 years – an annual rate of reduction, if real, of 0.3% per year. This at a time when IPCC scientists are reporting a need to reduce carbon emissions by 45% over the next 12 years.
Reading the letters I was taken back to the days of my youth when the tobacco industry was arguing that smoking was not a danger to health. Let us hope governments regulate this industry without delay to achieve the required 45% reduction in emissions by 2030, and thereafter insist that it reduces its carbon emissions to zero by 2050.
John Chapman
Moseley, Birmingham
• The idea that the aviation industry can continue to expand to give “more people the opportunity to sustainably travel and do business around the world” is just nonsense. For the sake of all our futures, we have to reduce our consumption and be thoughtful about our carbon footprints, and this includes our use of aviation. We cannot carry on in the same vein, taking flights as and when we wish.
There is no entitlement to air travel; indeed, mass air transit is a relatively recent thing, so it shouldn’t be difficult to turn the clock back to when air travel was an adventure every few years rather than a routine weekend break or one of several foreign holidays or business trips a year. The climate emergency is happening now; I write as we have experienced the hottest day of the year with a record 34C at, guess where, Heathrow!
Kim Hoare
Westhall, Suffolk
• Flying is unavoidably an energy-intensive way to travel. Apart from the fuel needed to lift hundreds of tons into the air, aircraft have higher drag as they travel faster than surface transport. And unlike water or land transport, energy has to be expended, via “induced drag”, to overcome gravity, so it will never become a fuel-efficient way to travel. And while electric propulsion may become feasible for small aircraft of limited range, it is unlikely this will become possible for larger, long-haul aircraft. Greta Thunberg is absolutely right in saying we have to give up flying, especially for pleasure trips to lie on exotic beaches for a week.
Michael Miller
Sheffield
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