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Graham Lawton's discussion of the tension between action on global warming and electoral outcomes brings to mind a grim precedent ( 14 September, p 23 ). Newfoundland cod was massively overfished until the fishery collapsed in the early 1990s. Scientists warned that quotas needed to be reduced. Elected representatives didn't dare impose the required limitations …

Crispin Piney suggests ways to book flights to minimise your carbon footprint ( Letters , 24 August ). Couldn't we adapt the technology that launches planes from aircraft carriers to take-offs from land-based airports? Clean power to catapults could be supplied off the grid and, for some, the buzz would be great.

I would like to add to the argument for an ammonia-based fuel economy suggested by Phil Pope ( Letters , 14 September ). You have reported that researchers at the University of Tokyo have developed a low-energy alternative to the Haber-Bosch process that makes ammonia from atmospheric nitrogen ( 27 April, p 8 ). This …

You suggest that humans are less likely to accept a choice attributed to an artificial intelligence when it concerns a social problem ( 24 August, p 38 ). Many people make decisions that are influenced by their social media interactions, which are governed by AI. Fake news spreads between users on Facebook, who may change …

Richard Dawkins tells Graham Lawton that he doesn't comment on topics such as fake news and the promotion of gut feelings over facts, or issues relating to the environmental crisis, because none of these are in his area of expertise and his amateur opinion would be no more interesting than anyone else's ( 21 September, …

Dawkins has usefully promoted scientific truth through his writing on evolution. We need to remember, however, that there is also historical truth, which differs from scientific truth in that history can't be repeated. It is important because it helps us to understand the cultures and countries around us and, we hope, to avoid serious future …

David Hambling reports that a company is using trees to find gold deep underground in Australia ( 17 August, p 12 ). Plants have been used for such purposes at least since modern metal prospecting began. Possibly the best known is Ocimum centraliafricanum, the copper flower , which has been used in the Central African …

Tom Chivers discusses solar technologies that could be used instead of fossil fuels, which would help address the increasingly urgent requirement to control global warming ( 10 August, p 34 ). There is a second reason to do this. All understanding of Earth's long-term cycling tells us that, on a much longer timescale than the …

It was good to read your interview with neuroscientist Dean Burnett and his conclusion that teenagers are how they are because it was evolutionarily useful ( 14 September, p 56 ). I've been going on about our adventurous species and the drive of the young towards risky behaviour and exciting experiences – looking to see …

Jessica Hamzelou reports that boosting circadian rhythms can help relieve perinatal depression ( 21 September, p 15 ). This prompts me to wonder how such rhythms work. How is it that I always wake at 7.20 am, plus or minus 30 seconds? How can the wetware of the mind be so precise? I get no …