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Cathy Cook suggests reasons to prefer organic food other than its alleged nutritional superiority, and mentions pesticide residues (Letters, 3 August ). All fruit and vegetables contain large numbers of naturally occurring pesticides. These are the result of an arms race with insect herbivores. If we tested for these, we would find that they are …

According to James Wong, a US study of the food system's carbon footprint says kitchen appliances generate nearly seven times as many emissions as food transport ( 3 August, p 24 ). Pointing out that eating vegan food benefits the climate is now common, but the burden of meal preparation is rarely mentioned. Recipes are …

Astrophysicist Ken Rice and climate scientist Gavin Schmidt are calling for a paper in Scientific Reports to be withdrawn ( 27 July, p 14 ). It claims that the rise in Earth's temperature is due to changes in the distance between Earth and the sun, which they point out is wrong. If Rice and Schmidt …

You recommend that people who have to fly shun business class because it has higher emissions per passenger (Leader, 20 July ). This is because these seats occupy more space on the plane, on average, than those in economy. But consider a case in which you have booked economy and find at check in you …

You say we should cut out short-haul flights because most aircraft emissions are associated with take-off and landing. But fuel consumption per passenger kilometre is greater for flights that go further than about 4000 kilometres, not least because of the mass of fuel the plane needs to get into the air. Your point that ground-based …

• Count on it: the formula for the distribution of Mersenne primes along the number line predicted that there would be fewer than four between 2 20,000,000 and 2 85,000,000 ( 10 August, p 38 ).

I enjoyed Graham Lawton's article on the exploitation of environmental language by the far right ( 17 August, p 24 ). I take exception, though, to the idea that this has only recently emerged. Far-right politicians have often linked notions of nationhood and the environment. This was particularly evident in the 1930s, when some Nazis …

Alan Gordon suggests hearing aids should replicate the directionality given by the shape of the ear (Letters, 27 July ). Most manufacturers use test equipment called a Head and Torso Simulator. This can be fitted with external ears to test the idea. It ought to work. I haven't yet tried it myself, but I might …

Butch Dalrymple Smith says we should plant trees and make things out of wood to sequester carbon (Letters, 3 August ). We are already doing half the job by farming trees to make paper and chipboard. When we have finished with them we recycle or destroy them. Why not preserve the paper and chipboard as …

Chelsea Whyte writes of moons ejected from their orbits around exoplanets, called “ploonets”. ( 13 July, p 15 ) She mentions the slow drift in our moon's orbit and the possibility that this might be its fate. Would this make it a “protoploonet"? That is such a cool word that it deserves to be used.