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Graham Lawton says wood is a carbon-neutral biofuel so long as trees are replanted ( 16 March, p 33 ). But Michael Le Page reports the European Union being sued for making global warming worse by burning wood ( 9 March, p 9 ). He notes that wood burning might seem an appealing alternative to …

Is wood burning good or bad for the climate ? The answer is: it depends. Foresters are used to taking a long-term perspective. Good forestry means managing wood harvesting so the forest can continue to provide ecosystem services and maintain its carbon stock in the long term. Whether or not wood can be considered as …

Some peoples cut off fingers in mourning, report Margaret McGovern from Canada (Letters, 23 February ) and Ted Webber from New Guinea (Letters, 23 March ). When I worked in Papua New Guinea, a young employee walked in with a large bandage on a finger of her left hand. She had cut off the top …

You report the alarming decline of insects due to habitat loss and climate change ( 16 February, p 6 ). The response of insects to the latter is likely to be adaptation by evolution. Creatures with shorter lifespans can adapt faster and displace those who live longer. Those with the shortest lifespans, such as cyanobacteria, …

Alan Wilkinson asks whether biologists should have noticed how windscreens were crushing fewer insects by the mid-1960s (Letters, 9 March ). I have seen such a decline, but I put it down to aerodynamic improvements in the cars I drive. Has this been taken into account? I am also a motorcyclist and I haven't noticed …

You illustrate the carbon footprint of a kilogram of cheese and other foods ( 16 February, p 30 ). It would be more useful to see the carbon footprint per kg of dry mass. I estimate that milk (90 per cent water) has an impact of 12.5 kg of CO 2 equivalent per kg of …

You make a persuasive case for looking at carbon dioxide emission per calorie. I would like to see a chart that shows this.

Having yeast make cannabinoids sounds useful to medicine ( 2 March, p 9 ). I cannot imagine, though, that they will stay cloistered in the lab for long. They could be transferred as easily as a sourdough starter, allowing interesting wine, beer and bread to be made.

You report that association football players are working harder and getting injured more often ( 2 March, p 16 ). These health and injury issues are common to many professional sports. One of the worst problems in association football, though, is that players are expected to be able to head the ball – as are …

• Inconstant wind: storm Idai crossed Mozambique into Malawi and went back out to sea. Then, upgraded to a cyclone, it crossed Mozambique to Zimbabwe ( 23 March, p 6 ). • They've really made the grade: it is the US space agency NASA that has a training cohort of whom half are women ( …