Letters archive

Adam Vaughan sees hope in the fact that India's prime minister has pledged that the country will achieve net-zero emissions by 2070 ( 6 November, p 10 ). However, promises made by ordinary people, let alone politicians, for 50 years in the future are clearly meaningless. Imagine if Lenin had promised a global utopia by …

Ingrid Newkirk, People for the Ethical Treatment of Animals, Washington DC, US Hurrah that many nations have pledged to stop razing forests by 2030, but, at the rate they are being felled, will any be left by then? Reactions to the COP26 climate summit show that while many are unhappy with the failure to take …

COP26 focused on persuading all nations to aim for net-zero carbon emissions by 2050, in the hope this will prevent global temperature rising by any more than 1.5°C ( 23 October, p 36 ). The major polluters are unlikely to meet the first target, and so the second will probably be exceeded in the near …

Cedric Lynch, Potters Bar, Hertfordshire, UK In your story about the upgrade to the branch of maths called calculus, you say "you could perhaps imagine calculating the rate of change of acceleration too, which would be a third-order derivative" ( 13 November, p 44 ). However, calculating this rate of change can be of more …

The skull of a small child found on a ledge in a cave with no signs of carnivore activity or large-scale water movement doesn't indicate to me that it is firm evidence of the early human species Homo naledi burying its dead ( 13 November, p 9 ). Young children hide in nearly inaccessible places …

Regarding Albert Einstein's wish, amid conundrums on the nature of reality thrown up by quantum theory, that he could be sure the moon was still there if he wasn't looking at it ( 6 November, p 38 ). I wonder if a related question sheds any light on this: is the sun there if I …

The increased demand for minerals to build renewable energy kit, such as wind turbines, solar panels and mega batteries, emphasises the need for a circular economy in which the necessary minerals, once extracted from the ground, are never reburied as waste, but reused again and again ( 13 November, p 38 ). It also highlights …

I have an idea regarding lifestyle approaches to try to reduce the chance of developing Alzheimer's disease ( 6 November, p 46 ). Older people aren't in a position to wait for a drug cure, so every beneficial lifestyle strategy should be practised. Two important ideas have been suggested: getting seven hours of sleep and …

The plant-based meat options in our supermarkets probably aren't marketed to be seen as healthier than the diet of nuts, vegetables and lentils that vegan pioneer Donald Watson enjoyed ( 30 October, p 38 ). But many are still preferable to the conventionally produced meat these products are designed to replace. A report led by …

I share concerns over increased tree mortality across Europe, but one assertion in your report on this needs to be revised ( 20 November, p 14 ). Your story concludes by citing a much-debated claim that wood harvesting in Europe has risen by 50 per cent since 2016. Subsequent evaluations suggest a substantially smaller value …