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Regarding the plan to dump iron in the oceans to promote plankton growth to capture carbon ( 3 July, p 13 ). This implies we must modify the chemistry of the oceans on a global scale so that fossil fuel companies don't have to change their business models and politicians can kick those difficult decisions …

You say that the lifting of all coronavirus restrictions in England is a gamble ( Leader, 10 July ). I agree. Covid-19 variants have, to date, emerged from locations with high infection rates and zero or low vaccination rates, including Kent, UK, in 2020. Government policy in England appears to be intent on creating a …

Robert Law writes of long covid-like symptoms in his 40-year-old daughter after coronavirus vaccination and asks if others have had the same experience ( Letters, 10 July ). Yes! I thought it was just me! I had the Oxford/AstraZeneca jab on 14 June, at the age of 68. That night, I had violent shivers. In …

When discussing consciousness, I am surprised that concussion isn't usually mentioned. Some years ago, I was in a concussed state for around an hour. I have no memory of this hour, but I was apparently talking and arguing with those around me. I have no doubt that I could have been eating, sleeping, mating and …

Emma Young writes that Christof Koch, in questioning the role of the prefrontal cortex (PFC) in consciousness, points to people who have had large regions of their PFC surgically removed. Koch is quoted as saying: "They go on living, by and large, a normal life, never complaining that they have been turned into zombies." May …

Surely the answer to the "hard problem" of consciousness must depend on the answer to the even harder problem: "What is life?" Life seems to be more than just chemistry, but what is that "more"? Does it make any sense to talk about consciousness that doesn't depend on life?

The only good climate change plan is zero fossil fuel use ( Leader, 10 July ). Net zero will see continued use of fossil fuels, compensating for this either by planting trees or removing the carbon produced in other ways. Greenpeace has shown that offsetting doesn't deliver , and absorbing carbon from the atmosphere would …

You mentioned the apocalyptic bushfires in Australia in 2019, and questioned the lack of climate action there. However, the climate damage had already been done, but not by Australia, which is responsible for less than 2 per cent of the world's carbon emissions . Those chiefly responsible are Europe, the US, China and India.

Mulling over Bryn Glover's thoughts on a "phased reduction" approach to achieving climate targets, I was struck by just how much reversal of "improving lifestyles" might be needed ( Letters, 10 July ). Things that were normal in my neighbourhood when I was young include heating just one room, water heater on once a week, …

You brought up valid points about problems caused by the materials used in sidewalks ( 10 July, p 46 ). However, the argument that "our ancestors evolved to walk on the savannah" has limits. Those ancestors didn't wear shoes, which can cause their own problems. Also, the harms of walking on even hard surfaces may …