Editor鈥檚 pick: We need to talk about natural pesticides in food
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 just as nasty as synthetic pesticides, but present in food in higher amounts. However, they don't affect us when we consume them because their concentration is only effective against insects, not anything large.
The real problem with organic farming is low yield. You need much more land to obtain similar yields to other forms of farming. I think we should be returning farmland to nature, not increasing its area.
Remember the carbon footprint of kitchen kit
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 full of instructions to blitz this and blend that – who has heard of a hand whisk these days?
The importance of being earnest about urban parks (1)
Graham Lawton praises London's self-declared status as a National Park City (20 July, p 24). Born and raised in the South Wales valleys, I have always felt the lure of green spaces. Lawton made me realise that I associate London as strongly with birdwatching and strolling around Hyde Park as I do with its landmarks. Breaking up the urban landscape isn't just beneficial for the environment, it also offers city dwellers the opportunity to step away from the hustle and bustle to connect with nature, with all the health and well-being implications 快猫短视频 has previously reported (22 June, p 18).
The importance of being earnest about urban parks (2)
Lawton praises London as the world's first National Park City. In Finland, we have nine National Urban Parks, created under the . At present, Helsinki is in the long and tedious process of trying to decide whether to join places such as Turku, Forssa and Kuopio.
The importance of being earnest about urban parks (3)
I was shocked by Lawton’s claim that the artificiality of ecosystems dominated by invasive species doesn’t matter. He notes that Hawaii is now a hotchpotch of mostly invasive and introduced species. That’s true 鈥� and the harm caused is incalculable. More than half of honeycreepers, a group of bird species endemic to Hawaii, have gone extinct since humans reached the islands and almost all the rest are now threatened.
More than 100 species of Hawaiian plants are already extinct and hundreds more are vulnerable. Lawton claims most invasive species don’t pose a threat to native biodiversity. Most don’t, but the ones that do cause immense damage.
Taking care of the willow seeds that we collect
Vijay Koul's experience makes him concerned about the viability of willow seeds (Letters, 13 July). Indeed, they are generally very short-lived in natural situations. For several years, we have been developing a protocol for long-term storage of Salicaceae species at the . This procedure addresses all stages, from seed collection in “Hundred Acre Wood” in Sussex and elsewhere (25 May, p 13) to storage conditions and monitoring, with the aim of maximising the longevity of the collections.
Importantly, we receive the seeds within three to four days of collection and place them into long-term storage within 14 days of arrival. This ensures the initial viability of the collection is as high as possible at the time of banking.
We also do germination tests on the seeds, both on arrival at the bank and after storage at -20°C and at -186°C. We will monitor the viability of each collection of seeds in the long-term. Our initial results are promising, with successful germination occurring after storage for two to three years.
I suggest it's better to rebut errors than retract them
Astrophysicist and climate scientist 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 succeed, climate change deniers will surely claim this as proof that evidence contradicting climate change is suppressed, despite the paper’s error. Surely a better approach would be to write a rebuttal and demand that the journal link to this from the original paper.
Better ways to reduce your carbon flightprint (1)
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 have been upgraded to business class. Are you suddenly less environmentally friendly? Should you refuse the upgrade? Should you refuse that flight?
The solution is to place an additional constraint on your booking. Certainly, book economy class, but select the flight with the lowest average level of emissions per seat on your chosen route. This depends on a number of factors under the airline's control, including the space devoted to non-economy passengers and the type of aircraft. This approach, if generalised, would pressure the airlines to clean up their act.
Better ways to reduce your carbon flightprint (2)
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 alternatives are more readily available for short distances is true, of course. It is great that you raise awareness of climate change. Keep up the good work.
Responding to sound when in a coma
I found Helen Thomson's report of findings that one in 10 people in vegetative states may be conscious very interesting (29 June, p 38). On 30 December 1990, I experienced a severe head injury in a car crash. I was placed in an induced coma, so I was more deeply unconscious for the most part than the states described. When I regained consciousness, I knew where I was and why. I presumed I had been asleep – until I saw the calendar. It was February.
A dream I had while in the coma involved my brother flying an aeroplane. I now think that was because he came to see me from Glasgow and those around me may have said that he flew down.
Thomson says people in such states are unresponsive to sound and pain. I don't know about pain, thankfully, but I think I must have been responsive to sound in some way – how else would I have dreamed that my brother was flying his own plane?
For the record 鈥� 24 August 2019
鈥� Count on it: the formula for the distribution of Mersenne primes along the number line predicted that there would be fewer than four between 220,000,000 and 285,000,000 (10 August, p 38).