Editor's pick – More common ground on the changes we need
Roger Taylor notes that recycling is one area where common ground can be found with climate change sceptics (Letters, 21/28 December 2019). There are many more.
Restoring fish stocks, reducing waste, combining conservation with careful usage, using alternatives to fossil fuels, making less use of cash crops, promoting tree growth and use via silviculture and cutting the impact per head of livestock and their overall numbers are examples.
Maddeningly, politicians and other policymakers could have supported these actions in the past 30 to 40 years, since they make sense whether climate change develops as expected or not 鈥� and even if temperatures fall following a major volcanic eruption. Further, trees can be good near-term carbon sinks, are a potential source of fuel and have other benefits. As usual, short-termism won out over intelligent win-win policies.
Can planting trees combat climate change very much?
Recent letters, like that from Adam Osen, focus on planting trees to help mitigate climate change through their storage of carbon (Letters, 7 December 2019). It may not always work.
Planting trees on open ground may change the reflectivity, or albedo, of land. At higher latitudes this can cause a warming effect, as three-dimensional woodland absorbs more radiation than the essentially two-dimensional open ground that it replaces.
In many places new planting is likely to be targeted at upland areas, which generally possess stratified soils with a high organic carbon content. In the UK there is an order of magnitude more carbon stored in soil carbon than plant biomass. Tree planting on such soils can oxidise this carbon, potentially releasing more than the amount taken up by the trees. And practices such as ploughing land before planting can dry out the soil, causing carbon release. At the other end of the forestry cycle, modern tree extracting machines can similarly churn up the soil.
So it isn’t clear to me whether tree planting will benefit the climate. There is also the issue of natural and semi-natural habitats being converted to woodland at the expense of biodiversity.
I believe the best approach would be to leave the extensive tracts of UK upland with a shallow humus layer unplanted, so that over time the soil carbon store builds up and, on level ground at least, goes on to form peat.
Reforesting is a stopgap solution to carbon woes
I appreciate Tom Crowther’s research on reforestation, which is vital and urgent (11 January, p 44). But reforestation is a stopgap solution to climate change while we decarbonise the economy. What if we plant enough trees to stabilise carbon dioxide levels in the air, while still burning fossil fuels? We would end up with a planet that is still warming and has nowhere left for new forests.
Forest restoration is essential 鈥� and will help with maintaining biodiversity. But it must be done alongside emissions reductions.
An obstacle to making deniers my friends
David Westmoreland and Connor McCormick say the flat-Earthers they meet are savvy about science (11 January, p 21). They also report flat-Earthers measuring shadow lengths at various latitudes to look for curvature of Earth and coming up with inconclusive results.
The African-Greek scholar used this method to calculate Earth’s circumference before 200 BC. He was correct to within 10 per cent. So much for the flat-Earthers’ experimental competence. There may be another explanation. My limited experience of such people leads me to think that many are just contrarians who enjoy the challenge, doubtless honed in school debating societies, of defending the indefensible.
Just when an autonomous car needs you most…
Will motion sickness be an issue for people deprived of a sense of control in autonomous cars, asks Frank Siegrist (Letters, 18 January). It will. I first heard of this in 2018, at a conference on highly automated vehicles at the University of Warwick, UK. Before we reach full vehicle autonomy, human drivers will need to take over in some circumstances. There is currently, as I understand it, no way of determining whether a driver may be impaired by motion sickness when required to do this.
Reasons why Neanderthals may not have died out
You report arguing that Neanderthals were such a small population that they may have been intrinsically at risk of extinction through a combination of unfortunate circumstances, rather than being actively exterminated or out-competed by Homo sapiens (7 December 2019, p 19).
Researchers could also, given the small size of the Neanderthal population relative to H. sapiens incomers, consider a further possibility: that Neanderthals never went extinct as such. Eurasian populations today have 1 to 4 per cent of Neanderthal DNA. It is possible that Neanderthals interbred with H. sapiens until, after a few thousand years, there were no “pure” Neanderthals left.
This process would have been accelerated if “mixed” offspring were infertile, except for female children of H. sapiens mothers and Neanderthal fathers. This idea is supported by reports that in modern H. sapiens neither the mitochondria 鈥� passed from mothers to all children 鈥� nor the Y chromosomes 鈥� passed from father to son 鈥� show Neanderthal traces ().
The topic is interesting and requires further research. Vaesen is right not to fall into the easy trap of seeing the Homo species or subspecies as necessarily in a state of life-or-death competition. At this remove, it is wrong to make assumptions about how the two populations would have seen each other at the time.
The editor writes:
We have discussed the idea that Neanderthals may have become absorbed into modern human populations (25 August 2018, p 7). And for more on Neanderthal DNA in people today, see Neanderthals never lived in Africa, but their genes got there anyway.
Ask an AI to explain how an AI made its decision
Paul Bowden is among the many people who are concerned that AI will not be able to reveal its reasoning (Letters, 14 December 2019). Although we should be aware that someone can make decisions without being able to give their full reasoning, or may even answer differently each time asked, I do think there may be a better way to evaluate AI decisions.
We could train another AI to interrogate it, using the same set of variables the original AI was given and varying them slightly on each iteration to infer what “mattered” to the decision maker.
Since computers can repeat the same process over and over again very quickly, this process should be able to ascertain the detail that was important in the decision. It seems to me eminently superior to interrogating humans, who may fear blame.
Don't ignore the personal in evaluating altruism
I read with great interest Joshua Howgego’s discussion of using evidence and reason to maximise the impact of kindness (7 December 2019, p 42). It reminds me of utility theory in economics.
The usefulness, or utility, of a given outcome depends markedly on the person involved and on their situation. Worse, utility can change significantly over time. We should surely recognise that personal perception lies at the very heart of decisions to donate.
Connecting giver to receiver is important 鈥� it often means that much more than money is shared. Human sympathy and interest matter greatly.
For example, building a specific school or clinic for specific recipients not only leads to effective application of funds, it also leads to greater giving. Donors who are personally interested gain an appreciation of the local problems. This can lead to personal trips by skilled builders or those who can offer training in medical matters.
This sort of thing doesn’t come from a scientific effectiveness measure alone. Aid agencies surely need to be held to account by some recognised methodology. But don’t ignore the personal. A purely scientific approach is rarely an adequate description of the realities of human community.
I still can't ride this big bang bandwagon
Chandra Prescod-Weinstein asks: are dark matter and dark energy related? Yes: both are imaginary constructs required to paper over the cracks in the “big bang” concept (4 January, p 20). I find it difficult, as an old physicist, to understand how far this illusion has gone within the physics community.
I remember the astrophysicist Fred Hoyle pouring scorn on the “big bang theory” in 1949. It is a shame that the word “theory” is used in the term, as it was always used to denote an idea which had some definite proof. The “theory”, as it stands, looks to me more like a creation by satirical novelist than a product of modern physics.
Is no one in the physics or cosmology communities working on alternative scenarios? It seems that every other issue of 快猫短视频 has an article outlining the failings of the big bang idea.
How can any serious physicist consider that a large percentage of the material in the universe is something about which we haven’t a clue? We now have a big bang bandwagon.
This all reminds me of Lewis Carroll’s poem , which warns: “If your Snark be a Boojum… you will softly and suddenly vanish away”. I believe the big bang theory is in fact the big bang boojum.
Did we hum a happy tune while we munched leaves?
A serendipitous concurrence of events has set me thinking (11 January, p 34). In your article on breathing and better memory and sleep you say that humming sets up swirls of air in the sinuses, which boost the production of nitric oxide 15-fold. And recently there was coverage of the finding that gorillas “sing” while they eat (5 March 2016, p 18).
The humming-like sounds they make certainly seem to be generated in the sinuses. Bearing in mind on smooth muscle tissue, such as that in the gut, could this be an aid to effective digestion?
It is tempting to think that we, too, may have evolved, as social arboreal primates, a musical mechanism that also offered such digestive benefits as well as effective social communication, pre-language. This may even add weight to the argument that music predated language.
If nothing else, it could also explain the way music can so easily elicit visceral responses. Is there any research into how such a link, forged in our evolutionary past, may have then become adapted subsequently?
For the record – 8 February 2020
鈥� Our comment on George Monbiot’s statement that the “land efficiency” of Solar Foods protein production from hydrogen and oxygen is roughly 20,000 times that of conventional agriculture, based on the area occupied by the factory, is only that it isn’t relevant: he also uses Solar Foods’ figure that the area of the factory, plus solar panels to power it, is 10 times smaller than equivalent fields, which is relevant (18 January, p 10).