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I agree that scientists and environmentalists should walk the walk, as Dave Berry writes in “Greenhouse gluttons” (18 September, p 23). That is why, when I was involved in organising the 2002 International Children’s Conference on the Environment I persuaded other delegates to plant trees to make up for the greenhouse gases that their flights produced.
It has to be best to reduce greenhouse gas emission, for example with teleconferencing. But if that won’t do鈥� if you do the crime, you must pay the fine.
Any frequent flyers wanting to offset their greenhouse gas emissions can do so through my website: . The tree calculator on the site will show you how many trees you need to plant. Native trees will be planted in South Yorkshire’s coalfields.
Listen to us kids!
Letter
At the Tyndall Centre for Climate Change Research, we are improving the sustainability of our activities as Berry suggests. On the challenging issue of travel, we measure greenhouse gas emissions from staff journeys and offset the carbon emitted using our core grant, through investment in renewable or low-energy projects overseas. The annual cost of offsets is around 拢500 at present.
Flying currently accounts for 80 per cent of our carbon emissions, and we recently set a target of reducing air travel by 10 per cent per year. There will always be a need for face-to-face meetings, but we are increasingly using teleconferencing. The UK research councils’ e-science initiative will further increase our scope for videoconferencing between universities.
We are working on a comprehensive sustainability strategy, and will explore other issues such as recycling, “green” purchasing and printing, and efficient energy use within our buildings. Simple steps often have the biggest impacts.
Nuclear arithmetic
Nick Marshall’s letter “Nuclear’s hidden cost” (18 September, p 22) couldn’t be more wrong. The costs of waste disposal, reactor decommissioning and accident liability are all included in standard cost and investment appraisal analyses, as can be seen in the recent review of generating costs by the Royal Academy of Engineering ().
Furthermore, his claim that a 1250-megawatt nuclear plant indirectly emits between 376 billion and 1300 billion tonnes of carbon dioxide per year is ludicrous. Credible estimates of the indirect CO2 emissions from nuclear plants vary. For example the US-based Nuclear Energy Institute, whose members include nuclear industry bodies in several countries, quotes a range 2 to 59 grams per kilowatt-hour on the basis of a life-cycle analysis, which is about the same as hydro-power. Conservatively, applying the upper estimate to a station with 1250-megawatt peak capacity operating at 85 per cent load factor, CO2 emissions would be 0.55 million tonnes per year, compared with 11 million tonnes for a comparable coal-fired plant, calculated on the same basis.
Letter
Nuclear power generation is not CO2 neutral, as Marshall indicates. The processing of ore, building of plant and disposal of waste all require energy. Cement production also releases CO2.
It is, however, difficult to calculate how much CO2 is released in the entire nuclear fuel cycle. Estimates range from 30 to 60 grams of CO2 for each kilowatt-hour of power 鈥� significantly less than those for burning fossil fuels.
The editor writes:
鈥� Nick Marshall asserted that a 1997 study by the Institute for Applied Ecology in Berlin (the 脰ko Institute) produced the estimated indirect CO2 emissions. What the 脰ko Institute calculated was that the nuclear cycle produces 34 grams of CO2 per kilowatt-hour of electricity generated, which would be up to 372,300 tonnes a year for a 1250-megawatt station.
Salt of the what?
The level of salt added to foods is currently seen by many consumers as the thing to worry about, since having too much can lead to medical problems and many foods contain large amounts.
Manufacturers supply information about what is in their products, but this can be quite technical and potentially misleading. Some provide the weight of salt per 100 grams, which is clear enough. Others 鈥� and I’m looking at a mini-packet of cornflakes at the moment 鈥� give the amount of sodium. Obviously there is not any free sodium in the product or there would be an interesting reaction. What is listed is the amount of sodium added, probably as sodium chloride.
How many consumers would know or understand this? In the case of the cornflakes the sodium is given as 0.95 grams per 100 grams. That already seems quite a lot, but do the maths and this equates to 2.42 grams of salt, which really is a lot.
Ivory fact and fantasy
In proposing a controlled trade in ivory, Daniel Stiles lays out certain conditions that would need to be met (28 August, p 16). The key to his proposal is to limit global demand. Unfortunately this is probably about as unrealistic as suggesting the key to the drugs trade is to limit demand.
Historical experience of trying to conserve other resource shows how difficult this will be. Although it may be in the long-term interests of quality artisans and carvers to limit the trade in ivory, the problem is that there are also actual or potential traders who will seek to maximise short-term profits, even at the risk of eventually depleting the resource. The global fisheries crisis and the unsustainable harvesting of tropical hardwoods shows how powerful the prospect of short-term gain can be.
To date, Japan has made only the most perfunctory efforts to collaborate in investigating and prosecuting those behind illegal shipments. Visiting Japan, I found shops selling ivory advertising sales to celebrate the impending lifting of the trade ban.
There is plenty of evidence that the ivory trade is already closely linked with other areas of illegal international trade, such as drugs and arms. These are not the sort of people who show a great interest in the concept of sustainability and restricting their trade.
Darwin's finches
Paul Chambers repeats the old chestnut that “fortunately for science, Darwin was later able to support his geographical isolation theory by analysing the Galapagos finches collected on the voyage” (11 September, p 38). This story has been extensively debunked, particularly by Frank Sulloway, who Chambers mentions in his article.
Darwin makes no mention of the finches in On The Origin of Species, and only a passing reference in The Voyage of the Beagle. It seems that the specimens he and others collected were not labelled according to their provenance, and it was not until well after he returned home that the ornithologist John Gould established that these birds were indeed all finches.
Paul Chambers writes:
One only has to look at Darwin’s excitedly scribbled notes, made during his meeting with John Gould, to see the effect that it had on his thinking. Gould looked at Darwin’s Galapagos birds and declared most of them to be endemic to the islands. The finch observations were not used in print, but in private they featured heavily in Darwin’s thoughts and notes and were instrumental in his decision to find a non-religious cause for organic evolution.
Grain worth the pain
It is difficult to think of fiddly farmed grains as “prestige items” compared with, say, the kidneys of a rare or dangerous animal (18 September, p 29).
More plausibly, grains may have justified the trouble of cultivation because they can be stored relatively easily. Tiny grains such as lentils lend themselves to being harvested by women and children, but this makes it less likely that they were regarded as prestige foods.
Or am I being sexist? Perhaps it was the old men who initially looked after the crops. Too slow to hunt and too curmudgeonly to childmind, they probably passed the time trapping small animals and birds and complaining how boring life had become. Perhaps these were the ancestral grumpy old men.
The Pleming test
In response to John Crocker’s challenge, I can offer something better than the Turing test (21 August, p 22). Two copies of the same artificial intelligence program are made to converse with each other. The result can evolve in several ways:
Pleming Level 0: The conversation between the two programs will stop, or never start.
Level 1: The conversation will evolve into a loop, with the same topics occurring in a predictable never-ending sequence.
Level 2: The conversation will meander around a random set of topics with no emergence of new ideas and concepts.
Level 3: The conversation will result in the creation of demonstrably new and original ideas and concepts.
I submit that a program behaving at Pleming Level 3 would show the creation of genuine artificial intelligence. Any resemblance to what happens in pub conversations is purely coincidental.
Letter
I think I have come up with a program that models the average 5-year-old. I hope you have space to print it all.
10 INPUT STATEMENT
20 PRINT “Why?”
30 GOTO 10
Face facts
On the face of it, your statement that “the mass media has a strong influence on who we find attractive” (4 September, p 27) conflicts with “Attractiveness is innate” (11 September, p 14). I suspect the media influences fashion rather more than our idea of beauty, especially when it comes to sexual attraction.
I suggest that certain individuals are discovered (not chosen) to be visually attractive. It is only then that one’s sexual orientation is revealed to oneself.
Researchers should focus less directly on behaviour, and turn instead to emotions and other “internal” motivating forces, though I accept that this approach has its difficulties. Given an innate “eye” for an attractive person, other inherent desires and an environment full of temptation, what better context is there for then understanding sexual behaviour?
For the record
鈥� One Soviet cosmonaut died during re-entry in the 1960s, not two as was stated in “We have a problem” (25 September, p 19). Vladimir Komarov’s parachutes failed to open on 24 April 1967.
鈥� The authors whose manuscripts we mentioned being housed in the Duchess Anna Amalia Library in Weimar were Johann Wolfgang Goethe and Friedrich Schiller (18 September, p 5).