Footprint size
Fred Pearce criticises ecological footprint accounting 鈥� which shows that humanity is using the equivalent capacity of 1.5 Earths 鈥� for underestimating human demand on the planet (23 November, p 28). Even if Pearce is correct, why would this make the metric “useless nonsense”?
Isn’t it better to take a conservative approach 鈥� like that adopted by the International Panel on Climate Change? Erring on the side of underestimating demand and overestimating capacity ensures that claims of overshoot cannot simply be dismissed as exaggerated.
Climate change is not dismissed because the IPCC underestimates its effects. Neither should we ignore what the footprint tells us: that people’s demand on the planet is more than its ecosystems can renew, and this course inevitably results in depletion of resources or accumulation of waste, such as additional carbon in the atmosphere.
Footprint accounting addresses a specific research question: how much of the planet’s productive capacity is appropriated by people? It measures a key dimension of sustainability, but not the only one. Additional metrics, like soil depletion, water use or population growth, are needed to provide a more complete picture.
Pearce admits that he “had imagined that the footprint analysis was a bit smarter” and that “it does not measure the things that most of us assumed it does”. We suggest that the footprint be critiqued on its own merits, not on misconceptions of what the metric actually does.
Oakland, California, US
Dead space
The “block” view of time (2 November, p 34) may be a sort of model of the universe as if it were a dead thing (no movement at all). 快猫短视频s assume the universe is non-living because physicists study it and inanimate things are what physicists study. There is no good reason for this assumption.
Clovelly, New South Wales, Australia
Feeling the heat
Further to your coverage of the shift in climate policy after the Australian elections (23 November, p 5), former Liberal prime minister John Howard recently of climate change sceptics in London and likened people who believed in climate change to “religious zealots”. He declared that his gut instinct told him there was no great catastrophe in the offing.
I, like many other Australians, find these backflips on climate of great concern.
Nana Glen, New South Wales, Australia
Beyond evolution
I have to take issue with Mark van Vugt’s view on Darwinian economics (23 November, p 30). I think the analogy between Darwinian evolution of species and the development of businesses and other organisations is most dubious. Businesses can draw ideas from each other, merge, expand, contract, lose bits and change “habitat” and “diet” in ways no species can.
Before drawing a Darwinian analogy, he needs to prove the appropriateness of the analogy, which I found unconvincing.
Newbury, Berkshire, UK
Beyond evolution
The article on evolutionary economics by Mark van Vugt was interesting, but also slightly disappointing in a way.
If the concept of economic activity as “red in tooth and claw” is wrong as the article suggests, then some of us will have to change our way of speaking: when Adam Smith’s metaphor of an “invisible hand” guiding the market is brought up in discussions of economics, we will no longer be able to refer to it as the “invisible claw”.
Chicago, Illinois, US
Must do better
You reported a slowing in the rate of increase of carbon dioxide production (9 November, p 6), with a related editorial that hails incremental change and says this is good news for the planet, and that “a global climate pact might be unnecessary after all” (p 3).
As you say, slowing the rate of CO2 increase, or even reducing the rate of CO2 production somewhat, is not enough to avoid major climate catastrophes such as sea-level rise, ocean acidification, and the loss of freshwater supplies. Halting the growth rate of CO2 levels is an essential step, but it is not even remotely the cure.
Waipahu, Hawaii, US
Death row
Charles Sawyer (30 November, p 33) wonders whether Arkansas is more humane with its method of killing chickens than Ohio is with the execution of death row inmates. Gregory Sams suggests administering morphine (p 33).
Surely we must realise that the years of psychological torture between sentencing and execution render the physical pain of death negligible. Indeed, one only need turn to the article in the same issue entitled “Nothing to fear but fear itself” (p 16), the first sentence of which is, “Anticipation of pain can be worse than pain itself, it seems.”
Rayne, Essex, UK
Ghost in machine
Fiona Stewart is pleased that the Mozilla Firefox browser plug-in Lightbeam can highlight third-party sites that snoop on her online activities (23 November, p 34). To go one step further and block these sites, I would recommend another plug-in: Ghostery. It is free, has versions for all the major browsers, and has lots of configuration options.
Henfield, West Sussex, UK
Let us play
Your article on school starting age decried the state of early years education in England and went on to say that a similar story applies in the rest of the UK (16 November, p 28).
In Wales, the foundation phase of education for those aged 3 to 7 is based on the principles of learning through play that authors David Whitebread and Sue Bingham describe.
Swansea, West Glamorgan, UK
<i>From Guy Cox</i>
Of course play has educational value, but the play in day care or preschool is so cocooned it is of limited value. The play at and after school, where young children can interact with and learn from older ones, is far more useful. There is also the question of how long we want education to last. For example Australian children, usually starting at age 6, finish school a year behind their British counterparts, educationally speaking.
Sydney, New South Wales, Australia
House of Ugh
Reading Genevieve von Petzinger’s description of the ancient abstract art found in the cave at El Castillo in Spain (23 November, p 36), I was struck that she could easily be describing medieval coats of arms rather than rock paintings.
Perhaps those individual symbols represent clan affiliations, and the divided rectangles a history of allegiances between clans? If those caves were indeed a meeting place in an increasingly socially complex world, it would become extremely important to record such allegiances. The markers would help individuals know who to trust, not merely within their own clan, but also in meeting strangers from other clans.
This hypothesis might even be testable. If the combinations of symbols represent allegiances, we would expect them to exhibit some of the characteristics typical of social graphs, such as triadic closures (of the “my enemy’s enemy is my friend” sort). I hesitate to describe El Castillo as a Stone Age Facebook, but it does seem that our ancestors were busy posting messages on each others’ walls.
Waterford, Virginia, US
House of Ugh
Your article on prehistoric art starts “All over the world, we’re finding art tens of thousands of years older than it should be. What awoke our creative minds so early?” Early compared to what? Why should our minds not have awoken even 1 million years ago?
Instead of congratulating our early ancestors on their intelligence, we should be asking why it took us 50 or 100 millennia to move on from the awakening of our creative minds to such things as the use of pottery or bronze.
Les Essarts-le-Roi, France
Unplug me
Ian Mapleson asks how we should respond if a self-aware robot requests not to be turned off (23 November, p 33). Surely a more thorny moral dilemma lies in store when a self-aware robot asks to be turned off.
Mt Eliza, Victoria, Australia
How many ETs?
You conclude that 40 billion sunlike stars in our galaxy have Earth-like planets in their habitable zone (9 November, p 12). Even assuming each has a single such planet, that is still an impressive number. But if we look at the Earth as an example of the timelines those planets might face, the maximum number of possible intelligent civilisations drops dramatically.
Working on the assumption that intelligent life has been here for roughly 100,000 years on a planet that has existed for 4 billion years, let us also assume that other Earth-like planets are undergoing similar biological timelines, and that just as humankind’s reign on Earth may be brought to an end by an asteroid impact or some unforeseen calamity in the next several thousand years, the same fate is likely to befall other galactic civilisations. If so, the Kepler data and these assumptions would indicate a rough upper limit of 1 million intelligent civilisations in existence at any moment in our galaxy.
Poquoson, Virginia, US
Gas guzzler
In his letter Martin Savage, discussing how doubling an aircraft’s speed from Mach 3 to Mach 6 might affect the rate of fuel use, says it would burn through its fuel in a quarter of the time (30 November, p 33). The reality is the power needed to propel the aircraft varies with the cube of its velocity. In theory, doubling the speed will cause it to burn fuel eight times as fast. This would only strengthen his argument.
Sunbury on Thames, Surrey, UK
For the record
鈥� We fudged the role of insulin in our story on the link between Alzheimer’s and diabetes (30 November, p 6); we should have said the hormone instructs cells to absorb glucose.
鈥� Our claim that 500 tonnes of methane per square kilometre was bubbling up from the Arctic seabed (30 November, p 18) was inflated: it should have read 500 kilograms.