Editor's pick: We worked out petrol's 'gearing ratio'
Chris Eve wonders how much more heat burning a kilogram of petrol generates through the greenhouse effect than it does through the energy of combustion (Letters, 23 March). He calls this a “gearing ratio”, the name for the proportion of debt to capital used in finance. With colleagues, I , though we called it the relative radiative forcing commitment (RRFC).
This describes the ratio of the energy absorbed into the world's atmosphere and surface to the pulse of fuel energy. Our computations started with models of the climate effects of carbon dioxide, methane and nitrous oxide. We found that the RRFC is a ratio of about 150 if we integrate these climate forcings over 100 years.
Other emissions from combustion, such as black carbon, have some effect too. And the real global impact is roughly doubled because warming increases the amount of water vapour in Earth's atmosphere. We concluded that the RRFC for diesel fuel is of the order of 300. That for petrol will be approximately the same.
First class post 鈥� 13 April 2019
They’ll be saying this about Earth in a few decades
Lesley Wise the news that Venus may have had a climate suitable for life billions of years ago (6 April, p 10)
The goldilocks planet and how evolution works (1)
Bob Holmes discusses the idea of Earth as a superorganism featuring selection by persistence (23 March, p 34). This is intriguing and quite convincing. We should, however, make clear what we know about the actual process of evolution: namely, that the processes of natural selection, drift and other drivers of evolution operate at and below the level of an organism.
Organisms survive and may reproduce. With perhaps a few exceptions, the results we see at higher levels such as populations are manifestations from these lower levels. Certainly, properties emerge at these higher levels that may determine the fates of populations and the organisms that comprise them, but it is the survival and reproduction of the organism that ultimately matters. Without this, these higher levels of organisation wouldn’t exist.
The goldilocks planet and how evolution works (2)
I see that some critics of the idea that evolution by persistence could explain why our planet has been able to maintain relatively stable environmental conditions argue that spontaneous self-regulation can arise easily only in simple systems, and that it would be less likely to evolve the more complex a system becomes.
But the more complex a system becomes, the more feedbacks there will be, both positive and negative. Positive feedbacks are destabilising, but extra negative feedbacks should mean that a system is unlikely to deviate far before a compensating negative feedback kicks in. Since the advent of life will massively increase a planetary system’s complexity, once it gets a foothold it is likely to limit environmental fluctuation.
It will also tend to keep fluctuations within limits that are compatible with its own persistence.
The goldilocks planet and how evolution works (3)
James Lovelock’s Gaia theory has always made sense to me. The concept of selection by persistence seems entirely logical too. But a fundamental rule predating individual selection seems to be missing. Any randomly emerging biological chemistry cannot be selected for if it makes its immediate environment toxic to itself.
Untold chemical trials and errors could happen until one arises that doesn’t randomly poison itself through its own biology. Harmony will dominate because instability is lethal.
More challenges to adopting electric cars (1)
Jason Barlow applauds electric cars for personal transport entering the mainstream (23 March, p 24). Of course, getting rid of fossil-fuel-powered vehicles is a step in the right direction.
But even if electrically powered, a car conveying one person to and from work five days a week is hugely inefficient. Our road networks cost a fortune to maintain and enlarge in both financial and environmental terms, purely to support this ever-expanding daily migration.
Cars degrade the environment with noise, tyre wear, lubricants, construction, disposal and maintenance, regardless of the energy source used. Until the semi-mythical autonomous car arrives, time spent commuting is wasted. Electrify them by all means, but please make the majority of non-freight vehicles on the roads be buses and allow employees to work from home where possible.
More challenges to adopting electric cars (2)
Barlow asks what would make people switch to a pure electric car. I would switch when they are as practical and affordable as standard vehicles. A serious impediment is charging the batteries, but not because of the “range anxiety” that Barlow mentions. Like many people in the UK, I have to park my car on the street, and charging at home is impossible for me. The closest charging point that I know of is at a supermarket more than a kilometre away. I wouldn’t leave a car there to charge overnight.
Fog in Channel, humour reinstated for a bit (1)
I nominate Richard Webb for a prize for bringing science to the rescue of humans beset by political imbroglios (9 March, p 30). His account of “the original Brexit” offers proof that humour survives in the UK and is perhaps the most effective defence, at least of our equilibrium.
Fog in Channel, humour reinstated for a bit (2)
Webb mentions the headline “Fog in Channel: Continent Cut Off”. It isn’t just apocryphal, but one of the great misquotations. “Fog in Channel: Continent Isolated” appeared in a cartoon by Russell Brockbank in Round the Bend with Brockbank in 1948.
Do not be LED astray by coloured indicator lights (1)
John van Someren asks for the match of colour and function in indicator lights to be standardised (Letters, 9 March). On behalf of the many millions who are red-green colour blind, could we please never use red and green LEDs for off and on.
Do not be LED astray by coloured indicator lights (2)
I would suggest getting rid of indicator lights. What is the point of wasting energy on an indicator to tell you that the TV is on?
What is new about this form of old plywood?
Your article about the potential of wood makes much of building with cross-laminated timber or CLT (16 March, p 33). Plywood has been around for many years – Samuel Bentham . It has been used in furniture, buildings, cars, aircraft, spoons and much else.
The nominal distinction is that plywood is glued from cross-laminated sheets of wood peeled from a log, while CLT is assembled from sawn sheets. But Bentham's plywood was sawn.
The editor writes:
• No one, that we can find, has built an entire medium-rise apartment block or a skyscraper from plywood as now defined.
The periodic table is an index to knowledge
Your article on attempts to improve the layout of the periodic table was interesting (2 March, p 36). But I am not holding my breath for anything to come of it, any more than I was after your previous articles on this (12 July 2014, p 38, and 12 February 1994, p 36). Nice as it might be to attempt to summarise everything that is known on a single poster, attempting to be all things to all people ends up being less useful.
The beauty of the traditional arrangement of the periodic table, ordered by the number of protons in the nucleus, is that it provides a simple index in which you can easily find the desired entry and can then look up material from reference sources based on the information in it.
We need to teach uncertainty to all
Wendy Glauser's interview with Timothy Caulfield about the misinformation landscape was engaging (9 March, p 42). May I suggest that the root cause of the misunderstandings that fertilise this is that science education in general doesn't tackle the difference between determinism and probabilism until much too late in any individual's career.
School exams deal only in certainties. The concept of uncertainty is often not broached until you study a science at university – an experience enjoyed by a small minority of the population. Thus asbestos producers were able to sweep aside concerns that first arose in the late 1930s. Tobacco companies asserted as late as the 1990s that there is “no proof” that smoking causes cancer. And just last month the UK's prime minister felt able to between police numbers and knife crime.
A major part of the problem is that some wretched popular papers, their editors and their owners with private agendas delight in headlines about dithering scientists – and demand certainty. But science can offer only the best explanations that fit the evidence.
Perhaps those who make television programmes about interesting aspects of the natural world could be persuaded to look at the need to explain uncertainty and to disabuse people and politicians alike of the notion that it is possible to always speak in the certain language of 2+2=4.
For the record 鈥� 13 April 2019
鈥� A sweeter cube: mathematician Louis Mordell’s question is whether each integer can be expressed as the sum of the cubes of three integers (23 March, p 16).
鈥� Looking for alignment of black holes’ spins is one way to find out what brings them together; there may be others (30 March, p 13).
鈥� The trial of manipulation of cell surface sugars to help treat cancer is being run by a company called Phytoquest (30 March, p 34).