Methane matters
Kirk Smith does a great job of explaining the importance of addressing emissions of all greenhouse gases rather than focusing exclusively on carbon dioxide (27 June, p 24).
According to the , rice produces 19 per cent of global calories for its 34 megatonnes of methane, while .
Rice frequently feeds people who have few other choices, while big consumers of red meat generally have lots of food options. Beef in particular is also responsible for much of the world’s deforestation. The best course of action is clear: if it were not for the unhealthy and undue influence of the red meat industries on decision-makers in wealthy countries, that action would be immediate.
From William Hughes-Games
Fred Pearce discusses the implications of exploiting methane clathrate reserves in Siberia for fuel (27 June, p 30).
The extraction of methane from the ice crystals in which it is trapped, either by pressure reduction or adding heat via hot water or steam, will turn the ice to liquid water, which must then be blown or sucked out of the well. The pressure reduction in the resulting pocket risks creating an unstable cascade effect, allowing excess methane to escape from the solid clathrate from the ever-expanding extraction front.
A suggested solution to these challenges is to extract the methane from the ice crystals by displacing it with carbon dioxide. However, the carbon dioxide clathrate produced is more stable than its precursor, and is likely to inhibit any further methane extraction.
Kirk Smith is right to point out that, in the atmosphere, a tonne of methane eventually turns to 2.75 extra tonnes of carbon dioxide (27 June, p 24).
However, he did not state that this applies only to methane from fossil sources. Biogenic methane, such as that emitted by livestock and rice paddies, represents the removal by photosynthesis of 2.75 tonnes of carbon dioxide from the atmosphere for every tonne of methane that is subsequently emitted when this plant material is broken down in the absence of oxygen. The methane breaks down in the atmosphere, with a half-life of 8.5 years, slowly returning the carbon dioxide to the pool from which it came.
Failure to allow for this difference between fossil and biogenic methane means that the contribution of methane to global warming has been overestimated, resulting in the demonising of agriculture, particularly its ruminant livestock industries.
Mosman, New South Wales, Australia
鈥� It is true that biogenic methane does not add to net carbon dioxide in the atmosphere when it oxidises, but this does little to mitigate its warming impacts. The Intergovernmental Panel on Climate Change’s estimate of methane’s 100-year global warming potential, calculated relative to the effect of the same mass of carbon dioxide over that time, is 25. Taking biogenic origins into account only decreases this figure by 4 per cent, to 24. Alas, agriculture is not off the hook.
Virtual security
Bennett Daviss reported on how the OpenFlow system can be used to reprogram routers remotely, which would protect against network collapses due to trawlers cutting cables or thieves stealing submarine lines (27 June, p 38).
However, the system could open the internet to new vulnerabilities. Until now, the reliance on hard-wired programming in routers has usually deterred hackers. By introducing external reconfiguration capabilities, OpenFlow could be easily harnessed by hackers as a tool to misdirect traffic.
Hackers do this nowadays by exploiting security holes in the Domain Name System, but a worldwide introduction of OpenFlow could make it much easier for them to pull nastier tricks than just redirecting some company’s web page to a porn site.
Jim Giles reports on the work of Conficker hunters, who are dissecting the history of this computer virus (13 June, p 36). Their work is like carrying out a “DNA analysis” of the threat, and prompts me to put forward my idea of computer immunisation.
One of the luxuries of using a Linux operating system is knowing you can download software and open attachments without fear of being infected. This immunity has often been attributed either to good luck or to the unimportance of the Linux OS in the eyes of criminals and hackers. However, the inventors of Unix, Linux’s grandfather, had developed an effective security model long before the first computer virus was invented or the internet thought about.
Vulnerable computers could benefit from the strong immune defences of the Linux/Unix system through a programme of immunisation. The Linux community could distribute a benign virus that would re-engineer vulnerable computers by installing the Unix security model. As each vulnerable computer is discovered and dosed with a “computer vaccine” it becomes immune to viruses, and thus contributes to the growing “herd immunity” of the worldwide, installed computer base.
We need not worry about antibiotic resistance with this model; the Unix/Linux model seems as secure now as it did 40 years ago when it was invented.
Fusion out in the cold
I do not think that your editors and contributors fully understand the damage you are doing to your reputation by continuing to take “cold fusion” seriously, as your interview with cold fusion investigator Martin Fleischmann appears to (18 July, p 28). The problem with the idea is not that it violates established principles of physics, but that it is completely unparsimonious: it proposes a complicated explanation where a simple one would suffice.
The original experiment by Fleischmann and his colleague Stanley Pons failed to demonstrate anything at all. It could not have done so because of serious flaws in its design and execution. That cold fusion might be elicited by any variant of the apparatus they used is no more likely than the existence of unicorns: it might be so, but we have no reason at all to believe that it actually is or to go looking for it in any particular way.
All of this is laid out in detail in Gary Taubes’s 1993 book Bad Science, the definitive account of the whole fiasco. In the meantime, you do neither yourselves nor Fleischmann any service by continuing to rake through the ashes as if there were still an open question to be considered.
Fetching waves
In his article on forecasting oceanic waves, Rick Lovett says that surfers don’t know why waves come in groups of different sizes (27 June, p 46).
I spent eight years in the merchant navy, navigating tankers and survey ships around the world. It was quite common to have two swells coming from different directions, as there can be more than one storm generating waves.
The size of a wave depends on its fetch 鈥� the distance the wave has travelled 鈥� and the wind it experienced during its journey. A longer fetch relates to stronger waves. If two different swells have a similar direction but different fetches, then the two wave sets will interfere with each other either destructively or constructively.
The same article puzzles over how waves lose energy. As it is the wave that travels, not the water, each wave has to raise a large amount of water up against gravity. This requires work and is surely how the energy is lost.
Celebrate copyright
Peter Eckersley argues, that rather than cling to the old model of scarcity and strict copyright laws, we need to refocus on disseminating knowledge (27 June, p 28). He suggests that record labels switch to “licences that allow unlimited, restriction-free file sharing in exchange for flat fees”.
Subscription-based music download services such as this depend on the copyright owner giving permission for their work to be distributed in this way. Without copyright law neither the pay-per-track model nor the subscription model would be viable: people would have no incentive to pay.
It is unfashionable to argue in favour of what Eckersley calls “the old institution of copyright”, but copyright was invented for a reason: to allow creative people to earn a living from their work if it is good enough. If he is in favour of that, as he asserts, Eckersley should argue, as I do, that respect for copyright is more important than ever in the digital age when copying is so easy.
There is no reason why copyright must imply scarcity. I expect that most creative people would be very happy to sell their work at a tenth of the price if they got 20 times as many sales. Some may continue to be happy to give their work away for nothing. As copyright owners, they are free to do this if they want to.
Giant minutiae
In your interview with James Dyson, he is quoted as saying: “We wanted a quantum leap, not just tiny changes…” (11 July, p 20).
I guess that we pedants must accept we have lost this battle.
Law of evolution
Peter Household questions whether evolution is better described as a law or a theory (13 June, p 24).
Evolution will occur in any system that involves replication, variation and selection, regardless of whether the system is biological, mechanical or software. It is as inevitable as the laws of thermodynamics and is of the same nature. We should stop referring to evolution as either a theory or a hypothesis.
Evolution is a law of nature. Quibbling over terms will not change that.
For the record
鈥� The total costs for the purchase and ongoing management of land in Sabah, Malaysia, that would link fragments of the Kinabatangan Wildlife Sanctuary is over $566,000, double what we stated (25 July, p 8), and negotiations to buy it are not yet complete.
鈥� The US Joint Nonlethal Weapons Directorate wishes to make it clear that the new antenna in our report on microwave weapons (25 July, p 21) will not necessarily be used in the airborne version of the Active Denial System.
鈥� Fiona Maisels is the surveys and monitoring adviser for the Wildlife Conservation Society in central Africa, not its coordinator (25 July, p 34).
鈥� The German V-1 flying bomb used a pulse-jet engine, rather than the similar pulse detonation engine as we stated (25 July, p 30).