QJM Advance Access originally published online on October 17, 2006
QJM 2006 99(11):809-810; doi:10.1093/qjmed/hcl114
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Coda |
Burning your relatives
If you want to dispose of a dead body, either human or animal, there are only a few ways you can do it, and they all have much the same effect. You can leave the body out in the open, so that other creatures of various kinds can eat most of it, metabolizing it into water and carbon dioxide. The bits that remain will be oxidized, essentially undergoing the same process but more slowly. An alternative option is to burn the body. This will also lead to the same results, but of course at a much faster rate. Or you can slow the process down by burying the body in the earth or at sea. In that case, consumption of the body by other creatures may still take place, but oxidization of the uneaten remains will not occur until the body is somehow exposed to the atmosphere once more.
In certain circumstances, geological change on top of a burial site will compress bodies and reposition them at increasing depths under the surface of the earth; in the case of some species—marine animals are a case in point—they may remain there for considerable periods of time, perhaps even millions of years. If you eventually disinter such long-buried corpses in the form of their liquefied or gaseous residues, you can ignite them with a spark in an enclosed space, and produce a very accelerated form of combustion, thereby releasing great amounts of energy. This process was perfected around 150 years ago, when Etienne Lenoir invented the internal combustion engine. Since then, we have been burning dead plankton at a tremendous pace. At a rough estimate, reserves of marine corpses took about a hundred million years to build up (although in reality this probably took place only in short epochs during that time). We have probably got through over half of these reserves already, and at the present rate of usage, the rest is unlikely to last us another forty years. Currently we are burning dead marine animals at around a million times the rate that it took to create them. This is comparable to raising a fellow human being for 25 years, and then burning him or her up for fuel purposes alone in around a minute.
There are a number of peculiarities about this business. One is that we are undoing a planetary process that has allowed us to emerge as a species, and to survive. If every organism remained on the surface of the earth after death, decomposition would soon replace much of the oxygen in the atmosphere with carbon dioxide. This would possibly reduce the net balance of surviving animals to nil. It is only the accidental burial of a large proportion of creatures that has sustained enough free oxygen to result in our own existence, and we are now reversing that process. Another peculiarity is our emotional disengagement from what is happening. Even if we are aware of the fact intellectually, we do not as a rule drive around in our cars exclaiming: ‘Oh my God, I am cremating my ancestors and cousins in prodigious quantities, and turning them into noxious gases!’ But that of course is exactly what we are doing.
It has become fashionable recently to try and become aware of some of the damage that we are doing by burning our fossils, not because we are worried about oxygen depletion in the very long term but because it will warm up the globe in the very short term. There are now schemes that allow you to calculate how much carbon dioxide you are putting into the atmosphere personally, mainly through the means of transport that you use, and to ‘pay it back’ symbolically by funding the planting of trees. These schemes are based on units of carbon consumption per year, although an alternative approach would be to look instead at the time it took to create the fuel we consume, and to compare this with the time it takes us individually to burn it up. It seems that the planet produced around 380 thousand billion litres of oil in total; according to this estimate, a three-hour car trip up the motorway using 38 litres of petrol will consume roughly the amount that it would have taken the entire earth five minutes to produce. On this basis, it should be fairly easy to work out how many ‘earth hours’ of fossil production you use up each year by car travel. (I have obtained all the figures here from the internet and done the sums on the back of the proverbial envelope, since I cannot find these calculations anywhere else. If anyone is prompted to offer a more scholarly formula, I will be very pleased. Even if my arithmetic is out by some orders of magnitude, I doubt that the result will be reassuring.)
One irony about this rate of oil consumption is that we are using the stuff up so fast that it may run out before the effects of its combustion become terminal. Economists and politicians tend to speak out either about global warming, or about the exhaustion of oil supplies, but they rarely address both at the same time. Yet the real challenges that face the world are likely to be due to the social and political consequences of a coincidental interplay between these two processes. There is no logical reason in evolutionary history why global warming should not have happened long before we were able to use up all the oil, or vice versa, and it is tempting to imagine some unfathomable meaning in the fact that these are more or less going to converge. The ancient prophets of many religions may have used expressions that we now find alienating, when they made a connection between impending natural calamities and our failings as human beings. They may also have been slightly awry in their predictions about the timing. But intuitively they understood the fundamental nature of the problem: we think as individuals and with our heads, but we cannot act collectively and with our hearts.
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