The warship in question was the teutonically-titanic Tirpitz [the heaviest European battleship ever, and sister to the only-slightly-more-famous Bismarck], which was launched by Nazi Germany during the Second World War in 1942. The ‘puff of smoke’ was a cloud that was created when chlorosulphuric acid [also known as chlorosulphonic acid], released from the ship and other sites nearby, attracts water from the atmosphere and forms an impenetrable mist in a matter of minutes. Hidden by the cloud in the Norwegian fjord where it rested pending forays out to the open ocean to deal destruction to Allied shipping and death to its crews, it was obscured from Allied aircraft that repeatedly tried to bomb and sink it. Does this sound like maritime ‘magic’? What seafaring sleight-of-hand, what poseidonic prestidigitation is this?
If true, such an extraordinary claim requires extraordinary evidence [David Deming, Philosophia 44: 1319–1331, 2006]. There might be photographs of the phenomenon. Yes, there may be, but that’s not that extraordinary. And, as we know from plant science and publications, pictures can be manipulated – the camera can, and frequently does, lie. There may be eye-witness accounts. But that’s a rather ordinary source. Plus, humans may misremember, be misled or lie (remember, we’re considering events in wartime…). No, we need something that’s independent, objective, and trustworthy. We need a source that’s water-tight, cast-iron, copper-bottomed, unimpeachable and irrefutable. So, what do we have? Tree–rings!
In an intriguing example of scientific serendipity, forest ecologist Claudia Hartl (Johannes Gutenberg University in Mainz, Germany) and her students, were trying to answer the question: Why did some of the trees in the Kåfjord area of northern Norway have either no growth rings or one that was barely discernible for the year 1945? Pursuing this puzzle they found even more extreme examples – some trees living nearest to the fjord had stopped growing for as long as 7 years [i.e. showed seven years devoid of annual growth rings], returning to normal annual growth patterns only after 12 years. Why?
The explanation is apparently the damage caused to tree growth * by the chlorosulphuric acid cloud, which is inferred to have caused a defoliant effect on the trees – Scots pine [Pinus sylvestris L.] ** and downy birch [Betula pubescens Ehrh.]. Tellingly, the reduced growth was the most severe for those trees closest to the Tirpitz’s moorings in Kåfjord fjord in 1944. This loss of leaves – and hence reduction in supply and transport of energy-giving, growth-supporting sugars from their photosynthesis– is evidenced in the much-reduced, or even non-existent, tree growth in girth [i.e no annual rings].
So there we have it: Botany, evidently, and evidentially, an extraordinary science. The fact that those trees survived is a remarkable testimony to their ability to withstand years of no growth – indicative of very reduced photosynthesis – and is a remarkable example of plant persistence in the face of great environmental hardship. Recognising that this work could be employed to provide evidence of other wartime events, the new field of ‘warfare dendrochronology’ [Claudia Hartl et al., Anthropocene Volume 27, September 2019, 100212] has been spawned.
Truth maybe the first casualty of war – and there are always too many human victims of conflict – but clearly the plants can also suffer as a result of man’s inhumanity to his fellow kith and kin, and represent an under-appreciated form of ‘collateral damage‘. However, although they may suffer in silence, these mute sentinels of the forest can still bear damning witness to mankind’s warmongering wilfulness and wantonness. With such potential and powerful phytoforensic sources of evidence no scandalous environmental-detrimental activity or war-crime need now be unwitnessed or recorded (even if they all too often go unpunished…). This area of ‘conflict ecology’ – and the new sub-discipline of ‘warfare dendrochronology’ – is fascinating, and one predicts more environmentally-enlightening exposés in future.
* Although the effects of chlorosulphuric acid on tree physiology are quite dramatic, we don’t know what impact the noxious cloud may have had on the battleship’s crew, or civilians in the nearby area. However, in the 1940s the chemical was apparently considered safe for humans “because cows exposed to it didn’t die immediately”. In 2019 we now consider chlorosulphuriuc acid to be harmful to human health as exposure results in severe skin burns and eye damage, and may cause respiratory irritation. One suspects that standards of health-and-safety may not have been as strict during the Second World War as they are today.
** But, please, Bas den Hond Freelance Journalist, don’t tease, tantalise, torment, titillate, tempt, torture, or taunt us with the notion of scotch pines (whether of Norway or elsewhere…). Scotch is the name for Scottish whisk(e)y. The trees are Scots pines – which is correctly spelt in quotes from the scientist in the study, but mis-spelt in Bas den Hond’s report of their work. However, any evidence that the news item’s writer may have that these trees have whisky in their xylem, or phloem – or anywhere else within the plant body come to that! – would be most welcome(!): Cheers!