We are all familiar with images of mud and death in the trenches of the First World War. But it's only over the past year that many of us have seen photos of the influenza pandemic that raged during the last year of the war and on into 1919. Foreshadowing our own time, they show wards full of sick and dying patients, masked nurses, police and ordinary citizens, and even anti-mask protesters.
The Great War (as it was then called) directly caused the deaths of between 15 and 22 million people, about half of whom were civilians, and a roughly equal number of severe injuries. But the 1918-19 pandemic was even more deadly, claiming the lives of around 50 million people, or roughly 3 per cent of the world's population at that time. The loss of life was greater even than most estimates of the toll of the Second World War, generally regarded as the most deadly event in history.
The link between the Great War and the influenza pandemic was more than a mere coincidence of timing. Massive movements of troops around the world - unprecedented at the time, but foreshadowing our own world of extensive tourist and business travel - were a major factor in spreading the 1918-19 pandemic. And, as with current pandemics, the close proximity of humans and food-producing animals played a major role. But recent research has also pointed to more direct links to the war, including the role of poison gas and the local climate change created by the conflict.
The 1918-19 pandemic was originally called the Spanish flu because of the extensive publicity given to cases in Spain, notably that of King Alfonso XIII, who fell gravely ill. As a neutral power, Spain had not imposed the wartime censorship that prevailed in other European countries.
The first recorded case - involving Albert Gitchell, an army cook at Camp Funston in Kansas - occurred in the United States on March 4, 1918. At this stage it was no more deadly than the usual seasonal influenza epidemic. It was in the trenches and camps of the Western Front that the disease took the deadly form that would kill millions, and particularly young people.
In 2005, a team of researchers led by J. S. Oxford of St Bartholomew's Hospital in London concluded that the prime culprit was a British base camp at Étaples in Northern France. "The Étaples camp had the necessary mixture of factors for emergence of pandemic inuenza," they wrote, "including overcrowding (with 100,000 soldiers daily changing), live pigs, and nearby live geese, duck and chicken markets (and) horses." It also had an additional factor: "24 gases (some of them mutagenic) used in large hundred-ton quantities to contaminate soldiers and the landscape."
The gases used in the Great War included chlorine, phosgene and (perhaps the most horrible of all) mustard gas, which not only caused disabling blistering but is also highly carcinogenic and mutagenic. The outbreak of flu, particularly deadly to the young men among whom it spread, probably arose from the mutagenic effects of one or more of these gases, combined with repeated transmission from humans to animals and vice versa.
Even more striking is the possibility that soil particles, explosives and other chemicals generated by the continuous bombardment on the Western Front played a role in generating a six-year European climate anomaly characterised by unusually cold and rainy weather - weather that contributed both to the infamous mud of the trenches and to the severity of the pandemic. As well as the obvious effects of cold weather, which weakened immunity and encouraged crowding indoors, the climate anomaly disrupted the migratory patterns of mallard ducks and other birds that were important vectors for the disease.
The existence of the climate anomaly has been demonstrated recently by a team including Alexander More and Paul Mayewski of the University of Maine Climate Change Institute. Using an ice core taken from the European Alps they showed the existence of a six-year period of heavy rain, snow and cold weather, driven by an influx of cold air. As they report, these conditions played a major role in "setting the stage for the onset, spread, and mutation of the H1N1 pandemic, while also increasing all-cause deaths due to widespread harvest failures and worsening battlefield conditions".
The researchers showed that mortality increases in times of lower temperatures and higher rainfall. These conditions were present during many of the major battles of the Great War, and may have increased the virulence of the influenza.
As with the war and the pandemic, the researchers suggest that the timing of the climate anomaly was not coincidental. The massive amounts of dirt and dust thrown into the air by continuous bombardment, along with the vast range of chemicals, could have provided the nucleus of rain clouds.
This was, perhaps, the first instance of a war amplifying its destructive power through climatic effects. Later, during the Second World War, the destructive effects of incendiary bombing were amplified by firestorms, the powerful winds generated when fire consumes all the oxygen in areas struck by bombs. Even worse, though still thankfully hypothetical, is the prospect of a nuclear winter created by the massive fires a nuclear exchange would create.
History does not repeat itself, but it rhymes. In 1914, nationalism and imperialism unleashed the four horsemen of the apocalypse. The pestilence, famine and death unleashed by the fighting was made worse by climate change, itself caused by the war. Now, as the world struggles, and mostly fails, to deal with a new pandemic, the threat of catastrophic warming looms over us all, as does a global failure of democracy. Perhaps we can make better choices than the leaders of 1914, and their millions of enthusiastic followers. But it's hard to be optimistic.
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