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An abnormally bad season of weather may have had a significant impact on the death toll from both World War I and the 1918 Spanish flu pandemic, according to new research, with many more lives being lost due to torrential rain and plummeting temperatures.
Through a detailed analysis of an ice core extracted from the Swiss-Italian Alps, scientists were able to get a close look at the climate patterns across Europe between 1914 and 1919, linking them to the war and the pandemic for the first time.
The unusually wet and cold conditions could well have contributed to more lives being lost out on the battlefield, as well as interfering with bird migration behaviour – potentially pushing birds and people closer together than they would otherwise have been.
"Atmospheric circulation changed and there was much more rain, much colder weather all over Europe for six years," says climate scientist Alexander More from Harvard University. "In this particular case, it was a once in a 100-year anomaly."
"I'm not saying that this was 'the' cause of the pandemic, but it was certainly a potentiator, an added exacerbating factor to an already explosive situation."
Of course, accounts of atrocious conditions in the trenches of the First World War are not new – the rain and mud has been well documented. What this new research does is link those conditions with the once-in-a-century environmental patterns.
Traces of sea salt trapped in the ice core revealed extremely unusual influxes of Atlantic ocean air and associated rainfall in the winters of 1915, 1916, and 1918 – coinciding with peaks in mortality rates on the European battlefield.
Close to 10 million military personnel are thought to have died in the First World War in total. Problems such as trench foot and frostbite would have been exacerbated by the constantly damp conditions, while the quagmires created on the battlefield meant it was much harder to recover and rescue wounded soldiers. Drowning, exposure, and pneumonia claimed more lives.
"We found the association between increased wetter and colder conditions and increased mortality to be especially strong from mid-1917 to mid-1918, spanning the period from the third battle of Ypres to the first wave of Spanish flu," says archaeologist Christopher Loveluck from the University of Nottingham in the UK.
Besides making bad conditions worse for soldiers, the researchers suggest this climate anomaly may have played a big role in creating the perfect environment for the H1N1 influenza strain to trigger a deadlier second wave of the Spanish flu, which picked up as the war ended.
This part of the research is more speculative, but the study points to the bad weather as a reason for mallard ducks – a primary reservoir of H1N1 – to stay put in western Europe, rather than migrating to Russia as normal. This would have kept them closer to military and civilian populations already struggling with unhygienic conditions.
More water would've meant a faster spread of the virus as it mixed with bird droppings, the researchers suggest, and perhaps the transmission of a more virulent strain of the flu that went on to kill 2.64 million people in Europe. With the world once again facing a pandemic and climate anomalies today, there might be important lessons to learn here.
The research has been published in GeoHealth.