A team of more than a dozen scientists collected and analyzed an Alpine ice core to reconstruct the environmental conditions of Europe during the World War I. The process involves using a laser that melts a tiny bit from the ice surface and analyzing the chemicals released from each layer of water vapor. It’s so precise they can pinpoint exact seasons from each layer of ice.
Researchers then compared that ice core data to historical records of deaths during that time period and records of precipitation and temperatures from each month.
The researchers discovered that lingering cold, wet weather during the winters of 1915, 1916 and 1918 was caused by abnormally high rushes of marine air from the North Atlantic. Deaths in Europe peaked three times during World War I and all the spikes occurred during or soon after heavy rain and cold weather, according to the study.
“The rain basically matches how many people died. There’s a double peak in the fall of 1918, which is when the second wave and the most lethal wave of the Spanish flu occurred,” More told CNN. “So of course as we’re looking at the second wave of Covid right now and what will happen … this is a warning of what may come.”
The study also shows that this six-year atmospheric anomaly may have disrupted the migratory patterns of several bird species during the war years, including mallard ducks, which are the main animal hosts of H1N1 flu viruses.
That meant more Mallard ducks remained in Europe, where they could continue to transmit the flu to humans through water contaminated with bird droppings.
Climate change and Covid-19
The research on 1918 has eerie similarities to the current crisis, as many parts of the world appear to be entering a second wave of Covid-19, or remain in a prolonged first wave of the virus.
“It is really the convergence of our two major crises — man-made climate change and infectious disease,” More said. “Absolutely, climate is going to affect the likelihood of infectious disease outbreaks. It has in the past and it will in the future.”
According to More, the same patterns created by climate anomalies that affected the severity and spread of the 1918 flu pandemic are happening right now. And Covid-19 is not the only infectious disease impacted by climate change.
“Many other ongoing epidemics are affected by climate and especially man-made climate change. For example, zika and dengue fever are transmitted by mosquitoes, and now those mosquitoes are reaching places that they never reached before,” he said. “The same can be said about other bacteria and diseases throughout the world.”
In an unprecedented year that seems to bring one crisis after another, climate scientists say that it’s important to look at the connections between them, and how climate-related issues such as extreme weather, storm surges, wildfires, and homelessness created in the wake of natural disasters can create adverse conditions that allow infectious diseases to spread more easily.
“There’s no question that they are connected,” More said, adding that more interdisciplinary research is needed to better understand the links between climate change and pandemics.