As the H1N1 "swine" flu hit pandemic levels in early fall of 2009, comparisons with the 1918 Spanish flu grew. That event, according to reports published by the National Institutes of Health, claimed as many as 100 million lives around the world. There are both similarities and differences between the two events, but climate conditions may set the stage, at least in part, for the rapid global proliferation of the virus.
El Nino Grows
By early fall of 2009, a moderate to strong El Niño with a relatively unique pattern was forming in the Pacific and the H1N1 flu strain was making a vigorous resurgence after its spring appearance. A study published in the September issue of “The Bulletin of the American Meteorological Society” suggests that one of the strongest El Nino’s of the 20th century bearing the same unique pattern, may have coincided with the 1918 pandemic, and the study author questions the connection.
El Niño occurs when unusually warm surface waters form over vast stretches of the eastern Pacific Ocean, affecting weather systems worldwide. It may seem a stretch to tie the two together, but Texas A&M University professor of oceanography, Benjamin Giese, sees parallels in global climate conditions.
According to Giese, “The 2009 El Nino is strikingly similar to 1918 in that the largest warming is displaced to the west, unlike the El Nino events of 1982-83 and 1997-98, which have the greatest warming at the coast of South America.”
Cold Winter and Spring
Both time periods are also characterized by unusually low temperatures in North America during the preceding winter and spring just as the influenza started to spread in the region.
The parallels between 1918 and 2009 are not perfect, however. While 2009 saw a very cool spring in Canada (about four degrees C below normal), the United States had a slightly warmer than normal spring. In 1918, winter and spring were exceptionally cold in the central and eastern US.
In both cases, as is expected for off-season influenza, the virus became pandemic in the fall, and El Niño began to mature. El Nino generally peaks sometime between December and February, so, in November, Giese said it was still too early to say for sure how things would go. “There is no indication that the 2009 El Nino will be particularly strong, although it is growing rapidly right now,” said Giese. Most predictions suggest that the 2009 El Nino will be much weaker than 1918.
Brewing of the Perfect Storm?
While El Nino may not cause the H1N1 virus to appear or to spread, it may contribute to the course of the disease through the human population. The concept that seemingly unrelated factors converge under the right circumstances and timing to cause specific effects on human society is not new. Perhaps even moderately strong El Nino conditions with the unique pattern of 1918 and 2009, when combined with the emergence of H1N1, can create the right conditions for the virus to become a pandemic.
El Nino affects weather conditions important to society across the globe. For instance, it is well known that there is a connection between El Niño and the failure of the Indian monsoon. In fact, the exceptionally strong El Niño of 1918 coincided with one of the worst droughts in India. As India was also particularly hard hit by the pandemic, “It seems probable that mortality from influenza was high in India because of famine associated with drought.” said Giese, “So, it is likely that El Niño contributed to the high mortality from influenza in India.”
Overall, 2009 is considered a drought year in India. Monsoon rains started late, and up to July the drought was considered severe. However, the July rainfall looks about normal, and so the 2009 India drought is not nearly as severe as 1918.
El Nino's affects on weather in other parts of the world could have similar impacts on the severity of H1N1. As El Nino gears up Giese will be watching for the answer to his question “Could the events of 1918 be a harbinger of what might occur in 2009?”
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