Most of my friends, upon learning that I was raised in sunny California, are shocked to find that winter is my favorite season. Since first moving to this area in the mid-90s, I’ve relished in the fact that I now live in a place with seasons, a region of the country that enjoys subzero temperatures and frequent snow during the darkest months of the year. No wonder then that the Snow Miser from the classic cartoon ‘A Year Without a Santa Claus’ is my yuletide Facebook avatar.
Much to my dismay and my local friends’ glee, that has not been the case so far this year. In fact, until this past Tuesday when we received a dusting of snow hardened into place by relentless freezing rain, this region of the country has had abnormally warm temperatures. It was so warm on Christmas Eve, a stunning 72°F, that my husband and I drove out to my in-laws house with the convertible top down on my car. For the Northeast, this December will go on record as the warmest in over 200 years.
A lot of the warmth that we are experiencing, and the similarly unusual weather in other parts of the country – including unexpectedly low temperatures in the Southwest, snow and ice storms in the Southeast, tornadoes in Texas, and flooding in Missouri – can be chalked up to the cyclical weather pattern known as El Niño. But global climate change is also likely playing a major role in this year’s (and future year’s) extreme weather patterns.
El Niño, more appropriately called the warm phase of the El Niño Southern Oscillation (or ENSO), is a global pattern of climatic variation that occurs when an unusually warm band of seawater develops in the equatorial region of the Eastern Pacific Basin. It normally develops around December, thus giving this natural event is name; El Niño means can mean little boy, but more often means Christ Child in Spanish.
When it occurs, El Niño creates increased rainfall across the east-central and eastern Pacific Ocean. While the effects of El Niño are more direct and stronger in South America, it is also associated with warmer weather in the western and northern US states, and heavy rainfalls in the south and southeast.
El Niño is associated not only with the natural disasters that we have seen on the news this past week — where dozens of people in the Midwest and South lost their lives and hundreds more lost their homes to raging floodwaters and swirling tornados — it is also linked to outbreaks of infectious diseases that threaten the health and lives of millions more.
Until 1991, for example, the entire Western hemisphere had been free of cholera for more than 100 years. When the disease re-emerged in Peru, later spreading throughout South and Central America, it coincided with an El Niño event that resulted in much warmer than normal coastal waters.
Among the many hypotheses about the re-emergence of cholera in this part of the world is that the bacteria that causes the disease, Vibrio cholerae, was able to proliferate in these unusually warm waters which set the stage for increased exposure and transmission to humans. Cholera is now re-established in Central and South America, and it is only a matter of time before it re-emerges in the US. That may occur this year. The US National Oceanic and Atmospheric Administration (NOAA) predicts that this year’s event “could be among the strongest in the historical record,” and the average temperature of US coastal waters has similarly surpassed prior historical accounts.
Cholera is not the only disease that US public health officials are worried about with this year’s unusal weather. Cases of the disease Cryptosporidiosis can also be linked to unusual and increased rainfall patterns. The disease is caused by a chlorine-resistant parasite that normally infects cattle and waterfowl, but which can be transmitted to humans when our drinking water becomes contaminated with agricultural waste.
In the US, the largest outbreak of Cryptosporidiosis occurred in Milwaukee, Wisconsin, in 1993 when agricultural runoff from local pastures contaminated the water supplies of the Howard Avenue Water Purification Plant. Over 400,000 people contracted the illness and nearly 100 died, with one study suggesting that the outbreak cost nearly $100 million in medical treatments and lost productivity.
While the US has not had an outbreak on that scale since, sporadic epidemics often occur during times of flooding. I would not be surprised if there is a localized outbreak in Missouri in light of the record floods that El Niño has caused.
There are, in fact, a whole host of endemic, emerging and re-emerging diseases that we should worry about given this year’s unusual weather. These include not only diarrheal diseases like cholera and Cryptosporidiosis, but also mosquito-borne illnesses like dengue fever, chikungunya and malaria, as well as Lyme disease, rabies and spongiform encephalopathy.
However, while El Niño makes this situation bad, global climate change makes the problem even worse. During the last several decades, the number of El Niño events has increased, and studies of historical data suggest that the increased frequency and intensity of these events is linked to global climate change.
As the average temperature of our planet increases, so too will the likelihood of weather-triggered outbreaks of disease. Given this state of affairs, it is unfortunate then that most of our leaders in Washington, and the current slate of Presidential candidates, seem to be largely dismissive of the threat that climate change poses to the public health. Until the economic costs of disaster relief, medical treatment and lost productivity directly affect their bank accounts and those of their corporate backers, however, I fear that little will change.
[This blog entry was originally presented as an oral commentary on Northeast Public Radio on December 31, 2015, and is available on the WAMC website.]