by Sarah Blunt ‘17
Eavesdropping on my classmates’ conversations around campus on a particularly cold day a few weeks ago (all in the name of science), I was surprised to hear the words “El Niño,” and “global warming” almost as often as “cold,” “brr,” and “polar vortex.” I remembered learning about El Niño in high school, but I couldn’t see how it related to global warming, if at all. I decided to do some digging, to inform the population of Brunonia once and for all about what El Niño is, how it’s measured, and how it relates to global warming.
El Niño is a result of the continuous exchange of water between the Earth’s atmosphere and its largest ocean, the Pacific. (It’s just a large-scale water cycle). Periodic disruptions in this cycle that stem from massive, planet-traversing ocean waves cause pressure differences between the ocean and the water-vapor-filled atmosphere. These differences are cyclical, just like the massive waves that cause them, and therefore have both high and low pressure extremes. El Niño occurs when the difference between the pressures of the atmosphere and the Pacific is lowest, and is characterized by increased precipitation and higher temperatures in equatorial regions of the Earth. Since the Earth’s atmosphere flows (it’s a fluid, after all, mostly made up of water vapor), these El Niño conditions can have far-reaching effects all around the globe . In Rhode Island, for example, the average temperature during an El Niño year is almost 2 degrees hotter than during a normal year! 
Scientists measure El Niño by calculating a quantity known as the Southern Oscillation Index (SOI). Floating buoys in the Pacific measure air pressure, then send their data to climatologists, who calculate the departure from what they think the pressure should be. If the pressure difference is large, the scientists can decide whether El Niño or another weather phenomenon is the cause .
The SOI is a measure of departure from the expected pressure difference between the Pacific Ocean and the atmosphere. Values below -8 indicate El Niño events [image via]
El Niño is fairly unpredictable, occurring anywhere from every 2 to every 7 years. Scientists have not yet discovered whether global climate change will have an impact on the frequency or intensity of El Niño events, but it is a current hot topic for research. Might the super storms of the past ten years be linked to a deadly combination of climate change and El Niño? Climate scientists are scrambling to find out .
Although the Providence cold snaps we’ve been feeling recently are not the results of an El Niño event, the interest in El Niño and its relationship to global climate change is justified. Climate change tinkers with the delicate ecosystems put in place over millions of years of evolution, and a change of a few degrees can set off a domino effect that we hadn’t anticipated. To fight climate change, we need to look creatively at the problem, and think about phenomena we might not have thought to be linked. El Niño is a starting point, but if we want to fully understand our role in what is happening to our planet, it should only be the beginning.