Climate change and El Niño pushed explosive hurricane ‘Polo’ to the highest category

In barely a day, hurricane Polo, which formed in late September in the Pacific off the coast of Mexico, reached the highest category — level 5, corresponding to winds above 252 kilometers (156 mph) per hour. It was the second most powerful tropical cyclone recorded in the Pacific to date. Polo later weakened before making landfall as a storm — at category 2 — in Baja California Sur, Mexico. It left behind torrential rains, floods and infrastructure damage in northwest Mexico and the southwestern United States, and five deaths linked to those floods in Mexico.World Weather Attribution (WWA), an international group of scientists that produces studies estimating the influence of human-caused climate change on extreme weather events, has analyzed this explosive hurricane and its rapid intensification. Scientists from Mexico, the United States, the United Kingdom, Ireland and the Netherlands who collaborated on the study evaluated the atmospheric and oceanic conditions that produced the storm’s notably rapid intensification. They conclude that climate change was at least as influential as El Niño in contributing to that rapid strengthening.Polo formed near the epicenter of El Niño, the cyclical natural phenomenon characterized by warmer-than-usual sea surface temperatures in the tropical eastern Pacific. But El Niño, which this year is reaching record levels, is also disrupting many other parts of the world, fueling droughts, floods, and extreme heat.WWA researchers examined sea surface temperature, air temperature, and humidity conditions. They say climate change “made the conditions that fed hurricane Polo roughly 23 times more likely.” At the same time, “El Niño also strengthened the storm,” making “the conditions roughly 14 times more likely.” “Climate change is amplifying natural climate cycles,” the rapid attribution study concludes.Scientists, on a positive note, emphasize that “despite Polo’s rapid intensification at sea, human losses were small thanks to a successful emergency response and because the storm struck a sparsely populated region.” They therefore stress the importance of early warning systems so communities can be prepared for extreme events that are becoming more frequent, more intense, or both.The relationship between El Niño and climate change is still under study, and there are no clear conclusions about their links. In other words, the role that warming plays, if any, in the formation and development of this cyclical event is unknown. But, as Ben Clarke, a researcher at Imperial College London and one of the WWA investigators, has pointed out: “It is important to remember that every El Niño happening now is occurring in a warmer world” because of climate change.Simon Stiell, the UN climate chief, has noted that the “El Niño phenomenon is already raising the risk level for the Pacific hurricane season.” “This new study [referring to WWA] shows how climate change is increasing the danger and costs associated with storms, as humanity continues to burn vast amounts of coal, oil, and gas.” The solution, Stiell added, is to “accelerate the transition to clean energy and invest in early warning systems and resilient infrastructure to protect people and economies exposed to these threats.”Sign up for our weekly newsletter to get more English-language news coverage from EL PAÍS USA Edition