GREENFIELD — With 95-degree heat waves, Greenfield’s temperatures in May resembled summertime highs, not spring’s typical transition to the hottest season of the year. May 20, which peaked at 95 degrees, marked the hottest May 20 ever recorded in Greenfield, according to data from the National Oceanic and Atmospheric Administration (NOAA) that dates back to 2000. Similar data in nearby Amherst, which dates back to 1893, also identified May 20 as its hottest on record. Over the last 10 years, May temperatures in 2022, 2017, and 2016 came the closest to this May’s heat with 93.9 degree days, according to the U.S.
Climate Data website. Michael Rawlins, the associate director of the Climate Research Center at the University of Massachusetts Amherst, traced these highs to rising levels of greenhouse gases in the atmosphere heating up the climate. “Under a warming climate, we’re essentially loading the dice in that it’s much, much more likely to see record high temperatures over a given month or year than it is to see record lows,” Rawlins explained. In the same month, temperatures dropped to 32 degrees in Greenfield on May 3, the month’s coldest chill.
Although these temperature swings may brought whiplash to residents as they switched between tank tops and sweaters, Rawlins described this as typical patterns with weather, a science known for its curveballs. “Temperatures swing back and forth… nothing stays right at the normal,” Rawlins said. “That’s weather.” Although the climate scientist said a May with hot and cold days indicates “normal weather variability,” he added that global warming is stretching the gaps between these highs and lows as temperatures continue to rise. “What we think is normal would not be normal to people living back in the 1800s,” Rawlins said. “Our normals are skewed.” In 1893, the oldest year on record in Amherst, the hottest May day was 85 degrees, 10 degrees lower than this May’s 95-degree heat, according to NOAA data. NOAA also recently predicted an 82% chance of an El Niño occurring this summer before making its way to the Northern Hemisphere this winter. An El Niño refers to a natural climate pattern of weaker trade winds that push warmer water in the Pacific Ocean toward North and South America. Climate scientist and Tufts University professor Erin Coughlan de Perez told PBS that an El Niño could cause heat waves across the United States, especially in the North, flooding in the South and wildfires in the Rocky Mountains. “If that El Niño builds, the impact will be probably profound,” Rawlins said.
With a looming El Niño and warming climate, Rawlins predicts twice as many days with record high temperatures as record low temperatures this year, worsening the “adverse impacts” on plants and animals, like trickier tick seasons that have already attacked the moose population in Maine. For Rawlins, curbing greenhouse gas emissions represents the only solution for mitigating climate change and its “host of impacts.” “If we don’t start reducing our reliance on fossil fuels and [mitigating] the impact on the atmosphere and thus our climate, then we’re going to see many more record highs set, and we’re going to see more cases of extreme heat events and other extreme weather events,” Rawlins said. “The atmospheric concentrations of carbon dioxide and methane, they have to come down, and they’ll only come down once we stop pumping the gases into the atmosphere.”