What’s notable to scientists isn’t just the potential scale of the event, but the speed of the transition. According to Nat Johnson, a meteorologist with NOAA’s geophysical fluid dynamics laboratory, last winter’s conditions were still consistent with a La Niña, the cooler counterpart phase in the same Pacific oscillation cycle. Moving from that baseline to a potentially record-setting El Niño within roughly a year is an unusually rapid shift, and researchers say it isn’t yet clear why this year’s swing has been so pronounced, or what role, if any, climate change is playing in it.
