So far, the RONI has been running a bit cooler than the previous index, known as the Oceanic Niño Index, or ONI, which does not take the effects of human-caused global warming into account. Instead, the ONI just looks at the temperature departures from average in a benchmark region of the tropical Pacific. This may make it more likely that this El Niño will set an intensity record using the ONI rather than RONI, although the latter has other advantages. |