A record El Nino, still growing
The El Nino that formed in the Pacific this summer has already tied the all-time record for daily strength. Carbon Brief analysis of NOAA data shows the daily Nino 3.4 sea surface temperature anomaly reaching 3.07 degrees Celsius above the long-term average in October, higher than the peaks of 1997 and 2015.
Forecasts point to a monthly peak near 4.2 degrees Celsius above average in December, well above anything measured since 1850. The World Meteorological Organization says central and eastern tropical Pacific sea surface temperatures are expected to rise to record levels during October, November and December.
Water piled up along the California coast
One effect is already visible on the other side of the ocean. Weak trade winds allowed a bulge of warm water near Indonesia to drift east along the equator. When it reached South America, the continents blocked it and it split north and south, becoming what scientists call a coastally trapped Kelvin wave.
Sea levels along Southern California are running about a foot above normal, and the wave is expected to keep moving north toward Oregon and Washington. Daniel Swain, a climate scientist at UCLA, said this is about as large as Kelvin waves get and described the El Nino as unprecedented, driven by extremely strong westerly wind bursts. Flooding from heavy surf already forced the evacuation of about 20 homes in Long Beach last month.
What comes next
Kelvin waves raise the baseline sea level, so ordinary winter storms and high tides push further inland. Beaches and cliffs face more erosion, coastal roads flood more often, and marine life shifts as warm water spreads. Because global temperature responds to the ocean with a lag of months, much of the warming signal from this event is expected in 2027, on top of a year that is already tracking as the warmest or second-warmest on record.
The drought and fire side of the pattern is showing up too. Indonesia's fire season has produced emissions on track to match the record for this century, and dry conditions have driven haze across Southeast Asia. Forecasters say the event may also linger further into 2027 than earlier models suggested.