Global Surface Temperatures Above 17.0°C for Six Days; Ocean SST Sets 55th Consecutive Daily Record

ERA5 reanalysis from Copernicus Climate Change Service shows daily global mean surface temperature above 17.0°C since late July 2024. This streak follows the 2023-2024 sequence where the threshold was first breached. Niño 3.4 sea-surface temperatures currently sit at +1.8°C, feeding sustained heat into the atmosphere. Ocean skin temperatures reached a new daily record 0.14°C above the prior July 26 maximum, 3.8 standard deviations above the 1991-2020 baseline.

The 55-day streak of daily ocean temperature records coincides with reduced Saharan dust and IMO 2020 sulfur cuts that lowered marine cloud albedo. These factors compound the developing El Niño. Full-year 2027 now carries greater than 50% probability of exceeding 1.70°C above 1850-1900 per updated CMIP6 ensembles conditioned on current trajectories. Daily peaks above 17.5°C are projected with 35% likelihood next boreal summer.

Operational impacts include accelerated coral bleaching across the Pacific and Indian Ocean basins, poleward migration of commercial fish stocks, and elevated tropical cyclone rapid intensification rates. Marine heatwave duration has already doubled relative to the 1982-2012 climatology in the North Atlantic. No near-term reversal appears in seasonal forecasts from ECMWF or NOAA CPC.

Next three months will test whether August ocean temperatures establish a new annual maximum before the typical late-March peak. Persistent anomalies above 2.0°C monthly would confirm breach of Paris Agreement long-term limits within the current El Niño cycle.