Distinct Oceanic Apparent Temperature Responses to Global Warming Driven by Near-Surface Wind Speed

Human-perceived temperature changes, quantified as apparent temperature (APT), have been studied extensively over land but are less well understood over the oceans. APT combines temperature, humidity, and wind speed to provide a thermal comfort index. Oceanic APT trends and their drivers, particularly the role of near-surface wind speed (NSWS), remain unclear despite widespread air temperature (AT) increases. In this study, ECMWF Reanalysis v5 data for 1950 to 2023 are analyzed using a linear sensitivity framework to quantify the contributions of AT, relative humidity (RH), and NSWS to APT trends. Over land, AT is the dominant driver of global APT changes. Over the oceans, by contrast, both AT and NSWS are important, with their relative dominance varying by region: AT warming prevails in most areas, while NSWS cooling dominates across large parts of the Southern Ocean and the Eastern Tropical Pacific. A pronounced land–sea contrast is found: terrestrial APT rises faster than AT over 96% of the land, while oceanic APT warms significantly less than AT, with more than 30% of the ocean showing nonwarming or cooling APT trends. This divergence is primarily due to oceanic NSWS-driven cooling, especially strong in the Southern Hemisphere (−71%) compared to the Northern Hemisphere (−14%). These results reveal that oceanic thermal comfort is governed by the interplay between AT warming and NSWS cooling, with the role of wind shifting from beneficial moderator in the tropics to hazard amplifier in the Southern Ocean, highlighting the need to incorporate wind dynamics in marine heat stress and cold stress assessments.