Team explores how oceans respond to global warming with a study of “feels like” temperature
image: A and B show long-term trends of apparent temperature (APT); C and D show long-term trends of air temperature (AT); and E and F show the difference between APT and AT trends (ΔT = APT trend − AT trend). Panels A, C, E show global spatial distributions. Panels B, D, F show zonal-mean averages over ocean (blue) and land (red). Over land, APT rises faster than AT over more than 96% of the area. Over the ocean, however, APT warms significantly slower than AT, with more than 30% of the ocean showing no significant warming or even cooling—a pattern particularly pronounced in the Southern Hemisphere.
Credit: Longshi Liao, Simon F. B. Tett, Hairong Li, Zichen Li, Boyang Jiao, and Qingxiang Li
Temperature, humidity, wind analyzed
A research team set out to discover how the apparent temperature, or “feels like” temperature, over the ocean differs from the apparent temperature on land and found that a pronounced land-sea contrast is evident.
Their research was published in the journal Ocean-Land-Atmosphere-Research on May 22, 2026.
Human influence has brought climate changes in the atmosphere and oceans. In the last 50 years, there has been large-scale development of marine-based industries, including fishing, offshore energy production, maritime transport, mining, and tourism. Along with this growing development, there are concerns about its health impacts on marine workers.
It is important for scientists to understand the changes in human-perceived temperature over the oceans and the factors that drive these changes. This apparent temperature (APT) combines temperature, humidity and wind speed to provide a thermal comfort index – the “feels like” temperature.
Earlier research has been focused mainly on changes over land. Over land, it is well established that human-perceived temperature (such as APT, one of the human-perceived temperature indices) is rising much faster than air temperature. “But what happens over the ocean, where vast marine economies are rapidly growing? This study set out to answer a fundamental question: how do oceanic APT trends differ from those on land, and what roles do temperature, humidity, and wind play in driving these differences?” said Longshi Liao, a Ph.D. student at Sun Yat-sen University.
The research team quantitatively separated the contributions of each factor – temperature, humidity, and wind – during the period from 1950 to 2023. “We aimed to uncover whether the ocean responds to global warming in the same way as land in terms of how it is actually felt by humans—and, if not, why,” said Liao.
They used the European Centre for Medium-Range Weather Forecasts (ECMWF) Reanalysis v5 data for their study. ERA5, produced by Copernicus Climate Change Service, is the fifth-generation ECMWF atmospheric reanalysis of global climate.
Over the past 70+ years, the ocean has experienced a remarkably slower warming in human-perceived temperature than the land—and over more than 30% of the ocean, APT has shown no significant warming or even cooling, despite widespread rises in marine air temperature. “The key to understanding this stark land–ocean contrast lies not in temperature alone, but in wind,” said Liao.
Over land, near-surface wind speed plays a negligible role in large-scale APT trends; over the ocean, however, it acts as a powerful natural "air conditioner" with enhanced winds producing a substantial cooling effect that offsets a large portion of the warming from rising air temperatures. There are also differences between the Northern Hemisphere and Southern Hemisphere. This wind-driven cooling also explains the pronounced hemispheric asymmetry over the oceans. In the Southern Hemisphere, wind contributes a cooling of −71%, far stronger than the −14% in the Northern Hemisphere, making Southern Ocean APT warming particularly sluggish and even causing cooling in some regions. “In short, it is the unique role of wind over the oceans that fundamentally shapes how global warming is actually felt at the sea surface, creating both a striking land–ocean divide and a strong north–south asymmetry in oceanic thermal comfort changes,” said Liao.
“As the ‘blue economy’—including offshore wind energy, shipping, fishing, and marine tourism—continues to grow rapidly, ensuring the health and safety of marine workers under changing thermal conditions becomes increasingly urgent,” said Liao. The research team’s next steps include: (1) investigating how wind variability modulates the frequency and intensity of extreme apparent temperature events (both heat and cold extremes) over the oceans; and (2) developing early warning systems and adaptive strategies tailored to marine occupational settings, to provide precise scientific support for policy-making and operational safety in marine industries. “Our ultimate goal is to establish a comprehensive marine human thermal risk assessment framework that fully incorporates wind dynamics,” said Liao.
The research team includes Longshi Liao, Hairong Li, Zichen Li, and Qingxiang Li from Sun Yat-sen University; Simon F.B. Tett from the University of Edinburgh; and Boyang Jiao from Guangzhou University.
The research is funded by the National Key Research and Development Program of China, the Natural Science Foundation of China, the Wellcome Trust, and the Department of Education of Guangdong Province.