Warming Oceans Driven by Shifting Winds and Western Boundary Currents
Unsettling changes in the planet’s wind patterns are heating ocean currents and reshaping marine environments, especially near the poles. This trend threatens the ecosystems and the livelihoods of thousands of people. Australian researchers have traced why and how ocean hot spots emerge so rapidly by studying the winds that drive currents warming these regions.
Researchers from the University of New South Wales in Sydney have observed that broad shifts in strong wind patterns are accelerating the warming of westerly currents in the southern hemisphere, altering climates and habitats across the globe.
Western ocean boundary currents, including the East Australian Current, transport substantial heat toward the Earth’s poles. They play a pivotal role in moderating coastal climates worldwide. In recent years, zones extending toward the poles have warmed at two to three times the global average, forming ocean hot spots. Yet the reasons behind this rapid heating remained unclear for some time.
In a published study in Nature Climate Change, UNSW researchers have unraveled the mystery behind this phenomenon.
The team found that accelerated warming results from climate change nudging easterly winds to drift southward in mid-latitudes. Lead author Junde Li explained that this shift increases poleward spillover of the Western Boundary Current, generating large ocean eddies that trap and transport warm waters toward higher latitudes.
Impacts on the livelihoods of hundreds of millions of people
These wind-driven changes redistribute heat, dissolved gases, and nutrients across the oceans, altering local weather patterns and marine ecosystems. Western boundary currents in the Southern Hemisphere touch the lives and livelihoods of hundreds of millions of people along the coasts of South Africa, Australia, and Brazil.
In southeast Australia, the warming trend is alarmingly swift. Periods of record-high coastal water temperatures have been documented, with February 2022 standing out as particularly intense. Co-author Professor Moninya Roughan observed that hotspots are stressing coastal species and potentially driving irreversible habitat loss. Warmer waters have pushed south along the east coast, carrying many species away from their traditional ranges, including sea urchins off Tasmania. The resulting impacts have also affected kelp forests and the local economy, including tourism and the crayfish industry, which depend on healthy coastal habitats.
Li noted that while the study centers on the southern hemisphere, its implications may extend to the northern hemisphere and its western boundary currents, such as the Gulf Stream, offering clues about what triggers ocean warming and marine heatwaves in other regions as well.
As the atmosphere continues to warm, oceans are expected to follow suit. There is a need to develop high-resolution datasets that illuminate the dynamics of global heat transfer. Such data can help scientists predict and prepare for the impacts of warming on marine ecosystems, coastal communities, industries, and broader climate change challenges.
Researchers emphasize that understanding these dynamics will assist in forecasting regional shifts and formulating responses to protect vulnerable ecosystems and human communities affected by changing ocean conditions. The findings contribute to a broader effort to map heat distribution and its effects on ocean chemistry, biology, and weather patterns across continents. This body of work is supported by ongoing analysis in Nature Climate Change, with the 2022 study contributing a crucial perspective on winds, currents, and heat transport.
Reference work: Nature Climate Change, 2022.
…
Environment department contact details were previously listed in informal notes but are not part of this publication.