Poleward Shift of the Major Ocean Gyres Detected in a Warming Climate

Abstract

Recent evidence shows that wind‐driven ocean currents, like the western boundary currents, are strongly affected by global warming. However, due to insufficient observations both on temporal and spatial scales, the impact of climate change on large‐scale ocean gyres is still not clear. Here, based on satellite observations of sea surface height and sea surface temperature, we find a consistent poleward shift of the major ocean gyres. Due to strong natural variability, most of the observed ocean gyre shifts are not statistically significant, implying that natural variations may contribute to the observed trends. However, climate model simulations forced with increasing greenhouse gases suggest that the observed shift is most likely to be a response of global warming. The displacement of ocean gyres, which is coupled with the poleward shift of extratropical atmospheric circulation, has broad impacts on ocean heat transport, regional sea level rise, and coastal ocean circulation.

Subsurface Ocean Warming Hotspots and Potential Impacts on Marine Species: The Southwest South Atlantic Ocean Case Study

“…During the past decades, a consistent poleward shift of the major subtropical ocean gyres driven by climate change has been reported, and a stronger surface ocean warming trend has occurred over the western boundary currents of the oceans (Wu et al, 2012;Yang et al, 2016Yang et al, , 2020. In the South Atlantic Ocean, a poleward displacement of the subtropical gyre at a rate of 0.11 • /decade has been observed (Yang et al, 2020), and the western boundary current -the Brazil Current (BC) -has been reported as one of the most extensive and intense surface warming hotspots in the global ocean (Hobday and Pecl, 2014).…”

“…During the past decades, a consistent poleward shift of the major subtropical ocean gyres driven by climate change has been reported, and a stronger surface ocean warming trend has occurred over the western boundary currents of the oceans (Wu et al, 2012;Yang et al, 2016Yang et al, , 2020. In the South Atlantic Ocean, a poleward displacement of the subtropical gyre at a rate of 0.11 • /decade has been observed (Yang et al, 2020), and the western boundary current -the Brazil Current (BC) -has been reported as one of the most extensive and intense surface warming hotspots in the global ocean (Hobday and Pecl, 2014). Although changes in the distribution and productivity of marine species have been recorded over faster ocean warming regions worldwide (Burrows et al, 2014;Sunday et al, 2015;Pecl et al, 2017), potential changes remain largely unexplored in the southwest South Atlantic Ocean (SWAO, see Franco et al, 2020).…”

“…The MC transports cold and nutrientrich waters northward along the continental slope and shelfbreak of Argentina, while the BC transports warm and salty waters southward along the continental slope and outer shelf of Brazil and Uruguay. Changes in sea surface temperature (SST), sea surface height (SSH) and numerical simulations indicate that the BC is shifting southwards 0.81-0.39 • /decade driven by the poleward displacement of the subtropical gyre (Goni et al, 2011;Lumpkin and Garzoli, 2011;Combes and Matano, 2014;Yang et al, 2020). Intense surface ocean warming hotspots in the SWAO have been observed mainly along the BC path and at the BMC (Yang et al, 2016(Yang et al, , 2020Oliver et al, 2018).…”

Große, windgetriebene Meeresströmungen verschieben sich polwärts

“… Ozeanzirkulation Darstellung der großen windgetriebenen Ozeanzirkulation (schwarze Pfeile) und ihrer Verlagerung (weiße Pfeile) unter globaler Erwärmung (nach ). …”

“…Mit unserer Methode kann man auch abschätzen, wie groß der anthropogen verursachte Trend gegenüber natürlichen Fluktuationen ist, und wie schnell sich die Ozeanzirkulation verschiebt. Demnach bewegt sich die großräumige Zirkulation mit einer durchschnittlichen Geschwindigkeit von 800 Metern pro Jahr polwärts . Auch die Aufzeichnungen der Ozeansedimente vom Meeresboden, die vergangene Klimawechsel aufzeigen können, zeigen, dass während der letzten Eiszeit vor 21000 Jahren Teile der Ozeanzirkulation im Vergleich zu ihrer heutigen Position 800 km näher am Äquator gelegen haben.…”