Hydro International –
Oceanographers have identified a series of ocean ‘hotspots’ around the world. Strengthening wind systems have driven a number of oceanic currents, including the East Australian Current, polewards beyond their known boundaries.
The hotspots have formed alongside ocean currents that wash the east coast of the major continents, and their warming is proceeding at a rate far exceeding the average rate of ocean surface warming, according to an international science team, whose work is published in the journal Nature Climate Change.
Paper co-author, CSIRO’s Dr Wenju Cai, said that while the finding has local ecological implications in the region surrounding the hotspots, the major influence is upon the ocean’s ability to take up heat and carbon from the atmosphere.
In Australia’s case, scientists report intensifying east-west winds at high latitudes (45º-55ºS) pushing southward and speeding up the gyre or swirl of currents circulating in the South Pacific, extending from South America to the Australian coast.
The resulting changes in ocean circulation patterns have pushed the East Australian Current around 350 kilometres further south, with temperatures east of Tasmania as much as two degrees warmer than they were 60 years ago.
CSIRO’s climate scientist at CSIRO’s Wealth from Oceans Research Flagship Dr Wenju Cai said that detecting these changes has been hindered by limited observations but with a combination of multi-national ocean watch systems and computer simulations CSRIO have been able to reconstruct an ocean history in which warming over the past century is 2-3 times faster than the global average ocean warming rate.