The world's strongest ocean current should be getting
faster - instead, it is at risk of failing.
Antarctica's remote and mysterious current has a profounp
influence on the climate, food systems and Antarctic
ecosystems. Can we stop it weakening by 2050? The
Antarctic Circumpolar Current is the strongest ocean
current on the planet. It's five times stronger than the Gulf
Stream and more than 100 times stronger than the
Amazon River. It forms part of the global ocean "conveyor
belt" connecting the Pacific, Atlantic and Indian oceans.
The system regulates Earth's climate and pumps water,
heat and nutrients around the globe. But fresh, cool water
from melting Antarctic ice is diluting the salty water of the
ocean, potentially disrupting the vital ocean current.
The Antarctic Circumpolar Current is like a moat around
the icy continent. The current helps to keep warm water at
bay, protecting vulnerable ice sheets. It also acts as a
barrier to invasive species such as southern bull kelp and
any animals hitching a ride on these rafts, spreading them
out as they drift towards the continent. It also plays a big
part in regulating the Earth's climate.
The influence of climate change:
Ocean currents respond to changes in temperature, salt
levels, wind patterns and sea ice extent. So the global
ocean conveyor belt is vulnerable to climate change on
multiple fronts. Previous research suggested one vital part
of this conveyor belt could be headed for a catastrophic
collapse. Theoretically, warming water around Antarctica
should speed up the current. This is because density
changes and winds around Antarctica dictate the strength
of the current. Warm water is less dense (or heavy) and
this should be enough to speed up the current.
Far-reaching consequences:
The consequences of a weaker Antarctic Circumpolar
Current are profound and far-reaching. As the main current
that circulates nutrient-rich waters around Antarctica, it
plays a crucial role in the Antarctic ecosystem. Weakening
of the current could reduce biodiversity and decrease the
productivity of fisheries that many coastal communities rely
on. It could also aid the entry of invasive species such as
southern bull kelp to Antarctica, disrupting local
ecosystems and food webs.