Climate scientists don’t like surprises. It means our
deep understanding of how the climate works isn’t quite
as complete as we need. But unfortunately, as climate
change worsens, surprises and unprecedented events keep
happening. In March 2022, Antarctica experienced an
extraordinary heatwave. Large swathes of East Antarctica
experienced temperatures up to 40°C (104°F) above normal,
shattering temperature records. It was the most intense
heatwave ever recorded anywhere in the world. So shocking
and rare was the event, it blew the minds of the Antarctic
climate science community. A major global research project
was launched to unravel the reasons behind it and the damage
it caused. The results are alarming. But they provide scientists
a deeper understanding of the links between the tropics and
Antarctica – and give the global community a chance to
prepare for what a warmer world may bring.
The papers tell a complex story that began half a world
away from Antarctica. Under La Niña conditions, tropical
heat near Indonesia poured into the skies above the Indian
Ocean. At the same time, repeated weather troughs pulsing
eastwards were generating from southern Africa. These
factors combined into a late, Indian Ocean tropical cyclone season.
Between late February and late March 2022, 12 tropical
storms had brewed. Five storms revved up to become tropical
cyclones, and heat and moisture from some of these cyclones
mashed together. A meandering jet stream picked up this air
and swiftly transported it vast distances across the planet
Luck was on Antarctica’s side
The event caused the vulnerable Conger Ice Shelf to finally
collapse. But the impacts were otherwise not as bad as they
could have been. That’s because the heatwave struck in March,
the month when Antarctica transitions to its dark, extremely
cold winter. If a future heatwave arrives in summer – which
is more likely under climate change – the results could be catastrophic.
Despite the heatwave, most inland temperatures stayed below zero.
The spike included a new all-time temperature high of -9.4°C (15.1°F)
on March 18 near Antarctica’s Concordia Research Station.
To understand the immensity of this, consider that the previous
March maximum temperature at this location was -27.6°C (-17.68°F).
At the heatwave’s peak, 3.3 million square kilometres in East
Antarctica – an area about the size of India – was affected by the heatwave.
The impacts included widespread rain and surface melt along coastal areas.
But inland, the tropical moisture fell as snow – lots and lots of
snow. Interestingly, the weight of the snow offset ice loss in
Antarctica for the year. This delivered a temporary reprieve from
Antarctica’s contribution to global sea-level rise.
Learning from the results
This research calculated that such temperature anomalies occur
in Antarctica about once a century, but concluded that under
climate change, they will occur more frequently.
The findings enable the global community to improve its planning
for various scenarios. For example, if a heatwave of similar
magnitude hit in summer, how much ice melt would there be? If
an atmospheric river hit the Doomsday glacier in the West Antarctic,
what rate of sea level rise would that trigger? And how can
governments across the world prepare coastal communities for
sea level rise greater than currently calculated?
This research contributes another piece to the complex jigsaw
puzzle of climate change. And reminds us all, that delays to
action on climate change will raise the price we pay.
UNIVERSITY OF WOLLONGONG AUSTRALIA
Provided by the IKCEST Disaster Risk Reduction Knowledge Service System