Our next talk is an online virtual presentation that really highlights the important role that
Antarctica plays in influencing weather and climate in our region, and particularly the
flow-on effects that can result from a small change in one location thereby thereby causing
major disruptions thousands of kilometres away. The presentation is by Professor Dana Bergstrom
and it's called 'Biodiversity, extreme events and butterfly wings'. Dana is an integrative
ecologist who leads AAD's terrestrial biodiversity research in Antarctica and
sub-Antarctic Macquarie Island. Dana collaborates broadly on really big picture questions and last
year she was awarded the 2021 Eureka prize for leadership and innovation in science.
Hi I'm Dana Bergstrom, I'm an integrative ecologist and we focus on a number of things
in terrestrial ecological research. Firstly the fundamental documenting of living values. Our
recent major focus has been on the assessment of biodiversity in the Vestfold Hills.
We carry out horizon scanning for threats such as non-native species ... managers with
conservation decision making and we examine change both in space and time such as here
using satellite imagery to map change on World Heritage Heard Island. But today I want to talk
about examining change in Antarctica and placing it in context with elsewhere. We've been trying to
understand what happened during the first six months of 2022. It's not a resolved story by
any means but gives the flavour what we in our BoM/CSIRO/University collaborators do.
Widespread calamity is how I would describe this year. In March a heatwave hit Antarctica.
Temperatures deep inland rose to 40 degrees above normal, complete with a huge dump of snow.
Luckily temperatures failed to rise above zero. At Casey we had plus 5.6 degrees.
Adelies had left for the sea but mosses would have been woken up and wet at a time
they were preparing to shut down for winter and pollutants would have been mobilised in the soil.
Records broke in February on Macquarie Island with a 18 degree day and the highest rainfall
ever recorded for the month. This would provide pressure on the threatened endemic
keystone cushion plant which is under attack from a pathogen. On either side of the Antarctic heat
wave, multiple storms and flood events occurred in Australia between Brisbane and Wollongong. Massive
multiple flooding occurred in the Mary, Brisbane, Wilson, Richmond, Hawkesbury and Nepean Rivers.
Drought however was reported for Southwest Tasmania. Storm surges washed away beaches
and flooded coastal areas such as near Bondi Beach. Flooding resulted in multiple pressures
including fuel spills near an oil refinery in Botany Bay and coral bleaching was widespread
along the Great Barrier Reef. Other observed biological impacts included loss of seagrass,
dugong's food in Moreton Bay, death in turtles, fish, weedy sea dragons and temperate corals.
On the west coast of New Zealand there was an extraordinary death of sponges.
The impact of short-term extreme events can have long tails. In the past they have been
reported to last for at least a decade. So how did it happen? It began the year in a La Nina
with normal things happening. The Madden-Julian oscillation moving tropical air west to east.
The La Nina warm marine water heat tongue coming south. Tropical cyclones and storms
in the Indian Ocean and blocking high pressure systems occurring repeatedly south of Australia.
But what wasn't normal - the first butterfly wings - was the ocean temperatures. Marine
heatwave conditions all around the continent of Australia that stretched out to the west
coast of New Zealand. We are thinking this energy supercharged the weather systems.
The ocean released heat into the atmosphere across the Indian Ocean and the Tasman Sea sectors.
Seven tropical storms and five cyclones formed in the Indian Ocean, more than normal. One cyclone,
Vernon in the Indian Ocean, sent warm moist tropical air southward. It ran into a blocking
high below Australia. This created an atmospheric river that funnelled heat and moisture deep into
Antarctica. Oh and did I mention a small ice shelf, the Conger, collapsed. This possibly
was also linked to the lower summer sea ice, ever. So two more sets of butterfly wings.
Blocking highs also sent Tasman Sea moisture northward combining with east coast lows,
again creating atmospheric rivers, this time flooding the east coast of Australia.
And the East Australian current delivered tropical waters along the coast two degrees above normal.
And the last kicker butterfly wings was in the tropics. The Madden-Julian oscillation oscillates
through eight phases. In February it didn't get much past phase two. Any moisture that cools the
northern parts of Queensland during La Nina didn't arrive and this contributed to the coral bleaching
of the Great Barrier Reef. BoM colleagues think this has to do with the Tongan volcano sediments
in the atmosphere. So a taste of the very complicated jigsaw puzzle of weather observations
that we hopefully are turning into climate and ecological knowledge. And finally I'd like to
acknowledge the 80 plus colleagues all over the globe who are part of these investigations.