ABC
Australia's tallest mountain — with its active volcano — is one of the country's best-kept secrets, and holds clues to understanding the Earth's past and its future.
Credits
Journalist: Marty McCarthy
Graphics: Kate Doyle
Photography: supplied by Pete Harmsen, Doug Thost, Matt Curnock, Kieran Lawton, Karl Rollings, Kate Kiefer, Michael Trapp & Australian Antarctic Division |
Even if you could get to Australia's most remote island, chances are you still wouldn't quite see it.
The little-known landmass, Heard Island, hides in dense cloud for around 360 days a year.
The
rare few who do reach this distant wonder are more likely to hear the
gurgle of molten rock bubbling up through the island's violent core.
The
active volcano on Heard Island, known as Big Ben, is adorned with vast
glaciers stretching to the crashing waves of the ocean far below.
At a soaring 2,745 metres, it is 517m taller than Mount Kosciuszko,
giving it the little-known title of the tallest mountain in
Australian-owned territory excluding Antarctica.
Heard Island takes seven days to reach by boat from Fremantle.
The
4,000-kilometre journey over rough and stormy seas is usually
undertaken only by fishermen and the occasional research scientist.
Doug Thost, a former glaciologist with the Australian Antarctic
Division, which administers the island, has made the journey twice. He
describes it as a "danger and a privilege".
Humanity
deserves to know a bit more about this place; it is a jewel in the
southern Indian Ocean. I'd hate to see it loved to death, but I'd love
to see it on Australia's list of things to do from a research
perspective," he told the ABC.
"Being
in such a remote and wild place is pretty humbling. You have to be very
aware of the potential danger you could be in and how unlikely it is
that you could be rescued if something does go wrong, but it's
invigorating."
One of Dr Thost's colleagues almost died traversing the island.
Fifteen years ago, on Christmas Eve, Dr Thost and his colleague were
climbing one of the glaciers, Brown Glacier, to study how fast it was
melting.
The island acts as a sentinel for a warming planet and the impacts of climate change in the Southern Ocean.
"We
were at the top of the glacier and my co-researcher and I turned around
to go back. We were roped up, thank God, because my colleague suddenly
fell into a crevasse. He was a dead weight hanging down there for a
bit," Dr Thost said.
The colleague survived but the incident highlighted one of the many perils of the remote subantarctic island.
The weather can be equally as nasty. Wind speeds at Heard Island can average about 33 kilometres per hour.
Dr
Thost once recorded a 200kph gust on the glacier — equivalent to a
category three cyclone. The winds can whip up a blizzard on a glacier in
an instant.
Australia's Hawaii, but colder
Big Ben formed
about one million years ago and now looks like a classic volcano —
conical, built up over the years by layers of hardened lava, tephra,
pumice and ash, with smoke billowing from the top.
It would be
bigger if the cooled lava was not in constant battle with glacial ice.
At the lava cools, the expanding ice on the glaciers shatters the rock,
and the fragments get carried down to the sea.
While Heard Island
is larger, the volcanic action on the smaller McDonald Island group,
about 43km to the west, is much more violent.
"Big Ben oozes runny lava, but McDonald Island explodes," said Jodi
Fox, a graduate student in volcanology at the University of Tasmania.
The
lava at McDonald is thicker, which traps the gas inside until it almost
reaches the surface and then when it does, the gas expands rapidly and
causes the explosion.
McDonald
became Australia's second active volcano when it broke its 75,000-year
dormancy in 1992, according to UNESCO. A large eruption in 1996-97 saw
the island double in size to 2.4 square kilometres.
"That part of Australia is growing. Heard is probably producing small
lava flows every few months, so it is gradually getting bigger," Ms Fox
said.
Ms Fox was part of a team of researchers aboard the CSIRO's
Investigator research vessel in 2016 that mapped the seafloor around
the islands in search of underwater volcanoes.
"There
are features that are almost certainly volcanoes below the surface as
well, they just don't have names and we don't know what the extent of
their volcanic activity is yet," she said.
Mike Coffin, the chief scientist on that trip, said it was hard to
measure the growth of the islands even above the ocean surface. Access
to Heard Island is largely restricted to keep it free of introduced
animal pests. The volcano itself has only been successfully climbed
three times.
"The height of Heard Island at Mawson Peak appears to
have grown. Officially Heard is 2,745m, but we think it's now about
2,813m. We'd love to take a helicopter with a device to measure it
properly, but the winds are usually too strong for drones or
helicopters," Professor Coffin said.
Tom Trull, principal research scientist and marine biochemist for the
CSIRO in Hobart, also studied the islands during the 2016 research
trip, and said it was unlike any Australian landscape he had ever seen.
"Both islands are a contrast, and beautiful in different ways," Dr Trull said.
"Heard
has its big high cone with glaciers glistening in the sun and a plume
of ash coming out the top and black lava pouring down the side, and
vegetation and wildlife at the bottom.
"Then you go to McDonald.
It's a small, fuming, stinky, hot, covered bunch of rough rocks that you
couldn't imagine stepping on. It's somewhere between idyllic and
hellacious; it's like another planet," Dr Trull said.
Researchers believe the islands are formed by the Kerguelen Hotspot — similar to the way the Hawaiian Islands are forming.
A
hotspot is a place where an unusually high flow of convective heat,
known as a mantle plume, rises from deep within the earth. The plume
melts through the earth's crust, forming a volcano.
"The source of
their volcanic material is deep in the earth — about halfway down to
the core — about 2,900 kilometres down," Professor Coffin said.
Volcanoes are more common at the boundaries of tectonic plates, where
plates split or collide and magma escapes. That type of volcanism is
well understood and proven but hotspots are not.
"These very
deep-rooted volcanoes that sit in the middle of tectonic plates, like at
Heard and McDonald, would make up less than 5 per cent of the earth's
volcanoes. Hawaii would be the most well-known example," Professor
Coffin said.
The plume hypothesis is not universally accepted, but
it is the most widely cited explanation for how volcanoes form far away
from plate boundaries.
One of the reasons behind the addition of Heard and McDonald Islands
to UNESCO's World Heritage List in 1997 was their potential clues to
understanding this process better, and its role in the formation of
ocean basins and continents.
"They [the islands] offer an active
example of plume volcanism, providing direct geological evidence of the
action of the longest operational plume system known in the world,"
UNESCO said.
Researchers also believe if it were not for the volcanoes, marine
life would not exist in such an abundance in this harsh part of the
world. The volcanoes act as a food source, of sorts.
"The
island's volcanic activity is a source of iron. Iron enters the water
and fertilises phytoplankton productivity in the Southern Ocean," Dr
Trull said. "Phytoplankton are the plants of the sea."
Smaller animals, like krill, eat the phytoplankton. Crustaceans and fish then eat the krill. Birds and seals eat the fish.
"Like
on land, any animal can eat another animal, but first an animal has to
feed on a plant. So the whole history of volcanic activity has made the
island, not just physically, but also biologically," Dr Trull said.
"Most
of the Southern Ocean has very low levels of [marine life]
productivity, but around these islands the levels are high. So the first
question is, 'Why are they are high?'"
A forgotten gift from Britain
When Captain John Heard of the
merchant vessel Oriental made the first official sighting of Heard
Island in 1853, he thought it was a massive iceberg that had drifted
from Antarctica.
The captain's wife wrote in her diary: "the sun
seemed so dazzling on the water, and the tops of the apparent icebergs
covered with snow. We were all the time nearing the object and on
looking again, the captain pronounced it to be land".
The first
landing happened two years later, and the island became a base for
sealers who hunted elephant seal, fur seal and sometimes penguins. One
hundred thousand barrels of elephant seal oil were made there before the
practice ended in 1877, giving way to an era of scientific expeditions.
Britain's HMS Challenger paid the islands a visit in 1874 to collect
scientific samples. Australian geologist and Antarctic explorer, Douglas
Mawson, visited Heard Island in 1929.
The United Kingdom formally
claimed the islands in 1910 but transferred them to Australia in 1947.
However, Australia's interest in the islands' research potential dried
up once Mawson Station was established on Antarctica in 1954 and the
base on Heard closed the following year.
The most recent expedition to Heard was in 2016 by RV Investigator —
it took a team of 40 scientists for six weeks. Mike Coffin, the
expedition's chief scientist, said that trip took eight years to plan,
and no-one stepped off the boat.
"I would like to see Australia
set a year-round research station there and give it the attention it
cries out for. It is a fascinating place geologically, biologically,
chemically, and physically. But its costs would be in the millions of
dollars per year," he said.
Australia's spending on subantarctic research mostly goes to Antarctica, such as the new
$2-billion icebreaker vessel currently being built for reasons that are becoming increasingly political.
Despite
countries like China and Russia having no territorial claims to
Antarctica, both have recently started investing heavily in the region.
China is
building research stations and airfields and is calling for
more access to the continent.
The Australian Government announced a $200 million funding boost to the Antarctic program in 2016.
"Science is the currency of Antarctica, that's how you make your reputation on Antarctica," Professor Coffin said.
A
ban on mining in Antarctica comes up for renegotiation in 2048 when the
Antarctic Treaty System (ATS) expires. Mineral exploitation aside,
there is a concern countries are eyeing Antarctica for its strategic
importance:
it's an ideal place to build satellite receivers and global positioning systems (GPS).
Robb
Clifton from the Australian Antarctic Division, who is also one of a
handful of people to successfully climb Big Ben, acknowledges many
scientists want a permanent research base established on Heard Island,
but says doing so could taint it.
"There really is not a need for a
research station now. We needed it in the past to help us get to
Antarctica. But in terms of having a small ecological footprint there,
there isn't a requirement to build a station there. We have a
subantarctic station on Macquarie Island, which means Heard is left to
be a very wild and largely untouched place."
A canary in the coal mine for climate change
Researchers
argue a permanent presence on Heard Island is critical because they
believe it holds clues to understanding not only the earth's formation,
but also its future.
Heard Island has 12 major and several minor
glaciers that together cover 70 per cent of the island. They are shallow
and fast flowing, meaning they respond very quickly to a warming
climate.
UNESCO said the glaciers on Heard were responding to
climate change "faster than any glaciers elsewhere, making them
particularly important in monitoring climate change".
When Dr Thost made his last visit to the island in 2003, that's
exactly what he was doing. For four days a week over two-and-a-half
months he climbed glaciers, clocking up 25 vertical kilometres by the
end of the expedition.
"Based on our study of Brown Glacier over a
period from 1947 to 2004, it lost 29 per cent of its original area. In
1947 the glacier stretched all the way to the ocean and ended in a
20-metre-high ice cliff, but now it has retreated by nearly 600m," Dr
Thost said.
Dr Thost said from the 1940s to 2003 the temperature on Heard had
increased by 1 degree Celsius in the winter months, and .8 of a degree
in the summer months. He pointed to climate change.
"Heard and
McDonald Islands are the frontier between cold Antarctic conditions and
more temperate conditions. Heard Island is a sentinel island, like a
canary in the coal mine. It is telling you that something is happening
and temperatures are changing along that convergence."
Wildlife's playground
As the glaciers retreat, they create lagoons and exposed beaches, enabling wildlife to thrive.
Three
species of seal live on and around the islands. There are also two
endemic bird species, the Heard Island sheathbill and Heard Island
cormorant. Fifteen species of flying birds breed there as well as four
species of penguin.
Antarctic cod and icefish live in the shallow nearshore waters while
crustaceans, skates, toothfish, and even lantern fish reside further
out.
The human-sized Patagonian toothfish, which lives more than 2
kilometres below the water's surface and is prized globally for its
sweet omega-3 rich flesh, is often a target of illegal fishers.
Since 1997 Australia has operated a legal fishery in the area, for toothfish and mackerel icefish.
"It's an amazing place. You feel liked you walked into a David Attenborough special," Dr Trull said.
Part
of UNESCO's decision to grant the islands world heritage status was
because of their biological purity. Heard is the only subantarctic
island virtually free of introduced species. That purity is reflected in
the behaviour of the wildlife that inhabit it.
"The penguins are
so curious, they aren't fearful of humans, so they come up to the boat
and get so excited that they get silly. They dive and jump like
dolphins, trying to get a look at the boat, and they just look stunned,"
Dr Trull said.
"The entire place is stunning, and it's ours. It's
our volcano and glaciers and animals. It startles me that Australians
think of their beaches and red deserts, but they don't know about this
other part of their landscape."
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