30/01/2019

Australia's Heard Island: A Mysterious Land Of Fire And Ice

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.
A map showing the location of Heard Island and the McDonald Islands. 
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.
A map of Heard Island and the McDonald Islands. 
"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.
The McDonald Islands group has doubled in size over the past 30 years due to volcanic activity. 
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.
A hotspot under Heard Island and the McDonald Islands is responsible for the volcanic activity in the region.
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.
The islands are mostly composed of phonolitic low-silica pumice, dikes and lava domes, and sit atop an underwater plateau known as the Kerguelen plateau. (Supplied: Matt Curnock and Australian Antarctic Division)
 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.
Australia's new icebreaker, RSV Nuyina, is seen under construction in Romania. (Supplied: Damen/AAD)
"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."
Robb Clifton, Tim Curtis, Stu Davies and Matt Rogerson on the summit of Mawson Peak on Big Ben in 2000. (Supplied: Robb Clifton and Australian Antarctic Division)
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.
Researchers investigate glacial retreat on Heard Island caused by climate change. (Supplied: Doug Thost)
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.
Patagonian toothfish is caught predominantly by longline in deep waters in the remote Southern Ocean, however the species is unsuitable for intense fishing. (Supplied: Austral Fisheries) 
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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2 comments :

  1. Nice post.pics are looking so good.poveglia island ghost adventures is also an island.

    ReplyDelete
  2. Really this island have an mystery.i am also visit your blogs regular.lake natron is also an mysterious place in the world.

    ReplyDelete

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