Health & Science
A world of difference
by Veronika Meduna
New Zealand professor Peter Barrett, this month honoured for decades of Antarctic research, has predicted the end of civilisation as we know it within the century unless global warming is curbed.
When Kiwi Peter Barrett was finishing his degree in 1961, he was more interested in caves than Antarctica. He had plans for a PhD in speleology. But a chance introduction and a serendipitous discovery sealed a lifelong connection with the frozen continent.
More than four decades later, the quietly spoken “supremo of the geological drilling community” received the inaugural Scientific Committee for Antarctic Research President’s Medal in front of hundreds of fellow Antarctic scientists at a conference in Hobart last week. It was the latest in a string of awards he’s had for his outstanding achievements in Antarctic research.
His first major discovery was in his graduate student days at Ohio State University’s Institute of Polar Studies. In 1967, he was on a geological expedition, high up in the mountains at the head of the Beardmore Glacier, close to the South Pole route followed by Shackleton and Scott.
Crawling over a sandstone bluff to check a pebbly layer, he spotted a stone that looked like nothing else – and clinched one of the scientific debates of the time. That small fragment of fossilised jawbone belonged to a salamander-like creature that lived 200 million years ago in the early Triassic period. This “missing link” was the first evidence that land vertebrates had roamed Antarctica when it was warmer. What’s more, the fossil belonged to a group of long-extinct freshwater amphibians also known to have lived in both South America and Australia – and so Barrett’s discovery validated the theory of continental drift and the southern supercontinent Gondwana, then both controversial ideas.
“When Antarctica was part of Gondwanaland, it was a green continent,” says Barrett, now professor of geology and director of the Antarctic Research Centre at Victoria University. “It had rivers, plains, forests, reptiles, amphibians and even dinosaurs, and we know quite a bit about that because the records are preserved in the layers of rock in the transantarctic mountains. We find river sands, from which we can tell which way the rivers were flowing and how big they were, we find coal beds, tree stumps – we can tell the nature of the climate from the tree rings – and of course the bones of reptiles and amphibians.”
Right from those early days, Barrett’s focus has been on Antarctica’s climatic history and its role in global climate. He says understanding past ice-sheet behaviour has increasing relevance with satellite monitoring “now showing the beginnings of Antarctic ice melting around the edges”. This is why, when it comes to global warming, he doesn’t mince his words. He caused a stir last year when he predicted that we will be facing the end of civilisation as we know it by the end of this century unless there is determined action to curb global warming. He stands by that statement.
“In the next 100 years, climate scientists are projecting that the global climate will be between two and six degrees warmer. Even if temperatures are in the lower part of the range, the increase in storm power and the extremes of flooding in some areas and droughts in others will profoundly affect people around the world. If temperatures are in the upper part of that range, the Earth will return to the climate it once had before the big ice sheets formed on Antarctica 34 million years ago. It would be a different world from the one that both humans and large mammals evolved in, and it would be a very difficult place in which to survive, let alone live comfortably.”
Barrett’s interest in Antarctic sediment cores and what they could reveal began in 1973 when he was one of three “lucky Kiwis” on an expedition aboard the Glomar Challenger, the first research vessel equipped for deep-sea drilling. After drilling in the Ross Sea, the team brought up sediment cores with layers of glacial deposits and mud that showed Antarctic glaciation had begun more than 20 million years earlier than previously thought. A few months later, another cruise led by New Zealander Jim Kennett obtained the first isotope records of climate from the deep sea, confirming that Antarctica’s icy coat began to spread across the continent about 40 million years ago.
Barrett went on to lead several drilling projects in McMurdo Sound, culminating in the multinational Cape Roberts Project during the late 1990s. The team drilled three holes, down to 1500m, near the edge of the mountains and recovered a remarkable “sedimentary tape recorder”, verifying that massive ice sheets had covered Antarctica around 34 million years ago. However, the cores also showed that the ice was highly dynamic, coming and going in response to climate variations and perturbations in the Earth’s orbit, known as Milankovitch cycles, which affect the amount of radiation that the planet receives.
A key element in the success of these projects, Barrett says, has been his former student Alex Pyne, who has worked on the drilling technology since 1979. With Webster Drilling in Porirua, Pyne has just completed development of an even bigger drilling system for ANDRILL, another multinational consortium, to drill through the Ross Ice Shelf – 100m of ice, 900m of water and 1000m into the sea floor.
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