Extract from ABC News
By Antarctic reporter Jano Gibson
In short:
Australian researchers have chronicled the impact of climate change on Antarctic glaciers by creating a 3D model of how they looked more than six decades ago.
The 3D model was developed using powerful software to stitch together hundreds of historical images taken by US cartographers in 1968.
What's next?
The researchers say photogrammetry could be used to create 3D models in other parts of Antarctica.
In 1968, an aircraft flew over the Larsen B ice shelf on the edge of the Antarctic Peninsula.
On board were US Navy cartographers taking photographs of the icy landscape below.
Hundreds of those black-and-white images have now been transformed into a 3D model that reveals the impact of climate change on glaciers in the region.
"The information that these images contain about such a remote and often inaccessible location is priceless," University of Wollongong PhD candidate Ryan North said.
The Larsen B ice shelf was the size of a large city, but in 2002, it rapidly disintegrated into the ocean.
The extraordinary event was captured in a series of satellite images.
"After a few summers of unusually warm temperatures and ocean temperatures, it actually suddenly collapsed over the course of a week," Mr North said.
"So, an area of more than 3,000 kilometres squared… shattered and then turned into complete icebergs and melted away."
The collapse of Larsen B has had a major impact on five neighbouring glaciers, Mr North said.
Without an ice shelf to protect them from the ocean, the glaciers have experienced a significant reduction in their volumes over the past two decades.
Mr North was able to calculate the scale of that reduction by comparing his 1968 model with observations from 2001 and 2021.
"After constructing an accurate 3D model of the landscape using more than 850 photos, I found the glaciers were essentially unchanged between 1968 and 2001, just before the collapse occurred," Mr North said.
"After the collapse, I measured at least 35 billion tonnes of land-based ice was lost to the ocean from five glaciers.
"This is the equivalent [of] every single person on the Earth tipping out a one litre water bottle every day for 10 years."
Mr North estimated the combined ice loss from the five glaciers had the potential to increase sea levels by just under 0.1 millimetres.
While it might sound insignificant, he said the trend of warming temperatures, particularly in the Antarctic Peninsula, was cause for concern.
"[This was] one event in a decade [and] it contributed that much," Mr North said.
"And when you put that into scale, that is quite scary, because these things will keep happening in one way or another as climate change continues."
Powerful software used to create volumetric representation
Mr North's 3D model was developed using photogrammetry, which harnesses powerful software to stitch hundreds of 2D photos into a volumetric representation of a subject matter.
While the technique is not novel, he said the US Navy's archive of Antarctic images was an untapped treasure trove for researchers like himself.
Between 1946 and 2000, more than 300,000 images were captured as the cartographers criss-crossed the frozen continent.
"Historical images like those taken by the US Navy can extend the record of glaciers by decades."
Mr North's research is the subject of a new paper which has been published in the journal Scientific Reports.
It was co-authored with Professor Timothy Barrows from the University of New South Wales.
Mr North said photogrammetry based on historical Antarctic images could be applied in a variety of ways.
"In addition to glaciers, it can allow us to view sea ice extent, penguin colonies, moss growth, or freshwater lakes from up to 80 years ago."
"Archived data can be incredibly valuable and there are another 299,000 images waiting to be analysed."
No comments:
Post a Comment