Extract from ABC News
Tasmania's rugged coastline is home to the Kennaook/Cape Grim air monitoring station. (Supplied: CSIRO)
The 80-metre tower and small scattering of sheds perched on the cliffs of Tasmania's remote north-western edge seem fairly unassuming.
But it was this site that helped deliver the receipts to prove something monumental: that humans are changing the Earth's climate.
The Kennaook/Cape Grim Air Quality Testing Station, run by a small team of scientists, has also delivered proof that change can happen when the world comes together.
And on its 50th birthday, this place that's been chronicling the air for half a century may be more important than ever.
The view of Kennaook/Cape Grim from a drone.
One world, one atmosphere
Graeme Pearman, a former CSIRO scientist, was one of the few people there from the start — setting up what would become one of the world's most important stations for tracking human-induced changes to the global atmosphere.
Its early days were unglamorous.
Equipment was housed in an old NASA caravan, once used during the Apollo missions.
Graeme Pearman helped establish the Cape Grim Baseline Air Pollution Station 50 years ago.
The story of how Dr Pearman ended up there began far from the rugged clifftop overlooking the Southern Ocean.
In the early 1970s, he was measuring carbon dioxide (CO2) above a wheat crop on another project when he noticed something curious.
The Cape Grim air monitoring station was initially run out of an old NASA caravan, used in an Apollo mission. (Supplied: CSIRO)
The concentrations were almost identical to those being recorded on the other side of the world by scientist Charles David Keeling, who had been tracking CO2 levels in Hawaii.
It didn't seem to make sense.
"We couldn't understand why two hemispheres that were very different — one hemisphere covered by ocean primarily, one by land primarily; one with lots of people and one with not so many people — why would the concentration be so similar?" he said.
But over the next year, through an aircraft-based observational program, he came to realise his measurements were right, and supported suspicions shared by Dr Keeling.
CO2 levels were rising across the globe, and fossil fuels were to blame.
"I [didn't] believe that Mother Nature [could be] so flimsy that humans [could] really interfere with it,"he said.
Over the next three years, plans were made to establish a permanent Australian background observing station, jointly managed by the Bureau of Meteorology and CSIRO, now known as Kennaook/Cape Grim.
Technology has vastly changed since the early days of the site. (Supplied: CSIRO)
Bottling the cleanest air on Earth
For 24 hours a day, air is drawn from the surrounding coastline through inlets — one located 80m up a tower — and analysed in real time.
But what the station captures is far from local. It's why the site is one of just three "premier" global stations.
An interview with CSIRO scientist Melita Keywood at Kennaook/Cape Grim.
Strong westerly winds from the Southern Ocean, known as the "roaring forties", put the station directly in the path of air that has travelled thousands of kilometres without touching land.
It makes it some of the cleanest on the planet.
And for scientists, it's gold.
For 24 hours a day, air is drawn from the surrounding coastline through inlets and analysed in real time. (ABC News: Jano Gibson)
CSIRO scientist Melita Keywood, who leads the aerosols and reactive gases program at Cape Grim, says measurements taken there reflect the true global background atmosphere, without the interference of local contamination.
"Once we see a change in the clean air that we're measuring at Cape Grim, we know that something's happened globally. So that's what's really important about Cape Grim," Dr Keywood said.
"A lot of things that we're interested in do have an impact on people, on human health, and ecosystem health as well."
The Cape Grim site is part of a global network of air monitoring outposts and the only one of its kind in Australia. (Supplied: CSIRO)
Each season, air samples are also bottled and stored at the air archive in Melbourne — the oldest in the world — which allows researchers to go back and test the air for gases that haven't been studied in the past.
More recently, donated scuba tanks have also been added to the collection, extending their records back even further.
How has the world changed in 50 years?
One of the clearest stories shown in the site's data is the rising concentration of the greenhouse gas CO2.
Just as Dr Keeling's early measurements in Hawaii suggested, CO2 — the main driver of human-caused warming — has been climbing steadily.
What was around 330 parts per million in 1976 is now above 420.
On its own, that increase is significant.
But placing it alongside ice core records, which can extend back hundreds of thousands of years, reveals the true scale.
"This is an enormous change in the composition of the atmosphere that occurred in a period of less than 100 years and was not observed anywhere near that size change over the last million years," Dr Pearman said.
The story of the ozone hole
While Cape Grim's greenhouse gas data keeps climbing, another data set has had a remarkable turnaround.
Soon after opening, the station began measuring chlorofluorocarbons (CFCs) — a gas that would later be linked to the ozone hole over Antarctica.
From the late 70s to the 80s, they rose rapidly, driven by widespread use in aerosol cans, refrigeration and manufacturing.
But in the 1990s, after the establishment of the Montreal Protocol — a global agreement to phase out ozone-depleting substances — levels began to fall.
While British scientists discovered the "hole" over Antarctica in 1985, Cape Grim's long-term record helped confirm the cause, and later track the recovery.
CSIRO scientist Paul Krummel, who leads the greenhouse gas and ozone-depleting substances program, said the data even helped detect illegal emissions of CFCs coming out of China in the 2010s.
"We noticed that CFC-11 was not decreasing at the rate that we thought it should be," Dr Krummel said.
"And, because we're part of a global network, through that we traced it to illegal emissions and production in eastern China."
Paul Krummel at the CSIRO's Kennaook/Cape Grim air archive at Aspendale in Melbourne. (ABC News: Jordan Young)
The realisation led to international pressure — and a crackdown on the illegal production.
The recovery of the ozone layer is widely considered one of the most successful global environmental responses, showing how unified global action can spark change.
Uncertainty looms for 'Cinderella science'
Lacking the flashy discoveries of hypothesis-driven science, the work at Cape Grim is sometimes labelled as "Cinderella science".
But Dr Krummel said it underpins much of what we know about the atmosphere.
"You can't really mitigate what you can't measure," he said.
An aerial view of the Cape Grim air monitoring station in Tasmania. (Supplied: CSIRO)
The observations have also helped prop up climate models and informed both national and international policy.
Yet, as the world barrels past another global emissions record, Cape Grim's 50th birthday comes at an uncertain moment for science.
In Australia, the CSIRO is facing significant cuts to its research divisions, including reports of over 100 job losses in its Environmental Research Unit, which houses atmospheric sciences like that of Cape Grim.
In an open letter, Australian Meteorological and Oceanographic Society (AMOS) president Sarah Perkins-Kirkpatrick said long-term monitoring depended on sustained investment and expertise, and that protecting that capability was "essential".
"Reductions in scientific capacity risk undermining the datasets that underpin our understanding of environmental change," Professor Perkins-Kirkpatrick said.
"Ensuring that this work can continue is vital — both for Australia's contribution to global climate science and for our ability to adapt to the changes ahead."
In the United States, President Donald Trump has already taken the axe to major climate and science agencies, with further cuts on the table.
The National Oceanic and Atmospheric Administration (NOAA) has already faced significant cuts in the US, with proposals for more on the table. (Getty Images via AFP)
Proposals have been put forward to scale back major climate and science programs — including the original Mauna Loa observatory in Hawaii.
Dr Keywood said it would be "a significant loss", as each site played an important role in piecing together the bigger global picture.
"Stations in the northern hemisphere, the one at Mauna Loa in particular, [are] when we see things changing first," Dr Keywood said.
"But by the time they move to the southern hemisphere, and we measure them at Cape Grim, there's a bit of a lag.
"They're all different bits of information that are really important to bring together to understand the big picture, especially if we want to predict what's going to happen to the future.
"We need to understand all of those different processes."
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