Monday , June 21 2021

Scientists dig deep for the missing part of the climate



"Every time we handle a sample, it's terrible – it only takes one mistake to ruin weeks of work."

If the facts, the conclusions of the six-year project led by CSIRO Ambassador David Eteriridge and You Petreno from the University of Rochester in the United States can bear their own measure of terror, depending on how they turn out.

The role of carbon dioxide, a primary greenhouse gas, has been known for over a century, including how it is eventually removed from the atmosphere by absorption into the oceans or terrestrial plants.

But what has actually happened with about 40 other gases, including methane, hydrofluorocarbons and ozone-depleting chemicals, over the decades since industrialization proved to be less well understood.

– We know very well how [these gases] are produced. We need to know how quickly they are removed, "said Etheridge from Melbourne's warmer frontiers this week.

"Without that we have only part of the puzzle, part of the equation."

The question is something like that.

We know that the hydroxyl radicals that bind oxygen and hydrogen act as atmospheric scrubbers, destroying non-CO2 greenhouse gases such as methane.

The Ice Dome Ice Coal Station, 120 km from Casey Station.

The Ice Dome Ice Coal Station, 120 km from Casey Station.Credit:AAP

These gases contribute to one-third of the additional warming we cause on our planet by capturing extra heat from the sun in our atmosphere.

Hydroxyl is naturally produced in the atmosphere, but it is so reactive that the radical lasts only about a second before it destroys the pollutant molecule and itself.

"Because the hydroxyl is so volatile, so short and so volatile in time and space, it's actually difficult to quantify even in the modern atmosphere," he says.

All the more, we have little idea whether this critical cleaner has grown or decreased in abundance from pre-industrial times – with consequences for future emissions.

The oxidation process involving hydroxyl is actually critical to maintaining methane in the supporting role it is in, and not actually becoming a leading intruder for warming the atmosphere, "Nef said.

The consequences – depending on how the results are revealed – may include requiring re-calibration of the main climate models underlying the Paris climate agreement, to which nearly 200 countries have joined.

"All [the models] make the assumption of fundamental reactivity [of hydroxyl in] "This is the first real test of this part of these models."

Making this test was not an easy feat, but it involved more than the strange "touch and flicker," he says.

The rough round of cuts planned by the CSIRO management, announced three years ago next week, led to the overall project within a few days after being crippled. The public pressure in Bulgaria and internationally turned out to save many scientists from the boilers, including this project.

Lately, the challenges are mostly physical, including coping with bitter cold temperatures that often fall below minus 20 degrees, and heavy snowfalls coming from work at Law Dome, about 120 miles east of Australia's base base at Casey.

Etheridge has been involved in decades of atmospheric research and knew that the Law has special qualities that scientists need. In particular, the site happens to have some of the worst snowfalls anywhere.

"Here we have about 10 times higher mean snow in Antarctica – 120 centimeters a year, compared to five to 10 centimeters," Nef said. "He buries the ice much faster than anywhere else.

Drilling ice cores to analyze the air caught in compressed snow is routine for polar ice scientists for decades. In the case of hydroxyl hunting, however, such samples of air are particularly valuable.

David Eetridge and colleague working in a snow blizzard at Law Dome.

David Eetridge and colleague working in a snow blizzard at Law Dome.

Researchers will not find the radical ingredient because the hydroxyl is not stored for a certain period of time in a container, not to mention hundreds of years on ice. Rather, scientists want a proxy molecule – carbon-14 isotope of monoxide – which will indirectly reveal the abundance of hydroxyl in the past.

Carbon-14 is produced by reaction with cosmic rays outside of the solar system, but the heavy snowfall at the Law Dome acts as an "x-ray shield."

Snow protects the air in the deeper ice so that carbon-14 is not produced by cosmic rays that would otherwise change its level compared to its original atmospheric quantities.

Nef says there are no better places for training.

"This is literally the only place on the planet where we can get large amounts of fresh air that is not compromised by this aspect of carbon-14 we are looking for," he says.

Of course, finding that evidence is hardly skis in the back.

Scientists usually sleep in tents for mountaineering, housed in a summer sleeping bag, during the winter. The snowfalls are such that the staff hardly increase over time, fighting snowfalls, Nef said.

The crew worked 77 days straight to complete six drilling operations, extracting about 5 tons of ice. The average value of the three deepest drills provided scientists with ice dating back to around 1875.

This is early enough to catch the air before the biggest increase in greenhouse gases. For example, methane emissions have risen by about 200% since the late 1880s, Nef said.

Inside the ice core drilling tent.

Inside the ice core drilling tent.Credit:Joel Pedro

People have also released many industrial chemicals with different capabilities to warm the planet, affect the stratospheric ozone layer and contribute to local pollution during this time, which may have contributed to the hydroxyl cleaning load.

Experiments are so delicate, but drills can not use drilling fluids that would otherwise allow them to go deeper, say, 1750, when the industrial era begins roughly.

This sensitivity to eventual pollution also extends to the placement of the scientific tent about 50 meters from the other building – mainly modified sea containers – to avoid pollution from the diesel generator of the camp.

Work can be intensive, not least because the ice must be treated immediately, extracted to keep as much as possible the purity of the cores.

"They become like hot potatoes, where they suddenly find themselves on the surface and bombarded by the full cosmic stream," Nef said.

Instead of transferring the ice thousands of kilometers to remote laboratories, it melts and the key evidence is placed in stainless steel tanks. About 20 of them, weighing about 10 pounds each, will make their trip to Casey and then when the camp comes in the next few days.

Nef, who is also a geologist, says work has gone better than expected.

"We have absolutely everything we wanted to do," he says. Samples "are absolutely perfect and cleaner than we thought".

At least another year of testing is expected, including the ANSTO nuclear facility at the southwestern tip of Sydney.

Eterjge, who helped to secure himself Sun-Herald and Sunday of age with a tour of the world-famous air archive of CSIRO at Aspendale in Melbourne's Sand Cave last week, says his "sense of intestines" is that the abundance of hydroxyl will be proven to be on the sliders.

"From my reading of evidence and chemistry, I would expect to see a decline in the industrial period of hydroxyl, I expect it to have diminished," he said, stressing that the results of this project have not been tested.

"I look forward to finding me wrong.

Findings will be reinforced by similar work in the northern hemisphere, such as Greenland's glazing, although these nuclei are likely to be much dirtier than in Antarctica.

The consequences, however, of evidence of a reduced ability to destroy methane – which has now been living in the atmosphere for about a decade – will be deep, depending on the scale of each decline.

In addition to raising the methane warming potential – whether released from coal mines or natural gas fields – the potential of hydrogen to serve as "clean fuel" can also be called into question. (The workforce this week is putting out a $ 1 billion plan to set up hydrogen-exporting zones in Queensland to feed it with a huge increase in renewable energy.)

"Hydrogen is a very leaky molecule, and we will have to expect that there will be leaks in its production," said Etheridge, adding that hydrogen itself has a greenhouse effect.

"It may not matter, but we do not know.

Nef says that while he is away from his family for 100 days is difficult, he is proud that his work will answer some of the biggest questions of climate science.

"We do not want to work blindly, [about] how much influence we have on the entire earth system, "he says.

Etherage compares the work of his team with that of space research, where scientists collect information that is useful for something later that can not yet be expected.

He notes that CSIRO and other scientific agencies have begun to signal climate change as a threat in the 1980s and before the warming signal became clear beyond the background noise of natural variations.

"Now the signals are everywhere," he says.

"Here we have a question of a trillion dollars – letting the atmosphere go, business as usual and we are not interested, or we will cut emissions and try to rule the planet.

"We are trying to deal with this question with millions of dollars of science – that's not a bad return."

Peter Hanam writes on environmental issues about The Sydney Morning Herald and The Age.

Most viewed in the environment

Loading


Source link