Climate Change: Satellites Record History Of Antarctic Melting

BBC - Jonathan Amos

Ice shelves can extend under the water for many hundreds of metres. Getty Images

Twenty-five years of satellite observations have been used to reconstruct a detailed history of Antarctica's ice shelves.These ice platforms are the floating protrusions of glaciers flowing off the land, and ring the entire continent.

The European Space Agency data-set confirms the shelves' melting trend.

As a whole, they've shed close to 4,000 gigatons since 1994 - an amount of meltwater that could all but fill America's Grand Canyon.

But the innovation here is not so much the fact that the shelves are losing mass - we already knew that; relatively warm ocean water is eating their undersides. Rather, it's the finessed statements that can now be made about exactly where and when the wastage has been occurring, and where also the meltwater has been going.

Some of this cold, fresh water has been entering the deep sea around Antarctica where it is undoubtedly influencing ocean circulation. And this could have implications for the climate far beyond the polar south.

"For example, there've been a couple of studies that showed that including the effect of Antarctic ice melt into models slows global ocean temperature rise, and that can actually lead to an increase in precipitation in the US," explained Susheel Adusumilli from the Scripps Institution of Oceanography in San Diego.

Artwork: Esa has flown a continuous series of radar satellites since the early 90s. ESA

Mr Adusumilli and colleagues analysed all of the observations made by Esa's long series of radar altimeter missions - ERS-1, ERS-2, EnviSat and CryoSat-2.

These spacecraft have tracked the change in thickness in Antarctica's ice shelves since the early 1990s.

Combining their data with ice velocity information from other sources, and the outputs of computer models - the Scripps group has gained a high-resolution view of the pattern of melting during the study period.

As might be expected, there's been quite a lot of variation, with mass loss and gain, even within the same individual shelf. And the rate of mass loss over time has also gone up and down. But the overall picture is clear: the shelves are wasting.

"We see that melting is always above the steady state values," Mr Adusumilli told BBC News. "You need some amount of melting just to keep the ice sheet in balance. But what we've seen is an amount of melting by the ocean that is more than is needed to keep it in balance."

The fascinating aspect to this study is that the scientists can also now trace precisely where at depth the melting is occurring. Some of these floating platforms of ice (the biggest is the size of France) extend many hundreds of metres below the sea surface.

The researchers can tell from the satellites' data whether the wastage is happening close to the thinnest parts of the shelves or at their fronts, or deep down in those places where the glacier ice coming off land first becomes buoyant and starts to float.

"That kind of information can tell us a lot about the melting processes involved, how they're working - and the effects that meltwater can have," said Scripps' Prof Helen Fricker.

"So, it's not just that the shelves are melting. It's how they're melting - and where their meltwater is being injected into the ocean."

Scripps

Thinning ice shelves do not contribute directly to sea-level rise. That's because the floating ice has already displaced its equivalent volume of water.

But there is an indirect consequence. If the shelves are weakened, the land ice behind can flow more quickly into the ocean, and this will lead to sea-level rise. This is happening, and has been measured by other satellites.

Prof David Vaughan is the director of science at the British Antarctic Survey. He was not connected with the study which is published in Nature Geoscience.

He told BBC News: "The Scripps team has produced a map of Antarctica that shows thinning around the margin in a strip of mottled red and blue colours. The detail at the coastline is absolutely phenomenal.

"We really can now identify the parts of ice shelves that are most crucial to the story of thinning. There'll be a lot of oceanographers spending a lot of time looking at where the melting and the thinning is actually occurring, and trying to work out exactly why those areas have been affected."

Links

• Coronavirus severely restricts Antarctic science
• Thwaites: Journey to the 'doomsday glacier'
• Deepest point on land found in Antarctica
• Carbon Emissions Are Chilling The Atmosphere 90km Above Antarctica, At The Edge Of Space
• Biggest Ice Sheet On Earth More Vulnerable To Melting Than Thought
• First Active Leak Of Sea-Bed Methane Discovered In Antarctica
• (AU) Australia Wants To Build A Huge Concrete Runway In Antarctica. Here’s Why That’s A Bad Idea
• What An Ocean Hidden Under Antarctic Ice Reveals About Our Planet’s Future Climate
• 'Nowhere To Hide': South Pole Warms Up With Climate Change A Factor
• Climate Change Turning Antarctica's Snow Green
• Climate Change Is Turning Antarctica's Snow Green And The Effects Can Now Be Seen From Space
• Doomsday: By 2300, Global Sea Levels Could Rise by An Astounding 16 Feet

(AU) National Fire Monitoring Agency Needed To Track Rising Threats: Paper

Sydney Morning Herald - Peter Hannam

The lack of nationally consistent data on bushfires resulted in an overestimation of the extent of last season's bushfires by as much as a quarter, while also hindering longer-term preparations to cope with climate change, scientists say.

Researchers led by the University of Tasmania's David Bowman say Australia needs a national monitoring agency to track trends for everything from ignition sources – such as thunderstorms or arson – to the ecological impact of more extreme fires and the effectiveness of suppression efforts, such as prescribed burning.

The lack of a national database of bushfires and their impacts is making it harder to adapt to the changes brought by a warming, drying climate, researchers say. Credit: Nick Moir

"Precise real-time information about the area burnt and the intensity of the fires was not available when it was needed," the researchers wrote in an article published in Nature on Thursday. "In other words, we’re navigating uncharted territory without a compass."

Using satellite imagery, they found the area burnt since July 2019 was 30.38 million hectares compared with 39.8 million estimated by the National Indicative Aggregated Fire Extent Datasets assembled by the states.

While the satellite data also indicated the area of eucalyptus forest burnt was overestimated by about 19 per cent, the 5.67 million hectares charred was still likely to be the most on record. The tally amounted to about one-fifth of the forests and was 7.5 times the average burnt during the 2001-18 years, the researchers found. The official estimates count in patches that satellites indicate were not burnt.

"We need historical, solid data to contextualise the strange things we're observing in the bushfire space," Professor Bowman said. "Imagine if every state reported weather slightly differently."

The creation of a national monitoring agency would enable the public, researchers and the government to better understand the frequency, extent and severity of bushfires, including the impacts on biodiversity.

Social impacts from economic disruption, greenhouse gas emissions from the fires and also the health effects from bushfire smoke would also be better tracked with such a body, he said.

Understanding the impact of smoke from bushfires better would be one aim of a new national data service. Credit: Walter Peeters

Professor Bowman said he and other scientists had to come up with new datasets to prepare their submission to the NSW Bushfire Inquiry, with similar approaches needed for the latest royal commission into bushfires.

"Pretty everyone of these has to reinvent the discipline of pyrogeography, and assemble data," he said.

The national standards would also be able to monitor better the impact of so-called hazard-reduction burns on reducing bushfires in different vegetation types. That knowledge is likely to be increasingly necessary as southern Australia's warming and drying climate make big fire seasons more likely.

"It’s truly incredible what happened [last season], the scale and the shock of this huge event," Professor Bowman said. "We need to understand what’s going on with fire because fire is certainly changing."

Separately, a research paper also published in Nature on Thursday has found tropical soils are "highly sensitive" to temperature changes.

The study, by researchers including Patrick Meir from the Australian National University, found that warming soil on an island in Panama by just 4 degrees triggered a rise in carbon dioxide emissions by 55 per cent.

As the tropics contain about a third of the world's carbon stored in soil, "even a small increase in respiration from tropical soils could have a large effect on atmospheric carbon dioxide concentrations, with consequences for global climate", the researchers said.

Links

• Wildfires: Australia needs national monitoring agency
• ‘Deathly silent’: Ecologist describes Australian wildfires’ devastating aftermath
• The race to decipher how climate change influenced Australia’s record fires
• Climate change made Australia’s devastating fire season 30% more likely
• (AU) Under Climate Change, Winter Will Be The Best Time For Bush Burn-Offs – And That Could Be Bad News For Public Health
• (AU) Fossil Fuel Industry Levy Should Pay For Bushfire Impact, Climate Action Group Report Says
• ‘Unequivocal Link’ Between Extreme Bushfires And Climate Crisis
• (AU) Almost 3 Billion Animals Affected By Australian Bushfires, Report Shows
• (AU) 'Climate Change War' Demands National, Military-Style Response: Ex-Fire Chiefs
• (AU) Australia’s Shifting Mood On Climate Change
• (AU) Two Dry Wet Seasons Spark Early Start To NT's Grass Fires, Leaving Experts Worried
• (AU) 'Mass Mortality Event' Devastates Sydney's Coastal Ecosystems
• (AU) More Than A Third Of NSW Rainforests Found To Have Been Hit By Australian Bushfires

A Mesmerizing "Blue Whirl" Could Change The Future Of Fossil Fuels

INVERSE - Sarah Wells

This new type of flame has big potential for low-emission combustion.

(A) Stable blue whirl. (B) Slightly unstable blue whirl with soot in the middle, suggesting a bubble mode of vortex breakdown. Photo credit: H. Xiao, University of Science and Technology of China.

Science Advances Abstract The blue whirl is a small, stable, spinning blue flame that evolved spontaneously in recent laboratory experiments while studying turbulent, sooty fire whirls. It burns a range of different liquid hydrocarbon fuels cleanly with no soot production, presenting a previously unknown potential way for low-emission combustion.

Fire may be one of humanity's original innovations, but it is still surprising us hundreds of centuries after the first manmade flames.

In 2016 scientists at the University of Maryland stumbled upon an entirely new type of flame while investigating the use of fire whirls to clean oil spills in water. Initially, the flame began as a large, violent, yellow flame — then unexpectantly transitioned into a small, quiet, spinning blue flame.

They dubbed it a "blue whirl" for the way it twisted and spun. But this whirl was more than beautiful — it also burned soot-free.

Four years later, a new study confirms the blue whirl is unique and indicates the flame could be very useful in the pursuit of clean fuel consumption.

"This flame has the potential to be used as an ideal energy source with reduced pollution and reduced complexity," the study team told Inverse by email. "It is usually a very difficult process to burn liquid hydrocarbon fuels in a clean way with no soot production. The blue whirl can burn many different types of liquid hydrocarbon fuels without producing harmful soot, all within the same and simple configuration."

These findings were published on Wednesday in Science Advances.

Finding the "flow structure" of the blue whirl — The researchers used computer models to better understand the origin and structure of this bizarre blue flame. The goal was to better understand the scalability of this flame and how it could be used in the future to offer a low-emissions way to burn fossil fuels.

While blue whirls are described as tame and stable, the scientists observed that, initially, they pass through a "noisy, turbulent, yellow fire whirl" stage. The study team notes that this turbulence caused previous experimental attempts to wrangle this flame to be tricky. That's why, in this case, they decided to model it from a safe distance using computer simulations.

In the future, further controlled simulations could help answer fundamental questions like whether or not these blue whirls are scalable and if they can be created without passing through their unruly fire state, the team writes.


This video compares the numerical simulation (center) to two experimental visualizations of the blue whirl.

In order to accurately recreate this blue whirl in the digital world, the researchers first had to simulate the same parameters used in the lab, such as the geometry of the air and gas flow. From there, they could tweak different inputs to see how different environments would affect the emergence and stability of this blue flame.

While some of the experimental and simulated parameters did differ — for example, the simulated version included a fuel injection while experimental set-ups included fuel evaporation — the authors write that the differences are not outside the realm of physical possibility.

Through looking at their simulated blue whirls, the researchers were able to identify that the flame was not in fact a single flame, but rather the culmination of three different types of flames:

• Diffusion flame
• Premixed rich
• Lean flame

The nexus of these flames came together to form a fourth structure, a triple-flame, that appeared as the whirling blue flame. This was a result of a vortex breakdown in the system.

They also found that this top-like flame could reach a temperature of over 3,500 degrees Fahrenheit.

Benefits and Unknowns — Being able to accurately simulate this blue whirl phenomenon is an important first step toward understanding how (or even if) this can be scaled commercially, the researchers explain.

Because this flame is capable of burning soot-free, it offers exciting opportunities for scientists to explore the potential for low-emission combustion using fossil fuels. The researchers tell Inverse that the flame could "possibly be used for the oil industry as a method for fuel-spill remediation and for the energy and propulsion industry, which may benefit from a fuel-flexible combustion device with reduced pollution."

They note that the blue whirl is also a new, potential way of "extracting energy from traditional fossil-fuel sources of energy in a clean energy way with minimal environmental impact."

While burning fossil fuel, low-emissions or not, would still be worse for the environment than sustainable options like solar and electricity, a solution like this could offer a way to improve the existing fuel infrastructure while other, greener energy methods are refined.

Links

• The structure of the blue whirl revealed
• From fire whirls to blue whirls and combustion with reduced pollution
• The future of deep space travel could come down to tiny solar panels
• Sunlight could solve drinking water's biggest problem in 30 minutes
• A massive change is coming to the Himalayas
• Biodiversity loss is making humanity sicker
• Is humanity doomed because we can’t plan for the long-term?