Source BBC www.bbc.com/news/science-envir…

One of the biggest icebergs ever recorded has just broken away from Antarctica.

The giant block is estimated to cover an area of roughly 6,000 sq km; that's about a quarter the size of Wales.

An US satellite observed the berg on Wednesday while passing over a region known as the Larsen C Ice Shelf.

Scientists were expecting it. They'd been following the development of a large crack in Larsen's ice for more than a decade.

The rift's propagation had accelerated since 2014, making an imminent calving ever more likely.

The more than 200m-thick tabular berg will not move very far, very fast in the short term. But it will need to be monitored. Currents and
winds might eventually push it north of the Antarctic where it could become a hazard to shipping.

An infrared sensor on the American space agency's Aqua satellite spied clear water in the rift between the shelf and the berg on Wednesday. The water is warmer relative to the surrounding ice and air - both of which are sub-zero.

"The rift was barely visible in these data in recent weeks, but the signature is so clear now that it must have opened considerably along its whole length," explained Prof Adrian Luckman, whose Project Midas at Swansea University has followed the berg's evolution most closely.

The event was confirmed by other spacecraft such as Europe's Sentinel-1 satellite-radar system.

How does it compare with past bergs?

The new Larsen berg is probably in the top 10 biggest ever recorded.

The largest observed in the satellite era was an object called B-15. It came away from the Ross Ice Shelf in 2000 and measured some
11,000 sq km. Six years later, fragments of this super-berg still persisted and passed by New Zealand.

In 1956, it was reported that a US Navy icebreaker had encountered an object of roughly 32,000 sq km. That is bigger than Belgium. Unfortunately, there were no satellites at the time to follow up and verify the observation.

It has been known also for the Larsen C Ice Shelf itself to spawn bigger bergs. An object measuring some 9,000 sq km came away in 1986. Many of Larsen's progeny can get wound up in a gyre in the Weddell sea or can be despatched north on currents into the Southern Ocean, and even into the South Atlantic.

A good number of bergs from this sector can end up being caught on the shallow continental shelf around the British overseas territory of South Georgia where they gradually wither away.

What is the significance of the calving?

In and of itself, probably very little. The Larsen C shelf is a mass of floating ice formed by glaciers that have flowed down off the eastern side of the Antarctic Peninsula into the ocean. On entering the water, their buoyant fronts lift up and join together to make a single protrusion.

The calving of bergs at the forward edge of the shelf is a very natural behaviour. The shelf likes to maintain an equilibrium and the ejection of bergs is one way it balances the accumulation of mass from snowfall and the input of more ice from the feeding glaciers on land.

That said, scientists think Larsen C is now at its smallest extent since the end of the last ice age some 11,700 years ago, and about 10 other shelves further to the north along the Peninsula have either collapsed or greatly retreated in recent decades.

The two nearby, smaller shelves, Larsen A and Larsen B, disintegrated around the turn of the century; and a warming climate very probably had a role in their demise.

But Larsen C today does not look like its siblings. Prof Helen Fricker, from the Scripps Institution of Oceanography, told BBC News: "The signs we saw at Larsen A and B - we're not seeing yet. The thinning we saw for Larsen A and B - we're not seeing. And we're not seeing any evidence for large volumes of surface meltwater on the order of what you would need to hydro-fracture the ice shelf.

"Most glaciologists are not particularly alarmed by what's going on at Larsen C, yet. It's business as usual."

Researchers will be looking to see how the shelf responds in the coming years, to see how well it maintains a stable configuration, and if its calving rate changes.

There was some keen interest a while back when the crack, which spread across the shelf from a pinning point known as the Gipps Ice Rise, looked as though it might sweep around behind another such anchor called the Bawden Ice Rise. Had that happened, it could have prompted a significant speed-up in the shelf's seaward movement once the berg came off.

As it is, scientists are not now expecting a big change in the speed of the ice.
One fascinating focus for future study will be a strip of "warm", malleable ice that runs east-west through the shelf, reaching the ocean edge about 100km north from the Gipps Ice Rise. This strip is referred to as the Joerg suture zone. There is a large queue of cracks held behind it.

"Calving of the iceberg is not likely itself to make the existing cracks at the Joerg Peninsula suture zone more likely to jump across this boundary," observed Chris Borstad, from the University Centre in Svalbard (UNIS).
"At this stage we really don't know whether there is some larger-scale process that might be weakening this zone, like ocean melting at the base of the shelf, or whether the current rift was just a random or episodic event that was bound to happen at some point.
"We know that rifts like this periodically propagate and cause large tabular icebergs to break from ice shelves, even in the absence of any climate-driven changes.

"I am working with a number of colleagues to design field experiments on Larsen C to answer this specific question (by measuring the properties of the Joerg suture zone directly). But until we get down there and take some more measurements we can only speculate."

Source BBC www.bbc.com/news/science-envir…

Global wildlife populations have fallen by 58% since 1970, a report says.

The Living Planet assessment, by the Zoological Society of London (ZSL) and WWF, suggests that if the trend continues that decline could reach two-thirds among vertebrates by 2020.

The figures suggest that animals living in lakes, rivers and wetlands are suffering the biggest losses.

Human activity, including habitat loss, wildlife trade, pollution and climate change contributed to the declines.

Dr Mike Barrett. head of science and policy at WWF, said: "It's pretty clear under 'business as usual' we will see continued declines in these wildlife populations. But I think now we've reached a point where there isn't really any excuse to let this carry on.

"We know what the causes are and we know the scale of the impact that humans are having on nature and on wildlife populations - it really is now down to us to act."

However the methodology of the report has been criticised.

The Living Planet Report is published every two years and aims to provide an assessment of the state of the world's wildlife.

This analysis looked at 3,700 different species of birds, fish, mammals, amphibians and reptiles - about 6% of the total number of vertebrate species in the world.

The team collected data from peer-reviewed studies, government statistics and surveys collated by conservation groups and NGOs.

Any species with population data going back to 1970, with two or more time points (to show trends) was included in the study.
The researchers then analysed how the population sizes had changed over time.

Some of this information was weighted to take into account the groups of animals that had a great deal of data (there are many records on Arctic and near Arctic birds, for example) or very little data (tropical amphibians, for example). The report authors said this was to make sure a surplus of information about declines in some animals did not skew the overall picture.

The last report, published in 2014, estimated that the world's wildlife populations had halved over the last 40 years.

This assessment suggests that the trend has continued: since 1970, populations have declined by an average of 58%.
Dr Barrett said some groups of animals had fared worse than others.

"We do see particularly strong declines in the freshwater environment - for freshwater species alone, the decline stands at 81% since 1970. This is related to the way water is used and taken out of fresh water systems, and also the fragmentation of freshwater systems through dam building, for example."

It also highlighted other species, such as African elephants , which have suffered huge declines in recent years with the increase in poaching, and sharks, which are threatened by overfishing.

The researchers conclude that vertebrate populations are declining by an average of 2% each year, and warn that if nothing is done, wildlife populations could fall by 67% (below 1970 levels) by the end of the decade.

Dr Robin Freeman, head of ZSL's Indicators & Assessments Unit, said: "But that's assuming things continue as we expect. If pressures - overexploitation, illegal wildlife trade, for example - increase or worsen, then that trend may be worse.

"But one of the things I think is most important about these stats, these trends are declines in the number of animals in wildlife populations - they are not extinctions. By and large they are not vanishing, and that presents us with an opportunity to do something about it."

However, Living Planet reports have drawn some criticisms.

Stuart Pimm, professor of conservation ecology at Duke University in the United States, said that while wildlife was in decline, there were too many gaps in the data to boil population loss down to a single figure.

"There are some numbers [in the report] that are sensible, but there are some numbers that are very, very sketchy," he told BBC News.
"For example, if you look at where the data comes from, not surprisingly, it is massively skewed towards western Europe.

"When you go elsewhere, not only do the data become far fewer, but in practice they become much, much sketchier... there is almost nothing from South America, from tropical Africa, there is not much from the tropics, period. Any time you are trying to mix stuff like that, it is is very very hard to know what the numbers mean.

"They're trying to pull this stuff in a blender and spew out a single number.... It's flawed."

But Dr Freeman said the team had taken the best data possible from around the world.

"It's completely true that in some regions and in some groups, like tropical amphibians for example, we do have a lack of data. But that's
because there is a lack of data.
"We're confident that the method we are using is the best method to present an overall estimate of population decline.

"It's entirely possible that species that aren't being monitored as effectively may be doing much worse - but I'd be very surprised if they were doing much better than we observed. "

Source -----> www.popularmechanics.com/scien…

youtu.be/t7EYQLOlwDM

Scientists at the Oak Ridge National Laboratory in Tennessee have discovered a chemical reaction to turn CO2 into ethanol, potentially creating a new technology to help avert climate change. Their findings were published in the journal ChemistrySelect.

The researchers were attempting to find a series of chemical reactions that could turn CO2 into a useful fuel, when they realized the first step in their process managed to do it all by itself. The reaction turns CO2 into ethanol, which could in turn be used to power generators and vehicles.

The tech involves a new combination of copper and carbon arranged into nanospikes on a silicon surface. The nanotechnology allows the reactions to be very precise, with very few contaminants.

"By using common materials, but arranging them with nanotechnology, we figured out how to limit the side reactions and end up with the one thing that we want," said Adam Rondinone.

This process has several advantages when compared to other methods of converting CO2 into fuel. The reaction uses common materials like copper and carbon, and it converts the CO2 into ethanol, which is already widely used as a fuel.

Perhaps most importantly, it works at room temperature, which means that it can be started and stopped easily and with little energy cost. This means that this conversion process could be used as temporary energy storage during a lull in renewable energy generation, smoothing out fluctuations in a renewable energy grid.

"A process like this would allow you to consume extra electricity when it's available to make and store as ethanol," said Rondinone. "This could help to balance a grid supplied by intermittent renewable sources."

The researchers plan to further study this process and try and make it more efficient. If they're successful, we just might see large-scale carbon capture using this technique in the near future.

Source: The Guardian -----> www.theguardian.com/environmen…

Experts say human impact on Earth so profound that Holocene must give way to epoch defined by nuclear tests, plastic pollution and domesticated chicken

Humanity’s impact on the Earth is now so profound that a new geological epoch – the Anthropocene – needs to be declared, according to an official expert group who presented the recommendation to the International Geological Congress in Cape Town on Monday.

The new epoch should begin about 1950, the experts said, and was likely to be defined by the radioactive elements dispersed across the planet by nuclear bomb tests, although an array of other signals, including plastic pollution, soot from power stations, concrete, and even the bones left by the global proliferation of the domestic chicken were now under consideration.

The current epoch, the Holocene, is the 12,000 years of stable climate since the last ice age during which all human civilisation developed. But the striking acceleration since the mid-20th century of carbon dioxide emissions and sea level rise, the global mass extinction of species, and the transformation of land by deforestation and development mark the end of that slice of geological time, the experts argue. The Earth is so profoundly changed that the Holocene must give way to the Anthropocene.

“The significance of the Anthropocene is that it sets a different trajectory for the Earth system, of which we of course are part,” said Prof Jan Zalasiewicz, a geologist at the University of Leicester and chair of the Working Group on the Anthropocene (WGA), which started work in 2009.

“If our recommendation is accepted, the Anthropocene will have started just a little before I was born,” he said. “We have lived most of our lives in something called the Anthropocene and are just realising the scale and permanence of the change.”

Prof Colin Waters, principal geologist at the British Geological Survey and WGA secretary, said: “Being able to pinpoint an interval of time is saying something about how we have had an incredible impact on the environment of our planet. The concept of the Anthropocene manages to pull all these ideas of environmental change together.”

Prof Chris Rapley, a climate scientist at University College London and former director of the Science Museum in London said: “The Anthropocene marks a new period in which our collective activities dominate the planetary machinery.

“Since the planet is our life support system – we are essentially the crew of a largish spaceship – interference with its functioning at this level and on this scale is highly significant. If you or I were crew on a smaller spacecraft, it would be unthinkable to interfere with the systems that provide us with air, water, fodder and climate control. But the shift into the Anthropocene tells us that we are playing with fire, a potentially reckless mode of behaviour which we are likely to come to regret unless we get a grip on the situation.” Rapley is not part of the WGA.

Martin Rees, the astronomer royal and former president of the Royal Society, said that the dawn of the Anthropocene was a significant moment. “The darkest prognosis for the next millennium is that bio, cyber or environmental catastrophes could foreclose humanity’s immense potential, leaving a depleted biosphere,” he said.

But Lord Rees added that there is also cause for optimism. “Human societies could navigate these threats, achieve a sustainable future, and inaugurate eras of post-human evolution even more marvellous than what’s led to us. The dawn of the Anthropocene epoch would then mark a one-off transformation from a natural world to one where humans jumpstart the transition to electronic (and potentially immortal) entities, that transcend our limitations and eventually spread their influence far beyond the Earth.”

The evidence of humanity’s impact on the planet is overwhelming, but the changes are very recent in geological terms, where an epoch usually spans tens of millions of years. “One criticism of the Anthropocene as geology is that it is very short,” said Zalasiewicz. “Our response is that many of the changes are irreversible.”

To define a new geological epoch, a signal must be found that occurs globally and will be incorporated into deposits in the future geological record. For example, the extinction of the dinosaurs 66m years ago at the end of the Cretaceous epoch is defined by a “golden spike” in sediments around the world of the metal iridium, which was dispersed from the meteorite that collided with Earth to end the dinosaur age.

For the Anthropocene, the best candidate for such a golden spike are radioactive elements from nuclear bomb tests, which were blown into the stratosphere before settling down to Earth. “The radionuclides are probably the sharpest – they really come on with a bang,” said Zalasiewicz. “But we are spoiled for choice. There are so many signals.”

Other spikes being considered as evidence of the onset of the Anthropocene include the tough, unburned carbon spheres emitted by power stations. “The Earth has been smoked, with signals very clearly around the world in the mid-20th century,” said Zalasiewicz.

Other candidates include plastic pollution, aluminium and concrete particles, and high levels of nitrogen and phosphate in soils, derived from artificial fertilisers. Although the world is currently seeing only the sixth mass extinction of species in the 700m-year history of complex life on Earth, this is unlikely to provide a useful golden spike as the animals are by definition very rare and rarely dispersed worldwide.

In contrast, some species have with human help spread rapidly across the world. The domestic chicken is a serious contender to be a fossil that defines the Anthropocene for future geologists. “Since the mid-20th century, it has become the world’s most common bird. It has been fossilised in thousands of landfill sites and on street corners around the world,” said Zalasiewicz. “It is is also a much bigger bird with a different skeleton than its prewar ancestor.”

The 35 scientists on the WGA – who voted 30 to three in favour of formally designating the Anthropocene, with two abstentions – will now spend the next two to three years determining which signals are the strongest and sharpest. Crucially, they must also decide a location which will define the start of the Anthropocene. Geological divisions are not defined by dates but by a specific boundary between layers of rock or, in the case of the Holocene, a boundary between two ice layers in a core taken from Greenland and now stored in Denmark.

The scientists are focusing on sites where annual layers are formed and are investigating mud sediments off the coast of Santa Barbara in California and the Ernesto cave in northern Italy, where stalactites and stalagmites accrete annual rings. Lake sediments, ice cores from Antarctica, corals, tree rings and even layers of rubbish in landfill sites are also being considered.

Once the data has been assembled, it will be formally submitted to the stratigraphic authorities and the Anthropocene could be officially adopted within a few years. “If we were very lucky and someone came forward with, say, a core from a classic example of laminated sediments in a deep marine environment, I think three years is possibly viable,” said Zalasiewicz.

This would be lightning speed for such a geological decision, which in the past would have taken decades and even centuries to make. The term Anthropocene was coined only in 2000, by the Nobel prize-winning scientist Paul Crutzen, who believes the name change is overdue. He said in 2011: “This name change stresses the enormity of humanity’s responsibility as stewards of the Earth.” Crutzen also identified in 2007 what he called the “great acceleration” of human impacts on the planet from the mid-20th century.

Despite the WGA’s expert recommendation, the declaration of the Anthropocene is not yet a foregone conclusion. “Our stratigraphic colleagues are very protective of the geological time scale. They see it very rightly as the backbone of geology and they do not amend it lightly,” said Zalasiewicz. “But I think we can prepare a pretty good case.”

Rapley also said there was a strong case: “It is highly appropriate that geologists should pay formal attention to a change in the signal within sedimentary rock layers that will be clearly apparent to future generations of geologists for as long as they exist. The ‘great acceleration’ constitutes a strong, detectable and incontrovertible signal.”

Evidence of the Anthropocene
Human activity has:

Pushed extinction rates of animals and plants far above the long-term average. The Earth is on course to see 75% of species become extinct in the next few centuries if current trends continue.

Increased levels of climate-warming CO2 in the atmosphere at the fastest rate for 66m years, with fossil-fuel burning pushing levels from 280 parts per million before the industrial revolution to 400ppm and rising today.

Put so much plastic in our waterways and oceans that microplastic particles are now virtually ubiquitous, and plastics will likely leave identifiable fossil records for future generations to discover.

Doubled the nitrogen and phosphorous in our soils in the past century with fertiliser use. This is likely to be the largest impact on the nitrogen cycle in 2.5bn years.

Left a permanent layer of airborne particulates in sediment and glacial ice such as black carbon from fossil fuel burning.