Limestone

• As the weight of ice builds up, the ice sheet begins to move towards the oceans.
• When the ocean water has a temperature close to 0°C, these ice shelves can persist for a long time.
• Ice shelves in West Antarctica are particularly prone to melting from the ocean, as many are close to water masses above 0°C.
• Our new research explores how heat brought by El Niño can warm the ocean around West Antarctica and increase melting of the ice shelves from below.

How can El Niño-Southern Oscillation affect Antarctica?

• Giant convective thunderstorms in the Pacific’s equatorial regions move east during El Niño and intensify in the West during La Niña.
• Within two months, these atmospheric waves reach the Antarctic continent, where their energy can affect the coastal atmosphere and ocean circulation.
• During El Niño, the energy from these waves weakens the easterly winds off West Antarctica (and vice versa for La Niña).
• Using satellite data, researchers recently found that West Antarctic ice shelves actually gain height but lose mass during El Niño.

Finding a needle in the ice stack

• We take a high-resolution global ocean circulation model and added El Niño and La Niña events to the baseline simulation.
• Normally, most of the warm water reservoir is located off the continental shelf rather than on the continental shelf.

• But that’s enough to begin melting ice shelves, which are at or below freezing point.
• Winds along the coast strengthen, pushing more cold surface water onto the continental shelf and preventing warm water from flowing under the ice shelves.

What does this mean for the near future?

• If this trend continues, as climate projections suggest, we can expect warming around West Antarctica to get even stronger during El Niño events, accelerating ice shelf melting and speeding up sea level rise.
• The only way to stop the worst from happening is to get to net zero carbon emissions as quickly as humanly possible.
• Read more:
  We can still prevent the collapse of the West Antarctic ice sheet – if we act fast to keep future warming in check

Maurice Huguenin receives funding from the Australian Research Council. Matthew England receives funding from the Australian Research Council. Paul Spence does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.

• 029 Group SE (ISIN: DE000A2LQ2D0), a global hospitality and lifestyle platform, announces that its portfolio company Limestone Capital AG, a leading alternative asset manager with a focus on hospitality and travel, has bolstered its Italian presence with the acquisition of a luxurious resort hotel in Costa Smeralda, Sardinia.
• The acquisition marks a significant addition to the growing portfolio of four hotels in Italy.
• Benjamin Habbel, CEO of Limestone Capital, expresses his enthusiasm for this acquisition, stating, "This acquisition represents a great milestone for Limestone Capital by expanding our presence in Italy and adding a luxurious asset in a globally renowned resort destination to our European portfolio.
• The acquisition of the Sardinia hotel marks a significant milestone in bringing this vision to fruition.

• The new results are from results that continue to be received from drilling completed in 2023 to define the Helen Zone, the first horizon expected to be accessed at the Cove Mine.
• The program is confirming high‑grade mineralization over appreciable thickness including multiple lenses in some parts of the deposit (see Figure 2).
• Highlight new results from drilling at McCoy-Cove include:
  "Results received to-date have met or exceeded our expectations as definition drilling continues to confirm that Cove is one of the highest-grade, development-stage, gold deposits in North America.
• "Deposits with grades in excess of ten grams per tonne gold over widths frequently in excess of ten metres are rare.

• More than 380 million years ago, a sleek, air-breathing predatory fish patrolled the rivers of central Australia.
• Known from at least 17 fossil specimens, Harajicadectes is the first reasonably complete bony fish found from Devonian rocks in central Australia.

Meet the biter

• This group had strongly built paired fins and usually only a single pair of external nostrils.
• Tetrapodomorph fish from the Devonian period (359–419 million years ago) have long been of great interest to science.
• They include the forerunners of modern tetrapods – animals with backbones and limbs such as amphibians, reptiles, birds and mammals.

A long road to discovery

• Packed within red sandstone blocks on a remote hilltop were hundreds of fossil fishes.
• The vast majority of them were small Bothriolepis – a type of widespread prehistoric fish known as a placoderm, covered in box-like armour.
• These included a lungfish known as Harajicadipterus youngi, named in honour of Gavin Young and his years of work on material from Harajica.

• There were early attempts at figuring out the species, but this proved troublesome.
• Then, our Flinders University expedition to the site in 2016 yielded the first almost complete fossil of this animal.

A strange apex predator

• Likely the top predator of those ancient rivers, its big mouth was lined with closely-packed sharp teeth alongside larger, widely spaced triangular fangs.
• It seems to have combined anatomical traits from different tetrapodomorph lineages via convergent evolution (when different creatures evolve similar features independently).

• Similar giant spiracles also appear in Gogonasus, a marine tetrapodomorph from the famous Late Devonian Gogo Formation of Western Australia.
• They are also seen in the unrelated Pickeringius, an early ray-finned fish that was also at Gogo.

The earliest air-breathers?

Other Devonian animals that sported such spiracles were the famous elpistostegalians – freshwater tetrapodomorphs from the Northern Hemisphere such as Elpistostege and Tiktaalik. These animals were extremely close to the ancestry of limbed vertebrates. So, enlarged spiracles seem to have arisen independently in at least four separate lineages of Devonian fishes.

• The only living fishes with similar structures are bichirs, African ray-finned fishes that live in shallow floodplains and estuaries.
• It was recently confirmed they draw surface air through their spiracles to aid survival in oxygen-poor waters.

Brian Choo receives funding from the Australian Research Council and is employed by Flinders University. Alice Clement receives funding from the Australian Research Council and is employed by Flinders University. John Long receives funding from The Australian Research Council.