Ozone Hole Over Antarctica Is One of the Biggest in 15 Years
The hole in the ozone layer over Antarctica is one of the largest and deepest in the past 15 years, the World Meteorological Organization (WMO) said Tuesday.
The ozone hole over Antarctica usually starts to grow in August and reaches its peak in October, The Associated Press explained. This year, it peaked at 24 million square kilometers (approximately 9.3 million square miles) and is now at 23 million square kilometers (approximately 8.9 million square miles), the WMO said. This means the hole is larger than the average for the past decade and extends over most of Antarctica.
"With the sunlight returning to the South Pole in the last weeks, we saw continued ozone depletion over the area. After the unusually small and short-lived ozone hole in 2019, which was driven by special meteorological conditions, we are registering a rather large one again this year, which confirms that we need to continue enforcing the Montreal Protocol banning emissions of ozone depleting chemicals," Vincent-Henri Peuch, director of the EU's Copernicus Atmosphere Monitoring Service (CAMS) at ECMWF, said in the WMO press release.
The #ozone hole over the #Antarctic is one of the largest and deepest in recent years, per @CopernicusECMWF,… https://t.co/k8DUe65iqV— World Meteorological Organization (@World Meteorological Organization)1601986657.0
The ozone layer is important because it protects the earth from dangerous ultraviolet radiation, CAMS explained. In the late 20th century, that layer was damaged by the human release of ozone-depleting halocarbons, which the Montreal Protocol of 1987 sought to control.
But the size of the ozone hole every year is also impacted by specific weather conditions. This year, a strong polar vortex has chilled the air above Antarctica, and consistently cold air creates the ideal conditions for ozone depletion.
"The air has been below minus 78 degrees Celsius, and this is the temperature which you need to form stratospheric clouds — and this quite (a) complex process," WMO spokesperson Clare Nullis said at a UN briefing reported by The Associated Press. "The ice in these clouds triggers a reaction which then can destroy the ozone zone. So, it's because of that that we are seeing the big ozone hole this year."
Specifically, the ice can turn nonreactive chemicals into reactive ones, the WMO explained. Light from the sun then triggers chemical reactions that deplete the ozone layer.
The Montreal Protocol has been hailed as an example of effective international collaboration on a major environmental problem. Last year's hole over Antarctica was the smallest it has been since the hole was discovered, but this was due to unusual weather, not emissions reductions, ABC News reported.
"There is much variability in how far ozone hole events develop each year," Peuch said in the WMO release.
The 2018 hole was also on the larger side.
Still, the WMO and the UN Environment Programme determined in 2018 that the ozone layer was on the road to recovery and could return to pre-1980 levels over Antarctica by 2060.
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By Aaron W Hunter
A chance discovery of a beautifully preserved fossil in the desert landscape of Morocco has solved one of the great mysteries of biology and paleontology: how starfish evolved their arms.
The Pompeii of palaeontology. Aaron Hunter, Author provided<h2></h2><p>Although starfish might appear very robust animals, they are typically made up of lots of hard parts attached by ligaments and soft tissue which, upon death, quickly degrade. This means we rely on places like the Fezouata formations to provide snapshots of their evolution.</p><p>The starfish fossil record is patchy, especially at the critical time when many of these animal groups first appeared. Sorting out how each of the various types of ancient starfish relate to each other is like putting a puzzle together when many of the parts are missing.</p><h2>The Oldest Starfish</h2><p><em><a href="https://www.biorxiv.org/content/10.1101/216101v1.full.pdf" target="_blank" rel="noopener noreferrer">Cantabrigiaster</a></em> is the most primitive starfish-like animal to be discovered in the fossil record. It was discovered in 2003, but it has taken over 17 years to work out its true significance.</p><p>What makes <em>Cantabrigiaster</em> unique is that it lacks almost all the characteristics we find in brittle stars and starfish.</p><p>Starfish and brittle stars belong to the family Asterozoa. Their ancestors, the Somasteroids were especially fragile - before <em>Cantabrigiaster</em> we only had a handful of specimens. The celebrated Moroccan paleontologist Mohamed <a href="https://doi.org/10.1016/j.palaeo.2016.06.041" target="_blank" rel="noopener noreferrer">Ben Moula</a> and his local team was instrumental in discovering <a href="https://www.sciencedirect.com/science/article/abs/pii/S0031018216302334?via%3Dihub" target="_blank" rel="noopener noreferrer">these amazing fossils</a> near the town of Zagora, in Morocco.</p><h2>The Breakthrough</h2><p>Our breakthrough moment came when I compared the arms of <em>Cantabrigiaster</em> with those of modern sea lilles, filter feeders with long feathery arms that tend to be attached to the sea floor by a stem or stalk.</p><p>The striking similarity between these modern filter feeders and the ancient starfish led our team from the University of Cambridge and Harvard University to create a new analysis. We applied a biological model to the features of all the current early Asterozoa fossils in existence, along with a sample of their closest relatives.</p>
Cantabrigiaster is the most primitive starfish-like animal to be discovered in the fossil record. Aaron Hunter, Author provided<p>Our results demonstrate <em>Cantabrigiaster</em> is the most primitive of all the Asterozoa, and most likely evolved from ancient animals called crinoids that lived 250 million years before dinosaurs. The five arms of starfish are a relic left over from these ancestors. In the case of <em>Cantabrigiaster</em>, and its starfish descendants, it evolved by flipping upside-down so its arms are face down on the sediment to feed.</p><p>Although we sampled a relatively small numbers of those ancestors, one of the unexpected outcomes was it provided an idea of how they could be related to each other. Paleontologists studying echinoderms are often lost in detail as all the different groups are so radically different from each other, so it is hard to tell which evolved first.</p>
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