Tropical Forests Are Losing Their Ability to Absorb Carbon, Study Finds
The world's tropical forests are rapidly losing their ability to absorb carbon from the atmosphere, worrying scientists that a major carbon dump will transform them into a carbon source, according to research published Wednesday.
The study, which was published in the journal Nature, found that in 15 years the Amazon could turn into a carbon source, due to wildfires, deforestation, and the excess greenhouse gasses pumped into the atmosphere, as The Guardian reported.
An international consortium of European and African scientists led by researchers from the University of Leeds studied more than 300,000 trees over the course of 30 years in the Amazon and the African tropics. The researchers found that climate models that typically predict that tropical forests will serve as carbon sinks for decades are inaccurate. Instead, the decades of analysis found that the uptake of carbon into the world's tropical forests actually peaked in the 1990s, according to a press release from the University of Leeds.
"Our findings show that back in the 1990s intact tropical forests were absorbing 4.6 billion tons of carbon dioxide every year," Simon Lewis, professor of Global Change Science at University College London, and Lee White, the government of Gabon's Minister for Water, Forests, the Sea and Environment, wrote in The Independent. "This has slumped to an estimated 2.5 billion tons each year over the last decade. To put these colossal numbers in context, the decline of 2.1 billion tons each year is equivalent to five times the annual carbon dioxide emissions of the UK. Tropical forests have been helping us, but that help is starting to wane."
Manmade emissions continue to climb year after year, which is taxing already oversaturated tropical forests, which account for around half of all land-based carbon absorption. The oversaturation is threatening the forests' ability to provide people with medicine, food, shelter and water, as ScienceAlert reported.
"The cause of this is climate change impacts - in terms of heat stress and droughts - on these remaining intact forests," Lewis said, as Reuters reported. "Humanity has been really lucky so far in that these forests have been mopping up our pollution, and they might not keep doing that for that much longer."
Many industrialized nations aim to offset their greenhouse gas emissions by restoring forests, but that might not be enough. However, the new research shows that preserving forests may not be enough in the absence of cutting emissions.
To conduct the research, the scientists combined data from two large research networks of forest observations in Africa and the Amazon. They also spent years in remote field sites. The researchers tagged individual trees and measured them and estimated the height of every single tree within 565 different patches of forest. The researchers returned every few years to repeat the process, enabling them to figure out the carbon stored in the trees that survived and the ones that died, as The Guardian reported. Their calculations showed that the African tropics have been more resilient than the Amazon, but both are now on a worrying trend line.
"There is a lot of talk about offsetting, but the reality is that every country and every sector needs to reach zero emissions, with any small amount of residual emissions needing to be removed from the atmosphere," Lewis said as The Guardian reported. "The use of forests as an offset is largely a marketing tool for companies to try to continue with business as usual."
Writing in The Independent yesterday, Lewis and White explained, "We need to see emissions declining fast, by almost half by 2030, in order to avoid reaching that feared point where critical carbon sinks become carbon sources and climate change begins to run out of control."
Their thoughts were echoed by Doug Parr, chief scientist at Greenpeace UK, who said to The Guardian, "For years, we have had scientific warnings about tipping points in the Earth system and they've been largely ignored by policy and decision-makers. That forests are now seemingly losing the ability to absorb pollution is alarming. What more of a wake-up call do we need?"
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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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