Study That Saw 62% Climate Hit to GDP Is Criticized by Peers
An analysis of a paper published last April in Nature argues that anomalies in data for Uzbekistan, one of 83 counties examined in the original study, caused the results to overstate the potential economic hit. When Uzbekistan is removed, the projected losses by 2100 are reduced to 23%, in line with other similar modeling, according to the new article, published Wednesday in the same journal.
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Lightning Kills Way More Trees Than You Would Ever Believe
A first-of-its-kind study estimates that lightning strikes kill 320 million trees every year. For perspective, these dead trees account for up to 2.9 percent of annual loss in plant biomass and emit up to 1.09 billion tons of carbon dioxide. Even more striking (pun unintended), the study includes only tree deaths caused directly by lightning. It does not include tree deaths caused indirectly by lightning-induced wildfires. Altogether, these findings can improve statistical models that help researchers study forest structure and carbon storage on a worldwide scale. Researchers from the Technical University of Munich (TUM) ascertained these figures using novel mathematical models, which offer an unprecedented overview of how lightning-induced tree mortality impacts the global ecosystem. Related: Classifying tree mortality was no easy task. Dead trees often lack clear visual signs of their cause of death, while others may be too decomposed for meaningful forest forensics. Some tree deaths occur slowly, and most surveys are limited to infrequent observations of isolated deaths after the event has occurred. Some areas, like temperate and boreal forests, are not as well-studied as those in the tropics. So the researchers combined multiple methods to make their global estimate, including using results from another team's camera-based lightning detection system in an old-growth tropical forest in Panama's Barro Colorado Island (BCI). These camera observations were followed up with drone and ground surveys to confirm lightning-struck trees. This BCI data revealed that lightning is highly contagious. A lightning strike can cause a 'flashover' as electricity crosses the air gap between the crowns of neighboring trees, reaching as far away as 45 meters (almost 150 feet) from the initially struck tree. As a result, each lightning strike killed 3.5 trees on average. Testing their model against the real data, they found their model adequately simulated the trees killed by lightning strike. The researchers then applied the validated model to other temperate and tropical forests around the world. To pad out the global averages, the researchers also incorporated two hefty datasets of lightning frequency and density, one from a spaceborne optical network and the second from ground-based observations. According to the simulations, "286–328 million lightning strikes hit the Earth's surface each year," with the majority occurring over ice-free land areas, particularly in the tropics. This resulted in the annual death of 301-340 million trees over the 2004-2023 period, including 24-36 million large trees (over 60 centimeters in diameter). For comparison, natural causes kill around 50 billion trees annually, occasionally creating 'farting' ghost forests. So while lightning is only responsible for 0.69 percent tree deaths overall, it is responsible for up to 6.3 percent of large-tree deaths. Additionally, these numbers appear to be rising. "Currently, lightning-induced tree mortality is highest in tropical regions," says Andreas Krause, a computer scientist at TUM's Land Surface-Atmosphere Interactions lab and the study's lead author. "However, models suggest that lightning frequency will increase primarily in middle-and-high-latitude regions, meaning that lightning mortality could also become more relevant in temperate and boreal forests." The impact may be significant; a separate study predicts a 9-18 percent uptick in large-tree deaths for a 25-50 percent increase in lightning frequency. Most importantly, the study provides evidence that lightning-induced tree deaths are underestimated – if estimated at all. The researchers note that tree mortality is a neglected aspect in the dynamic models that scientists use to study how forests respond to environmental shifts, and should be included in future carbon calculations. This research is published in the journal Global Change Biology. Related News Scientists Found a Mysterious Barrier in The Ocean That Jellyfish Won't Cross Leopard Seal Mating Songs Are Eerily Like Our Nursery Rhymes Massive Earthquake Could Strike Canada as Ancient Fault Line Wakes Solve the daily Crossword
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Prehistoric Air Has Been Reconstructed From Dinosaur Teeth in an Amazing First
A collection of dinosaur teeth hailing back to the Cretaceous and Jurassic periods has given scientists a new window into the world's prehistoric climate. By studying an isotope of oxygen in the fossils to infer atmospheric carbon dioxide levels, a team led by geochemist Dingsu Feng of the Georg August University of Göttingen in Germany has reconstructed the very air the dinosaurs breathed. The results show that dinosaur teeth are a powerful tool for scientists, not just for understanding the world in which the dinosaurs lived, but the events that took place, since changing isotope levels can imply events such as massive volcanic eruptions. Related: The Rise of The Dinosaurs Can Be Tracked in Their Fossilized Poop "Our findings provide a new research avenue to reconstruct a direct link between land-living vertebrates and the atmosphere they breathed," paleontologist and geochemist Thomas Tütken of the Institute of Geosciences at Johannes Gutenberg Universität, Mainz in Germany told ScienceAlert. "Even after up to 150 million years, isotopic traces of the oxygen molecules of the Mesozoic atmosphere that the dinosaur inhaled are still preserved in fossil tooth enamel and can tell us something about the ancient atmosphere composition and global photosynthetic biomass production." You don't just exist in this beautiful world of ours. It also exists in you. Everything you take in – from the food you eat, to the liquid you drink, to even the very air that you breathe – leaves a chemical imprint on your body, including your bones and teeth. This is true for all vertebrates, including the dinosaurs. Ratios of atoms of the same elements but different masses, known as isotopes, can hint at a variety of ecological and climatic variations that dominate in an organism's lifetime. Oxygen atoms attached to carbon dioxide is just one such isotope. In particular, Feng and her team looked for tracers of an isotope called oxygen-17. Processes in the atmosphere result in a lower amount of this particular isotope in the dioxide oxygen gas that is then inhaled by living organisms. "Air-breathing vertebrates incorporate a fraction of this anomalous air oxygen into their body water pool due to oxidative metabolism of food," Tütken explained. "A fraction of this oxygen isotope anomaly is incorporated during biomineralization processes into dental enamel, and survives over millions of years in this vertebrate high tissue and can thus be used to infer past atmospheric CO2 levels." The researchers recently demonstrated that oxygen isotope ratios in the tooth enamel of living, modern animals provide an accurate representation of atmospheric CO2 levels. The next logical step was then to see if they could do the same thing with fossils that are millions of years old. "Dinosaur tooth samples were prime targets to be analyzed as large triple oxygen isotope anomalies were to be expected and could quite precisely be measured," Tütken said. Using enamel powders previously taken from specimens obtained from museum collections across Europe for other diet-related reconstructions, Tütken and his colleagues concluded concentrations of CO2 had been high during the Mesozoic; a finding in agreement with previous investigations into Earth's CO2 history. In the late Jurassic, CO2 levels were at about 1,200 parts per million, for example; in the late Cretaceous, around 750 parts per million. By comparison, Earth's atmosphere currently has around 430 parts per million CO2, and counting. During the Mesozoic, atmospheric CO2 was probably produced by much higher levels of volcanic activity than we see today. Two teeth, in particular, seemed to suggest a spike in volcanic activity. "There were surprising high triple oxygen isotope anomalies found for one T. rex and one sauropod (Kaatedocus) tooth analyzed compared to the other near-contemporaneous dinosaurs," Tütken said. "These potentially reflect atmospheric spikes of high CO2 levels during the time these individual dinosaurs were alive. Most likely related to volcanic CO2 emission during large flood basalt eruption events. Thus our study provides new insights into the composition of the Mesozoic atmosphere in which the dinosaurs breathed and indicates that CO2 levels fluctuated (up to 160 percent) over geologically short time scales." Now that the team has shown their technique works, they plan to look at teeth from an event known as the Great Dying, the Permian-Triassic global extinction that took place 252 million years ago and wiped out the vast majority of all animals on Earth. This event has been linked to a devastating period of volcanic activity that wrapped our planet in a volcanic shroud for millions of years. By reconstructing the atmospheric CO2 from this period, the researchers hope to learn more about how the Great Dying impacted life on Earth. The research has been published in the Proceedings of the National Academy of Sciences. Related News Lightning Kills Way More Trees Than You Would Ever Believe Scientists Found a Mysterious Barrier in The Ocean That Jellyfish Won't Cross Leopard Seal Mating Songs Are Eerily Like Our Nursery Rhymes Solve the daily Crossword
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Evidence of World-Changing Comet Explosion 12,800 Years Ago Found in The Ocean
Microscopic grains of alien dust buried in the sediment at the bottom of the ocean could be evidence of a comet that exploded in Earth's atmosphere 12,800 years ago. This hypothetical event, known as the Younger Dryas impact, was invoked to explain a sudden, 1,200-year period of rapid cooling to near-glacial conditions during a time when Earth's climate was on a warm upswing. It's a controversial proposal, to say the least, with many scientists roundly rejecting it while others remain more open to the possibility. One of the leading refutations is that no crater has been found, as one might expect from such a world-changing event… but the evidence may be much smaller than a crater. Related: Led by geoscientist Christopher Moore of the University of South Carolina, a team of researchers puts forward a new line of evidence: four sediment cores from Baffin Bay near Greenland. These are cylinders of material excavated vertically that preserve layers upon layers of seafloor sediment that were deposited over many millennia. "We chose to analyze marine cores from Baffin Bay to determine if Younger Dryas impact proxies reported from dozens of terrestrial sites globally were present in ocean cores," Moore explains in an interview with the science journal PLOS One. "The sites were significant because they were a considerable distance from potential anthropogenic [human] contamination, and in most cases, the cores were highly laminated, indicating that the record was relatively undisturbed." The researchers used radiocarbon dating to determine the ages of the layers, and then used a technique called single-particle inductively coupled plasma time-of-flight mass spectrometry to look for signs of comet dust in the layers deposited during the time of the Younger Dryas cooling. This analysis revealed tiny particles of metal with compositions consistent with a cometary origin, including iron with low oxygen and high nickel content, and microspherules rich with iron and silica. These microspherules, the researchers say, consist mostly of material from Earth, but with a little bit of impactor material mixed in – likely from an airburst event as the comet exploded after atmospheric entry. "The Younger Dryas sediment layer in the Baffin cores contains multiple proxies consistent with an impact event. Microspherules, twisted and deformed metallic dust particles with chemistry consistent with comet or meteoritic material, meltglass, and identification of nanoparticle peaks in key elements (e.g., platinum and iridium) suggest an impact event," Moore says. "This evidence is supported by the findings on terrestrial sites on multiple continents in both hemispheres. This work builds on other evidence that the Younger Dryas impact event was likely global in scale." The researchers next plan to broaden the scale of their investigation by examining sediment cores from other ocean sites around the world. Their findings have been published in PLOS One. Related News 'Hot Blob' Heading For New York Following Ancient Greenland Rift Prehistoric Air Has Been Reconstructed From Dinosaur Teeth in an Amazing First Lightning Kills Way More Trees Than You Would Ever Believe Solve the daily Crossword
