Atmospheric Carbon Dioxide Levels Are at Their Highest in 23 Million Years
Human activity has pushed atmospheric carbon dioxide to higher levels today than they have been at any other point in the last 23-million-years, potentially posing unprecedented disruptions in ecosystems across the planet, new research suggests.
Understanding atmospheric concentrations of CO2 is "vital for understanding Earth's climate system" because it "imparts a controlling effect on global temperatures," said scientists in a study published in Geology.
Climate change is largely driven by a disproportionate increase of CO2 in the atmosphere largely resulting from the burning of fossil fuels like coal, oil and gas as well as cutting down or burning forests that serve as carbon stores, according to the Union of Concerned Scientists. A 2013 study published by the Intergovernmental Panel on Climate Change found that climate change from CO2 and greenhouse gas emission is not only caused by humans but has had "widespread impacts on human and natural systems."
Previous measurements have turned to ice cores to determine CO2 levels present in the atmosphere throughout Earth's history, but have only pieced together the last 800,000 years. To expand upon this record, researchers at the University of Louisiana at Lafayette used fossilized remains of ancient plant tissue to produce a record of atmospheric CO2 dating back 31 million years of "uninterrupted Earth history."
As plants grow, the amount of two stable carbon isotopes, carbon-12 and carbon-13, change in response to CO2 levels in the atmosphere. With this in mind, the research team measured the relative amount of these carbon isotopes in fossil plant materials from 700 measurements, published in 12 studies, characterizing ancient plants and their lipids in order to calculate concentrations of CO2 in the atmosphere during the timeframe that the plants grew.
This atmospheric "timeline" did not show fluctuations in CO2 that are comparable to increases seen in the last century. In fact, the highest concentrations of CO2 were found during the Miocene, between 5 and 23 million years ago, but were still determined to have been below present-day levels.
"These data suggest present-day CO2 exceeds the highest levels that Earth experienced at least since the Miocene, further highlighting the present-day disruption of long-established CO2 trends within Earth's atmosphere," write the study authors in Geology.
The abrupt increase of greenhouse gas distribution today is unprecedented in Earth's 23-million-year history, indicating that ecosystems and global temperatures may be more sensitive to smaller changes in CO2 levels than previously thought. Though CO2 levels have varied widely throughout Earth's history, researchers believe that they have never fluctuated nor been as high as in recent years.
"One of the most pressing messages that climate scientists attempt to convey to the public is that current CO2 is elevated compared to the geological past," write the study authors, adding that the results also indirectly imply that major changes in plant and early humans were not driven by large changes in CO2 but rather "relatively small-amplitude changes."
Humans have increased atmospheric CO2 concentration by more than one-third since the Industrial Revolution began, according to NASA. Though the BBC reports "worst-case scenario" for emissions of CO2 in the 21st century is considered unlikely by researchers, scientists still expect a rise of around 3 degrees Celsius by 2100, according to The Guardian — 1.5 degrees Celsius above goals set forth by the Paris agreement. A report published by the National Oceanic and Atmospheric Administration earlier this year corroborates the findings, confirming that CO2 levels in 2018 were higher than at any other point in the past 800,000 years. The last time amounts were this high was more than 3 million years ago, when global temperatures were between 3.6 and 5.4 degrees Fahrenheit higher than during the pre-industrial era, and sea level was 50 to 80 feet higher than today.
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By Peter A. Kloess
Picture Antarctica today and what comes to mind? Large ice floes bobbing in the Southern Ocean? Maybe a remote outpost populated with scientists from around the world? Or perhaps colonies of penguins puttering amid vast open tracts of snow?
Giants of the Sky<p>As their name suggests, these ancient birds had sharp, bony spikes protruding from sawlike jaws. Resembling teeth, these spikes would have helped them catch squid or fish. We also studied another remarkable feature of the pelagornithids – their imposing size.</p><p>The largest flying bird alive today is the <a href="https://www.nationalgeographic.com/animals/birds/group/albatrosses/" target="_blank">wandering albatross</a>, which has a wingspan that reaches 11 ½ feet. The Antarctic pelagornithids fossils we studied have a wingspan nearly double that – about 21 feet across. If you tipped a two-story building on its side, that's about 20 feet.</p><p>Across Earth's history, very few groups of vertebrates have achieved powered flight – and only two reached truly giant sizes: birds and a group of <a href="https://www.amnh.org/exhibitions/pterosaurs-flight-in-the-age-of-dinosaurs/what-is-a-pterosaur" target="_blank" rel="noopener noreferrer">reptiles called pterosaurs</a>.</p>
Full-size model of a Quetzalcoatlus on display at JuraPark in Baltow, Poland. Aneta Leszkiewicz / Wikimedia<p>Pterosaurs ruled the skies during the Mesozoic Era (252 million to 66 million years ago), the same period that dinosaurs roamed the planet, and they reached hard-to-believe dimensions. <a href="https://www.wired.com/2013/11/absurd-creature-of-the-week-quetz/" target="_blank" rel="noopener noreferrer">Quetzalcoatlus</a> stood 16 feet tall and had a colossal 33-foot wingspan.</p>
Birds Get Their Opportunity<p>Birds originated while dinosaurs and pterosaurs were still roaming the planet. But when an <a href="https://www.smithsonianmag.com/science-nature/dinosaur-killing-asteroid-impact-chicxulub-crater-timeline-destruction-180973075/" target="_blank">asteroid struck the Yucatan Peninsula 66 million years ago</a>, dinosaurs and pterosaurs both perished. Some <a href="https://www.audubon.org/news/how-birds-survived-asteroid-impact-wiped-out-dinosaurs" target="_blank">select birds survived</a>, though. These survivors diversified into the thousands of bird species alive today. Pelagornithids evolved in the period right after dinosaur and pterosaur extinction, when competition for food was lessened.</p><p><a href="https://doi.org/10.1002/spp2.1284" target="_blank">The earliest pelagornithid remains</a>, recovered from 62-million-year-old sediments in New Zealand, were about the size of modern gulls. The first giant pelagornithids, the ones in our study, <a href="https://doi.org/10.1038/s41598-020-75248-6" target="_blank" rel="noopener noreferrer">took flight over Antarctica about 10 million years later</a>, in a period called the Eocene Epoch (56 million to 33.9 million years ago). In addition to these specimens, fossilized remains from other pelagornithids have been found on every continent.</p><p>Pelagornithids lasted for about 60 million years before going extinct just before the Pleistocene Epoch (2.5 million to 11,700 years ago). No one knows exactly why, though, because few fossil records have been recovered from the period at the end of their reign. Some paleontologists cite <a href="https://doi.org/10.1080/02724634.2011.562268" target="_blank" rel="noopener noreferrer">climate change as a possible factor</a>.</p>
Piecing it Together<p>The fossils we studied are fragments of whole bones collected by paleontologists from the University of California at Riverside in the 1980s. In 2003, the specimens were transferred to Berkeley, where they now reside in the <a href="https://ucmp.berkeley.edu/" target="_blank" rel="noopener noreferrer">University of California Museum of Paleontology</a>.</p><p>There isn't enough material from Antarctica to rebuild an entire skeleton, but by comparing the fossil fragments with similar elements from more complete individuals, we were able to assess their size.</p>
In life, the pelagornithid would have had numerous 'teeth,' making it a formidable predator. Peter Kloess, CC BY-NC-SA
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As U.S. Election Nears, Polling Shows 82 Percent of Voters Support 100 Percent Clean Energy Transition
By Jessica Corbett
With an estimated 66 million ballots already cast and only a week to go until Election Day, new polling released Tuesday shows the vast majority of U.S. voters believe the nation should be prioritizing a transition to 100% clean energy and support legislation to decarbonize the economy over the next few decades.
<div id="5206f" class="rm-shortcode" data-rm-shortcode-id="584d1641628f692ff103aee7ed74b45e"><blockquote class="twitter-tweet twitter-custom-tweet" data-twitter-tweet-id="1321080152328208384" data-partner="rebelmouse"><div style="margin:1em 0">Biden should get "uncontrolled climate change would cost $486 trillion" tattooed on his forehead imo https://t.co/nTbVdHa9gD</div> — Emily Atkin (@Emily Atkin)<a href="https://twitter.com/emorwee/statuses/1321080152328208384">1603805027.0</a></blockquote></div>
Arctic Ocean sediments are full of frozen gases known as hydrates, and scientists have long been concerned about what will happen when and if the climate crisis induces them to thaw. That is because one of them is methane, a greenhouse gas that has 80 times the warming impact of carbon dioxide over a 20 year period. In fact, the U.S. Geological Survey has listed Arctic hydrate destabilization as one of the four most serious triggers for even more rapid climate change.