Rocks from two hundred million years ago show us how everything died and how nothing is new.
- A new study suggests that the mass extinction that gave dinosaurs the evolutionary upper hand was caused by oceanic oxygen deprivation.
- Using ratios of sulfur isotopes, researchers could estimate changes in ocean oxygen levels in ancient seas.
- The authors suggest a similar mechanism as that which can cause dead zones in oceans today caused a mass extinction.
How to tell what the world was like 201 million years ago using rocks<p>The mass extinction that ended the Triassic period was a massive die-off that saw somewhere between a quarter and a third of ocean life vanish alongside most large land <a href="https://en.wikipedia.org/wiki/Triassic%E2%80%93Jurassic_extinction_event" target="_blank">animals</a>. Plants were not spared a culling either, with perhaps 60 percent of plant species also dying. The event took less than 10,000 years to carry out this morbid work. This remarkable event paved the way for dinosaurs to become the dominant land animal during the Jurassic period, as most of their competition was dead.</p><p>Explanations for this event's cause have ranged from gradual climate change, to asteroid impacts, to rampant volcanism. New evidence suggests that <a href="https://en.wikipedia.org/wiki/Anoxic_event" target="_blank">ocean anoxia</a>, the depletion of oxygen supplies in the ocean, played a large role. </p><p>The researchers examined the levels of two isotopes of sulfur in rocks that would have been on the seafloor during the extinction event from British Columbia, Sicily, and Northern Ireland. The two isotopes, <sup>32</sup>S and <sup>34</sup>S, can become trapped in limestone and other rocks and exist at different ratios depending on how much oxygen is in the water around them. By examining the changes in the ratio of the two isotopes in rocks formed at the time, we can know what was happening to oxygen levels in the oceans hundreds of millions of years ago. </p><p>The scientists noticed "large spikes" in the ratio of <sup>34</sup>S to <sup>32</sup>S in the samples from all of the locations, indicative of a substantial fall in the amount of oxygen available. These findings can be applied far beyond the sites the rock samples came from, suggesting that oxygen levels fell across large portions of the globe-spanning superocean, known as <a href="https://en.wikipedia.org/wiki/Panthalassa" target="_blank" rel="noopener noreferrer">Panthalassa, </a>that existed alongside Pangea.<strong> </strong></p>
And you thought the Dead Zone in the Gulf of Mexico was bad.<iframe width="730" height="430" src="https://www.youtube.com/embed/yObCpYLLJSk" frameborder="0" allow="accelerometer; autoplay; encrypted-media; gyroscope; picture-in-picture" allowfullscreen></iframe><p>This study isn't the only one suggesting Ocean anoxia caused the extinction event. A previous <a href="https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2017GC006941" target="_blank">study</a> from 2017 reached a similar conclusion by measuring the trace uranium levels in rocks formed at the time. Similarly to the ratio of sulfur isotopes considered above, the amount of uranium in these rocks varies with the amount of oxygen. That study suggests that the low oxygen levels may have lasted 50,000 years after their initial fall, with a full 250,000 years needed before coral reefs could <a href="https://phys.org/news/2017-08-global-oceanic-dead-zones-persisted.html" target="_blank">recover</a>.</p><p>In the present day, the researchers hypothesize that this anoxia was connected to significant volcanic activity at the time. By releasing massive amounts of greenhouse gasses, this would have both acidified the oceans by increasing their carbon content and lowered their oxygen levels by raising global temperatures, as warm water holds less oxygen <a href="http://limnoloan.org/waterquality/dissolved_oxygen/#:~:text=Warm%20water%20holds%20less%20dissolved,to%20escape%20from%20the%20water.&text=Therefore%20the%20warmer%20and%20saltier,dissolved%20oxygen%20it%20will%20contain." target="_blank">overall</a>. Together, these effects can annihilate marine <a href="https://en.wikipedia.org/wiki/Ocean_acidification#Ecosystem_impacts_amplified_by_ocean_warming_and_deoxygenation" target="_blank" rel="noopener noreferrer">ecosystems</a>. It is known that major volcanic activity was occurring at the time, lending credence to this <a href="https://en.wikipedia.org/wiki/Central_Atlantic_magmatic_province" target="_blank" rel="noopener noreferrer">hypothesis</a>. </p><p>It's a good thing that nothing is causing the oceans to heat up and have lower oxygen levels these days! Oh, <a href="https://en.unesco.org/sites/default/files/iucndeoxreportbook15-11-2019.pdf" target="_blank" rel="noopener noreferrer">wait</a>. Never mind. </p>
If Arctic ice continues to melt at its projected rate, the bears will go extinct due to starvation by the end of the century according to a first-ever projected timeline.
- A new report on climate change by the University of Toronto is projecting that most of the polar bear population could reach extinction in under 100 years due to starvation.
- Polar bears are dependent on sea ice for hunting seals, a primary component of their diet. As temperatures rise and sea ice continues to shrink it has become increasingly challenging for the carnivores to hunt for food.
- The Arctic is likely to have warmed more than double the amount of the global average this year compared to pre-industrial temperatures.
Starving into extinction<span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="6a66d2ea09b66ae24f3d997218f573f0"><iframe type="lazy-iframe" data-runner-src="https://www.youtube.com/embed/_JhaVNJb3ag?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span><p>Polar bears are dependent on sea ice for hunting seals, a primary component of their diet, and aren't exactly built for swimming to catch their prey in the open water. As temperatures rise and sea ice continues to shrink it has become increasingly challenging for the carnivores to hunt for food. The species could be starved out within the next 80 years, save for a few high-Arctic subpopulations.</p><p>"Here, we establish the likely nature, timing and order of future demographic impacts by estimating the threshold numbers of days that polar bears can fast before cub recruitment and/or adult survival are impacted and decline rapidly," the authors of the study said.</p><p>The study looked at 13 of the world's 19 subpopulations of polar bears that account for 80 percent of the species' total population. Researchers modeled the energy use of the polar bears to calculate the number of days the bears can fast before their reproductive abilities become impacted. They then mapped that onto the number of estimated iceless days that will be faced in the coming decades, determining that the amount of time the bears would be forced to fast surpassed the amount of time they were capable of fasting. In 20 years from now, some polar bears living in Canada will begin to face reproductive failure and in 40 years a majority of the global population will more than likely be affected. </p><p>"The dire predictions in our study result from polar bear's dependence on sea ice and the projected rapid loss of that ice due to human-driven climate change," Marika Holland, co-author of the paper <a href="https://time.com/5869316/climate-change-pushes-polar-bears-towards-extinction-study-finds/" target="_blank">told TIME</a>.</p><p>While the scientists noted that moderate cuts in emissions could potentially extend the bears' estimated life-expectancy for a bit, it won't be able to save some species populations from extinction by the end of the century.</p><p>"Land-based feeding is unlikely to occur at scales that shift the timelines for recruitment and survival declines by more than a few years, because foods that meet the energy demands of polar bears are largely unavailable on land," the study said, pointing out that some polar bear populations are already feeling the impact.</p>
The melting arctic<p>Of course, as the <a href="https://www.iucn.org/content/action-now-save-polar-bears" target="_blank">International Union for Conservation of Nature</a> has cited, climate change is the main cause of the population's suffering and decline.</p><p>According to the World Meteorological Organization, the Arctic is likely to have warmed more than double the amount of the global average this year compared to pre-industrial temperatures. Since the 1970s, satellites have shown sea ice melting by 13 percent per decade. If greenhouse gas emissions stay on their current trajectory, the only polar bears that will be left by the end of the century will likely be those living in the Queen Elizabeth Islands in Canada's Arctic Archipelago. </p><p>Keeping tabs on polar bears, the largest land-dwelling carnivore on earth, is how scientists keep their finger on the pulse of the health of Arctic populations at-large. Their loss, as Holland <a href="https://time.com/5869316/climate-change-pushes-polar-bears-towards-extinction-study-finds/" target="_blank">told TIME</a>, "would reverberate throughout the ecosystem." </p><p>But the bears won't go down without a fight for their survival. As Arctic temperatures rise, melting the species' normal hunting grounds, the bears may begin to move toward land to find food. For example, in 2019 authorities in Russia's remote arctic region declared a state of emergency as a mob of starving polar bears charged into villages. </p>
Any hope?<img type="lazy-image" data-runner-src="https://assets.rebelmouse.io/eyJhbGciOiJIUzI1NiIsInR5cCI6IkpXVCJ9.eyJpbWFnZSI6Imh0dHBzOi8vYXNzZXRzLnJibC5tcy8yMzUxMTYxMy9vcmlnaW4uanBnIiwiZXhwaXJlc19hdCI6MTYxMTM5ODY0M30.RqKPGBEzFaJsP81U2JcpbnMglhCYfg-TQpG7qPZT6H4/img.jpg?width=1245&coordinates=0%2C301%2C0%2C302&height=700" id="c7cea" class="rm-shortcode" data-rm-shortcode-id="f92dedfaaf59e0d8df8c00e016d1f288" data-rm-shortcode-name="rebelmouse-image" alt="arctic fox in snow" />
Arctic foxes are another species endangered as their habitats and diets are threatened by melting sea ice due to greenhouse gas emissions.Photo by Jonatan Pie on Unsplash<p>Polar bears have faced extermination in the past. In 1965, scientists were worried that commercial polar bear hunting would cause the species to go extinct. A 1973 worldwide ban on hunting led to a resurgence in bear population, yet the melting sea ice that now threatens the lives of the <a href="http://pbsg.npolar.no/export/sites/pbsg/en/docs/2019-StatusReport.pdf" target="_blank">estimated 26,000</a> that live on earth today is a much more complex issue to solve. While the species' future looks grim, the study does point out that decreasing fossil fuel burning may reduce Arctic sea ice loss. </p><p>If there is a sliver of hope left for the polar bears and <a href="https://www.un-habitat.org/endangered-animals-arctic-region/" target="_blank">other Arctic species</a> endangered by melting Arctic ice, it rests on rapid and radical human action against fossil fuel emissions.</p>
Scientists discovered footprints made by some of the largest creatures ever to walk the Earth.
- Paleontologists published a paper on the discovery of dinosaur footprints on the roof of a French cave.
- The prints are deep underground and were made during the Middle Jurassic period.
- The footprints belonged to titanosaurs, the largest land animals ever.
The titanosaur Alamosaurus.
Credit: Bogdanov, 2006. Creative Commons.
Dinosaur tracks in the ceiling of Castelbouc Cave in France.
Credit: Jean-David Moreau et al./J. Vertebr. Paleontol.
Australia's beloved and bizarre egg-laying mammal could start vanishing in coming years if current trends continue.
- Platypuses are nocturnal, semiaquatic animals that are endemic to Australia and Tasmania.
- A new study suggests that the species could lose half its population over the next 50 years, due mainly to drought, human development and climate change.
- In 2019, the United Nations reported that some 1 million species of plants and animals are at risk of extinction.
Pixabay<p>"There is an urgent need for a national risk assessment for the platypus to assess its conservation status, evaluate risks and impacts, and prioritize management in order to minimize any risk of extinction," Bino <a href="https://www.sciencedaily.com/releases/2020/01/200121112922.htm" target="_blank">told</a> <em>Science Daily.</em></p><p>The study estimated the future decline of platypus populations by considering current rates of climate change, drought, and land and water development. Under this model, the results showed that the platypus population is likely to drop 47 percent over the next 50 years. Drought is expected to be a particularly deadly threat to the species.</p>
Heinrich Harder/Public Domain<p>Australia has recently suffered some of its worst droughts on record. The researchers suggested that even more extreme droughts are likely to occur in the future, considering that the changing climate will bring even hotter temperatures. Droughts can destroy platypuses' burrows, which the animal usually constructs by digging into the riverbank with its claws. When droughts dry up these hiding spots, platypuses are forced to move into new areas where they risk becoming prey to predators like foxes, dogs, and cats.</p><p>Droughts can also increase the likelihood of deadly bushfires. The <a href="https://bigthink.com/strange-maps/australia-bushfires-photo">current bushfire crisis</a> in Australia wasn't mentioned in the recent study, but experts estimate that some 1 billion animals have been killed so far in the fires. As for how many platypuses died:</p><p>"The short answer is that we simply don't know," Josh Griffiths, an ecologist with the environmental consulting firm Cesar Australia, <a href="https://www.atlasobscura.com/articles/australia-platypus-bushfire" target="_blank">told</a> <em>Atlas Obscura</em> in an article published January 24, 2020. "The scale of the fire we've got at the moment is unprecedented. [...] It's one more nail in their coffin."</p>
How to save the platypus<p>Human development, especially that which involves altering rivers, is another major threat to the platypus. Study co-author Richard Kingsford, director of the UNSW Centre for Ecosystem Science, noted that many platypuses live in areas of Australia currently undergoing development.</p><p style="margin-left: 20px;">"These include dams that stop their movements, agriculture which can destroy their burrows, fishing gear and yabby traps which can drown them and invasive foxes which can kill them," Kingsford told<em> Science Daily</em>.</p><p>The researchers offered several suggestions for how to protect the platypus:</p><ul><li>Ban enclosed cray-fish traps</li><li>Prevent land clearing in key areas</li><li>Build "platypus-ways" that provide safe passage from ferals predators</li><li>Citizens can report platypus sightings via the app <a href="http://platypusspot.org/" target="_blank">platypusSpot</a></li></ul>
How can we stop extinction? One solution scientists have been developing for decades is de-extinction — the process of resurrecting extinct species through genetic engineering.