We may be in the midst of a major human-driven extinction crisis, but it turns out that humans may have been pushing other species to the brink long before the industrial era.
A new study published in Scientific Reports Thursday found that humans played a potentially "significant" role in the extinction of the cave bear, a giant Pleistocene relative of the brown bear that could weigh as much as 2,000 pounds and went extinct around 20,000 years ago, according to The Washington Post.
The researchers used mitochondrial DNA from cave bear bones found across Europe to track the animals' population diversity and size. They found that their population stayed stable through two cooling and warming cycles before starting to decline when modern humans arrived.
"We see this dramatic drop in the population of the cave bear starting from 40,000 years ago, which coincides with the arrival of anatomically modern humans in Europe," study leader Prof. Verena Schünemann of the University of Zurich told BBC News. "It is the clearest evidence we have so far that humans might have played a big role in the extinction of the cave bear."
A debate has long raged in the scientific community over what exactly caused large mammals like cave bears, mammoths and saber-tooth cats to go extinct. Some blame the last glacial maximum 26,500 years ago, but others point to the hunting prowess of modern humans, National Geographic explained.
At least in the case of the cave bear, it appears that humans played an important role.
"If not for our arrival in Europe, I don't see any reason why cave bears should not be around today," study coauthor and University of Tübingen paleobiologist Hervé Bocherens told National Geographic.
Axel Barlow, a biologist at the University of Potsdam, Germany who was not involved with the research, told The Washington Post that the study was "very nice" and made it clear that something "quite profound happened to the global cave bear population around 40,000 years ago."
Of course, it's possible that climate change and human activity together shaped the bears' ultimate fate, Schünemann told The Washington Post. An increase in human hunting may have coincided with a decline in food, for example. And studying that interaction can help scientists understand what is happening today.
"Looking at the impact of climate change and human impact on large mammals can tell us a lot about the general process and consequences of large mammal extinction," Bocherens told The Washington Post. "Studying the past to save the future: This is what we try to do."
Every September for the past 11 years, non-profit the Climate Group has hosted Climate Week NYC, a chance for business, government, activist and community leaders to come together and discuss solutions to the climate crisis.
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By D. André Green II
One of nature's epic events is underway: Monarch butterflies' fall migration. Departing from all across the United States and Canada, the butterflies travel up to 2,500 miles to cluster at the same locations in Mexico or along the Pacific Coast where their great-grandparents spent the previous winter.
Millions of People Care About Monarchs<p>I will never forget the sights and sounds the first time I visited monarchs' overwintering sites in Mexico. Our guide pointed in the distance to what looked like hanging branches covered with dead leaves. But then I saw the leaves flash orange every so often, revealing what were actually thousands of tightly packed butterflies. The monarchs made their most striking sounds in the Sun, when they burst from the trees in massive fluttering plumes or landed on the ground in the tussle of mating.</p><p>Decades of educational outreach by teachers, researchers and hobbyists has cultivated a generation of monarch admirers who want to help preserve this phenomenon. This global network has helped restore not only monarchs' summer breeding habitat by planting milkweed, but also general pollinator habitat by planting nectaring flowers across North America.</p><p>Scientists have calculated that restoring the monarch population to a stable level of about 120 million butterflies will require <a href="https://doi.org/10.1111/icad.12198" target="_blank">planting 1.6 billion new milkweed stems</a>. And they need them fast. This is too large a target to achieve through grassroots efforts alone. A <a href="https://www.fws.gov/savethemonarch/CCAA.html" target="_blank" rel="noopener noreferrer">new plan</a>, announced in the spring of 2020, is designed to help fill the gap.</p>
Pros and Cons of Regulation<p>The top-down strategy for saving monarchs gained energy in 2014, when the U.S. Fish and Wildlife Service <a href="https://www.fws.gov/southeast/pdf/petition/monarch.pdf" target="_blank">proposed</a> listing them as threatened under the Endangered Species Act. A decision is expected in December 2020.</p><p>Listing a species as endangered or threatened <a href="https://www.fws.gov/endangered/esa-library/pdf/listing.pdf" target="_blank">triggers restrictions</a> on "taking" (hunting, collecting or killing), transporting or selling it, and on activities that negatively affect its habitat. Listing monarchs would impose restrictions on landowners in areas where monarchs are found, over vast swaths of land in the U.S.</p><p>In my opinion, this is not a reason to avoid a listing. However, a "threatened" listing might inadvertently threaten one of the best conservation tools that we have: public education.</p><p>It would severely restrict common practices, such as rearing monarchs in classrooms and back yards, as well as scientific research. Anyone who wants to take monarchs and milkweed for these purposes would have to apply for special permits. But these efforts have had a multigenerational educational impact, and they should be protected. Few public campaigns have been more successful at raising awareness of conservation issues.</p>
<span style="display:block;position:relative;padding-top:56.25%;" class="rm-shortcode" data-rm-shortcode-id="91165203d4ec0efc30e4632a00fdf57d"><iframe lazy-loadable="true" src="https://www.youtube.com/embed/KilPRvjbMrA?rel=0" width="100%" height="auto" frameborder="0" scrolling="no" style="position:absolute;top:0;left:0;width:100%;height:100%;"></iframe></span>
The Rescue Attempt<p>To preempt the need for this kind of regulation, the U.S. Fish and Wildlife Service approved a <a href="https://www.fws.gov/savethemonarch/pdfs/Monarch%20CCAA-CCA%20Public%20Comment%20Documents/Monarch-Nationwide_CCAA-CCA_Draft.pdf" target="_blank">Nationwide Candidate Conservation Agreement for Monarch Butterflies</a>. Under this plan, "rights-of-way" landowners – energy and transportation companies and private owners – commit to restoring and creating millions of acres of pollinator habitat that have been decimated by land development and herbicide use in the past half-century.</p><p>The agreement was spearheaded by the <a href="http://rightofway.erc.uic.edu/" target="_blank">Rights-of-Way Habitat Working Group</a>, a collaboration between the University of Illinois Chicago's <a href="https://erc.uic.edu/" target="_blank" rel="noopener noreferrer">Energy Resources Center</a>, the Fish and Wildlife Service and over 40 organizations from the energy and transportation sectors. These sectors control "rights-of-way" corridors such as lands near power lines, oil pipelines, railroad tracks and interstates, all valuable to monarch habitat restoration.</p><p>Under the plan, partners voluntarily agree to commit a percentage of their land to host protected monarch habitat. In exchange, general operations on their land that might directly harm monarchs or destroy milkweed will not be subject to the enhanced regulation of the Endangered Species Act – protection that would last for 25 years if monarchs are listed as threatened. The agreement is expected to create up to 2.3 million acres of new protected habitat, which ideally would avoid the need for a "threatened" listing.</p>
A Model for Collaboration<p>This agreement could be one of the few specific interventions that is big enough to allow researchers to quantify its impact on the size of the monarch population. Even if the agreement produces only 20% of its 2.3 million acre goal, this would still yield nearly half a million acres of new protected habitat. This would provide a powerful test of the role of declining breeding and nectaring habitat compared to other challenges to monarchs, such as climate change or pollution.</p><p>Scientists hope that data from this agreement will be made publicly available, like projects in the <a href="https://www.fws.gov/savethemonarch/MCD.html" target="_blank">Monarch Conservation Database</a>, which has tracked smaller on-the-ground conservation efforts since 2014. With this information we can continue to develop powerful new models with better accuracy for determining how different habitat factors, such as the number of milkweed stems or nectaring flowers on a landscape scale, affect the monarch population.</p><p>North America's monarch butterfly migration is one of the most awe-inspiring feats in the natural world. If this rescue plan succeeds, it could become a model for bridging different interests to achieve a common conservation goal.</p>
The annual Ig Nobel prizes were awarded Thursday by the science humor magazine Annals of Improbable Research for scientific experiments that seem somewhat absurd, but are also thought-provoking. This was the 30th year the awards have been presented, but the first time they were not presented at Harvard University. Instead, they were delivered in a 75-minute pre-recorded ceremony.
By Betsy Mason
For decades, climate scientist David Keith of Harvard University has been trying to get people to take his research seriously. He's a pioneer in the field of geoengineering, which aims to combat climate change through a range of technological fixes. Over the years, ideas have included sprinkling iron in the ocean to stimulate plankton to suck up more carbon from the atmosphere or capturing carbon straight out of the air.
Solar geoengineering would involve injecting reflective aerosols from high-altitude planes into the layer of the upper atmosphere known as the stratosphere, which stretches between 10 to 50 kilometers (6 to 31 miles) above Earth's surface. The idea is that the aerosol particles would reflect a small amount of sunlight away from the planet, reducing the amount of heat trapped by greenhouse gases and mitigating some of the effects of climate change.
The planned Stratospheric Controlled Perturbation Experiment will send a balloon carrying scientific instruments in a gondola into the stratosphere. The instruments will release a small amount of material — likely ice or mineral dust — to form a kilometer-long plume of aerosol particles (left). Modified airboat propellers will allow the gondola to maneuver above the plume (middle) and lower instruments into the plume to take repeated measurements of how the particles spread through the stratosphere (right). ADAPTED FROM J.A. DYKEMA ET AL / PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY A 2014
David Keith envisions using multiple approaches to combat climate change. The red line shows how the impacts of climate change would worsen with a business-as-usual scenario of unabated burning of fossil fuels and other greenhouse gas emissions. Aggressively cutting emissions bends that curve, and removing carbon from the atmosphere offers further cuts, but there are still consequences from the already high levels of carbon dioxide. In this scenario, solar geoengineering would lessen the impact from existing atmospheric carbon dioxide, effectively carving the top off the curve.<p>Some people think we should use it only as a get-out-of-jail card in an emergency. Some people think we should use it to quickly try to get back to a preindustrial climate. I'm arguing we use solar geoengineering to cut the top off the curve by gradually starting it and gradually ending it.</p><p><strong>Do you feel optimistic about the chances that solar geoengineering will happen and can make a difference in the climate crisis?</strong></p><p>I'm not all that optimistic right now because we seem to be so much further away from an international environment that's going to allow sensible policy. And that's not just in the US. It's a whole bunch of European countries with more populist regimes. It's Brazil. It's the more authoritarian India and China. It's a more nationalistic world, right? It's a little hard to see a global, coordinated effort in the near term. But I hope those things will change.</p>
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