Well, drat. I was looking forward to those wooly mammoths....another hope dashed.
~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Jessica Gurevitch Distinguished Professor and Co-Chair Department of Ecology and Evolution Stony Brook University Stony Brook, NY 11794-5245 USA ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ On Tue, Dec 21, 2021 at 1:29 PM Renaud de RICHTER < [email protected]> wrote: > New study on PNAS > (PS: also an interesting funny reading > *Is Santa’s sleigh zero carbon? The answer lies in reindeer poo* > https://theconversation.com/is-santas-sleigh-zero-carbon-the-answer-lies-in-reindeer-poo-173800 > ). > Season's greetings to all the CDR group. > Rewilding the Arctic with mammals likely to be ineffective in slowing > climate change impact > *phys.org*/news/2021-12-rewilding-arctic-mammals-ineffective-climate.html > <https://phys.org/news/2021-12-rewilding-arctic-mammals-ineffective-climate.html?utm_source=nwletter&utm_medium=email&utm_campaign=daily-nwletter> > <https://phys.org/archive/20-12-2021/> > > December 20, 2021 > > by University of Southampton <http://www.soton.ac.uk/> > > A new study has shed new light on why large mammals died out at the end of > the ice age, suggesting their extinction was caused by a warming climate > and expansion of vegetation that created unsuitable habitat for the > animals. The findings, published in the journal *PNAS*, have major > implications for proposals to prevent the soils in the Arctic today from > thawing by re-introducing animals such as bison and horses. > > About 14,000 years ago, at the end of the last ice age, open, grassy > landscapes that had extended eastwards from France across the now submerged > Bering Sea all the way to the Yukon in Canada were transformed by the rapid > spread of shrubs. At the same time, several iconic mammal species that > inhabited what is now Alaska and the Yukon, such as the woolly mammoth > <https://phys.org/tags/woolly+mammoth/>, became extinct, and archaeology > records human presence <https://phys.org/tags/human+presence/> in the > region. > > These ancient coincidences have led to the suggestion that human hunting > caused the demise of the mammals, and their loss led to the shrub > <https://phys.org/tags/shrub/> expansion, as they were not there to > trample down the vegetation and put nutrients back into the soil. > > Today, with strong arctic warming, shrubs are spreading even further north > into tundra regions. It is now popular to advocate that a form of > rewilding—where animals <https://phys.org/tags/animals/> are returned to > their original ecosystems to restore more "natural" conditions—might > reverse the trend of increasing shrub cover, with possible benefit of > keeping carbon stored in the ground. This is because low-growing vegetation > exposes the ground to colder conditions than shrub cover does, and thus the > ground and the carbon it contains remain well frozen. > > Others advocate that climate change drove the vegetation and landscape > changes, and these led to the loss of the animals as their habitat > disappeared. > > To test these alternative hypotheses, an international research team > examined records of fossil pollen preserved in lake sediments across Alaska > and Yukon for thousands of years. By focussing on records that met strict > dating criteria the team could accurately pinpoint the timing of shrub > expansion across this region. They then compared this with how the numbers > of radiocarbon-dated bones from horse, bison, mammoth and moose changed > through time—which provided them with an estimate of their changing > population sizes. > > Their results showed that willow and birch shrubs began to expand across > Alaska and Yukon around 14,000 years ago, when records of dated bones > indicate that large grazing mammals were still abundant on the landscape. > > "Our study uses a clear predictive test to assess two opposing hypotheses > about large animals in ancient and modern tundra ecosystems: that the > animals disappeared before the shrubs increased, or that the shrubs > increased before the animals disappeared," said Professor Mary Edwards of > the University of Southampton who was part of the study team. > > Dr. Ali Monteath, the lead author from the Universities of Alberta and > Southampton, adds "The results support the idea that at the end of the last > ice age a major shift to warmer and wetter conditions transformed the > landscape in a way that was highly unfavorable to the animals, including > mammoths". > > The findings suggest that climate change > <https://phys.org/tags/climate+change/> was the primary controller of > northern ecosystems and that the large herbivores were not able to maintain > their environment as the shrubs spread. "While humans may have compounded > population declines, our results suggest climate-driven vegetation change > was the primary reason the mammals disappeared," added Professor Edwards. > > Returning to the concept of rewilding the North with large mammals > <https://phys.org/tags/large+mammals/> that are currently absent from the > region, the research team concludes that this would probably not transform > the vegetation over large areas and so do little to curtail release of > carbon from the Arctic permafrost. > > Study co-author Professor Duane Froese of the University of Alberta said: > "Rewilding experiments at the scale of local paddocks, as has been done for > example at Pleistocene Park (NE Siberia), show that megaherbivores can > alter their environment, drive changes in vegetation and even cool soil > temperature, but these animal densities are much higher than we would > expect for Pleistocene ecosystems. Our study shows that the effect of > megafauna grazing is small at sub-continental scales even with the presence > of mammoths, and climate, once again, is the main driver of these systems." > > Benjamin Gaglioti of the University of Alaska-Fairbanks added: "The > hypothesis that reintroducing megafauna will prevent or slow warming-driven > permafrost thaw and vegetation change in the Arctic has been bolstered by > the idea that Pleistocene megafauna were instrumental in maintaining ice > age ecosystems. In contrast to this prediction, our results show that > high-latitude ecosystems responded sensitively to past warming events, even > though megafauna were abundant on the landscape. These results lend support > to the hypothesis that reintroducing megafauna today will do little to > desensitize high latitude ecosystems to human driven warming." > *More information:* Late Pleistocene shrub expansion preceded megafauna > turnover and extinctions in eastern Beringia, *Proceedings of the > National Academy of Sciences* (2021). DOI: 10.1073/pnas.2107977118 > <http://dx.doi.org/10.1073/pnas.2107977118>. > > > > Le lun. 27 janv. 2020 à 18:10, Andrew Lockley <[email protected]> > a écrit : > >> Poster's note: Cross posting, due to the albedo and Carbon storage >> dimensions >> >> https://royalsocietypublishing.org/doi/10.1098/rstb.2019.0122 >> >> Pleistocene Arctic megafaunal ecological engineering as a natural climate >> solution? >> Marc Macias-Fauria, Paul Jepson, Nikita Zimov and Yadvinder Malhi >> Published:27 January 2020https://doi.org/10.1098/rstb.2019.0122 >> Abstract >> Natural climate solutions (NCS) in the Arctic hold the potential to be >> implemented at a scale able to substantially affect the global climate. The >> strong feedbacks between carbon-rich permafrost, climate and herbivory >> suggest an NCS consisting of reverting the current wet/moist moss and >> shrub-dominated tundra and the sparse forest–tundra ecotone to grassland >> through a guild of large herbivores. Grassland-dominated systems might >> delay permafrost thaw and reduce carbon emissions—especially in Yedoma >> regions, while increasing carbon capture through increased productivity and >> grass and forb deep root systems. Here we review the environmental context >> of megafaunal ecological engineering in the Arctic; explore the mechanisms >> through which it can help mitigate climate change; and estimate its >> potential—based on bison and horse, with the aim of evaluating the >> feasibility of generating an ecosystem shift that is economically viable in >> terms of carbon benefits and of sufficient scale to play a significant role >> in global climate change mitigation. Assuming a megafaunal-driven ecosystem >> shift we find support for a megafauna-based arctic NCS yielding substantial >> income in carbon markets. However, scaling up such projects to have a >> significant effect on the global climate is challenging given the large >> number of animals required over a short period of time. A first-cut >> business plan is presented based on practical information—costs and >> infrastructure—from Pleistocene Park (northeastern Yakutia, Russia). A 10 >> yr experimental phase incorporating three separate introductions of herds >> of approximately 1000 individuals each is costed at US$114 million, with >> potential returns of approximately 0.3–0.4% yr−1 towards the end of the >> period, and greater than 1% yr−1 after it. Institutional friction and the >> potential role of new technologies in the reintroductions are discussed. >> >> -- >> You received this message because you are subscribed to the Google Groups >> "Carbon Dioxide Removal" group. >> To unsubscribe from this group and stop receiving emails from it, send an >> email to [email protected]. >> To view this discussion on the web visit >> https://groups.google.com/d/msgid/CarbonDioxideRemoval/CAJ3C-04YPqxfKgCVT8jpxZp4-3-66Stq38BbUkXfLr9g5iEDWQ%40mail.gmail.com >> <https://groups.google.com/d/msgid/CarbonDioxideRemoval/CAJ3C-04YPqxfKgCVT8jpxZp4-3-66Stq38BbUkXfLr9g5iEDWQ%40mail.gmail.com?utm_medium=email&utm_source=footer> >> . >> > -- > You received this message because you are subscribed to the Google Groups > "geoengineering" group. > To unsubscribe from this group and stop receiving emails from it, send an > email to [email protected]. > To view this discussion on the web visit > https://groups.google.com/d/msgid/geoengineering/CAHodn99mC9xEytpN%3DNL0Ay6XVotJzSD_fC3aUNECLe0NLH%3D%2BiQ%40mail.gmail.com > <https://groups.google.com/d/msgid/geoengineering/CAHodn99mC9xEytpN%3DNL0Ay6XVotJzSD_fC3aUNECLe0NLH%3D%2BiQ%40mail.gmail.com?utm_medium=email&utm_source=footer> > . > -- You received this message because you are subscribed to the Google Groups "geoengineering" group. 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