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Mass extinctions: are we there yet? Palaeontologists recognize five major extinction events from the fossil record, with the most recent, the Cretaceous mass extinction, ending some 65 million years ago. Given the many species known to have disappeared in the past few thousand years, some biologists suggest that a sixth such event is now under way. Barnosky et al . set out to review the evidence for that claim, and conclude that the recent loss of species is dramatic and serious, but not yet in the mass extinction category — usually defined as a loss of at least 75% of Earth's species in a geologically short time frame. But that said, there are clear indications that the loss of species now classed as 'critically endangered' would soon propel the world into its sixth mass extinction. Palaeontologists characterize mass extinctions as times when the Earth loses more than three-quarters of its species in a geologically short interval, as has happened only five times in the past 540 million years or so. Biologists now suggest that a sixth mass extinction may be under way, given the known species losses over the past few centuries and millennia. Here we review how differences between fossil and modern data and the addition of recently available palaeontological information influence our understanding of the current extinction crisis. Our results confirm that current extinction rates are higher than would be expected from the fossil record, highlighting the need for effective conservation measures.

As the public increasingly questioned the war in Vietnam, a group of American scientists deeply concerned about the use of Agent Orange and other herbicides started a movement to ban what they called \"ecocide.\" David Zierler traces this movement, starting in the 1940s, when weed killer was developed in agricultural circles and theories of counterinsurgency were studied by the military. These two trajectories converged in 1961 with Operation Ranch Hand, the joint U.S.-South Vietnamese mission to use herbicidal warfare as a means to defoliate large areas of enemy territory. Driven by the idea that humans were altering the world's ecology for the worse, a group of scientists relentlessly challenged Pentagon assurances of safety, citing possible long-term environmental and health effects. It wasn't until 1970 that the scientists gained access to sprayed zones confirming that a major ecological disaster had occurred. Their findings convinced the U.S. government to renounce first use of herbicides in future wars and, Zierler argues, fundamentally reoriented thinking about warfare and environmental security in the next forty years. Incorporating in-depth interviews, unique archival collections, and recently declassified national security documents, Zierler examines the movement to ban ecocide as it played out amid the rise of a global environmental consciousness and growing disillusionment with the containment policies of the cold war era.

\"In 2023, hundreds of AI luminaries signed an open letter warning that artificial intelligence poses a serious risk of human extinction. Since then, the AI race has only intensified. Companies and countries are rushing to build machines that will be smarter than any person. And the world is devastatingly unprepared for what would come next. For decades, two signatories of that letter -- Eliezer Yudkowsky and Nate Soares -- have studied how smarter-than-human intelligences will think, behave, and pursue their objectives. Their research says that sufficiently smart AIs will develop goals of their own that put them in conflict with us -- and that if it comes to conflict, an artificial superintelligence would crush us. The contest wouldn't even be close. How could a machine superintelligence wipe out our entire species? Why would it want to? Would it want anything at all? In this urgent book, Yudkowsky and Soares walk through the theory and the evidence, present one possible extinction scenario, and explain what it would take for humanity to survive. The world is racing to build something truly new under the sun. And if anyone builds it, everyone dies.\" -- Provided by publisher.

Anthropogenic stressors to marine ecosystems from climate change and human activities increase extinction risk of species, disrupt ecosystem integrity, and threaten important ecosystem services. Addressing these stressors requires understanding where and to what extent they are impacting marine biological and functional diversity. We model cumulative risk of human impact upon 21,159 marine animal species by combining information on species-level vulnerability and spatial exposure to a range of anthropogenic stressors. We apply this species-level assessment of human impacts to examine patterns of species-stressor interactions within taxonomic groups. We then spatially map impacts across the global ocean, identifying locations where climate-driven impacts overlap with fishing, shipping, and land-based stressors to help inform conservation needs and opportunities. Comparing species-level modeled impacts to those based on marine habitats that represent important marine ecosystems, we find that even relatively untouched habitats may still be home to species at elevated risk, and that many species-rich coastal regions may be at greater risk than indicated from habitat-based methods alone. Finally, we incorporate a trait-based metric of functional diversity to identify where impacts to functionally unique species might pose greater risk to community structure and ecosystem integrity. These complementary lenses of species, function, and habitat provide a richer understanding of threats to marine biodiversity to help inform efforts to meet conservation targets and ensure sustainability of nature’s contributions to people.

\"A book for middle-school-aged children about previous extinctions and possible threats to humans, from volcanoes, to asteroids, to pollution and diseases\"-- Provided by publisher.

Aim Islands are regarded as ideal ecosystems for exploring biodiversity patterns. However, numerous islands have also suffered large numbers of species extinctions due to human activities. The extent to which such species extinctions have influenced our ability to understand biodiversity patterns, particularly the factors regulating island biodiversity, is still unclear. The purpose of our study was to disentangle the effects of recent human‐driven extinctions on island biodiversity patterns. Location Zhoushan Archipelago, China. Taxon Large and medium‐sized mammals. Methods We conducted field surveys on 30 islands with available recent data on large and medium‐sized mammals. We then calculated the alpha diversity and beta diversity from taxonomic, phylogenetic, and functional facets for natural (including both extinct and extant populations) and current assemblages (excluding extinct populations) on 24 islands that supported at least one extant mammal species. Finally, we assessed the changes in these diversity metrics and their key drivers between natural and current assemblages. Results Both alpha and beta diversity of taxonomic, phylogenetic, and functional facets have decreased in current assemblages compared to natural assemblages. Additionally, distance to the nearest mainland had significant effects on all alpha diversity metrics for natural assemblages, and island area significantly influenced all beta diversity metrics for natural assemblages, but these effects were not observed in current assemblages. Main Conclusions Our findings showed that fundamental diversity patterns at both alpha and beta levels have been rapidly altered by human‐driven extinctions, highlighting humans as a major force in island ecosystems. We thus emphasise that assessing biodiversity patterns based on natural assemblages is important to improve our understanding of the evolutionary and ecological determinants of island biodiversity as well as to provide a benchmark for biodiversity conservation.

Industrialization has raised the concentration of carbon dioxide (CO2) in Earth's atmosphere by half since 1770, posing a risk from ocean acidification to global biodiversity, including phytoplankton that synthesize approximately (∼) 50% of planetary oxygen. This risk is estimated here from the fossil record and implications for our energy and economic future are explored. Over the last 534 million years (Myr), 50 extinction events present as peaks of genus loss‐and‐recovery cycles, each spanning ∼3–40 Myr. Atmospheric CO2 concentration oscillates with percent genus loss, leading in phase by ∼4 Myr and sharing harmonic periodicities at ∼10, 26 and 63 Myr. Over the last 210 Myr, where data resolution is highest, biodiversity loss is correlated with atmospheric CO2 concentration, but not with long‐term global temperature nor with marginal radiative forcing of temperature by atmospheric CO2. The end‐Cretaceous extinction of the dinosaurs is anomalous, occurring during a 20‐million year depression in atmospheric CO2 concentration and rising global temperature. Today's atmospheric CO2 concentration, ∼421 parts per million by volume (ppmv), corresponds in the most recent marine fossil record to a biodiversity loss of 6.39%, implying that contemporary anthropogenic CO2 emissions are killing ocean life now. The United Nations Intergovernmental Panel on Climate Change projects that unabated fossil fuel use could elevate atmospheric CO2 concentration to 800 ppmv by 2100, approaching the 870 ppmv mean concentration of the last 19 natural extinction events. Reversing this first global anthropogenic mass extinction requires reducing net anthropogenic CO2 emissions to zero, optimally by 2% per year starting immediately. Plain Language Summary The rising concentration of carbon dioxide (CO2) in Earth's atmosphere from burning fossil fuels poses a risk to biodiversity from ocean acidification, threatening marine algae that produce ∼50% of planetary oxygen. This risk is estimated here based on the relationship between marine biodiversity loss and atmospheric CO2 concentration in the fossil record. Biodiversity loss varies cyclically with atmospheric CO2 concentration on million‐year timescales, but is not correlated with long‐term global temperature nor with radiative forcing (RF) of temperature by CO2. Atmospheric CO2 is therefore a plausible cause of past mass extinctions, while long‐term temperature change and RF by CO2 are excluded. Biodiversity and atmospheric CO2 cycle at periods similar to each other and to geological and astrophysical cycles, consistent with causal linkages. The concentration of CO2 in today's atmosphere corresponds to a decline in fossil biodiversity of 6.39%, implying that current human‐induced emissions of CO2 are killing ocean life now. The United Nations Intergovernmental Panel on Climate Change projects that continuation of the global fossil fuel economy could raise atmospheric CO2 to concentrations approaching the average of past mass extinctions by the year 2100. Arresting this first human‐induced global mass extinction requires eliminating net human‐induced emissions of CO2 starting immediately. Key Points Past mass extinctions are correlated with atmospheric CO2 concentration, but not with long‐term temperature nor radiative forcing by CO2 Present CO2 concentration is associated in the fossil record with a 6.39% genus loss, implying current human destruction of biodiversity Future anthropogenic mass extinction can be stopped only by cutting human emissions of CO2 to zero, optimally by 2% per year starting now