CARTA - Humans: The Planet-Altering Apes - Global Alteration of the Nitrogen Cycles by Humans with David Tilman

06/11/22 • 17 min

Humans now annually add more biologically available nitrogen to the Earth’s land surfaces than do all natural processes. For 3 billion years, available nitrogen had been the major limiting currency for life on Earth. The recent human disruption of the global nitrogen cycle is causing major environmental harm, including water and air pollution, marine dead zones, 10% of global greenhouse gas emissions, and species extinctions. Three major ways to solve this nitrogen problem are: (1) much more efficient global use of nitrogen fertilizers; (2) shifts to lower-meat and healthier diets; and (3) halting the conversion of food crops into biofuels, such as US corn ethanol used for transport. Series: "CARTA - Center for Academic Research and Training in Anthropogeny" [Humanities] [Science] [Show ID: 37910]

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CARTA - Humans: The Planet-Altering Apes - Sixth Mass Extinction the Tree of Life and the Future of Humanity with Gerardo Ceballos

We are losing species much more rapidly now than in the last two million years! At this pace, we may lose a large proportion of vertebrates, including mammals, birds, reptiles, amphibians, and fishes, in the next two to three decades. Modern extinctions caused by human activities are higher than the normal or natural extinction rate which tells us that we may be causing a mass extinction. In the history of life on Earth, there have been five mass extinctions – episodes where large numbers of species became extinct in a short period of time. All mass extinctions have been caused by natural catastrophes, such as the impact of a meteorite. We are the only species that has the capability to save all endangered animals. Paradoxically, saving them is the only way to save humanity. Series: "CARTA - Center for Academic Research and Training in Anthropogeny" [Humanities] [Science] [Show ID: 37904]

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CARTA - Humans: The Planet-Altering Apes - Loss of Species Loss of Genetic Variation and the Future of Earth’s Biota with Oliver Ryder

We are experiencing an accelerated rate of loss of species due to human activities. This anthropogenic phenomenon extends beyond extinction. It encompasses an expanded loss of biodiversity as the genetic diversity of species diminish, reducing gene pools to “gene puddles.” We know details of species extinctions events from the fossil record, historical record, and from ancient DNA studies, and that historical processes shape extinction risk. Habitat loss and changing eco-environmental conditions, competition, and other factors produce genomic impacts, also influencing extinction risk. The legacy of past events impacts resiliency of species in the current environment in interpretable ways. Demographic trajectories reveal vulnerability to extinction. Remarkable advances in genomics technologies portend a deeper understanding of the evolution of life and the vulnerability of extant species to changes now taking place through human agency. Series: "CARTA - Center for Academic Research and Training in Anthropogeny" [Humanities] [Science] [Show ID: 37906]