Ecosystem Crises Interactions. Merrill Singer. Читать онлайн. Newlib. NEWLIB.NET

Автор: Merrill Singer
Издательство: John Wiley & Sons Limited
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Жанр произведения: Физика
Год издания: 0
isbn: 9781119570011
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of significant changes in the rock layers of Earth’s stratigraphy. The conceptualization of the Anthropocene hinges on the idea that the geological epoch known as the Holocene (Greek for “entirely recent”), which began approximately 11 650 calendar years before the present, has ended, because “humankind has become a global geological force in its own right” (Steffen et al. 2005). The ICS has not as yet accepted the Anthropocene as a formally defined geological unit within the Geological Time Scale, though its Anthropocene working group has concluded that it is a plausible new layer in Earth geochronology. Establishing the Anthropocene as an accepted geologic unit of time requires that the ICS either: 1) identify a specific location in rock, sediment, or glacier ice that marks the transition to a new epoch (e.g., the Precambrian–Cambrian boundary marker has been placed at Fortune Head, Newfoundland, where there is clear fossil evidence of a lifeform transition); or 2) agree on a date for this transition, based on a survey of the available stratigraphic evidence. Various dates, such as the beginning of the Industrial Revolution, with its ever‐accelerating level of fossil fuel use and abundant greenhouse gas emissions (Crutzen 2002), or the period between 1945 and 1988, when nuclear weapons were tested with such frequency that their worldwide fallout left an identifiable mark in the chemostratigraphic record (Zalasiewicz et al. 2015), have been proposed.

      One of the most curious features in the evidence for the Anthropocene involves the common domestic broiler chicken, the source of everything from buffalo wings to pre‐sliced deli meat chicken sandwiches. While thus far no individual taxa have been suggested as the distinct marker of the Anthropocene, Bennett et al. (2018) propose Gallus gallus domesticus as the best choice. Driving the rise and global spread of this heavily engineered bird are human population growth, commercially impacted human consumption trends, and drops in the populations of wild animals. It is now by far the most numerous bird species around, with an estimated population of almost 23 billion individuals. This is an order of magnitude larger than stocks of the most abundant existing wild bird species, such as house sparrows, common pigeons, and red‐billed quelea, as well as the extinct passenger pigeon, and is likely the largest population size ever achieved by a single species in the 160 million‐year history of birds. Because of selective industrial breeding, the broiler chicken is distinctive in overall size, weight, bone size, genetic make‐up, and appearance from its wild progenitor, the red jungle fowl. In 2016, over 65 billion broilers were consumed globally. Production and consumption data mean “that the potential rate of carcass accumulation of chickens is unprecedented in the natural world” (Bennett et al. 2018). Much of this global accumulation finds its way into landfill sites by way of domestic garbage removal systems. Organic materials like chicken bones are often well preserved in landfills because their anaerobic conditions tend to mummify organic deposits (Rathje & Murphy 2001). Consequently, the broiler chicken produces a particularly widely distributed and distinctive biostratigraphic signal in the sedimentary record, allowing it to serve as a key fossil index taxon of the Anthropocene.

      Ultimately, whether or not the ICS decides that the Anthropocene meets the criteria for the establishment of an epoch in Earth history, it does not change the reality of the “perfect storm” of interacting human impacts on the planet, its global processes and ecosystems, and its lifeforms. For those at gravest risk from ecocrises interaction, whether their loss of access to adequate food, breathable air, survivable temperatures, or dry land occurs during a particular scientifically defined segment of geological time on ICS’ International Chronostratigraphic Chart is of negligible importance. What does matter is the utility of Anthropocene recognition in spurring useful new research and practical political and social action to avert a slide into hothouse Earth conditions.

      Most significant among the ecological crises Earthlings now face is global warming. Earth’s temperature has risen by 1.4 °F over the last 100 years, and is predicted to rise to 11.5 °F in the next few decades. Despite various disagreements about regional and temporal variations in temperature, the vast majority of climate scientists recognize both that the planet is getting hotter and that fossil fuel technology is playing a fundamental role in this risky process. Today, the carbon dioxide level in the atmosphere is the greatest it has been in 400 000 years, having jumped from about 280 parts per million (ppm) before the Industrial Revolution to about 410 ppm today. In the final report of The Lancet Commission on Managing the Health Effects of Climate Change (Costello et al. 2009), the warming of Earth was labeled “the biggest global health threat of the 21st century,” a conclusion affirmed by the Commission in 2015 (Watts et al. 2015). The WHO (2018) estimates there will be approximately 250 000 additional deaths due to climate change per year between 2030 and 2050, due to malnutrition, malaria, diarrhea, and heat stress. People living in coastal regions, megacities, island communities, and mountainous and polar regions are particularly vulnerable, especially children and elderly people. Notably, disproportionate morbidity and mortality rises due to climate change will affect the poorest and least powerful global citizens (Singer 2018).

      The hottest year on record was 2016, with 2014, 2015, 2017, and 2018 representing the next four hottest since the measurement of annual records began 139 years ago. As Climate Central (2018) points out “[w]ith the five warmest years occurring during the past five years—and the 20 warmest occurring over the past 22—a consistent warming trend couldn’t be clearer.” The trend continues. June of 2019 was the warmest June ever recorded. For climate scientists like Sarah Green, an environmental chemist at Michigan Technological University, “[a]t this point, the inexorable increase in global temperatures is entirely predictable” (quoted in Kaufman 2019).