Kindle Notes & Highlights
Started reading
January 1, 2019
The Keeling Curve.
In a paper published in 1970, atmospheric chemist Paul Crutzen suggested that Earth’s protective ozone layer might be threatened by emissions of a stable non-toxic gas produced naturally by bacteria living in soils.
At this point, Crutzen’s work attracted little interest.
A few years later, in 1974, Frank Sherwood Rowland and Mario Molina hypothesized that other types of inert gases, the chlorofluorocarbons (CFCs), might also be reaching the stratosphere and destroying ozone.
The Rowland–Molina hypothesis provoked an uproar across the industries producing and using CFCs, even while evidence mounted that stratospheric ozone was indeed under threat.
Within a few years, an international coordinated effort introduced new policy frameworks to address the ozone hole, beginning with the Montreal Protocol.
Crutzen, Rowland, and Molina shared the 1995 Nobel Prize in Chemistry.
Rachel Carson’s influential book Silent Spring,
In 1987, Paul Crutzen and Will Steffen were among the first to join the newly formed International Geosphere-Biosphere Programme (IGBP). With the formation of the IGBP, based in Sweden, Earth system science gained the institutional capacity it would need to build a robust interdisciplinary community of scientists dedicated to advancing Earth system science.
Using computer simulations of material and energy exchanges among the spheres, it became possible to confirm that increases in human activities were the cause of, not just correlated with, major long-term changes in the functioning of Earth as a system.
‘Amsterdam Declaration on Global Change’,
humans are now ‘overwhelming the great forces of nature’—
Moreover, these anthropogenic changes have the potential to produce even more rapid, surprising, and potentially catastrophic consequences as a result of tipping points and other complex feedbacks within the Earth system.
came at the IGBP’s 2000 meeting in Mexico
geological eons, eras, periods, and epochs.
It would be necessary to show that humans have left a clear, globally identifiable marker in the rocks.
Eight years after Crutzen’s outburst, geologists were ready to act. In their 2008 paper ‘Are we now living in the Anthropocene?’, Jan Zalasiewicz and colleagues at the Geological Society of London called on geologists to consider the Anthropocene as a new interval of geologic time.
Geologists who specialize in the study of such stratigraphic records, known as stratigraphers, are the keepers of geologic time.
His map still hangs in Burlington House, home of the Geological Society of London.
In this first calendar of geologic time, four different time intervals, or ‘orders’, were identified with four different types of rocks, and these were labelled in sequence from Primary to Quaternary.
half life of carbon-14 is brief, at 5,730 years,
In 1913, radiometric dating was used to determine the age of a rock sample at 1.6 billion years.
the Jurassic Period was established by Leopold von Buch in 1839, based on Alexander von Humboldt’s observations in 1795 of rock formations in the Jura Mountains of Switzerland.
Of the five mass extinction events commonly recognized in Earth history, in which exceptionally large numbers of species were lost within short intervals of time, four coincide with period boundaries. The most dramatic, which almost destroyed life altogether, occurred at the end of the Permian Period, currently dated at 252 million years ago, while the most famous, the mass extinction of the non-avian dinosaurs and marine reptiles, occurred at the Cretaceous–Palaeogene boundary (formerly known as the K-T boundary), 66 million years ago.
The events in Earth history that are marked in the GTS are only those that have left clear and recognizable global stratigraphic signatures,
the presence of readily identified animal fossils—the main basis for biostratigraphy—marks a profound division in the GTS, the divide between our present Eon and the Precambrian, a general term referring to all 4.06 billion years of Earth’s prior history.
To appear in the Geologic Time Scale, an event must leave the right kind of stratigraphic evidence.
‘boundary stratotypes’).
Global Boundary Stratotype Sections and Points (GSSP).
Global Standard Stratigraphic Ages (GSSA),
By this formal, international, scientific institutional procedure, the history of Earth is connected with the physical records of Earth history written in rock.
Earth’s most recent period, beginning 2.6 million years ago, is the Quaternary,
Moreover, as our species evolved entirely within the Quaternary, this has inspired alternative names—for example the term ‘Anthropogene’ was preferred by Soviet geologists in the 1980s.
The Quaternary represents a relatively cold interval of Earth history, also known as the ‘current ice age’.
In 2009, the ICS Subcommission on Quaternary Stratigraphy recommended Jan Zalasiewicz, a professor at Leicester University, UK, and an expert on biostratigraphy, to form an Anthropocene Working Group (AWG).
Paul Crutzen, Will Steffen, and myself, and even a lawyer, Davor Vidas, an expert on the Law of the Sea.
the stratigraphic basis for recognizing the Anthropocene would need to ‘critically compare the current degree and rate of environmental change caused by anthropogenic processes with the environmental perturbations of the geological past’.
There were also questions about the utility to geologic science of formalizing the Anthropocene—still a matter of debate.
Zalasiewicz’s question, ‘are we in the Anthropocene?’, was perhaps not the hardest one.
Option 1: Holocene epoch ends, followed by an Anthropocene epoch. (c) Option 2: Holocene replaced by an Anthropocene epoch, Holocene reduced to a Stage within the Pleistocene (this option is not currently under consideration by the AWG).
Paul Crutzen had tied the Anthropocene to the late 18th century and the Industrial Revolution, with combustion of fossil fuels causing an initial uptick in atmospheric carbon dioxide concentrations above those typical of the Holocene. Will Steffen, building on this earlier proposal, came to argue for the mid-20th century as the main point of onset for the Anthropocene, marked by the ‘Great Acceleration’ in human activities around that time. And geologist Bill Ruddiman even suggested that the Anthropocene might be recognized thousands of years before the Industrial Revolution as the result of
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For Will Steffen and others at IGBP, the claim that humans were transforming Earth’s functioning as a system was not new.
Published in 2004 as the now classic
IGBP report Global Change and the Earth System: A Planet Under Pressure,
In 2005, in analogy to Karl Polanyi’s The Great Transformation, ‘The Great Acceleration’ was coined and began making the rounds in scientific circles as the common term describing the dramatic mid-20th-century step-change in anthropogenic global environmental change.
From an Earth system perspective, the Anthropocene began in the middle of the 20th century.
Global estimates of contemporary land use vary, but generally indicate that 40 per cent to 50 per cent of Earth’s ice-free terrestrial surface is now in use for agriculture, forestry, and human settlements.
Domesticated chickens are now Earth’s most abundant bird and cattle biomass alone exceeds that of all other living vertebrate animals combined—including humans.
Humans began transforming the biosphere long before agriculture. Even before the Holocene, hunting and foraging pressures on terrestrial, freshwater, and marine species caused local populations to decline and caused a number of global species extinctions.
Phosphorus, like nitrogen, is a limiting nutrient for crop growth.
