The following are key excerpts of an outstanding article by Andrew Glikson, a visiting fellow at ANU school of science.
Glikson is well qualified to compare what some say is the sixth mass species extinction underway on Earth with previous such occurrences.
”The current growth rate of atmospheric greenhouse gases, in particular over the last 70 years or so, constitutes an extreme event in the recorded history of Earth,” he says.
Glikson is an Earth and paleo-climate scientist, who studied geology at the University of Jerusalem and graduated at the University of Western Australiain 1968. He conducted geological surveys of the oldest geological formations in Australia, South Africa, India and Canada; studied large asteroid impacts, including effects on the atmosphere and oceans ofmass extinction of species. Since 2005 he studied the relations between climate and human evolution.
the full article is available at John Menadue Pearls & Irritations weekly issued yesterday.
ANDREW GLIKSON.
“CO2 is rising at the fastest rate since 66 million years ago.
Posted on 8 November 2019
”As the CO2 level rises to 408 ppm and the total greenhouse gas concentrations in the atmosphere, including CO2, methane and nitrous oxide, reaches about 500 parts per million CO2-equivalent, the stability threshold of the Greenland and Antarctic ice sheets, currently melting at an accelerated rate, is exceeded. Under warming drought conditions, firestorms currently engulfing California, large parts of South America, Siberia, Australia and elsewhere are a direct consequence of the extreme changes in the composition of the atmosphere.
“Since the 18th century, combustion of fossil fuels has led to the release of more than 910 billion tons of carbon dioxide (GtCO2) by human activity, raising CO2 to about 408.5 ppm (September 2019), as compared to the 280-300 ppm range prior to the onset of the industrial age. By the early-21st century the current CO2 rise rate has reached 2 to 3 ppm/year.
”The current carbon dioxide rise rate exceeds the fastest geological rates estimated for the K-T asteroid impact (66.4 million years-ago) and the PETM (Paleocene-Eocene Temperature Maximum) hyperthermal event (55.9 million years ago) by an order of magnitude. The current growth rate of atmospheric greenhouse gases, in particular over the last 70 years or so, constitutes an extreme event in the recorded history of Earth.
”To try and avoid such calamities abrupt reduction in carbon emissions is essential, but since the high level of CO2-e is activating amplifying feedbacks from land and ocean, global attempts to down-draw 50 to 100 ppm of CO2 from the atmosphere using every effective negative emissions is essential. Such efforts would include streaming air through basalt and serpentine, biochar cultivation, sea weed sequestration, reforestation, sodium hydroxide pipe systems and other methods.
”As trillions of dollars continue to be poured into preparation of future wars, currently no government is involved in serious attempts at defending life on Earth.”
