On the 27 January, 2017, the Bulletin of the Atomic Scientists moved the arms of its doomsday clock to 2.5 min to midnight, the closest it has been since 1953, with enormous implications for humanity and nature. A book titled “The Plutocene: Blueprints for a post-Anthropocene Greenhouse Earth” elaborates the reasons for the decision of the Atomic Scientists.
In studying the past, geologists use a variety of proxy methods, including the geochemical and isotopic composition of ancient sediments, cave deposits, fossil plants and animals, tree rings, residual organic matter, and the distribution of species in different regions of the Earth. For the previous 800,000 years, ice cores are particularly useful. For periods in the order of thousands to tens of thousands of years, tree rings, the composition of organic matter in soils, fossil plants and animals are important.
None of these methods are available when it comes to projecting the geological record into the future. However the basic laws of physics, the principles of climate science and lessons from past climate trends and events, when coupled with observations of current developments, allow insights into the nature of future events.
Several factors that will determine the future course of the climate are:
- the past, current and future trends of solar insolation cycles;
- the evolving composition of the atmosphere, in particular greenhouse gases (CO2, CH4, NO2, Ozone) and oxygen levels;
- intermittent volcanic events, asteroid impacts, methane eruptions, plate tectonic and mountain building processes;
The regularity of solar insolation cycles (including the 100,000-years Milankovic cycle, 1470-year Bond cycle and the 11 years sun-spot cycle) and other solar insolation cycles are manifest in the geological record.
CO2 levels have reached up to a couple of thousand ppm CO2 during tropical geological periods including the early Devonian (400 million years [Ma] ago), early Permian (280 Ma), early Triassic (200 Ma) and early Eocene (50-40 Ma). The decline of CO2 levels to a few hundred ppm and less during the Eocene lowered the temperature of the Earth’s surface and produced the Antarctic ice sheet. This allowed the flourishing of mammal life, including the appearance of humans, and the evolution of the present biosphere.
Based on these observations, as reported by the Intergovernmental Panel for Climate Change (IPCC), a number of scientists have projected that the current interglacial period will extend by about 30,000 years, consistent with the longevity of atmospheric CO2. Future scenarios for the biosphere include Mark Lynas’ book “Six Degrees”, Elizabeth Kolbert book “The Sixth Extinction: An Unnatural History“, and from the nuclear perspective Jonathan Schell’s book “The Fate of the Earth”.
The likely increase of global temperatures by 4 degrees Celsius, amplified by feedback effects, mean that civilization and much of nature now face an existential threat. A planetary defense from catastrophic global warming and nuclear disaster requires that humanity diverts its resources from destructive wars to protection of the biosphere, including carbon draw-down through methods such as streaming of air through basalt( as experimented in Iceland),large scale sea grass cultivation, extensive biochar development, reforestation and chemical methods.
Space exploration, the so-called “new frontier”, is a wonderful thing, but the hundreds of $billions spent on space are required for the defense of the terrestrial biosphere which, with the exception of possible bacterial life elsewhere in the solar system, is the only habitable planet we know. The notion we can escape from a scorched Earth to some other planet is a science fiction illusion.
At present, there is a widespread cover-up in the mainstream media of the manifest connection between global warming and extreme weather events: cyclones, mega-floods and wildfires. This cover-up reinforces climate change denial.
Compounding the global warming impasse is the prospect of nuclear warheads, many on hair trigger alert, being released due to accident or design.
These issues are hardly discussed by national leaders and media mouthpieces, preoccupied with parochial and legalistic issues and overlooking or encouraging carbon emission and export, thus presiding over a Faustian Bargain which can only lead to the demise of the biosphere as we know it.
Unless there is effective sequestration of carbon gases, the amplifying feedback effects of melting of ice sheets, warming oceans, the release of CO2 and the desiccation of land surfaces, will see the Earth reach an average temperature of 4 degrees Celsius above pre-industrial levels or higher within a short time frame. Numerous species, including Homo sapiens, will be hard-pressed to adapt. The increase in evaporation from the oceans will lead to mega-cyclones, mega-floods and super-tropical terrestrial environments. Large scale fires and hurricanes are already occurring before our eyes. Arid and semi-arid regions will become overheated, severely affecting flora and fauna habitats.
The transition to such conditions is unlikely to be gradual. As the globe heats, there will be an increased polarity between ocean regions cooled through an influx of ice melt and regions where warming continues. The consequent increase in climate variability will include sharp transient cool intervals called “stadial”. Increasingly signs of a possible stadial are observed south of Greenland.
A close analogy can be drawn between future events and the Eocene-Paleocene Thermal Maximum about 55 million years ago, when the release of methane from the Earth’s crust resulted in an extreme rise in temperature. The current rise in the rate of CO2 and temperature exceeds that of the PETM.
Such conditions, compounded by high levels of radioactivity due to possible-to-probable nuclear conflicts, could see an onset of a new evolutionary cycle. One consequence may be the proliferation of heat and radiation-resistant arthropods. Humans are likely to survive in polar and cooler high mountain regions. At 2.5 minute to midnight, the only possible way to avoid such a calamity is to channel all available resources into planetary defense.
Andrew Glikson is an Earth and paleo-climate scientist at the Australian National University