Climate collapse worst-case scenarios and best-case scenarios.
I have previously on this blog guessed that civilization will collapse around 2030 *, that I will die around 2036, and that humanity will go extinct around 2040 (1) (mark my words, I say only humanity, all life will not go extinct by then, but it will later, maybe around 2050 (2). This latest statement is in harmony with Malcolm Light's prediction 2012 (3) and John Davies' prediction 2013 (4)). It is still my best guess. Is it a conservative guess? I suppose so. I will now discuss some of the most pessimistic climate collapse scenarios I have found on the internet:
Firing of the Arctic Methane Time Bomb already in 2008.
In 2008, Russian scientists of the Arctic Nathalia Shakhova, Igor Semiletov (both professors nowadays) and two more wrote together a classic, yes legendary paper for "Geophysical Research Abstracts, Vol. 10", called "Anomalies of methane in the atmosphere over the East Siberian shelf: Is there any sign of methane leakage from shallow shelf hydrates?". The short paper ends with the following words:
"...we consider release of up to 50 Gt of predicted amount of hydrate storage as highly possible for abrupt release at any time. That may cause ∼12-times increase of modern atmospheric methane burden with consequent catastrophic greenhouse warming."
It sounds incredible, but you can check it for yourself.
If the 50 gigaton burst of methane had happened in 2008, temperatures would have skyrocketed with at least 0,6 degrees Celsius, according to Peter Wadhams' conservative estimate, and mostly by 10 degrees Celsius, according to Malcolm Light's radical estimate.
In this blogpost on my blog from October 2020 I write the following:
"In this youtubevideo from 11. August 2020 Arctic sea ice professor Peter Wadhams is interviewed by Sandy Schoelles and Jennifer Hynes. In this interview Wadhams says that a 50 gigaton outbreak of methane in the Arctic that can happen at any time, proposed by Natalia Shakhova 2008, is a very conservative estimate. The real number would be 700 gigatons of methane. And this can happen at any time, during the next few years. Wadhams says that a 50 gigaton outbreak would increase the global temperature with 0,6 degrees celsius, so when I calculate, 700 gigatons would increase it with 14 times more, i.e. with 8,4 degrees celsius, which would almost instantly wipe out humanity.
According to Wadhams, the methane threat is the biggest threat to humanity and the planet that exists.
So according to Wadhams, doomsday is very, very near.
* * *
In this article, climate scientist Malcolm Light says that a 50 gigaton burp of methane from the Arctic will increase the global temperature with 10 degrees celsius. He writes thus:
"3. The Major Arctic Permian Style, Methane Blowout - Firestorm Event which will cause the release of some 50 Gt of methane from the Arctic shelf and slope (Shakhova, 2010), a 10 Degree Centigrade Rise in Mean Global Atmospheric Temperatures causing a Catastrophic Permian Style Global Extinction Event, is timed to begin on 4th September, 2021 using an Atmospheric Methane Global Warming Potential of 100. This is an end Summer event for the Northern Hemisphere."
If Malcolm Light is right, and a 50 gigaton burp really produces a 10 degrees celsius rise, then a 700 gigaton burp would rise global temperature with (mostly) 140 degrees, i.e. making it into a Venus-like planet."
Mark the words of Wadhams about Shakhovas estimate, that it is a "very conservative estimate."
So the worst-case scenario here would thus be that already in 2008 there could have happened a 700 gigaton burp of methane in the Arctic (which is only maybe roughly a third of all the methane on the sea-bottom there), followed by a 100-140 degrees Celsius rise of temperatures on earth over a short period of time (taking also into account the warming effect of the loss of Global Dimming, because of the subsequent collapse of civilization, and the total loss of Arctic Sea Ice, and all the other factors that Sam Carana lists in the picture below), making earth into a Venus-like planet, killing all life on the planet.
If you think that this could have happened (yes, it really could), then you understand the radical predictions of Sam Carana and Malcolm Light on the Arctic News blog, predictions that always fail to come true. Then you understand why Sam Carana could write a blogpost on the Arctic News blog 17.12.2019 named "Extinction in 2020?" If you don't know the background, you maybe laugh at him and call him a doomsday prophet and an unreliable alarmist.
The best-case scenario
So my prediction that humans will go extinct around 2040, and that temperatures will be around 3-4 degrees Celsius above preindustrial by then, is somehow a middle way between the most pessimistic climate scenario, and the most optimistic one by UN, which predicts a 3 degrees Celsius rise by 2100 above the preindustrial baseline, and do not talk about human extinction, not even about collapse of civilization (try to google "climate change + UN + collapse of civilization). See this article from 2019 about a UN report, which states:
"The new report said the world was on track to have average global temperatures rise to 3 degrees Celsius by 2100."
* defined by the first in the rich part of the world that dies from starvation.
(1) defined by when the last human dies in underground survival bunkers. This view is also shared by Robert J. Burrowes, in this article from 2018 on World News Daily, Information Clearing House.
(2) defined by when the last plant dies.
(3) "This process of methane release will accelerate exponentially, release huge quantities of methane into the atmosphere and lead to the demise of all life on earth before the middle of this century."
(The blogpost "Global Extinction Within a Lifetime as a Result of a Spreading Atmospheric Arctic Methane Heat wave and Surface Firestorm" by retired professor Malcolm Light on the Arctic News blog 9.2.2012)
(4) "The world is probably at the start of a runaway Greenhouse Event which will end most human life on Earth before 2040. "
(The blogpost "A runaway greenhouse event", by John Davies on the Arctic News blog 20.9.2013)
