Our Climate Crisis and Humanity’s Extinction: Just a Question of Time?

Philip Jamieson and Marianne Schmidt

As the world continues to endure the ravages of a global viral pandemic, we can easily lose our focus on the urgent need to address our growing climate crisis. Last month brought yet another record breaking climate extreme. It was globally the hottest September in the 141 year dataset record. In the image below, September 2020 global temperature differences world wide from the average are highlighted.  Those areas shaded in blue show locations up to 6°C cooler than average, while the far more dominant areas shaded in red show locations that were up to 6°C warmer.

September, temperature anomaly, global, 2020

Climate.gov image from Data Snapshots, based on maps processed by NOAA EVL from NCEI data (available at https://www.climate.gov/sites/default/files/Temperature–Monthly–Difference-from-average–Global–2020-09-00–large.png and sourced from https://www.climate.gov/news-features/features/september-2020-another-record-setting-month-global-heat)

Unfortunately, there are still some amongst us who consider humanity a privileged community amongst the species of our planet, immune through our technology, intellect and acknowledged adaptability from the impacts of climate change. Our lived experience should be enough to invalidate this false belief but, if more were needed, recent research continues to undermine the thesis.

Even apart from human-induced climate change, the Earth’s climate is widely accepted to be nearly constantly in flux. The last of 7 ice age cycles experienced on the planet over the past 650,000 years ended around 12,000 years ago and ushered in the relatively climatically stable Holocene period in which modern humanity has flourished.

However, we are only one of several Homo species that have lived on this planet over the past 3 million years. Apart from our own Homo sapiens, Homo neanderthalensis is perhaps the most well known. All have faced the need to cope with the planet’s climate variability. All are noted for their cognitive ability which, at least amongst more recent members of the genus Homo, has evidenced itself in controlled use of fire, adoption of clothing and the ability to disperse populations. All of these are mechanisms that would have allowed our Homo ancestors to mitigate at least some of the effects of past climate change.

Yet, we are the only remaining, extant member of the various Homo species. All others have become extinct. Theories about the causes of these extinctions have mostly focused on Homo neanderthalensis, and competition with modern humans has arguably become the most celebrated theory in popular culture.

neanderthal_child

A reconstruction of Neanderthal child by Tom Björklund – Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=87641467

Now a study published in One Earth earlier this month has identified climate change as a key factor. While not the first to point to the possible role of climate change in past Homo extinctions, the authors observe that their study provides “the first strong evidence that climate change was a common extinction factor shared by all our ancestors”.

Reflecting upon the significance of their study, the authors conclude that their analysis “suggests that the threat posed by the current, anthropogenic climate change for global wildlife and, by extension, ourselves, is possibly even more powerful than is generally appreciated” (fn omitted). Lead author, Professor Pasquale Raia, in commenting upon the paper, expressed his concern in even stronger terms:

It is worrisome to discover that our ancestors, which were no less impressive in terms of mental power as compared to any other species on Earth, could not resist climate change. … just when our own species is sawing the branch we’re sitting on by causing climate change. I personally take this as a thunderous warning message. Climate change made Homo vulnerable and hapless in the past, and this may just be happening again.

Should our hubris question the relevance of the experience of our Homo cousins, it is worth noting that some researchers consider that the climatic upheavals following the Toba volcanic eruption in modern day Indonesia some 74,000 years ago (the largest eruption on the planet in the past 2 million years) may have reduced the global population of modern humans to just a few thousand. It is equally salutary to remember that climate change is increasingly accepted as having been a major driver in the collapse of a number of our ancient civilisations, amongst them the Mesoamerican Mayans, the Mesopotamian Akkadians and the Harappan civilisation of the Indus valley.

mayan_temple_of_the_sun

Mayan Temple of the Sun at Palenque as seen from the Temple of the Cross by Ricraider – Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=20390010

Reflecting the lived experience of our ancestors, the consequences of over-exploitation of our natural environment is a theme also to be found in the mythology of our indigenous cultures. In Inuit tradition as described by Jamila Gavin, for example, the Raven having created humankind, and instructed them in the art of making hunting weapons, admonished them not to kill more animals than they needed to live. And so the Inuit promised that they would not. But as the numbers of Inuit grew, they killed more and more animals, plundering the Earth, sea and sky as they gave vent to their growing greed. When the Earth in its pain cried out to Raven, he angrily reminded the Inuit of their now broken promise. When it was clear to Raven that the humans did not care, he plunged the world into darkness causing everything to begin to die. There are other elements in the tradition but in the end, the Inuit never again forgot their promise and forever after respected and honoured all animals.

In both Indigenous tradition and science we find recognition of the consequences to humanity of over-exploitation of the environment. Nor can we rest comfortable in the belief that somehow our modern technologies will better shield us than our ancestors from these climatic challenges. Our settled lifestyles in high density urban communities, technologically dependent, artificially divorced from our relationship with the natural environment and reliant upon vulnerable production and supply chains for our agricultural and industrial supplies, arguably make us more vulnerable to the pressures of climatic change.

Nor is this just an issue for humanity. The planet’s entire biological systems and biodiversity are threatened.

In a paper published in Nature late last year, Climate tipping points – too risky to bet against, the authors cautioned that we may be dangerously close to exceeding a range of tipping points that could result in irreversible change. Exceeding any of these tipping points might itself then have a cascade effect on others. Ultimately, they fear that we may face a global cascade of tipping points and the possibility of global tipping, with the ominous conclusion that “[i]f damaging tipping cascades can occur and a global tipping point cannot be ruled out, then this is an existential threat to civilization”. Economics Professor John Gowdy in his 2019 paper, Our hunter-gatherer future: Climate change, agriculture and uncivilization, bleakly concluded that:

Given the large human population, the likely effects of climate change on economic and social stability, and the potential fragility of the world’s industrial agricultural system, it is unlikely that human civilization can survive the coming mega-greenhouse.

Gowdy nevertheless urges that:

The fact that civilization is likely to end does not mean that we should give up on climate change mitigation, radically changing the world’s industrial agriculture system, social justice or the rest of a progressive political agenda. Our prospects for survival will dramatically improve if we hold temperature increases to 3°C, rather than 6−8°C, by instituting social and environmental policies to reduce the worst climate change impacts.

His observations merely reinforce the need for urgency in the actions we must take.

Twenty-five years ago people could be excused for not knowing much, or doing much, about climate change. Today we have no excuse. — Desmond Tutu

We do not inherit the earth from our ancestors, we borrow it from our children. – Native American Proverb

References (as at 19 October 2020)

Concluding quotes sourced from Climate Change Guide: Quotes on Climate Change (https://www.climate-change-guide.com/quotes-on-climate-change.html)

David Bressan, Climate Change May Have Contributed To The Extinction Of Neanderthals And Rise Of Modern Humans (1 September 2018) Forbes (https://www.forbes.com/sites/davidbressan/2018/09/01/climate-change-may-have-contributed-to-the-extinction-of-neanderthals-and-rise-of-modern-humans/#130527e5652f)

Cell Press, Climate change likely drove early human species to extinction, modeling study suggests (15 October 2020) phys.org (https://phys.org/news/2020-10-climate-drove-early-human-species.html)

Jason Daley, Ancient Humans Weathered the Toba Supervolcano Just Fine (14 March 2018) Smithsonian Magazine (https://www.smithsonianmag.com/smart-news/ancient-humans-weathered-toba-supervolcano-just-fine-180968479/)

Tom di Liberto, September 2020: Another record setting month for global heat (16 October 2020) NOAA Climate.gov (https://www.climate.gov/news-features/features/september-2020-another-record-setting-month-global-heat)

Sean Fleming, Climate change helped destroy these four ancient civilisations (29 March 2019) World Economic Forum (https://www.weforum.org/agenda/2019/03/our-turn-next-a-brief-history-of-civilizations-that-fell-because-of-climate-change/)

Jamila Gavin, Our Favourite Stories: From around the world (HB Fenn and Company, 1997)

John Gowdy, Our hunter-gatherer future: Climate change, agriculture and uncivilization (January 2020) 115 Futures 102488 (https://www.sciencedirect.com/science/article/pii/S0016328719303507#!)

Michael Greshko, These Ancient Humans Survived a Supervolcano (12 March 2018) National Geographic (https://www.nationalgeographic.com/news/2018/03/toba-supervolcano-eruption-humans-south-africa-science/)

Timothy Lenton et al, Climate tipping points – too risky to bet against (27 November 2019) Nature (https://www.nature.com/articles/d41586-019-03595-0)

Pasquale Raia, et al, Past Extinctions of Homo Species Coincided with Increased Vulnerability to Climatic Change (15 October 2020) One Earth (https://www.cell.com/one-earth/fulltext/S2590-3322(20)30476-0?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS2590332220304760%3Fshowall%3Dtrue)

Gayathri Vaidyanathan and Climate Wire, How Have Hominids Adapted to Past Climate Change? (13 April 2010) Scientific American (https://www.scientificamerican.com/article/hominids-adapt-to-past-climate-change/)

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