We live on a « Pale Blue Dot » lost in space and time. Our small planet experienced numerous episodes of extreme cold and warm climate that help shaping life as we know it. Glacial epochs and mild periods set the pace to the evolution and migrations of our species. But today we are billions, human activity imposes a climate change of speed and amplitude unmet since the population began to rise. For the first time we have the freedom  to decide about our future. The modern Pascal’s wager: devoting all efforts to the energy transition, to developing anew a true circular economy, one wins in all cases. A no-brainer choice, since:

« We cannot hope that the Universe adopts our point of view. We have to conform to the point of view of the universe. It is the only desirable conformism. Because mankind will eventually have to pay the bill of a discord, not the Universe » (Samivel, in « L’Amateur d’Abîmes », 1940

Our « Pale Blue Dot » – a parenthesis in space and time

The first interplanetary space probe Voyager 1, before leaving the solar system for ever in 1990, turns back and takes a picture of Earth. In his book « Pale Blue Dot », the well-know astrophysicist Carl Sagan describes this image: 

« Look again at that dot. That’s here. That’s home. That’s us. On it, everyone you love, everyone you know, everyone you ever heard of, every human being who ever was, lived out their lives. »

« The Pale Blue Dot ». Image of the Earth shot in 1990 by the Voyager 1 space probe from a distance of 6.4 billion km, at the request of Carl Sagan. © NASA/JPL

This illustrates dramatically the challenges that we are facing today. During the last glacial episodes, our ancestors survived thanks to their adaptability – seeking refuge on the Iberian Peninsula and adopting similar strategies elsewhere in the world. But a that time we numbered in the hundreds of thousands. Now we are several billions. And we cannot escape form this Pale Blue Dot.

We live in a parenthesis in space and time that started 4.5 billion years ago and will close when our sun explodes in 1 to 2 billion years from now. Until then the Alps and the Himalaya will have long since eroded out, and many new mountain ranges will have risen from ocean floors. But until then also, and for the first time, we have the choice of our future. 

From a « timecopter » point of view

After a dramatic birth in the vortex of sun’s formation, our planet slowly cools down. Influenced by plate tectonics and the advent of life – influencing the CO2 cycle -, its climate undergoes cycles of deep glaciation and intense warming – temperature variations of tens of degrees Celsius. Traces of this far past are hard to read, but early moraines dating back 2.3 billion years are visible in today’s Europe and North America. Further colds affected our planet 800 – 600 million years ago – extreme episodes that might have frozen the entire globe – then twice again in the next 400 million years. Ultimately grouping all land masses, the Pangea supercontinent eventually breaks apart while the dinosaurs expand, rule the planet and disappear in a warm climate that culminates about 50 million years ago. 

A little (10 million years) later – the Alps still to emerge – a piece of land forming Antarctica has drifted to the South, ready to welcome a new polar ice cap and initiate a glacial period. When the Quaternary era begins, 3 million years from now, the Arctic ice cap has grown as well. Putting today’s debate on climate change into a geological perspective, one cannot but observe a paradox : we are living in a glacial period – as defined by the existence of ice caps on the poles. How and how much mass extinctions and life diversification on Earth are linked to the alternating patterns of intense glaciations and warm climate is still debated. But there is little doubt that this intense environmental pressure has plaid an important role on the evolution.

The glacial – interglacial cycles of the Quaternary set the pace for human evolution

At that point in time begins the history of mankind. The footprints of two adults and one little biped, fossilized 3.7 million years ago in today’s Tanzania are touching evidences of early hominins. Their evolution and migrations will be cadenced by the changing rythme of climate, the periodic glacial – interglacial cycles (fig. 2).

In Europe, the first traces of Homo (Neanderthalensis) date back from before-last glaciation, some 200’000 years ago. Neanderthal will survive the next 170’000 years, his presence attested throughout the continent, even in the Alps and the Pyrenees, migrating according to the patterns of glacial cycles. When the climate becomes too rigorous, the population decreases dramatically – as during the last Würm glaciation – but survival is made possible by a retreat to more temperate zones (in particular the South-West, beyond the Pyrenees). On the opposite, when glaciers recede, hunters venture again into high altitudes sites.

Sometime during the Würm glaciation, probably at the occasion of a climatic respite, Sapiens, our direct ancestor, enters the scene. When cold comes back, the Rhone glacier progresses towards its latest maximum close to Lyon (fig. 3), and retreat is the solution. At the onset of Spring – or rather our temperate interglacial climate – Sapiens is alone, Neanderthal has faded out. The deglaciation is rapid, so is the colonisation: first the periphery of the Alps, the the Southern Alps and finally, on the occasion of a stable and warm climate 5’000 year ago (of the Holocene optimum), the upper valleys, via the plains and high altitude passes. 

A big difference – we are billions

An optimum being an optimum, the climate deteriorates again, slowly, gradually, glaciers advancing towards the Little Ice Age (between the 14th and the mid-19th century). Around 1820 – 1850, they reach low positions never met since the dawn of the last glaciation. Oddly enough, Mountain meets History at this exact moment. The first scientists clear the field, the Alps become the playground of Europe, painters and early photographers immortalise sublime glaciers, thus forging a mythical representation of the mountain. If glaciers are used as a symbol of global warming, it is not because of their importance as water ressources, but because 19th century images form our reference system.  

Alpine glaciers during the Last Glacial Maximum 28’000 years ago. From S. Coutterand. © S. Coutterand.

We know the rest of the story. Since then, glacier retreat has become global – North and South,  mountains and ice caps. It accelerates dramatically since the 21st century. The front of Aletsch glacier – the largest in the Alps – will soon reach its known minimum from the Bronze Age. In other places, this minimum might have been surpassed. Many smaller ice patches have totally disappeared. And this we now know is largely due to the impact of human activity. The Earth climate is endlessly changing. The deep breathings between warm periods and intense glaciations are regulated by numerous interacting factors. But human activity imposes today an evolution of speed and amplitude unmet since our planet became so densely populated.  

A no brainer choice or the modern Pascal’s wager 

On the positive side, for the first time we have the choice, the freedom to decide about our future. And the choice is a no-brainer. Sooner or later (and rather sooner) fossile fuels and primary materials will be depleted. Devoting our efforts to the energy transition (renewable energies), to developing anew a true circular economy, one wins in all cases. It is the modern equivalent of Pascal’s wager:  not only will we then limit our impact on climate, but many other problems will be solved at the same time – pollution of air, river, groundwater, oceans,…. From an economic standpoint, pionniers will find a competitive advantage. Moreover, and this is far from negligible, it is a constructive vision, big enough and utopian enough to federate a society.

As Samivel, the French mountaineer, illustrator and writer, pointed out in the introduction of his novel « L’amateur d’abîmes » in 1940:

« We cannot hope that the universe adopts our point of view. It is up to us to conform to the point of view of the universe. This is the only desirable conformism. Because mankind will eventually have to pay the bill of a discord, not the Universe  »

(Nous ne pouvons espérer que l’univers adopte notre manière de voir. Il nous appartient donc de nous conformer à la manière de voir de l’univers. C’est le seul conformisme souhaitable. Car ce sont les hommes et non l’univers qui paieront en définitive les frais d’un désaccord ).