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Peter Brannen has an uncompromising opinion about carbon dioxide. It is the most important compound that has ever existed, he insists. Forget water or DNA or proteins or other life-enhancing materials. These are chemical parvenus compared with CO2, the miracle molecule, which he believes has shaped the course of evolution and which will soon determine the fate of Homo sapiens.
“C02 is the very stuff of life,” the US science journalist argues ; its behaviour on this planet “is what makes it Earthlike” . The gas is the permanent store on which all growing things depend and is the ultimate destiny of all flesh, he adds, borrowing a quote from Primo Levi.
Bigging up CO2 is certainly illustrative. Apart from highlighting its role in the creation of life, such a narrative reveals how the gas regulates the chemistry of our oceans and acts as the key control knob that governs Earth’s temperature. This last function is one of particular significance.
Carbon dioxide accounts for only 0.04% of the gases in our atmosphere, but that trace holds on to enough heat from the sun to provide our planet with a climatic stability that has continued for much of Earth’s history – with only a few dramatic exceptions.
One of these occurred around 600m years ago, when atmospheric CO2 reached such a low level that our world’s thermal insulation was denuded. Glaciers spread from the poles to the equator and ice covered the planet. This was Snowball Earth: “a glittering, dead, white orb” from which all life was very nearly extinguished, writes Brannen .
On other occasions, continent-wide eruptions of volcanic carbon dioxide produced the opposite effect and caused atmospheric levels of the gas to soar. Global temperatures surged and mass extinctions ensued.
These latter cataclysms have a particularly powerful resonance today because humanity – following in the wake of those ancient volcanoes – is now pumping carbon dioxide into the atmosphere in staggering amounts. We emit more than 41bn tonnes of this heat-retaining gas every year, such is our appetite for burning fossil fuels.
In fact, humans now make more CO2 than any other substance on Earth . It is our signature product and, as atmospheric levels rise, so the planet heats up. Deserts are spreading, ice caps are melting, sea levels are rising, coral reefs are dying and deadly heatwaves are increasingly frequent. An “overwhelming derangement of the carbon cycle is currently under way,” Brannen states early on in his story, a view that is later hardened to a pithier, more apposite warning about global warming. Basically, “ we’re in deep shit ”, he concludes.
In recent years, there have been many books on the climate catastrophe that we are inflicting on ourselves through the misuse of carbon dioxide. However, Brannen’s approach is unusual because of his focus on our long and intense relationship with the gas. Its presence and impact on the planet is not some recent phenomenon , he points out. It has always been around and has been a major player in Earthly affairs, for better or worse, since life first appeared .
‘An overwhelming derangement of the carbon cycle is under way.’ Basically, ‘we’re in deep shit’, Brannen says
At that time, around 4 b n years ago, carbon dioxide was a cause of global chemical disequilibrium. Seafloor vents had begun spewing alkaline liquids into oceans that had been made acid by CO2. It was a volatile mix. Then life appeared, not as an accident, but as a system that helped restore balance to the interplay of these chemicals – by removing the excess carbon from CO2. That carbon then became the stuff that would “ make up and energi se all life to this day ”, as Brannen puts it.
In other words, life was an almost inevitable outcome of the presence of carbon dioxide, and the fates of all living things and the gas have been intertwined ever since. We need to start appreciating our eons-old relationship with CO2, in short.
It is an intriguing argument, outlined by Brannen in unstinting, occasionally overwhelming detail – and in language that all too often verges on the ripe and florid. “Earth’s uneventful eternities midwifed the riotous pageant of animal life,” the reader is told . “Shimmering white ice sheets that once meekly coalesced at the poles raced to the equator … clasping crystalline hands over the entire Earth,” we learn elsewhere. Later, our world is described not simply as a rocky planet but as a “grain of sapphire in space”, while the jungles of the Carboniferous period are described as “throbbing” for no apparent reason.
This is not a bad book, it should be stressed, but it is overlong and overwritten . Its stylistic indulgences mar what is otherwise an insightful, unsettling analysis of how our species has developed its strange relationship with a single, primordial substance.
The Story of CO2 Is the Story of Everything: A Planetary Experiment by Peter Brannen is published by Allen Lane (£30). Order a copy from The Observer Shop for £27. Delivery charges may apply
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Photograph courtesy of Nasa