With a day off for my birthday, I’d planned an afternoon at the Natural History Museum and was waiting fairly serenely for the overground west into town. A cool southeasterly wind carried mid-height clouds across the half-blue sky. Green buds were swaying on the still-bare trees behind the platform. I’d left a bit later than planned. Steph, my partner, had asked if I wanted to go for a walk on the canal before she took the train home for a few days. A calm Monday morning and a faint afterglow from the weekend buoyed me.
I’d started working in January on a project penned The weather diary. What I’d written so far hadn’t amounted to anything I felt formed enough to share. I was trying to surface answers to questions slightly beyond reach: How does the weather affect us and shape our collective identity? Is the weather emergent, similar to consciousness or murmurations, arising as something more than its elements? How does the atmosphere connect us as a species, and to all the other life on Earth?
I realised my attempts at answering these questions would be better told through a story than explanations. I’d arrived at a possible protagonist, and planned to trips to to the Natural History Museum to get to know them a bit better.
A microorganism called cyanobacteria was what I’d set out trying to find. Cyan is the colour of the dominant pigments they use for photosynthesis, which give off those electric teal-aquamarines somewhere between blue and green. Cyanobacteria aren’t a single species, they’re a whole phylum containing thousands of different types that come in creatively abundant forms.
Each cyanobacteria is a fairly simple single-celled spheroid, usually with a slimy bacterial skin. They live in water, solitarily, or connected into long filaments, strands, coils, and clusters that can display collective behaviours. We often mistake them as algae drifting swampily at the surface of water. They’re often villainized for their toxifying jade-sapphire glows in lakes and ponds.
Cyanobacteria were some of the earliest lifeforms to evolve on Earth. A few thousand million years ago, before animals colonised the surface of the planet, a cyanobacteria recruited or evolved a pigment that starting oscillating in harmony with the vibration of sunlight. The energy that the pigment captured was harnessed by the bacteria to break off carbon atoms from CO2, bonding them together into chains for growth and repair. This gave the cyanobacteria an advantage that was distributed through the global population.
Oxygen was barely present in the atmosphere before that. Before photosynthesis evolved in cyanobacteria, most other organisms created their energy anaerobically. The cyanobacteria eventually produced so much oxygen that the air became toxic to all those anaerobic lifeforms. The balance of the atmosphere was gradually forced into a new equilibrium favouring oxygen. Empowered by the ability to recruit carbon from air, the array of plants and animals we know today evolved.
Different names are given to this chapter of natural history: the Oxygen Catastrophe, the Oxygen Revolution, the Oxygen Crisis, and the Great Oxidation. I prefer the latter. It played out slowly over billions of years and I wondered: did the anaerobic lifeforms feel it coming?
The museum’s website didn’t specify that the cyanobacteria featured in any of their permanent exhibitions, but I was confident that they must. ‘A journey through time from the big bang to the present’ and ‘the evolution of life on our planet’, sounded promising enough.
In planning the day, I’d dreamt up an almost empty museum, wandering slowly around sunlit galleries. But, as I ascended the underground station at South Kensington and approached the museum’s side entrance, it became quickly apparent I’d overlooked the Easter school holidays. In the much shorter ticketed queue, behind a waterproofed family from northern Europe, I began adjusting my ambitions.
I had popcorn and a giant strawberry sweet stuck to the bottom of my shoes within minutes of entering the museum. Navigating the heavily crowded galleries and hallways, I sought refuge and headed to the balcony of the central hall. The percussion of a hundred footsteps rippled up the floorboards and conversations roared like waterfalls.
My imagination was caught briefly on the way by a wall-mounted pterodactyl, the jagged spine of a delicately maquetted stegosaurus, and the giant molars of an ancient mammoth polished by fingerprints to a pearlescent shine. I rose up through the cacophony, finding space on the balcony on a bench with my back to a stained glass window.
Working through a cheese, chilli jam and sundried tomato sandwich resting between bites in tinfoil on my lap, I messaged Steph: ‘Hadn’t factored in Easter hols lol’. Then, ‘It is very noisy’. I share a photo of the pterodactyl, whose human-sized dimension had surprised me. It looked like an Icarus with the head of an Egyptian god holding elongated, taloned wings.
I scanned for anyone expressing similar tensions. A young German mother was sat next to me with her sleeping son traipsed over his lap. A man in jeans and a leather jacket stopped in front of us with his daughter. “Let’s try and find it on the way out, shall we darling?”, he said appeasingly. After a few diaphragmatic breaths and swigs of my water, I refilled my backpack and set off.
I missed a diversion sign and entered the exhibit through the exit, traversing back through billions of years of natural history in about forty paces or so down a dark submarine-like gallery. The solemnity of fossilised artefacts shadowed with ancient life clashed with the mission-control-styled displays. Attempts at formality were lost on the families swarming the humid room. Children pursued by parents bumped into me trying to take notes on our neighbouring planets.
Would the weather have been different before the skies were flushed with oxygen, I wondered. Faster, more violent, different colours?
I studied rust-red Mars and sulphur-yellow Venus. The gases making up atmospheres establish smells, colours, greenhouse effects, and the chemistries of life. Oxygen is almost invisible to light, barely insulates heat, gets catalysed into ozone, and provides the canvas but not the ingredients for clouds. Once the terrain on the Earth had solidified and the oceans had distilled, the weather emerged into the shapes and formations we’re familiar with.
Arcing over three wall-sized silver ovals dotted with portholes and cast in spotlights were three titles for a display: ‘Life evolves’, ‘Life shapes the atmosphere’ and ‘Living cells’. A shard of dark grey rock came into view as my nose drew close to the text engraved into metallic plaques describing the scene. The rock drawing my attention contained the oldest known remains of life on earth. It was 3.7 billion years old, a triangular piece of shale embedded with ‘microscopic grains of carbon produced by ancient organisms that lived in the sea’.
I could just about make them out, or imagine them, bubbling away, frozen in sediment that would over millennia morph into that piece of shale.
The slice of bacteria-bound shale was the centrepiece of the museum’s telling of the Great Oxidation, the evidence for cyanobacteria’s starring role in our natural history. After that, the spotlights panned to the next part of the story.
Running the remaining thirty dimly-lit paces back to the entrance, was a timeline charting the evolution of multicellular microorganisms into vegetation and trees, and then fish, animals and humans.
A creature from the depths mounted on a prop with a handful of tentacles dangling from a bulbous head had two eyes on antennae that peered into mine. I wondered what the animals which mammals had evolved from looked like. I was pretty sure they weren’t dinosaurs. I couldn’t remember, or didn’t know. All it said on the timeline, was that ‘mammals appear’.
I ambled briefly into a neighbouring exhibit on human evolution before crossing the halls to a high-ceilinged annex at the far-end of the museum facing out towards the gardens. Lining the gallery, glass-shelved cabinets were filled with jars containing ‘spirited animals’ preserved in formaldehyde. The jarred spirits, each a memory of life unlocked by cyanobacteria and their billion-year oxygen rave, interspersed views into empty laboratories. A scientist wasn’t going to appear to explain my unanswered questions, I admitted, but I’d traced enough of a story to tell.
With my winter coat collected from the cloakroom and draped over my arm, I strolled back through the hallways to the central hall. The crowds had thinned, sated or sedate. I took in a final look over the blue whale’s skeleton hung by cables in the vaulted roof of the entrance hall and returned to a greyed-over late-March afternoon. Perching against the sand-coloured wall in front of the museum, I reacclimatized in the breeze, relieved by the freshness of the air.
R