Stefano Mancuso is an Italian botanics expert, university professor, founder and director of LINV, the International Laboratory of Plant Neurobiology, and founding member of the International Society for Plant Signaling & Behaviour. He has also published several books on plants.

Mancuso was alone on the stage of Piazza Castello, without a host or even a table, and his simple yet powerful presence amplified the urgency and intensity of the facts he shared.

In 2020, the total weight of man-made materials, plastic and concrete in particular, exceeded the total weight of all living beings. Two thousand billion trees were cut down over the last two hundred years, setting several tragic domino effects in motion. For example, the destruction of habitats led to unusual interactions between humans and animals causing the spillover effect - the transmission of disease between species - to rapidly become the leading cause of epidemics.

Mancuso shared alarming statistics on the impact of humanity on the planet: 96% of all mammals on Earth are humans and animals bred for human consumption, 85% of birds are poultry, all scientific evidence points to the fact that soon no fish will exist outside of a human farming context.

As species disappear at up to ten thousand times normal extinction rates, it is clear that the planet is going through the sixth mass extinction. The fifth one took two millions of years and was the quickest until now. This one is taking decades.

The planet is becoming less and less habitable for humans too: in fifty years, London will have the temperature of Barcelona, and Barcelona will be moving towards a sub-saharan weather profile. Just under one percent of the Earth is currently uninhabitable, fifty years will change that number to 18%, causing over two billion people to migrate in the pursuit of survival.

And yet, Mancuso says, all hope is not lost. Trees are a thousand times more efficient than any man-made CO2 recycling technology and planting a thousand billion trees would be enough to give humanity an extra fifty years of time to change track.

The audience left the event informed, scared, and probably making plans to plant a few trees.