This post first appeared on the author's Facebook profile on 4 July

The Marmolada tragedy represents the changing climate. Not only because on the very day of the collapse, the highest peak of the Dolomites recorded its temperature peak (10.3 degrees Celsius at 3,300 metres above sea level). And not only because glaciers respond to heat in this way too — with sudden collapses, not just slow, gradual melting — which condemns them in any case to likely disappearance below 3,500 metres across the entire Alps.

The Marmolada tragedy is the beginning of a vicious cycle

But also because the disappearance of the Marmolada glacier, whether gradual or sudden, is a faithful image of how the climate crisis operates. A recent study by the National Research Council (Cnr) has established that over ten years the glacier has lost a third of its volume. It is a self-accelerating process, a tipping point: the melting ice exposes dark rocks that absorb more heat than the white frozen surface. At the same time, meltwater accumulates at the base of the glacier, flows between the ice and the rock, and lubricates the glacial mass, which then moves even faster. This is happening in Greenland, along the Himalayan range, and now in the Alps.

The same thing is occurring, on a larger scale, at various points around the Earth: the climate crisis triggers vicious cycles — self-feeding phenomena that risk spiralling out of control. The slowing of the Gulf Stream, the "savannisation" of the Amazon, the melting of permafrost: processes that accelerate suddenly and do not stop easily, and that would be better not to trigger in the first place.

What would happen if we stopped CO2 emissions today

If we stopped CO2 emissions today, temperatures would stop rising within a very short time. They would remain stable for a few decades, with all the effects we are seeing today, before slowly declining thanks to carbon absorption by natural ecosystems. But in the meantime, glaciers will largely have disappeared — including the Marmolada, in just twenty or perhaps thirty years.

And with them, the supply of water during summer will diminish. Twenty per cent of the water that reaches the plains each year comes from glaciers, especially during the warmest months. The serac on the Marmolada and the once-in-a-century drought engulfing Italy are closely linked — at the end of the day, they are the same story.

Today the concentration of CO2 in the atmosphere is 420 parts per million (ppm) — 50 per cent more than when we first began emitting it, 150 years ago.