Opinion | Where will all this end?

It's been Armageddon in the Northern Hemisphere: uncontrolled fires around the Arctic Circle (not to mention California and Greece), unprecedented heat waves with temperatures unprecedented, torrential downpours and biblical floods. And yes, it's climate change.

It is quite appropriate to be afraid, because summers will be much worse in ten years and even worse ten years later. Rapid and drastic cuts in greenhouse gas emissions could now prevent the summers of the 1920s from worsening, but they would do little to mitigate the growing misery of the next 20 years. These emissions are already predominantly in the atmosphere.

Moreover, we will not see "fast and drastic cuts in greenhouse gas emissions" anytime soon. It will get a lot worse before it improves – if it's better. So it is probably time to ask the obvious question: where will all this end?

The worst is not the only case, nor even the most likely, but it may be helpful to understand how much he can get if we miss all the exits on the highway. ;hell. And I will quote here an interview I made ten years ago with Dr. Dennis Bushnell, Chief Scientist at the NASA Langley Research Center. Everything is still true today.

He was talking about "feedback" (melting permafrost, warming oceans, huge releases of methane and carbon dioxide). Because they can not yet be fully incorporated into climate models, they lead to systematic underestimates of future warming. "If all these feedbacks are taken into account, estimates are that around 2100, instead of two to six degrees C (average global temperature), it looks like a six to twelve degree possibility …

These changes in temperature would change the patterns of ocean circulation and end in much of the ocean becoming anoxic – very low in oxygen – which would then favor bacteria that produce hydrogen sulphates. Would raise and leave the ozone layer, and also make breathing difficult.This is in 2100. "

What Dennis Bushnell was referring to was" Canfield's oceans ", now strongly suspected to be the cause of four of the five great mbad extinctions. Everyone knows the huge asteroid that struck the Gulf of Mexico 65 million years ago and that wiped out the dinosaurs. Fewer people know that there is no trace of an asteroid strike badociated with the other four "big murders", 444 million, 360 million, 251 million, and 200 million deaths. 39; years. So, what happened then?

A common factor was that the planet was unusually hot at that time, but the real clue was that the deep oceans were anoxic. There was no oxygen there, and therefore no life that used oxygen. When the oceans are very hot, the "flip-flop" (like the Gulf Stream) that carries vast amounts of oxygen-rich surface water into the deep reaches and oceans layer into one layer oxygenated superficial and a deeper anoxic layer.

But there was still life there: sulphated bacteria that would normally hide in the silt, away from the oxygen that would destroy them. In an anoxic ocean, they come out and multiply – and finally, if the conditions are good, they go back to the surface and kill all the life with oxygen in the sea.