About the climate
Climate change
- Talking about a climate change of +2°C does not seem, a priori, very worrying. We can easily endure an increase in the local temperature of +2°C.
- What we must realize is that what a change of +2°C does is to increase the frequency and intensity of extreme events, the standard deviations.
Climate dysregulation
- Standard deviations are increasingly frequent. The frequency of extreme climatic events in France has increased by a factor of 4.5 since 2000, compared to the period 1950 to 2000.
- So more serious and more frequent floods, larger and more frequent forest fires, warmer and longer heat waves, etc.
- It would be fairer to talk about climate dysregulation.
Loss of biodiversity
Sixth mass extinction
- In 50 years we have lost 70% of wild vertebrate animals on the continents, in mass. Note 1. This is not an “erosion of biodiversity”. Sometimes we hear talk of the 6th mass extinction – not the correct word.
- In terms of extinction, the last major extinction, the 5th, took place over a period of more than 33,000 years (disappearance of the dinosaurs Note 2); and it is described as a sudden mass extinction.
First major extermination
- A 70% loss of vertebrate mass in 50 years is 1,000 times faster than an extinction; it's the first major extermination, that's the right word.
- To our knowledge, we have no other extinction event of this magnitude in the history of the planet.
Source: Conference of Olivier Hamant at the Académie du Climat, in France, in February 2026
Note 1: World Wildlife Fund (WWF) Living Planet Report 2024
Note 2: The dinosaurs, in fact, had been in decline for 300,000 years (due to volcanoes in India), then a meteorite struck off the coast of Mexico, and it took another 33,000 years to complete the extinction of the dinosaurs. This is classified as a sudden mass extinction.