Global warming: new context and new situations

Heatwaves in parts of Europe and Japan, fires in Greece and Scandinavia, the latest manifestations of global warming are "the symptoms of something new in terms of climate," assures climatologist Hervé le Treut.

First of all, the certainties. Guest on the morning show of Hervé le Treut points out that "the climate has been warming almost continuously for 40 years now." The levels of normal climate variability were exceeded about fifteen years ago, says the climatologist. This now places us in "a new context," which calls for "situations that will also be new." The manifestations of the consequences of global warming are currently difficult to predict locally, because "the atmosphere is a turbulent fluid that calls for thousands of possible combinations," explains Hervé le Treut.

Uncertainties and climate models

Beyond the certainty of global warming, questions remain about the regions affected and the extreme effects at work there. "All this is taking shape randomly like a large puzzle and is being built little by little," explains Hervé le Treut. "We realize that the warming areas correspond to the models we've had for several years."Thus, among them, we find the poles and the regions between the tropics "where warming is not necessarily manifested in terms of temperatures, but in thunderstorms or storms."

Effects on biodiversity

Beyond the climatic and meteorological consequences, the current warming is not without effects on the living world. "We have animal migrations, we see it in fishing areas, we see it in our mountains" emphasizes Hervé le Treut. These climatic shifts have already been documented. A recent publication by around fifty European researchers in the journal Nature even shows an acceleration of plant migrations towards the European summits. "Afterwards, other changes are linked to human activity, to land use"with, again, impacts on the water cycle and the climate, underlines the climatologist.

Commitments and injustices in question

Faced with the challenges, the commitments of States through the Paris Agreement are not enough, believes Hervé le Treut. Judging what he calls "climate indifference to be dangerous, he denounces climate injustices. "We have a system of mixing greenhouse gases that distributes the climate signal across the entire planet. We are all dependent on each other." » Unfortunately, countries "that have not contributed much to emissions are also paying the bill." Finally, regarding the inevitable adaptation to current and future changes, Hervé le Treut believes that to adapt well, "we must keep in mind what we want to preserve" such as values, biodiversity and common heritage.

Cyrille Arnoux, web editorial manager