Timothy Palmer: “Today’s climate is like a rigged deck of cards”

What are the data that unequivocally show that the climate is changing and that it is not a “fluctuation”, as some argue?

“Certainly the global average temperature, which has remained stable for thousands of years and then, since the industrial revolution, has begun inexorably and incontrovertibly to rise. This is the reference figure for the scientific community. And then there are the anecdotal evidence of extreme events, which are increasingly frequent and increasingly extreme: last year in British Columbia, at very high latitudes, temperatures of 50 ° C were recorded. A large amount of ice has just disintegrated on the Marmolada, causing the tragedy we have all read about. And many other examples of this tenor could be made. It should be obvious to everyone that something strange, anomalous is happening “.

Let’s go back to climate models. How do they work? How reliable are they?

“Climate models are very complex. To simplify things, we can think that at the extremes of the spectrum there are the super-simplified models, which serve to corroborate or disprove the hypotheses of the theory, and the super-complex ones, which give quantitative and precise answers, but whose solution requires a lot. time and a lot of computational power. It is the so-called ‘model hierarchy’: with the first models we try to understand which are the important variables and which ones we can neglect; with the latter we simulate the evolution of the climate using only the important variables “.

What scenarios do they foresee for the future?

“It all depends on how rapidly the concentrations of carbon dioxide in the atmosphere will increase, a variable that, of course, the models cannot predict. In the scenario where we were to continue to put carbon dioxide into the atmosphere it is expected a further increase in temperature in the next century, even up to 4 degrees higher. It would be a catastrophe: the seas would rise, submerging many coastal cities; desertification, drought and the other extreme events we have talked about would increase; entire populations would be forced to move elsewhere. In short, nothing good “.