Earth’s climate has always been changing In the last 800 million years, there have been at least 6 ice ages and in one case the planet was almost entirely covered by ice! Only the equatorial belt was free of it. At other times, the sea was much higher and whales swam placidly on the plain where Milan now stands. The signs of these changes are evident in fossils, in the stratification of the soil, in the presence of trees and animals at different latitudes or in places that are different from where they originated. Even the millennia-old tombs of the Egyptians or of ancient Chinese dignitaries tell us about the climate that once was, in that place, at that time. There are even chronicles from the 1300s that tell us about when the River Thames was frozen for several days in a row. This information is important but not strictly scientific. Climatologists on the hunt for numbers Climatologists base their claims (i.e., that the Earth is rapidly overheating due to the anthropogenic component of the greenhouse effect) on numbers – numbers that are precise and, above all, collected systematically: for a long time every day, always in the same way (which is called scientific protocol) and in many different places in the world, in order to have global “coverage”. This is the work of meteorologists, which began scientifically at the end of the 18th century and by 1850 became sufficiently systematic to be able to give rise to what we can call “historical data”. Climate change: how did we discover it? We use historical data to show the rankings of the wettest, driest or snowiest years. It can tell us when a season began or ended, and it’s thanks to this data that today we can say without a shadow of a doubt that climate change is real. To see what we mean, just look at the striking, dramatic images produced by the photographer and mountaineer Fabiano Ventura who, in his exhibition “On the Trail of the Glaciers”, puts photos of what glacial valleys look like today next to images of the same valleys 80-100 years ago: it really hits home that mountain ice is disappearing dramatically all over the world. The ranking of the hottest years Since 1880, the numbers tell us that in 140 years the average temperature has increased by about 1°C all over the globe, and by more than double that in some particularly sensitive regions such as the Arctic and the mountains. In the European Alps, the average temperature increase was 1.5 °C, and since 1850 we have already lost between 60% and 70% of our glaciers. In the ranking of the hottest years since the mid-19th century, 2015, 2016, 2017, 2018 and 2021 are the five hottest years ever and all the years from 2000 onwards (probably all the years of your life) are in the ranking of the 20 hottest years of the modern era. And not just in one region: all over the world. A trend that needs to be reversed This is how we noticed the change: by measuring it. And we realized that 30-35 years of constant anomaly compared to the past are enough to say, scientifically and without a doubt, that the climate in that region has changed. Unfortunately, it’s almost always changed for the worse: disrupting people's lives, ruining crops, forcing animals to migrate and creating a distressing loss of biodiversity. Scientific knowledge is essential to know what to do Are you a little worried? That's right, you should be. But all this scientific knowledge is also “good news” – now that we understand precisely how and why the climate “broke”, we also have all the information we need to fix things: decarbonisation (giving up 90% of fossil fuels), electrification of mobility and personal services (with electricity from renewable sources), efficiency and the circular economy to make better use of raw materials and to minimize waste. We need the important choices of the heads of state, but all those small things that you and your family do every day are also really important.
