The Earth is 4.5 billion years old, and life on our planet blossomed 3.8 billion years ago. It was the climate – which is different from region to region – that stimulated the emergence of all kinds of living things, capable of adapting to any habitat in this gigantic experiment called evolution. Why do we have different climates at the poles or at the equator, in the Mediterranean or in the Alps? Because of a perfect combination of the Sun at the “right” distance and the greenhouse effect: at every moment, our star sends an incredible amount of energy to Earth and that energy is retained thanks to our atmosphere. There are other variables, too. Much more solar energy (thermal energy) reaches the equator than the poles; at the latitudes in between, the amount of solar energy changes depending on the seasons of the year. The presence of frozen plains or mountains, shallow seas or vast, deep oceans are other variables that make the climate a phenomenon full of subtleties and surprises. Climate is not the weather Scientists who study all this are called climatologists – not to be confused with meteorologists, who study the weather. Since they’ve studied the mechanisms of the physics of our atmosphere and know them very well, meteorologists can predict in the morning what will happen in the evening, what will happen tomorrow and even the day after tomorrow. To put it scientifically, the weather describes the characteristics of the atmosphere over a few hours or a few days, including rain, wind, snow, clear skies and humidity levels. The climate, on the other hand, is what we expect to find because we know the usual weather patterns in that location and in that season: the set of typical weather characteristics. To determine the climate of a certain region, we have to observe the weather – that is, we have to collect data on temperature, humidity, rainfall, pressure and more – for at least 30 years in a row. Evolve or adapt? Like all living things in Earth’s history, about 12-13,000 years ago (with the birth of agriculture), we humans adapted to the climate we found ourselves in. A generally stable climate, area by area, allowed us to organize life in the countryside and in cities and to arrive at the modern life that we know today. When the climate changes (the climate, not the weather!), the equilibrium of a habitat is thrown out of balance. There are two ways to adapt: with a new evolutionary process (but evolution is very slow and takes thousands of years) or by migrating to a more liveable habitat… but unfortunately, not everyone can do so. Having studied the climate of the near past (the last 10-12,000 years) and the climate of the distant past (the last million years), we have evidence that today's climate change is not a natural phenomenon and is clearly linked to the enormous quantities of new greenhouse gases that we started pumping into the atmosphere 300 years ago, altering the balance so dramatically and so quickly that it has made the meteorological and climatic mechanisms that we were used to go haywire. We’re in a climate crisis. But the good news is that we know how to face it and what to do to fix it – as long as we don't waste any more time just talking about it.
