The climate has always changed Our civilization is actually the result of climate change: 15,000 years ago an ice age ended, the conditions for agriculture and raising animals emerged, we stopped being nomads and cities were born. It was a beneficial climate change, easy to manage because it happened gradually. Above all, it was spontaneous: today we know that it was part of the natural cycles of the Earth's behaviour. Along comes industry, the flip side of the coin The climate change we’ve been witnessing for the last 150-200 years, on the other hand, is abnormal because it was triggered by humans and our technological activities: since the industrial revolution, we’ve pumped billions of tons of new carbon dioxide (CO2) into the atmosphere, the result of burning coal, oil and methane. A certain amount of greenhouse gases have been present on our planet for millions of years (in the form of water vapor, carbon dioxide, methane, ozone and nitrogen oxide), but we’ve added a lot more. The amount of CO2 has now doubled compared to the minimum of the last 700,000 years (410 parts per million compared to 200-180 parts per million). We know this thanks to scientists who have studied the ice in Antarctica, and thanks to hundreds and hundreds of scientific studies and data collected on land, at the bottom of the sea and by satellites. That’s why we talk about the "anthropogenic component of the greenhouse effect": the was that humanity has affected on the greenhouse effect. The climate on Earth has always changed, but for natural reasons and very slowly. The change that has occurred in the last 200 years or so has changed incredibly rapidly (compared to geological times) and now we know it is due to our massive use of fossil fuels to power industries, transportation and everything that makes life comfortable today. What the atmosphere is for The atmosphere is a kind of chemical blanket, made up of different types of gases which block heat from escaping. This ‘blanket’ lets the sun's rays pass through and retains some of the infrared rays that heat the surface of the Earth. The three main greenhouse gases in the atmosphere are: carbon dioxide (CO2), methane and water vapor, and they’re very efficient at retaining heat. Water vapor, the unexpected greenhouse gas From a physics point of view, the most effective gas at triggering the greenhouse effect is water vapor. The water molecule in gaseous form (H2O) is amazing and is obviously present in enormous quantities because over 70% of the Earth's surface is covered by water. Water vapor is linked to the water cycle and there is basically always the same amount in circulation. But as we said, the amount of CO2 present in the atmosphere has changed a lot in the last 200 years. Watch out for these gases: the greenhouse gases to watch out for are Methane (CH4), which is released into the air by open landfills, intensive farming and cultivation, and with the thawing of Arctic permafrost; nitrous oxide (N2O), which arrives in the atmosphere from uncontrolled industrial waste and transportation; finally, in smaller but not insignificant doses, there are ammonia (NH3) and hydrofluorocarbons and perfluorocarbons, which replaced CFCs in air conditioners and refrigerators when we started fighting the famous “hole in the ozone”, in the 1990s. As you can see, these are the results of human activity that can be controlled and for which valid alternatives exist.
