This is climate change video collection. Video 1. Climate on the Earth. The Greenhouse event. I've never seen such a warm crazy winter in the Arctic, Senator Director of the National Snow and Ice Data Center, Mark Siréza. The heat was relentless air temperatures over the Arctic Ocean for the months of December, January and February were 2 to 60 degrees Celsius above average, in nearly every region around the North Pole. That was year 2017, but according to this new word graph, year 2018 is even worse for the Arctic ice, showing new record negative anomalies. According to the same scientific sources, year 2017 was the wariest ever recorded, almost all over the world, as you can see from this global anomalies map, from NASA. This is not an isolated fact. The world is getting warmer rather fast. In years like 2014, 2015, 2016, they all set new records, while year 2017 was also near the top. Temperature on Earth is essentially regulated by the radiation balance. That means that as much energy arrives from the Sun, the same amount must leave the Earth, with a major difference, because the incoming energy is visible light, while the outgoing energy is invisible, in-prerid, long-wave radiation. But this is not enough. To understand the real climate, you must consider the greenhouse effect. That is interception of Earth infrared radiation by minor gases present in the air, the so-called greenhouse gases. They are transparent to visible light, but absorb infrared radiation. Here are the most relevant greenhouse gases. Water vapor, carbon dioxide, methane, and nitrous oxide. Water vapor concentration, there is a lot through time and space, due to evaporation from the oceans, precipitation, and is in general independent from human behavior. The other three gases instead are strongly influenced by human activities, as you will see in the following videos of this series. Please consider that the greenhouse effect is a good thing. Without it, the Earth temperature would be on average around minus 18 Celsius instead of the current plus 15. So the greenhouse effect is providing us a lot of use to warmth, but one should never exceed in good things. And no other greenhouse gases should be added to the atmosphere to avoid excessive heat. Remember that on planet Venus, there is far too much carbon dioxide in the atmosphere, so surface temperature exceeds 400 degrees. Let's keep far away from Venus. Next video in this series, which shows some facts about greenhouse gases in the contemporary world. Stay tuned and see you soon.