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The albedo effect: The influence of feedback mechanisms in Climate Change

Explanation of positive and negative feeback mechanisms which influence earth's climate, like the albedo effect and the cloud effect. Fullt text: In previous videos you have already learned that the climate has always changed during earths history and was caused by natural variations. However, global warming accelerated very fast in recent decades. Many scientists agree that people have caused this climate change through greenhouse gas emissions. But what are the consequences of this climate change? How climate change will develop is still difficult to estimate. Future expectations often vary widely. The Earth also reacts to the increase in the CO2 amount in the atmosphere and the temperature rise at the surface! This response is called a feedback mechanism. Some feedback mechanisms enhance global warming and are therefore called positive feedback mechanisms. These are not called positive feedback mechanisms because we like them, but they are called positive because they enhance the first effect of warming. There are also processes that counteract global warming. These are therefore called negative feedback mechanisms, because the first effect of warming is actually counteracted. The Earth has a lot of feedback mechanisms, of which it is not yet completely clear how they work and that makes it unclear how exactly the Earth reacts to current global warming. A fairly clear feedback mechanism is the albedo effect. The albedo is the degree of reflection of solar radiation from an object. Fresh snow reflects about 90% of the sun’s energy and thus has a cooling effect on the earth. When it gets warmer, more snow melts. As a result, less warmth of the sun is reflected and therefore it can get warmer, so that more snow can melt. So this is a clear example of positive feedback: The first effect of warming is amplified. This is an important feedback mechanism in the cycles of Milankovic's. You have already learned that he found out that the position of the Earth relative to the sun can make it slightly warmer or colder on Earth. When the soil gets a little colder, snow can accumulate, reflecting more heat and cooling the earth even more and creating an ice age. A more unclear feedback mechanism is, for example, cloud formation. Higher temperatures lead to more evaporation. This creates more clouds. Some clouds reflect a lot of sunlight and are an example of negative feedback. Due to global warming, there is more evaporation and therefore more cloud formation, which means that more solar radiation can be reflected and thus it can become cooler. Other clouds, on the other hand, block little sunlight, but retain the warmth of the earth. These clouds work just like a greenhouse gas. Due to global warming, there is more evaporation and therefore more cloud formation, which means that more heat is retained. So this is an example of positive feedback. Whether the earth becomes warmer or cooler from the extra cloud formation depends very much on, for example, the location of the cloud and the height of the cloud. Because this part of the climate is not yet well understood, scientists have different predictions for the future. Because there are many other feedback mechanisms, such as the influence of oceans and forests, there are many different future scenarios.