So what we need is atmosphere control. Controlling means sensing and actuating. We need to know the actual state of the atmosphere, compare it with an established standard and to have the means to modify it accordingly. This sounds easy, but is awfully difficult. Atmosphere is a global system. How can we measure atmospheric constituents entirely? What are acceptable limits for garbage constituents? And once we know the unwanted constituents and their wanted levels, how can nations ensure that every one sticks to reducing the un-wanted garbage? Let’s start with the first step: How can we measure garbage concentrations globally? Take a probe here, take a probe there? Even if we would do that at thousands of sampling stations worldwide, would this give us the overall concentrations? No, because we would also have to climb mountains and even would have to go much higher at any place to sample the entire atmosphere. What we rather need is a globally integrating sensor. We do have sensors like this. They are called environmental satellites. The most sophisticated of these is the European Environmental Satellite, ENVISAT. ENVISAT constantly monitors our atmosphere and Earth’s surface properties from space since March 2002. It is the biggest one as well, com-parable with a truck: 10 meters long, 3 meters wide, and weighting 8 tons. With 2.3 Billion Euros it was also by far the most expensive.

Let’s have a fundamental look at our atmosphere. What is it good for? You could say: „That we can breathe!“ But why do we need to breathe? Well, we are metabolizing: We need oxy-gen to burn carbon and hydrogen in our body cells to obtain energy, which enables us to do things. In turn we exhale carbon dioxide and oxygen dihydrate – you could also say “water”. Plants take up this CO2 and H2O and convert it back into carbohydrates (CH2O)n and pure oxygen O2. We buy these carbohydrates (food) in the store and burn it with the O2, which luckily is still free. So actually our atmosphere primarily serves as an environment to ex-change substances. Unluckily it can also be used as a garbage dump for any gaseous waste. Sulfur oxides SOx, nitrogen oxides NOx, and halogens, to name a few. Actually CO2 and H2O are also waste, but plants keep the CO2 level low. And water …, well we love it. Unwanted amounts of garbage my harm us, but during the last centuries it turned out that the thermal control property of our atmosphere blanket suffers more from the garbage than we do. And unfortunately, some of the garbage, such as halogens and fluorocarbons, don’t get recycled in the atmosphere. They just stay there for a long time. Tune in again soon!