How does excess CO2 harm the planet

Climate change: how carbon dioxide changes the climate

When we turn on the lights, turn on the heating, light the fireplace or drive a car, carbon dioxide is released into the atmosphere. Read how the gas is created and why it is so bad for the climate

What is carbon dioxide?

Carbon dioxide is an inconspicuous gas that we can neither see nor smell. We inhale tiny amounts of it with the air and exhale 100 times as much. The soda bubbles up as carbon dioxide, and plants need it to grow and thrive.

From a chemical point of view, a carbon dioxide molecule consists of a carbon atom (scientifically abbreviated: C) and two oxygen atoms (O2). Hence its short name: CO2. Incidentally, our atmosphere only contains a very small proportion, namely 0.04 percent.

Why is CO2 bad for the climate?

CO2 is a greenhouse gas: like the glass in a greenhouse, it prevents heat from escaping from the earth into space. In principle a good thing: If there were no greenhouse effects at all, our planet would be a barren ice desert with average temperatures of minus 18 degrees Celsius.

But we humans ensure that around 32 billion tons of additional carbon dioxide are released into the atmosphere every year. This could fill around 1.6 billion hot air balloons. Some of it remains in the atmosphere. The greenhouse effect is getting stronger and the earth is heating up more and more.

How does CO2 get into the air?

Roughly speaking, in two ways: Carbon dioxide is naturally present in the atmosphere. Because all animals and people breathe it out. The gas is also released when volcanoes erupt or plants rot. In addition to these natural sources of CO2, there are also man-made ones.

CO2 is created, for example, when power plants generate electricity, when steelworks produce iron or when aircraft take off - in short, wherever we burn fossil raw materials such as crude oil (and the gasoline or diesel made from it), natural gas or coal. All of these substances are as old as dinosaur bones or other fossils.

They emerged from dead organisms over the course of millions of years and for a very, very long time stored a large part of the carbon that is on our planet. If crude oil, gas and coal are burned today, the carbon is released again: It burns and combines with the oxygen from the air to form CO2 molecules that rise into the atmosphere.

Will the CO2 disappear from the atmosphere at some point?

Yes, because plants have been storing carbon since ancient times: With their leaves or needles, they absorb CO2 from the air and, with the help of water and light, convert it into carbon-containing sugar and oxygen. While they release the oxygen back into the atmosphere, the cells of the tree are created in many steps from the sugar - and with them the trunk, all branches and all leaves.

A tree binds at least ten kilograms of CO2 annually. But: If forests are burned to make room for plantations, for example, the carbon stored in them is converted back into carbon dioxide - and everything was in vain.

In addition, we are currently releasing much more CO2 from fossil sources than the plants on earth can even bind today: only a quarter of the CO2 we blow into the air. Another quarter is saved by the oceans.

Researchers fear, however, that the oceans will soon no longer be able to absorb as much carbon dioxide if the earth continues to heat up. The other half of our CO2 emissions initially remain in the atmosphere - for an average of 120 years.

Unlike many other molecules, carbon dioxide does not break down on its own after a certain period of time. Even if we stopped burning oil, coal and gas from tomorrow, the temperatures on earth will continue to rise for a long time.

Is CO2 the only greenhouse gas?

No, but the most important for the man-made greenhouse effect. Around three quarters of it is responsible for him. The second most important greenhouse gas is methane. It is mainly produced in landfills and in agriculture - more precisely: in the stomachs of cattle and sheep, which blow it into the atmosphere with every burp.

Methane heats the climate up to 21 times more than CO2, but not as much of it is produced. Overall, it therefore only accounts for around 15 percent of the greenhouse effect. Nitrous oxide, which is also produced in agriculture, is even rarer.

But because it is more than 300 times more harmful than CO2, it still contributes around eight percent to the greenhouse effect. In addition, there are so-called fluorocarbons, which are used as refrigerants in air conditioning systems and account for around one percent of the greenhouse effect.

By the way: the most important natural greenhouse gas is water vapor, which is created when water evaporates from lakes or oceans and rises into the atmosphere.

How do researchers and politicians want to reduce CO2 emissions?

In the future, all of our energy should be obtained from CO2-free sources such as wind, water or the sun. It is estimated that this will work in Germany in 2050 at the earliest. That is why politicians have come up with emissions trading for the period up to that point. An authority for companies in Europe determines how much CO2 they are allowed to emit per year.

If a company exceeds this limit, it has to pay dearly for additional emissions. However, if it stays below the specified amount, it is allowed to sell the "saved" carbon dioxide to other companies that emit more exhaust gases than the authorities have allowed them.

Climate-friendly companies should be rewarded, while climate-sinners pay extra. Will this plan really do anything? A good question, the answer of which even experts argue.

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