6,4°C more

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Temps de lecture : 2 minutes  

hausse temperature climat comprendre

What will the world look like if we keep operating in a “business as usual” way, without changing our habits? The Gross World Product (GWP) could increase 10- to 26-fold by 2100, compared to 1990. Our greenhouse gas emissions will increase in the same way. But how, exactly?

Possible futures were explored and thirty scenarios were suggested. They were then grouped into four main categories: A1, A2, B1 and B2. The first two are based on rapid economic growth but the world is more globalized in A1 than in A2. The last two are based on slower growth that is more concerned with the environment with, again, more globalized options in 1 than in 2. Researchers use these hypotheses to calculate greenhouse gas emissions and then calculate the concentration of gas in the atmosphere. They can then estimate the average temperature, rising sea levels, changes in precipitation…

The type of energy used is important in these scenarios. If this “cleaner” technology makes it possible to use less energy, – it is deemed more efficient, – or to emit less greenhouse gas, – it is less carbon-intensive – this will affect the scenarios. Hence, the A1 group is divided into three to consider different options: A1FI (mostly fossil fuels), A1T (mostly non-fossil fuels) and A1B (balance). Also, the average global warming goes from +1.4°C to +3.8°C for A1T and from +2.4°C to +6.4°C for A1FI at the end of this century – so, approximately twice the amount.

The economy is not the only thing that counts: demographic, social and political factors also play a role and they have been taken into account. Thus, if there are 15 billion human beings in 2100 rather than 7 billion, if the population increases faster rather than slower, GEG emissions will increase significantly. These scenarios therefore reflect society’s choices.


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