CO2 THROUGH TIME
The CO₂ content in the atmosphere has fluctuated greatly throughout Earth’s history. It is estimated that 500 million years ago, the CO₂ concentration was between 3 000 and 9 000 ppm, while in pre-industrial times it was around 280 ppm. Today, the values are over 420 ppm. This is a 50% increase over pre-industrial levels and higher than at any time in the last 3 million years
THREE POSSIBLE FUTURE SCENARIOS
According to the Intergovernmental Panel on Climate Change (IPCC, 2023), future global warming depends crucially on greenhouse gas emissions. If emissions remain very high, the average temperature could rise by more than +4 °C by 2100 compared to pre-industrial levels. With very rapid emission reductions, warming could be limited to +1.4 °C. Only through rapid and comprehensive reduction of emissions to net zero can serious consequences still be averted.
Scenario A: Without climate protection measures
If we do not take action to protect the climate, global temperatures will rise sharply. Many regions could become uninhabitable. Extreme weather events such as droughts, floods and fires will increase. Sea levels will rise, and millions of people will lose their homes. Ecosystems such as rainforests and coral reefs will collapse, and species extinction will accelerate. The economic and social consequences would also be significant.
Scenario B: With limited measures
If CO₂ emissions are continuously reduced (by at least two-thirds by 2050 compared to 2019), warming could be limited to around +3 °C. Nevertheless, the climate will change dramatically: heat waves, droughts and heavy rainfall will increase. Agriculture and water supply will come under pressure, adaptation measures will be necessary, costly and generally unable to restore what has been destroyed.
Scenario C: With consistent action
With more consistent emission reductions (84% by 2050 compared to 2019; followed by further reductions), warming could be limited to below +2 °C. This is also the basis for Switzerland’s net-zero target, which was approved in a referendum on 18 June 2023. This would mitigate many risks. Extreme weather would still occur, but the consequences would remain more controllable. Ecosystems would be more resilient, more habitats would be preserved, and the economic and social impacts would be significantly lower.