Based on climate simulations we know that global warming is caused by human activities that produce greenhouse gas emissions (mostly CO2). The validation of the models was the historical climate data set. Based on the validated models we know that the warming-up process will not slow down if we don’t reduce our CO2 emissions or extract enormous amounts of CO2 from the atmosphere. But even if we were able to extract enough CO2 from the air in a sustainable way, it would only give us a little extra time before the destruction of the planet becomes irreversible.