3.1 Why do we need numerical modeling?

The study of climate change is a special scientific field, where the classical experimental method is not always applicable. For example, we observe that for 150 years, the global temperature of the Earth has warmed by about 1°C. In parallel, the atmospheric concentration of $CO_{2}$, a greenhouse gas emitted by human activities, has increased. Is the temperature rise cause by the increase in $CO_{2}$ concentration? Or is it pure coincidence? To answer this question according to the classical experimental method, one should duplicate our planet, make it go back 150 years earlier, and let it evolve until now without emitting any $CO_{2}$, and then accelerate the time to quickly get the results. Impossible! Except through numerical modeling. The goal of numerical modeling is precisely to be able to create as many Earth planets as one wants, submit them to the $CO_{2}$ concentration one wants, go back in time, or accelerate the time... The experimental method is thus based on numerical experiments.