Computationally Irreducible?

For two decades, researchers have suspected that what makes such events so unpredictable is their inherent complexity. In the Earth's crust and its ecosystems, and in any economy, events depend on the delicate interactions of millions of parts, and seemingly insignificant accidents can sometimes have massive repercussions. Mathematicians have even declared that some complex systems are "computationally irreducible", meaning there is no short cut to knowing their future. The only way to find out what will happen is to actually let it happen...