Impacts of asteroid and comets constitute major geologic processes shaping the surfaces and evolution of planetary bodies. Impacts produce deep transient cavities, with excavation to deep crustal levels, fragmentation, and removal of large rock volumes. Formation of complex craters involves high pressures and temperatures resulting in intense deformation, fracturing and melting. Here, we analyze the crater-forming impacts and their effects on the Earth´s climate, environment and life-support systems, in relation to the Cretaceous/Paleogene (K/Pg) boundary....