What makes an event catastrophic?

We have an all out nuclear war leaving large areas of the earth uninhabitable due to radiation.We are struck by a large asteroid which kicks up so much dust in the air that the temperature drops and the earths returns to ice age conditions. Because we had switched over to almost 100% solar power nearly everyone dies because no power is available for food production, distribution or heating.The super volcano under Yellowstone park erupts without warning. The volcano dumps so much ash in the air that the temperature drops and the earths returns to ice age conditions. Because we had switched over to almost 100% solar power nearly everyone dies because no power is available for food production, distribution or heating.We completely computerize all forms of information and use a world wide satellite based communications system. A massive solar storm destroys the communications satellites. Without the ability to communicate or access data needed for power, food production and distribution massive starvation and a breakdown in society results.Robotic systems take over all food and power production and manages the distribution system. A computer virus moves through the robotic systems disabling them. No human alive knows how to fix it. Most of mankind dies due to lack of food and warmth.Have a awesome day/night❤️✨Explanation: