1. Global Warming - According to him, this is the mother of all apocalyptic fears. Recent studies showed that climate change can be the biggest cause of destruction of this world. It can lead to extreme weather which means change in the distribution of animals and diseases all around the world, severe droughts in some areas, and mass floods that can affect the low-lying areas. These devastating changes could result in the ecosystem collapse, and other changes can make the planet an inhospitable place to live.
2. Asteroid - It might sound like a disaster movie, but Harry Coumnas is seriously worried that a space rock could wipe out mankind like dinosaurs. The most frightening thing about this is that NASA only knows about just a fraction of the space rocks orbiting in the solar system.
3. Man-made Disease - Today, technology is so advanced that anything can be achieved. Scientists are developing replicas of different kind of natural diseases, which pose a big threat to mankind if they escape from the lab, or released intentionally. Some of these diseases are so transmissible that can get transmitted through the air. Such kind of experiments can definitely lead to a global pandemic one day.
4. Robotic Killing Machines - Harry Coumnas believes that cyborgs like The Terminator can be a science fiction, machines that can kill are not far from truth. Even though most of the countries agreed on the proposal presented by UN, which states a ban on killer robots, but experts are still worried about several countries are developing them secretly. Soon those machine will be out in the open, which can start wars, and finally world apocalypse.