The history of our planet is rife with disasters that have devastated local populations and global events that have threatened the very existence of life itself. The restless nature of the Earth accounts for the majority of natural disasters, but those from beyond the Earth perhaps pose the greatest threat.
Mass Extinctions
Mankind, in its short history, is fortunate to have thus far escaped the effects of global catastrophes responsible for the extinction of significant percentages of the Earth's species. The worst of these, the Permian-Triassic extinction, killed 95 percent of all species 251 million years ago. Scientists are in disagreement over the exact cause of the extinction, but the likely candidates are impacts from an extraterrestrial body or widespread volcanism. The most widely known mass extinction occurred 65 million years ago, when a five-mile-wide asteroid impacted the Earth in the area of the Yucatan Peninsula. Creating the huge Chicxulub crater, this impact either caused or contributed to the extinction of the dinosaurs. Fortunately for humankind, this led to the dominance of mammals and the eventual evolution of our species. Other mass extinctions have occurred during the Triassic era (214 million years ago) caused by volcanism and global warming, the Devonian era (364 million years ago) due to an unknown cause, and the Ordovician-Silurian era (364 million years ago) caused by a fluctuation in sea levels as a result of glaciation. A future event of this magnitude could seriously threaten the existence of mankind.
Land and Sea
Earthquakes, tsunamis and volcanoes are endemic events, meaning that they are specific to a certain area. They have reshaped the landscape since the dawn of creation. Because we choose to inhabit those areas of the Earth most susceptible to these kinds of natural disasters, we invite the possibility of deadly consequences. Almost 80 percent of all the planet's earthquakes, and a large number of the deadliest volcanoes, occur along the so-called "Ring of Fire," a huge area circumscribing the Pacific Ocean--a recent earthquake and tsunami near Sumatra killed over a quarter of a million people. Yet some of the deadliest earthquakes have hit mainland China. Shansi was devastated by magnitude 8 earthquake in 1556, which killed over 800,000 people.
Famines throughout history have a number of different causes. No country has been spared. The worst happened in the past century. The 1958 through 1961 Great Leap Forward famine in China resulted in over 30 million deaths by starvation. Famines killing hundreds of thousands of people have occurred with surprising frequency throughout our history.
Air
Like the land- and sea-based natural disasters, hurricanes, floods, blizzards and other weather-related phenomenon occur in specific areas and could be avoided if we chose not to live in those areas. The worst hurricane in the United States occurred in 1900 in Galveston, Texas, and killed 800 people. Typhoons, however, have been much deadlier. The Bhola cyclone, which hit Bangladesh in 1970, had a death toll estimated at up to 550,000. Several others had death tolls over 1,000. Floods, caused by heavy rains, have left their greatest mark in China. The Huang He (Yellow) River flooded in 1931, and the death toll was close to four million. The same river flooded in 1887, killing up to two million, and again in 1938, killing up to 900,000.
Microbes
We cannot hide from microbes and, until very recent medical advances, can do nothing to stop them. The great plagues have killed untold millions of people. The Black Death alone is responsible for killing a third of the European population in the Middle Ages. The great Spanish Flu pandemic of 1918 killed between 20 and 40 million. Bacteria and viruses are among the oldest species on Earth. Many more millions, perhaps billions, of people have succumbed to the ravishes of malaria, typhoid, smallpox, yellow fever and AIDS.
Threats From Space
Cometary bombardments, asteroid strikes, supernovae and gamma ray bursts are very rare events, indeed. But they have impacted the Earth in the past, and they will do so in the future. Thus far, not a single human has been a casualty of such an event, their infrequency limiting them to events in the deep recesses of the Earth's history. Unlike the more terrestrial of natural disasters, which are unlikely to exterminate the entire human race, the threat from beyond could easily see the end of humanity. Fortunately, it may be millions of years in the future.
Tags: million years, natural disasters, death toll, from beyond, have occurred, impacted Earth, killed over
