The World’s Greatest Weather And Environmental Catastrophe

The effect of volcanic activity on the world’s weather, though well known and documented, remains the subject of intense study. Part of this is in response to the on-going concerns relating to global warming, and how changes in atmospheric components, volcanic or otherwise, can drive climate. But major volcanic events are sporadic and tough to predict, increasingly forcing scientists to look back in time, piecing together the circumstances surrounding eruptions far more cataclysmic than anything experienced in our own short recorded history. In these titanic events, researchers can see the potentially catastrophic interplay of weather and geology.


And of all the volcanic events that are known to have taken place in the last 500 million years, none is believed to have had a bigger impact on the climate, and the life forms it supported, than the so-called Siberian Traps event. Occurring about 250 million years ago, before even the time of the dinosaurs, the Siberian Traps event is not really a single short-term geological occurrence. Rather, it was a massive and continuous expulsion of lava over a long period of time, perhaps a million years, that ultimately resulted in the greatest single extinction of life ever known to have taken place, the Permian-Triassic extinction. It’s strength was not only in its size, but in the fact that it just kept going, almost knocking out the planet’s thin coating of life.

First, a description of the almost unimaginable volcanic activity itself. It is believed by some to have been so massive because of its unusual source. That source is thought to have been what is called a mantle plume, an uncommonly huge upwelling of superheated rock from deep within the earth’s mantle, far deeper and larger than the heat source of most volcanoes that owe their energy to plate tectonics. (Some have speculated that mantle plumes could be the source of the hot-spots blamed for super volcanoes.)

According to the theory, when a large mantle plume broke through the earth’s crust 250 million years ago, the result was a vast and extended eruption from many volcanic vents, incessantly spewing oceans of lava over what is now northern Siberia. (Some have even suggested an asteroid impact as the initiator of the eruptions.) To get an idea of the total amount of lava ultimately ejected, imagine the entire surface of the earth covered by nearly 10 feet of lava. The lava, as it turned out, did not spread over the entire earth. Instead, it continually cooled, building up on itself and limiting its final size to an area roughly that of Western Europe, two miles thick in places.

But it was the unparalleled effect on Permian life of this environmental catastrophe that marks its significance. At first, the increasing lava flows caused a gradual change in the environment that put mounting pressure on surrounding life forms. Volcanic ash from explosive eruptions could have initially blocked the sun’s rays, cooling the planet. Gradually, however, the release of carbon dioxide and other gases generated other pressures, including global warming and ongoing acid rains. Dying plant life would have impacted animal life and oxygenation on the land and in the seas. As time went on, the oceans themselves began to warm significantly. Ocean levels would rise and ocean currents could shut down, further aggravating weather extremes. As the oceans continued to heat, methane gas hydrates started to thaw, releasing enormous amounts of methane gas into the atmosphere. Methane is a greenhouse gas many times more powerful than carbon dioxide, and would have greatly accelerated the warming process. The combination of extremes was simply too much for the majority of plants and animals.

The volcanic activity eventually stopped, but it was too late. In the end, over 90% of all species on earth were wiped out. Even insects, almost never connected with mass extinctions, were broadly hit. The loss in biodiversity was so great that it took tens of millions of years for life to get back to a level close to what it had been before the event.

Will such an event ever happen again? Today there are still hotspots that carry with them the potential of massive volcanic events able to change weather and threaten large segments of animal and plant populations. Perhaps the most famous is that underlying Yellowstone National Park in Wyoming. Its biggest eruption was 2.2 million years ago when it covered much of North America with ash, and unleashed over 2,000 cubic kilometers of lava, changing weather and threatening plant and animal life. But the Siberian Traps event is in a league of its own and may never be matched. Think of Yellowstone, and then multiply the volume by 1,000.

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