Why We May Be On The Brink Of Mass Extinction
[su_right_ad]Evolutionary biologist Sean B. Carroll explains:
Fifty years ago, we were just beginning to learn some important lessons from natural disasters, epidemics, and manmade tragedies. As we gather this holiday season to take stock of all that we have to be grateful for, at the top of our list should be those who have had the foresight and resolve to make our world safer…
But now, to that list of calamities to learn from, we need to add “mass extinctions.”
[su_thin_right_skyscraper_ad]Yes, because nature’s warning lights are flashing. In the past forty years, Earth has lost half of its wild animal populations. Africa’s lions are one telling example. Thought the King of the Beasts was protected?
Think again. Fifty years ago, about 400,000 lions roamed Africa. Today, there are only about 30,000 remaining, as they have disappeared from twenty-six countries.
The fraction of species now at risk of extinction in the near future includes over one quarter of all species being monitored including mammals, reptiles, birds, and fish.
The potential losses of species are on a scale that is rivaled by only a few events in the last 500 million years of Earth’s history. Five times during that span, the majority of species on the planet vanished in a short interval of time. Scientists have now identified the triggers of two of those events: an asteroid that struck Earth 66 million years ago and wiped out dinosaurs and much more, and massive eruptions of volcanoes underneath Siberia that decimated the world 252 million years ago.
While the triggers for these two calamities were different, detailed study of what unfolded in the past reveals a common mode of destruction that is relevant to understanding our predicament today: in each case, mass extinction resulted from large and rapid environmental change on a global scale. Indeed, the main weapons of mass destruction unleashed by the Siberian eruptions included enormous quantities of the very familiar climate-changing gas carbon dioxide. The great concern of scientists today is that the potential global temperature changes projected over the next century approach those that took place 252 million years ago.
But these concerns about climate-changing gases are hardly new. In February 1965, President Lyndon B. Johnson told Congress: “This generation has altered the composition of the atmosphere on a global scale through . . . a steady increase in carbon dioxide from the burning of fossil fuels.”
There are now a lot of scientists with tense stomachs.
Let’s hope that fifty years from now, future generations might be thanking us for heeding the warnings.
About the author: Sean B. Carroll, Ph.D., is an evolutionary biologist at the University of Wisconsin, Madison, and vice president for science education at the Howard Hughes Medical Institute. He is an executive producer of a new film, Mass Extinction: Life at the Brink, which will premiere on Smithsonian Channel Nov. 30 at 8 PM ET/PT.
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