Extinction Level Event #6

Over the course of time, science has discovered 5 major Extinction Level Events, otherwise known as ELE's. The first occurred roughly 440 million years ago (mya), the second, 367 mya, the third 245 mya, the fourth, 208 mya, and the fifth, about 65 mya.

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If my math is correct, there was roughly 73 million years between the 1st and 2nd events, 122 between the 2nd and 3rd, 37 million years between the 3rd and 4th, and 143 million years between the 4th and 5th. The average equals 93.75 million years between events, but that is far from accurate, as there was only 37 million years during the Triassic period.

The consensus among biologists is that we now are moving toward another mass extinction that could rival the past big five. This potential sixth great extinction is unique in that it is caused largely by the activities of a single species. It is the first mass extinction that humans will witness firsthand—and not just as innocent bystanders.

Source.

As climate changes, a major question is whether nature can adapt to the changing conditions? The answer lies in the past. Throughout Earth's history, there have been periods where climate changed dramatically. The response was mass extinction events, when many species went extinct followed by a very slow recovery. The history of coral reefs gives us an insight into the nature of these events as reefs are so enduring and the fossil record of corals is relatively well known (Veron 2008). What we find is reefs were particularly impacted in mass extinctions, taking many millions of years to recover. These intervals are known as "reef gaps".

What caused these mass extinctions? To find the major driver of coral extinction, Veron 2008 looks at the possible options and eliminates many as the primary cause. A meteorite strike is capable of creating huge dust clouds that lead to devastating darkness and cold. However, if this were the cause of coral reef extinction, 99% of the world's coral species would be wiped out in weeks or months. The fossil record shows coral extinction occurred over much longer periods.

What Veron 2008 found was each mass extinction event corresponded to periods of quickly changing atmospheric CO2. When CO2 changes slowly, the gradual increase allows mixing and buffering of surface layers by deep ocean sinks. Marine organisms also have time to adapt to the new environmental conditions. However, when CO2 increases abruptly, the acidification effects are intensified in shallow waters owing to a lack of mixing. It also gives marine life little time to adapt.

It appears life can adapt to changes, just not quickly. To continue:

So rate of change is a key variable in nature's ability to adapt. The current rate of change in CO2 levels has no known precedent. Oceans don't respond instantly to a CO2 build-up, so the full effects of acidification take decades to centuries to develop. This means we will have irretrievably committed the Earth to the acidification process long before its effects become anywhere near as obvious as those of mass bleaching today. If we continue business-as-usual CO2 emissions, ocean pH will eventually drop to a point at which a host of other chemical changes such as anoxia (an absence of oxygen) are expected. If this happens, the state of the oceans at the end Cretaceous 65 million years ago will become a reality and the Earth will enter the sixth mass extinction.

Source.

But what about humans? There is one near-extinction event that is fairly well-known, although it remains controversial. Roughly 70,000 years ago, give or take a few thousand years, an enormous eruption occurred in what is now Sumatra, leaving behind Lake Toba. The eruption coincides with a population bottleneck that is often cited as the reason for the relatively low genetic diversity across Homo sapiens sapiens. Research suggests as few as 2,000 humans were left alive by the eruption and its aftereffects.

Source.

Are we overdue for an ELE? Perhaps. Life fights for survival at all times, and due to the very fact that we are here right now, we need to seriously address issues related to our continuing survival. Global warming? Perhaps. Can we do anything to change the destructive path we are on? That's for you to decide.

NOTE: There is an entry to the latest ATS writing contest [D&R] with the same title. It ties together with this thread. If you like fiction, HERE IT IS.

nukes my friend.

Expansion into space. I still cant believe he havent started this. Its the only just logical conclusion for the human species at this point. To many mouths to feed, not enough space. Our current gio political setup with varrying nations needs to end. We need to be collective as a whole. We tear down and restart. Get the 3rd world countries up to speed, then start the re education of people on space, astronomy, physics and chemisty. Its a long ass road, but its the only way i see our species surviving.

Either that or the E/T show up and either clear us away or help our progress.

Both are very unlikely and we will most likely disappear in the next few hundred years. We are just simply to violent to be a good space faring species.

reply to post by AaronWilson


I have been a proponent of space exploration for many years. It's all about greed, and a return on your investment. There's not enough money available to fund a feasible space program, because there is no immediate return.

But, imagine the resources out there. If we have all the elements on this rock we live on, surely there are others out there with the same composition. You'd make a killing to stake a claim to the mineral rights alone. Sadly enough, it doesn't appear that is our future.

People are so short-sighted to see what you have obviously stated. We are running out of room. We do need to build colonies.

Are people afraid to explore? Heck no, there would be volunteers by the hundreds if we had a craft to fly them out on. Why don't we have a craft like that? Is it beyond our ingenuity? Nope.

I also see it as our downfall as a civilization. Too little, too late.

Pretty good thread. I do agree that we should leave/explore. I think its not about roi, I think it has more to do with control. Once you leave the earth, you are guided by the rules and governance you set forth. There doesn't need to be a fed on the moon or another planet and that scares the crap out of them, to loose control.