It’s hard to imagine how brief our existence on this planet is. Imagine if you will that we summarized how humans came to dominate the planet in your average 2-hour movie. The very first frame starts us off with the accretion of the planet. About 18 minutes into the film the first microbial life starts to take shape on this clump of space junk. Nothing much seems to be happening. People around in the theater are already running out of popcorn and getting cranky. Cellphones start illuminating the dark auditorium.
Most of the people sitting next to you start to pack up and leave, after all they are just staring at a circle anyways. Off to a pretty rocky start, the movie only starts to develop the main character around an hour and 5 minutes in as they develop into cells with Nuclei. How abundantly exciting. Finally, as the director seams to realize where the action is at, we witness the squirming of creatures bound to the ocean. These odd tiny creatures resembling fish and crustaceans are scuttling around at about an hour and 45 minutes into the movie.
They continue to do their thing for a while and suddenly, 10 minutes before the credits roll, they start to move out of the ocean and onto land. The stakes are high at this point. This total narrative curve-ball has the remaining audience in suspense. During 3 minutes, you watch the planet suddenly turn green, burn down, then it turns green again, and burns down, it turns green again, and poof. Somehow in the middle of this there are now gigantic reptilian beasts roaming coast to coast amidst the rapidly shifting green patches surrounded by ocean.
But only for a moment, a speck of dust hits the earth and It looks hazy for just an instant. You’re wondering what could possibly happen in the last 2 minutes of the film, but you notice that the giant scaly creatures now look like mammals. Shapes on the globe start to look familiar. The Planet strobes white, green, white and… Did you miss it? Of course you did. Movies run film at a rate of 24 frames second. That means that there are about 42 milliseconds between frames.
We can barely hope to recognize individual frames let alone count the milliseconds between them. We made the last 3 frames of the movie before the screen cut to black. We existed for about a 150 milliseconds of the movie (. 15 seconds). Mass extinction; This is a term that most don’t fully appreciate the severity of. Like many aspects in the time scale of our earth and solar system, it is difficult to comprehend its scale at the surface. A mass extinction is classified as a massive dying of animal species in a short geologic window.
In the above analogy that would mean having anywhere from 70% to 90% of creature species die in a fraction of a second. Mass extinctions are driven by a compounding of events. For example, the extinction that defined the beginning of the Triassic was called quite literally: The Great Dying. During the Great dying an estimated 54% of all families were lost. Just to clarify A family is such a broad term, it is the first category that would separate a panda from a fox. This was speculated to be caused by several events.
For starters, there Is thought that there was an impact event akin to what we believe killed off the dinosaurs, on top of that massive effusions of flood basalts which also released massive ash clouds and acidic aerosols that would have blotted out the sun; On top of that ocean waters became so devoid of oxygen that most of the biomass in the waters died and were replaced by bacteria that produced massive amounts of hydrogen sulfide, which would not only have poisoned all life on the ground but would have also destroyed the ozone so that any survivors were lightly baked by the Suns ultraviolet waves.
This event was so severe that life on earth took over 10 million years to recover, and the only reason that it could recover was due to these environmental factors eventually subsiding. This kind of event is so catastrophic that it can hard to imagine that humans could be causing a sixth mass extinction. These seemingly cataclysmic events have historically always been caused by a variety of pressures on life. One of the most defining of which is a sudden and drastic change in the status quo that various life-forms are not able to adapt to quickly enough.
This can be seen clearly when man migrated to what we now as Australia around 55,000 (± 5,000) years ago (Miller, 1990). At the time, the continent was host to a vast variety of life that would seem quite foreign today. Among them were the Dinornis (Giant Moa) and more specifically Genyornis, massive emu-like flightless birds that grew to 2-3 meters. The Genyornis was found to be quite common in the fossil record until 60,000 – 50,000 years ago and was speculated to have gone extinct 50,000 ± 5,000 years ago (Miller, 1990).
This extinction coincides with a slightly more arid climate and direct competition for their nutrient source in plants; As the new human inhabitants had been burning the plant life in the area which had previously not been prone to fires and was ill equipped to recover from the increased destruction. The giant birds were not known to have natural predators but there has been evidence of some direct predation by humans (Miller, 1990). While most of these birds vanished to never be seen again thanks to their food source being consumed in man-made fires, some of them managed to survive.
The Dromaius which transformed into the modern Emu (same area), was thought to have been able to survive on more diverse sources of plant life. Between This and the smaller body size meant that they were able more easily sustain themselves on the reduced foliage. This human invasion of Australia coincided with more than an 85% of Australian genera with a body mass over 44 kg going extinct in the late Pleistocene. There are so many ways in which humans deteriorate plant and animal populations. However Modern human interference in wildlife has not yet been able to achieve Mass extinction status.
We have talked about how much of an invasive species we are and just how virulently the spread of our influence grows, but for the first time in history we are now able to destroy environments across the globe. We are quickly approaching the devastation force of that tiny speck that hit the earth and stirred up so much dust in the movie. Most of the animals and plants that we displace or otherwise burden are not quite so fragile as the Genyornis. We now occupy massive amounts of land that otherwise would have been lush forests and homeland to various Animalia.
Many have had to find permanent new food sources and environments to live. Not only are we currently occupying more than half of the unfrozen land on the planet (Biello, 2014), we are also indirectly damaging the remainder of it. Throughout the history of the planet, massive outgassing of carbon from geologic stores directly into the atmosphere was uncommon, and frequently coincided with mass extinctions of the past. But our primary source of energy is doing just that. Normally this process is slowly reversed over time as plants consume atmospheric carbon, eventually die, and get buried in rock.
But thanks to us, plant mass is not as strong of a carbon neutralizing force since we routinely cut down their most robust members for resources and occupy much of their premium growing real estate. In the past increased environment toxicity and global warming akin to what we are managing to do with our incredible pollution has been known to devastate portions of the population, without which, the complex ecology of the time collapses. That is just it, we don’t need to directly kill everything to evoke a mass extinction, we just need to destabilize the biological systems in place, which we are doing.
The amount of green housing that we are causing on the planet is getting to be so severe that the amount of melting we are causing on the caps is starting to be a substantial figure. We have managed to raise sea levels so much that coastal cities are now in constant danger of destruction. In Venice Italy, they routinely experience hugely damaging floods and with such frequency, that the country is putting billions of dollars into a massive dam between the city and the Mediterranean Sea called the MOSE project (after Moses in the bible).
Raising temperature by only a couple of degrees on annual average can have huge repercussions on our environment and can even be enough for certain vulnerable species to die off. It doesn’t stop at the decaying of our planet through indirect and direct destruction of habitat and displacement of animals and plants. Humans have played a large role in directly hunting and killing off massive amounts of the earths megafaunal population (Large animals, often herbivores, that enable spreading of plant growth across large distances. Ranging from hundreds to thousands of pounds).
One of the major problems is that so many of these large animals take a massive amount of time to recover from large die off. Much like our ancestors that lived in caves and hunted and eventually decimated populations of giant sloths or woolly mammoths, our recent cousins have demolished the North American Buffalo population (go buffs! ), or even in very recent history we managed to obliterated rhino and elephant populations over their ivory. It’s truly quite astonishing that no living human being has witnessed nor fully comprehends what our ecosystem was supposed to look like before our disturbances.
Since 1500 CE terrestrial vertebrates (anything with a spine that lives on land) have lost 322 species and of the remaining, there is an on average 25% decline in abundance (Dirzo, 2014). A 25% reduction in terrestrial vertebrate wildlife is an astonishing amount of biomass when you take into consideration how big the planet is. That isn’t even the worst of our damages caused by defaunation (humans killing and replacing plants and animals). It was also found that of the estimated 67% of total invertebrates tracked that there was a 45% average abundance decline! Dirzo, 2014) This is all only in the last 500 years.
Remember how we were only present for about 150 milliseconds in the movie of our development? That 150 milliseconds represented about 100,000 years. That means that within that already inconceivably small time frame we are looking at large scale extinction change over about 8 microseconds (8 seconds x 10-6) into a potentially 13-16 microsecond process of replicating one of the worst biological disasters the planet has ever seen (at the timescale of a 2-hour movie).
For perspective, within the human brain, it takes about 5,000 microseconds for a neuron to fire (200 times per second). These numbers are not exact, but the scale is well within acceptable error. At the current extinction magnitude that we are facing, we have well exceeded previous mass extinctions in terms of how fast we are killing off wildlife. There is absolutely no doubt in my mind that, at our current heading, we are threatening to define one of the shortest periods or possibly even eras in geologic time (determined by mass die offs).
We are facing a whole new mode of driving a mass extinction event. Undoubtedly the situation that we are in is going to get worse before it gets better as mankind has never needed to make such a drastic course correction. But that is only if we can majorly change how we impact our environment. Like any other extinction event, it only can end once the cause has subsided.