Archive for the ‘global warming’ Category

One of the few spits of pavement stretched out before my wife and I as we made our way through the swamp. Ever aware of the ground nearby, our footfalls allowed us slow, deliberate progress. Speed is not the name of the game when looking for snakes. The sun was beginning its descent into the early autumn sky and as the temperature dropped, snakes of all species can be found on the warm pavement—the asphalt retains its heat from the day’s sun far longer than the surrounding earth, providing a perfect place for ectothermic creatures like snakes to rest and finish digesting a recent meal or gather the energy required to begin hunting for the night.

It was in this waning daylight that a small, awkward movement caught my eye. About fifty meters ahead, where the grass met the pavement, a small black snake looked to be trying to make its way to the warmth of the asphalt. Thinking it to be a racer or a dark variant of the gray rat snakes commonly seen at this swamp, I broke into a run in hopes of catching the creature before it could get away. As I approached, I realized my sprint was hardly necessary. The snake was moving a lot but making no progress. In fact, it seemed to be writhing in place. I also realized that it was not any species I had seen before at this swamp—it was the common, but almost never seen mud snake.

Mud snakes are gorgeous snakes—they are a glossy black with small red triangles that creep up their sides—and grow to be larger than nearly all other North American snakes. They peruse the mud of swamps across the eastern United States, fattening up on salamanders, frogs, and fish. They very rarely come onto land, preferring to remain in the water and mud all day. At night, mud snakes can very occasionally be found resting on warmer areas of pavement. As soon as I realized that I had found a mud snake, I was elated and immediately bent down to pick it up.

Before I did, however, I noticed its movements were irregular. It was erratically rubbing its head on the ground, the way a snake does before it is about to shed. I carefully picked it up. At once, I knew what was causing this snake to behave this way. Every twentieth scale (or thereabouts) was swollen with puss that was causing the afflicted scales to protrude out in an awkward way. Every few inches of the two-foot snake had dry, brown patches that almost looked like caked mud. After looking closely, it became apparent that the patches were in fact drying, dead skin and scales. Most disturbingly, though, was the snake’s head. Nearly half of the snake’s head, including the upper jaw and an eye, was eaten away by the brown crust. Its mouth was forced agape, unable to close. Its tongue, probably a snake’s most important sensory organ, was unable to retract and just lay limp, hanging out of the mud snake’s mouth. The remaining eye seemed to be leaking the same puss that some of the infected body scales leaked.

What was the cphoto(3)ulprit, the creator of all of this destruction? The aptly, if not creatively named Snake Fungal Disease. The fungus, Ophidiomyces ophiodiicola ,has been found to be the perpetrator of a shockingly increasing number of snake deaths across the eastern United States, from as far north as New Hampshire, where it has decreased local populations of timber rattlesnakes by as much as fifty percent, and down into Florida. It seems to primarily affect the faces and heads of a number of snake species and causing the death by eventual starvation or dehydration as it renders the snakes unable to drink or hunt. This fungus appears to be an invasive species, not dissimilar to the fungus behind the white-nose syndrome that is wiping out bats all across the Americas, the nosema fungus that is likely behind bee colony collapses globally, or the fungus that is perpetuating the near-extinction of the Panamanian golden frog.

The story of the Panamanian golden frog is where Elizabeth Kolbert begins her deep analysis of the staggeringly deadly effects of human expansion and industrialization on the rest of the natural world. The book, rightly titled The Sixth Extinction, is a harrowing and often depressing look at the various ways humanity is carrying out a new wave of extinctions, the likes of which have only been seen five other times in the tumultuous history of life on our planet. The most recent extinction event, the Cretacious-Tertiary asteroid impact that eliminated most of the dinosaurs and killed nearly half of all marine animals, occurred 65 million years ago. The causes of the four extinction events before it range from global warming due to volcanic activity and glaciation due to times of intense global cooling. None of the extinction events have been caused by a single species—until now.

Humanity, as Kolbert says in the book, is the most successful invasive species of all. Agriculture, language, and social structure has allowed humanity to “escape evolution,” as Kolbert quotes British paleontologist Michael Benton. The three main reasons seem to be directly intertwined: pollution and emissions, globalization, and habitat destruction. (Kolbert also covers intentional hunting of animals until the species is lost forever, like in the case of the great auk. This seems obvious that this would lead to extinction, so I will not spend any more time analyzing it.)  Each one of these, in its own way, would potentially be enough to bring about a devastating amount of extinction on its own. However, as Kolbert eloquently illustrates, these things all seem to work in conjunction with each other to disrupt virtually every ecosystem on the planet with devastating results.

Emissions, specifically of CO2, seem to be the major culprit behind the undeniable change in climate that is happening globally. Global warming is happening at a rate that species cannot out-adapt. One of the scientists that Kolbert discusses in the book created a computer model showing that individual animals would need to move poleward—that is, continuously north or south—at a rate of thirty feet per day in order to outrun the current increase in global temperature. CO2 emissions are currently also being absorbed by our oceans, resulting in a rapidly acidifying marine environment. Most marine species are not adapted for the level of acidity that scientists project our oceans will reach within a century. The devastation will be quick and widespread. Most projections, according to Kolbert, show that Australia’s Great Barrier Reef will be entirely bleached—dying—by 2050. We have already witnessed, in our lifetimes, about ten percent of the reef turn white as a result of the lack of the symbiotic algae that the corals rely upon for nutrients. These bleached reefs are veritable ghost towns already, with many parts of the ocean soon to follow. The photosynthesizing algae that provide nutrients to the coral also provide earth’s atmosphere with oxygen—if these algae die off, what will come of the oxygen-breathing land animals, humans included?

Globalization and habitat destruction go hand-in-hand. As humanity grows—quadrupling its population in the last century on its way to seven billion—it spreads. This population boom (though to call it a “boom” is a vast understatement) is due more to the efficiency of agriculture than better medicine, according to environmental journalist Alan Weisman. According to Weisman, forty percent of the land on earth is now devoted to feeding one species—humans. The destruction of habitats and ecosystems is devastating.  Not only does it wipe out entire species, like in the rainforests of South America where highly unique species may exist in a very localized area, it also has the more indirect effect of creating genetic bottlenecks.

In the United States, we have many protected areas of land that cannot be hunted, fished, farmed, or otherwise bothered. Sadly, this only seems to delay the inevitable for certain species—when certain small populations of organisms are protected while the rest are destroyed due to development and farming, it creates a situation where a species has a small amount of surviving members that are not as genetically diverse as the species was before. Thus, when a plague or infection spreads among the few populations left of an animal or plant, the chances of surviving members greatly diminishes. This effect has been blamed for the rash of white-nose syndrome in bats and nosema in global bee colony collapses—lack of genetic diversity among many species led to populations that could not adapt to the spreading fungal infection.

Kolbert’s book begins with the tale of a similar fungal infection in Panamanian golden frogs. The fungus prevented the frogs, who maintain hydration through their skin, to absorb water and killed them off in quick and ferocious fashion due to dehydration. The modus operandi of the fungus was twofold—humans introduced the fungus, unintentionally, as an invasive species. The local deforestation whittled the frogs’ numbers and created a situation wherein the amphibians were less resistant to the fungus.

As I read Kolbert’s account of the Panamanian golden frog, I thought of the mud snake. Humans introduced, unintentionally, a fungus that was particularly adept at harvesting on living snakes into the ecosystem of the southeastern United States. Human-induced climate change allowed this warm-weather fungus to thrive beyond its normal limitations, according to certain theories put forth by some herpetologists. Various local species of snakes, which have been winnowed down to only a few populations in many areas, may not have enough genetic diversity to withstand the spread of the fungus. 

The equation, of course, is this: when even one action would likely be enough to bring about the end of a species, many separate but interrelated actions actually work in conjunction to bring about an even more rapid demise of thousands of species the world over. Humanity, sadly, is an unknowing but efficient killer.

In the case of the mud snake, I set it back down after snapping some quick photos. It was too late to save it—sadly, the snake would likely die within a few days due to dehydration or starvation. About two months after I found that animal, the first reported case of Snake Fungal Disease in the state of South Carolina was announced—a copperhead. Had I reported the mud snake, it would have been the first. Sadly, for many vital parts of our local ecosystems—bats, bees, frogs—it may be too late as well. Humanity may have begun an extinction event that it cannot undo.

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