The State of Our Co-Evolutionary Kin: The 6th Mass Extinction?
Did you know that, according to Cousteau, half of the marine life he filmed in 1956 had disappeared by 1963 (and what is left today)?” (Gorz, 1987, pg. 64)
The answer to Gorz’s poignant query, ‘what is left today?’ is a truly terrifying one. Recent years have seen a proliferation of headlines from numerous environmental organizations, think tanks, and news sources, such as: ‘The Extinction Crisis’, ‘Earth on the Brink of a 6th Mass Extinction, Scientists Say, and Its Humans’ Fault’, and ‘6th Mass Extinction? Humans Kill Species Faster Than They’re Created’. In their analysis of current rates of species loss in comparison to those seen during previous extinction events on earth, Ceballos et al (2015) found that, even when background rates of extinction are considered to be twice as high as previous estimates, present extinction rates still vastly exceed historical rates of loss. Ceballos et al (2015) solemnly note that, “although biologists cannot say precisely how many species there are, or exactly how many have gone extinct in any time interval, we can confidently conclude that modern extinction rates are exceptionally high, that they are increasing, and that they suggest a mass extinction under way—the sixth of its kind in Earth’s 4.5 billion years of history” (pg. 3). WWF’s Living Planet Report 2016 has cited the findings from such indices as the Living Planet Index (LPI), which measures the global state of biodiversity and ecological health via an extensive compilation of over 3,000 data sources monitoring 14,152 populations of 3, 706 vertebrate species (mammals, birds, fishes, amphibians, reptiles) across the globe (WWF, 2016), and concludes that:
“From 1970 to 2012 the LPI shows a 58 per cent overall decline in vertebrate population abundance. Population sizes of vertebrate species have, on average, dropped by more than half in little more than 40 years. The data shows an average annual decline of 2 per cent and there is no sign yet that this rate will decrease. The Living Planet Report 2014 reported a 52 per cent decline from 1970 to 2010; although the marine and terrestrial datasets have been augmented with new data, it is the stronger decline in freshwater species that has had more influence on the global decline in this report” (2016, pg. 18).
The most common threats to vertebrate (and non-vertebrate) species are the same that threaten the integrity of global ecosystems, mainly the loss and degradation of habitat (IUCN, 2015), pollution, climate change, species overexploitation, and disease, threats which often interact in a number of complex ways, thus further exacerbating the impacts on species and natural systems. If current trends and levels of loss continue, by 2020, the cutoff point for UN biodiversity targets, measured vertebrate populations (to say nothing of those that we don’t have consistent or accurate data on) will have declined by a staggering 67% since 1970 (WWF, 2016). Amphibians (frogs, salamanders, and caecillians) are among the most threatened species globally due to their restricted distribution in tropical regions which makes them particularly susceptible to habitat loss via deforestation, and climate-change-related diseases such as chytriomycosis; Over one-third of species are threatened with extinction (Wake & Vredenburg, 2008).
The Local Biodiversity Intactness Index (LBII), which measures predicted changes in species richness of local ecological systems (number of species per given site) relative to the continued impacts of land-use change, pollution, climate change, and related threats portends a reduction of up to 30% of species richness in a regions most affected by climate change and agricultural expansion by 2095 (Newbold et al, 2015; WWF, 2016). In their analysis of the status of the world’s land and marine mammals, Schipper et al (2008) found that 25% of all mammals for which adequate data is available are threatened with extinction. They also found a positive association between body size and level of threat (Cardillo, 2005), wherein the world’s most threatened terrestrial species include primates and ungulates, though smaller mammals are still suffering similar levels of extinction (Schipper et al, 2008). Land mammals concentrated in the more precarious regions of South and Southeast Asia are among the most vulnerable, particularly primates, a shocking 79% of which face extinction. Perhaps nowhere is the tragic state of our coevolutionary kin more starkly illustrated than by the plight of orangutans who, due largely to mass deforestation in the subtropical forests of Sumatra and Borneo for the expansion of palm oil plantations and similar land-use changes, have been reduced to mere fragments of their former abundance (Nantha et al, 2009). On too numerous occasions I’ve come across heart-breaking images and stories featuring these poor creatures burned, scalded, and very near death after being chased out of their forested homes by fires, blades, and guns. Is this the shameful legacy that we will leave for posterity? Have we not a modicum of empathy left?
The state of our seas paints a similarly gloomy picture. Around 1 in 4 species of sharks and rays are now threatened with extinction due primarily to overfishing (WWF, 2015; Dulvy et al, 2014). Largely sought after for their fins, a highly prized ingredient in soup for many Asian cultures (Dell’ Apa et al, 2014), sharks are being slaughtered at estimated rates of a near incomprehensible 100 million per year (Worm et al, 2012). Such wildly unsustainable rates of slaughter, in addition to being morally repugnant, are also profoundly irresponsible in terms of the long-term viability of entire marine food webs, as sharks are apex predators and thus play vital roles in regulating lower trophic populations. Due to the slow maturation and gestation rates of sharks, the colossal rates of slaughter are all the more worrying. The world’s fisheries are in a dire predicament as well. While capture fishery production has relatively stabilized since the late 1980s due to the increasing role played by aquaculture in meeting global demands for fish consumption, growing populations and consequent demand have led to a decrease of the “share of fish stocks within biologically sustainable levels from 90 percent in 1974 to 68.6 percent in 2013” (FAO, 2016, pg. 5). In other words, “31.4 percent of fish stocks were estimated as fished at a biologically unsustainable level and therefore overfished. With regards to marine mammal populations, the two dominant threats facing them are accidental mortality (fisheries bycatch, for instance) and pollution (Schipper et al, 2008), and that while less adequate data is available for marine mammals, Davidson et al (2011) predict that at least 37% of all marine mammals are at risk of extinction, particularly those inhabiting coastal areas and productive areas in the high seas (Davidson et al, 2011). Deep sea trawling swallows up untold scores of marine creatures, many of them endangered and undiscovered, as well as ancient coral reefs, while long lines bearing baited hooks result in the deaths of millions more fish, turtles, birds, and marine mammals (Alaimo, 2012).
The substantially increased levels of anthropogenic greenhouse gases being released into the atmosphere are altering the very biogeochemical composition of the world’s oceans, leading to pelagic (upper ocean) warming, altered rainfall patterns, melting sea ice, and increased oceanic acidity due to the increased uptake of CO2 (Doney, 2010). The increased acidity in the oceans in turn leads to lower saturation states for calcium carbonate (CaCO3), the element used in the formation of the shells and bones of sea life (Doney, 2010), posing further threats to the wellbeing and continued resilience of our marine kin. Industrial pollution in its myriad manifestations- oil spills, plastics, microplastics, industrial discharges, heavy metals such as mercury, toxic chemicals, pesticide runoff- have permeated the bodies of virtually all marine life (Alaimo, 2012; Kaiser, 2010) and are now “distributed globally, found in even the most remote marine locations, transported through the atmosphere in the vapor phase, aerosols, and soot particles (i.e., black carbon); by ocean currents; and in some cases by migrating animals” (Doney, 2010, pg. 1515). Earle (2009) made the horrifying observation that,“[Since the] middle of the 20th century, hundreds of millions of tons of ocean wildlife have been removed from the sea, while hundreds of millions of tons of waste have been poured into it” (pg. 12).The enormous amounts of plastics, synthetic debris, and other forms of human pollution in the oceans have reached a crisis point. This horror of injurious human impacts is perhaps most starkly exhibited by the ‘Great Pacific Garbage Patch’ first discovered by oceanographer Charles Moore, a colossal swath of floating plastic garbage trapped in a whirlpool known as the Pacific Gyre that is twice the size of Texas (TED, 2009; Alaimo, 2012)
Every day new articles appear online highlighting the latest figures and animals under threat. More recently, giraffes and cheetahs have made the list of highly threatened species. In Zimbabwe, for instance, cheetah populations have plummeted by 85% over the past 16 years, trends that are occurring on other parts of the continent, prompting scientists to call for moving the cheetah from ‘threatened’ to ‘endangered’ on the IUCN Red List of Threatened Species. The curious pangolin, the world’s most trafficked mammal, is among the planet’s ‘critically endangered’ species, along with mountain, western, and eastern lowland gorillas, the black and Javan rhino, the vaquita, Hawksbill and leatherback sea turtles. Just yesterday, on March 7th, 2017, in a grizzly and unprecedentedly brazen attack, poachers broke into a French zoo and killed beloved white rhino Vince before sawing off his horn; he was only four years old. Satao II, a breath-taking ‘big tusker’ elephant, iconic giants revered for their unusually long tusks that nearly brush the ground as they walk, was found dead early this month in Tsavo National Park, Kenya. He was 50 years old, a mild-natured park veteran who was beloved by visitors and rangers alike. There are an estimated 25 of these evolutionary marvels left alive, all prized solely for a material arbitrarily deemed more valuable than their lives.
These incredible beings that have so captivated our imaginations and been the subjects of innumerable lores and folktales, may actually disappear within only a few years, and future generations will be forever deprived of their wonders. I must reiterate that the issue at hand is not loss per se, for our evolutionary trajectories have been forged by the ascendency and passing of countless species since the earth first harbored life. Indeed, change, birth, death, and transformation are essential components of life. What is profoundly unacceptable and unconscionable are the current rates of loss which are many times the normal background rates, and that this mass slaughter is being largely effected by the insatiable and wildly destructive activities of modern industrial man. 67%, a figure so staggering and shameful as to utterly defy comprehension…that is what we stand to lose of our beautiful, wonderful, priceless animal counterparts. This is the ultimate nightmare come to fruition, and yet, the crisis is far from receiving the frantic, concerted attention and action that it so desperately warrants. 67% of our planet’s life forms are set to disappear into the eternal abyss of extinction, a sentence from which there is no redemption. Let us act before we awaken to the hellish monotony of an exclusively human world.