Would Human Extinction Be a Tragedy? Todd May, NYT. Dec. 17, 2018.
Our species possesses inherent value, but we are devastating the earth and causing unimaginable animal suffering.
To make that case, let me start with a claim that I think will be at once depressing and, upon reflection, uncontroversial. Human beings are destroying large parts of the inhabitable earth and causing unimaginable suffering to many of the animals that inhabit it.
This is happening through at least three means. First, human contribution to climate change is devastating ecosystems, as the recent article on Yellowstone Park in The Times exemplifies. Second, increasing human population is encroaching on ecosystems that would otherwise be intact. Third, factory farming fosters the creation of millions upon millions of animals for whom it offers nothing but suffering and misery before slaughtering them in often barbaric ways. There is no reason to think that those practices are going to diminish any time soon. Quite the opposite.
Humanity, then, is the source of devastation of the lives of conscious animals on a scale that is difficult to comprehend.
Mammals cannot evolve fast enough to escape current extinction crisis. Science Daily. Oct. 15, 2018.
Summary:The sixth mass extinction is underway, this time caused by humans. A team of researchers have calculated that species are dying out so quickly that nature's built-in defense mechanism, evolution, cannot keep up. If current conservation efforts are not improved, so many mammal species will become extinct during the next five decades that nature will need 3-5 million years to recover to current biodiversity levels. And that's a best-case scenario.
Co-extinctions annihilate planetary life during extreme environmental change. Giovanni Strona & Corey J. A. Bradshaw, Nature. November 2018.
Abstract
Climate change and human activity are dooming species at an unprecedented rate via a plethora of direct and indirect, often synergic, mechanisms. Among these, primary extinctions driven by environmental change could be just the tip of an enormous extinction iceberg. As our understanding of the importance of ecological interactions in shaping ecosystem identity advances, it is becoming clearer how the disappearance of consumers following the depletion of their resources — a process known as ‘co-extinction’ — is more likely the major driver of biodiversity loss. Although the general relevance of co-extinctions is supported by a sound and robust theoretical background, the challenges in obtaining empirical information about ongoing (and past) co-extinction events complicate the assessment of their relative contributions to the rapid decline of species diversity even in well-known systems, let alone at the global scale. By subjecting a large set of virtual Earths to different trajectories of extreme environmental change (global heating and cooling), and by tracking species loss up to the complete annihilation of all life either accounting or not for co-extinction processes, we show how ecological dependencies amplify the direct effects of environmental change on the collapse of planetary diversity by up to ten times.
Introduction
Being in the midst of the sixth mass extinction1, it is fitting to quantify the relative contribution of different mechanisms driving catastrophic biodiversity loss. Drivers directly related to anthropogenic modifications of the biosphere are apparent and well-described: habitat destruction, over-exploitation, and biotic invasions2. Similarly, the effects of environmental change (e.g., temperature rise, increased droughts, ocean acidification, et cetera) can be easily interpreted — when the environmental conditions of a certain locality become incompatible with the tolerance limits of inhabiting species, in many cases these will go locally extinct, just like fish in an aquarium with a broken thermostat (even if there are counter examples of species that have been capable of rapid adaptation to novel environmental conditions3). Yet, there are other, more complicated mechanisms that can exacerbate species loss. In particular, it is becoming increasingly evident how biotic interactions, in addition to permitting the emergence and maintenance of diversity, also build up complex networks through which the loss of one species can make more species disappear (a process known as ‘co-extinction’), and possibly bring entire systems to an unexpected, sudden regime shift, or even total collapse4,5,6,7,8,9.
In a simplified view, the idea of co-extinction reduces to the obvious conclusion that a consumer cannot survive without its resources. Because resource and consumer interactions in natural systems (e.g., food webs) are organized in various hierarchical levels of complexity (e.g., trophic levels), it follows that the removal of resources could result in the cascading (bottom-up) extinction of several higher-level consumers8,10. Several studies based on either simulated or real-world data suggest that we should expect most events of species loss to cause co-extinctions5, as corroborated by the worrisome, unnatural rate at which populations and species are now disappearing11, and which goes far beyond what one expects as a simple consequence of human endeavour1. In fact, even the most resilient species will inevitably fall victim to the synergies among extinction drivers2 as extreme stresses drive biological communities to collapse. Furthermore, co-extinctions are often triggered well before the complete loss of an entire species12, so that even oscillations in the population size of a species could result in the local disappearance of other species depending on the first13.
This makes it difficult to be optimistic about the future of species diversity in the ongoing trajectory of global change, let alone in the case of additional external, planetary-scale catastrophes. A previous study14contended this idea by using the remarkable tolerance of tardigrades to extreme temperature, pressure, and radiation as a reference to calculate the likelihood of global sterilization on an Earth-like planet following different, dramatic astrophysical events. The stunning conclusion of that study is that life on our planet has the potential to survive asteroid impacts, supernovae, and gamma-ray bursts14. This ostensibly reassuring news highlights how some scientists still tend to disregard the role of co-extinctions within collapsing communities in driving global biodiversity loss, while focusing on individual species’ tolerance limits as the only criteria relevant to species survival in a changing world. Ecologists know the optimism is not supported quantitatively, but can we estimate the magnitude of the bias?
Here we attempt to do this by combining real-world ecological and environmental data to generate several virtual Earths populated by interconnected species-interaction networks where we allow species to move and adapt, that we then subjected to extreme, global environmental change. By comparing scenarios of extinctions based only on species’ environmental tolerances with others accounting also for co-extinctions, we show that neglecting to consider the cascading effect of biodiversity loss leads to a large overestimation of the robustness of planetary life to global change.
videos:
Human extinction in 10 years. Interview with Guy McPherson. Nov. 25, 2016. youtube. video (10 min)
Last Hours. RT. youtube.
The Sixth Extinction. it's okay to be smart. youtube.
6th mass extinction. Barry Sinvervo, TEDx, via youtube.
Peter Wadhams interview: Could modern civilization collapse? youtube. Dec. 16, 2015. video (18 min)
Racing to the precipice. Prof. Noam Chomsky. March 2017. via youtube. video (1hr 24min).
media articles:
Humanity is getting verrrry close to extinction. Nathan Curry, vice. Aug. 21, 2013.
Earth's worst-ever mass extinction of life holds 'apocalyptic' warning about climate change, say scientists. Ian Johnston, Independent. Mar. 24, 2017.
“Global warming triggered by the massive release of carbon dioxide may be catastrophic, but the release of methane from hydrate [its frozen state] may be apocalyptic."
Climate Change and the New Age of Extinction. Elizabeth Kolbert, New Yorker. May 13, 2019.
People easily forget “last of” stories about individual species, but the loss of nature also threatens our existence.
Life Itself Is Being Patented, Privatized and Re-engineered. By Mark Karlin, Truthout | Interview. Aug. 21, 2016.
