Drivers toward a potential planetary-scale, complete biosphere failure: The Tipping Point. Includes Video, highlights, and full text link.
In 2012, Anthony Barnosky at Berkeley, along with 21 other scientists and researchers dove into the question of whether or not we had or are nearing an environmental tipping point – a theoretical point at which one ecosystem after another, and many in parallel fail, like dominos, and become unable to sustain life as a result of human induced factors. Their study clearly identifies numerous drivers, yet it is almost impossible to put a precise point on any timeline or pollutant level that might cause such a planetary-wide failure.
Regardless of any such dot on the prediction scale, the alarming, primary drivers of such an event have been documented and as you’ll find elsewhere on this site, we encourage you and those you talk to and influence, to take serious the threat to our only current home: spaceship earth. Caution is the better part of valor when it comes to the thinly veiled rocky surface and finite, closed system ocean that we need to survive.
Here is a brief video introduction, then the remainder of the article refers to the image immediately following. It illustrates the sometimes subtle interactions of numerous, human-controlled drivers pushing us ever closer to the tipping point.
a – Humans locally transform and fragment landscapes. This includes deforestation, over-farming, poor land management practices that allow rich soil to erode into the ocean.
b – Adjacent areas still harboring natural landscapes undergo indirect changes as food sources disappear and the delicate balance of plant and animal species and populations built over eons is destroyed.
c – Anthropogeniclocal (human-induced) state shifts accumulate to transform a high percentage of Earth’s surface drastically; brown coloring depicts the approximately 40% of terrestrial ecosystems that have now been transformed to agricultural landscapes.
d – Global-scale forcings emerge from accumulated local human impacts, for example dead zones in the oceans from run-off of agricultural pollutants.
e – Changes in atmospheric and ocean chemistry from the release of greenhouse gases as fossil fuels are burned.
f – Beetle-killed conifer forests (browntrees) triggered by seasonal changes in temperature observed over the past five decades.
f thru h – Global-scale forcings emerge to cause ecological changes even in areas that are far from human population concentrations.
g – Reservoirs of biodiversity, such as tropical rainforests, are projected to lose many species as global climate change causes local changes in temperature and precipitation, exacerbating other threats already causing abnormally high extinction rates. In the case of amphibians, this threat is the human-facilitated spread of chytrid fungus.
h – Glaciers on Mount Kilimanjaro, which remained large throughout the past 11,000yr, are now melting quickly, a global trend that in many parts of the world threatens the water supplies of major population centers. As increasing human populations directly transform more and more of Earth’s surface, such changes driven by emergent global-scale forcings increase drastically, in turn causing state shifts in ecosystems that are not directly used by people.
The above image and overviews are but a tip of the iceberg. The full article describes in more detail the interacting complexities of what has been treated historically as separate ecosystems. We’re beginning to see that local pollutants have global effect. Perhaps exponentially. Straight extrapolation of pollutant volumes and surface temperatures no longer suffice to capture the real risk that a Global Ecological Tipping Point may soon be approaching.
Barnosky, Anthony D. et al; NATURE Magazine, VOL486, 7-JUNE-2012, Pg. 52-58