160
damming rivers, and excavated, mined, drilled, and pumped minerals, oil, gas, and
groundwater from vast tracts of land. We have changed the composition of the
atmosphere, and altered the water chemistry in streams, lakes, underground aquifers, and even in the oceans. All of this is stressing the biosphere, changing ecosystems, and killing off plants and animals, including entire species.
An event commonly used to establish boundaries between geological periods is
a mass extinction, defined as the loss of 75% or more of existing species (Webb
2013). There have been five great mass extinctions recorded in the fossil record of
the Earth: (1) the Ordovician-Silurian, (2) the Devonian-Mississippian, (3) the
Permian-Triassic, (4) the Triassic-Jurassic, and (5) the Cretaceous-Paleogene (also
known as the Cretaceous-Tertiary or K-T in older texts; this one took out the dinosaurs). The current rate of species loss is so great that many biologists have declared
that we have entered the sixth great extinction in Earth history (Kolbert 2014).
Previous extinctions were caused by external events such as supervolcano eruptions
or asteroid impacts. The extinction that is now underway is the only one in the history of the Earth where the actions of a single species (Homo sapiens) are wiping
out other species.
Human activities so far have led to the extinction or endangerment of about half
of the existing species on Earth. Many historical creatures like the aurochs, moa,
passenger pigeon, and dodo are long gone. The future survival of other, notable
threatened species such as the black rhino, blue whales, timber wolves, Bengal
tigers, and polar bears may also be in doubt. Thousands of other less charismatic
species like insects, plants, birds, shelled sea creatures, fish, and coral are also
endangered, and many have quietly gone extinct with little fanfare. Despite the fantasy of technological resurrection of extinct species in movies like Jurassic Park
(which bemuses most geologists because it was filled with Cretaceous dinosaurs)
extinction is pretty much forever.
The presence of humans on Earth will be preserved in sediments of the
Anthropocene Epoch by artifacts ranging from cuneiform tablets to nuclear submarine reactors. Millions of years from now, evidence of human civilization on Earth
will be available for future intelligent beings to study and ponder in the rock layers.
As promised by many an elementary school teacher, the bad behavior of humanity
will be recorded on our “permanent record” in Planet Earth’s geology until the end
of time. The upper boundary of the Anthropocene Epoch will be marked by the end
of the sixth mass extinction, which may very well include us. Some pundits have
proposed that the next post-human geological period following the Anthropocene
should be called “Weleftthescene” or “Weshouldhaveseen.”
It is very likely that some forms of life will survive an Anthropocene mass
extinction, and new species will evolve in the future. The Earth has been through
extinctions as bad, or even worse than anything humans are capable of causing. Past
extinctions were followed by new creatures evolving to gradually fill the ecological
niches left vacant by those that came before. There is no reason to believe that a
human-induced extinction, whether by way of resource depletion, climate change,
air and water contamination, release of a virulent disease, or that old standby, all-out
nuclear war, would be any different. Life always seems to make a comeback.
9 Fossil Fuels and Climate Change
damming rivers, and excavated, mined, drilled, and pumped minerals, oil, gas, and
groundwater from vast tracts of land. We have changed the composition of the
atmosphere, and altered the water chemistry in streams, lakes, underground aquifers, and even in the oceans. All of this is stressing the biosphere, changing ecosystems, and killing off plants and animals, including entire species.
An event commonly used to establish boundaries between geological periods is
a mass extinction, defined as the loss of 75% or more of existing species (Webb
2013). There have been five great mass extinctions recorded in the fossil record of
the Earth: (1) the Ordovician-Silurian, (2) the Devonian-Mississippian, (3) the
Permian-Triassic, (4) the Triassic-Jurassic, and (5) the Cretaceous-Paleogene (also
known as the Cretaceous-Tertiary or K-T in older texts; this one took out the dinosaurs). The current rate of species loss is so great that many biologists have declared
that we have entered the sixth great extinction in Earth history (Kolbert 2014).
Previous extinctions were caused by external events such as supervolcano eruptions
or asteroid impacts. The extinction that is now underway is the only one in the history of the Earth where the actions of a single species (Homo sapiens) are wiping
out other species.
Human activities so far have led to the extinction or endangerment of about half
of the existing species on Earth. Many historical creatures like the aurochs, moa,
passenger pigeon, and dodo are long gone. The future survival of other, notable
threatened species such as the black rhino, blue whales, timber wolves, Bengal
tigers, and polar bears may also be in doubt. Thousands of other less charismatic
species like insects, plants, birds, shelled sea creatures, fish, and coral are also
endangered, and many have quietly gone extinct with little fanfare. Despite the fantasy of technological resurrection of extinct species in movies like Jurassic Park
(which bemuses most geologists because it was filled with Cretaceous dinosaurs)
extinction is pretty much forever.
The presence of humans on Earth will be preserved in sediments of the
Anthropocene Epoch by artifacts ranging from cuneiform tablets to nuclear submarine reactors. Millions of years from now, evidence of human civilization on Earth
will be available for future intelligent beings to study and ponder in the rock layers.
As promised by many an elementary school teacher, the bad behavior of humanity
will be recorded on our “permanent record” in Planet Earth’s geology until the end
of time. The upper boundary of the Anthropocene Epoch will be marked by the end
of the sixth mass extinction, which may very well include us. Some pundits have
proposed that the next post-human geological period following the Anthropocene
should be called “Weleftthescene” or “Weshouldhaveseen.”
It is very likely that some forms of life will survive an Anthropocene mass
extinction, and new species will evolve in the future. The Earth has been through
extinctions as bad, or even worse than anything humans are capable of causing. Past
extinctions were followed by new creatures evolving to gradually fill the ecological
niches left vacant by those that came before. There is no reason to believe that a
human-induced extinction, whether by way of resource depletion, climate change,
air and water contamination, release of a virulent disease, or that old standby, all-out
nuclear war, would be any different. Life always seems to make a comeback.
9 Fossil Fuels and Climate Change