15 Jan 2018 - A study published in Science last week reveals that severe bleaching of coral reefs is occurring twice as frequently compared to what it was in 1980. To put it another way, the average period between bleaching events has been cut in half. Since reefs slowly recover over time after a bleaching event, the lost recovery time increases the likelihood that reefs will be killed off entirely by too many bleaching events in too short a span.
Coral bleaching is related to climate change effects on the ocean. Not only increased temperature but the increased concentration of CO2 in ocean water has wide-ranging effects, since CO2 dissolves in water to produce carbonic acid, throwing off the ocean’s natural pH balance.
When it comes to climate change, the idea of tipping points frequently refers to irreversible geophysical processes or milestone events, like the increased warming leading to increased evaporation, where evaporated water is itself a greenhouse gas, or the melting of permafrost releasing long-sealed methane, again leading to a runaway greenhouse effect that cannot be reversed past that point.
But there are limits to ecological resilience as well, with major marine ecosystem collapse in the vein of destroyed reef ecologies being just one example of an ecological tipping point that could radically and irreversibly change the ocean biologically, physically, and chemically.
Though I don’t assume this is the first time it has been done, this study does mark the first time I’ve personally seen the term Anthropocene used in the title of a scientific paper. The Anthropocene, following geological time divsion naming conventions, can be interpreted to mean “the age of humanity”. Geological divisions of time, from eras to periods to epochs, usually cover periods of at least millions of years, and the designation of one layer of rocks and fossils in the strata as being separate from another is typically marked by some significant and visible change in the climate.
It implies that tens or hundreds of millions of years in the future, intelligent life arising on or visiting our planet will be able to mark when human industry reached a point that it fundamentally altered the world. Previously, new epochs began when entirely new categories of life arose, like the first photosynthesizing organisms which filled the atmosphere with oxygen, or massive world-shaking events altered the chemistry and physics of the world, as with the asteroid that hit the Earth 65 million years ago and wiped out most of the dinosaurs and other major reptile groups.
What will happen when future intelligence discovers the anthropocene layer? Presumably the most significant geological force would be human-caused climate change, pollution, deforestation, and mass extinction, with the attendant affects on the atmosphere, climate, and land. We may also leave behind a lot of plastic and other inorganic garbage, depending on just how far in the future we are talking about.
This is our legacy if we don’t shift out of Anthropocene mode quickly and start living with the world instead of bending it to the breaking point. The coral reefs are not a bad place to start.