Big Changes and the Anthropocene

The pace of environmental change has picked up speed over the past 50 years and there are few reasons to think that it will slow anytime soon.  We are living through an unprecedented time of “Big Changes” in the world, whether we like it or not.  In fact, some scientists think that recent “Big Changes” are so huge that we have entered a new geologic epoch called the Anthropocene.

Describing an “Age of Humans” isn’t completely new, of course.  Proposals to elevate the most recent period of time — where humans have been incredibly influential — to a special status have been made before.  George Perkins Marsh (1874) describes how Stoppani, an influential Italian geologist in the late 1800s, thought that a new geologic age should be defined because “the creation of man was the introduction of a new element into nature, of a force wholly unknown to earlier periods.”

Establishing a new geologic age called the Anthropocene would recognize that human impacts on the Earth are on a magnitude similar to geologic processes.  It also would recognize that the record of this impact – the residue left to be found by future geologists – would be documented in the geologic record, just as a layer of ash provides a date for the eruption of a volcano in the past.

Is there evidence that human activities rival geological processes?  Here are a few of the reasons to think that they do, not listed in any particular order:

  1. Current estimates of the rate of species extinction today are as high or higher than the five major extinction events that are recognized in the geologic record.
  2. Human are now converting (“fixing”) atmospheric nitrogen gas and adding it to ecosystems at a magnitude that is greater than the amount converted naturally by all the world’s plants (both land and ocean combined).
  3. We are acidifying the world’s oceans (by adding carbon dioxide), which is altering the rates of chemical reactions and influencing how hard-shelled organisms and corals reefs form.
  4. Climate is changing at a rate that is similar to or faster than Pleistocene glacial cycles and will lead to substantial changes in species ranges and ecosystem characteristics.
  5. Sedimentation rates have increased rapidly as a result of both urbanization and intensive agriculture.  (Also note that three billion people now live in urban environments, which have transformed the natural landscape into metal, glass, and concrete.)

Of course, some of these will leave more lasting indicators in the geologic record than others, but it’s a hefty list (and more can be added).

So, a working group has been formed within the International Commission on Stratigraphy to discuss whether the Anthropocene should be given official “epoch” status, similar to the Holocene or the Pleistocene.  They expect to bring it to a vote in 2016.  In the meantime, there are a few issues to work out.  The first is to evaluate whether recent human activities are large enough to be recorded in the geologic record.

A second issue is to agree on a beginning date.  Many people think that the year 1800 is the best selection because it represents the start of the industrial revolution and our shift toward fossil fuel use.  Others argue for the middle of the 1900s when the most rapid period of change started and the presence of radioactivity worldwide would provide a clear marker everywhere.  Still others suggest that the epoch begin with the start of agriculture around 8000 years ago (essentially eliminating the Holocene).

To me, the scientific debate about whether we should carve out the most recent period of life and call it the Anthropocene simply represents another step in recognizing what’s happening around us.   We have reached the point of comparing the massive changes resulting from humans to the massive changes resulting from geologic forces.  Whether or not a new epoch is defined, we are left with the fact that “Big Changes” are happening and they will likely continue, especially as our global population will see several billion more people over the coming decades.

There is a strong argument to be made that if we want to address these large, global environmental changes then we must act more like global citizens.  At the very least, international groups must be able to collaborate more effectively than they do now.  This is where the science of documenting human impacts on the planet meets the arena of political and social issues … which makes things very messy.  And it’s clear from the politics surrounding global climate change that we are far from a resolution.

Online resources to investigate this topic in more depth …

Steffen et al. 2011 The Anthropocene: conceptual and historical perspectives Phil. Trans. R. Soc. 369: 842-867  Good article covering the main arguments in favor of establishing the Anthropocene.

Elizabeth Kolbert’s article in National Geographic summarizes the scientific discussion of the Anthropocene and is a revision of her previous article at Yale 360.

The Working Group on the Anthropocene may bring this whole issue up for a vote in 2016.  Check out the long list of articles and news stories at the bottom.

Welcome to the Anthropocene is an informational, persuasive-style website with some amazing images of human impacts from around the world.

Generation Anthropocene is an interesting student-led podcasting project at Stanford using interviews of faculty working on projects related to global change.  I’d love to start something like this in the future on other topics.

A NYTimes article by Marris and others (2011) takes the view that “The Anthropocene means that humans are having a large impact, but that doesn’t mean that we live in ‘an ecological hell.’”  I plan to follow up with this thread in the future.

(Photo credit: NASA, public domain)