The Anthropocene: Humankind as a Turning Point for Earth
According to this theory, the present epoch -- still known as the Holocene, which started 11,000 years ago -- would have ended somewhere between the end of 18th century and the 1950s (when the Anthropocene began). The earlier time limit considers the increasing amount of carbon dioxide and other greenhouse gases in Earth’s atmosphere that is mostly due to the burning of fossil fuels for energy to power our growing industrial technology.
We may consider this process to have started in 1784, with the invention of the steam engine by James Watts. The present high levels of greenhouse gases in our atmosphere are probably causing the climate to change to a long warm period. The later time period takes into account the increasing background radiation from the nuclear tests by US and USSR military during the beginning of the Cold War.
This new frontier in the geological timeline is potentially more precisely defined than any was before, due to its recent occurrence. It is also supported by increasing evidence of human influence on natural global processes, such as the sediment transport being supplanted by our construction processes; land occupation and transformation; water course deviation and water reserve appropriation; massive extinction and introduction of species into new regions; development and widespread use of previously non-existent chemical substances (eg. plastics and persistent organic pollutants); and even the creation of new elements (the last 20 in the Periodic Table).
In this interview, Dr. David Grinspoon, Baruch S. Blumberg Chair of Astrobiology at the Library of Congress and Curator of Astrobiology at the Denver Museum of Nature & Science, talks about a book he is writing on the Anthropocene from an astrobiology point of view.
Q: What should be considered the geological marks of the Anthropocene?
DG: There are a number of reasonable suggestions for this, but my favorite is the signature of the first atomic bomb tests. This produces a signature, both isotopic and in terms of new geological structures, that cannot be interpreted in any other way. And the symbolism is so potent – the moment we grasped that terrible promethean fire that, uncontrolled, could consume the world. Now it’s true that humans were altering the Earth before this time, as several scientists have pointed out – for example land use, agriculture, urbanization and atmospheric carbon dioxide. But, you know, other species have come along and changed the world before and we don’t name a geological epoch after each of them. What is really different now is that we are aware of our world changing role. Or potentially aware – some of us are at least. So for me, regardless of how you define the Anthropocene, this is when it gets interesting – when the mass of humanity starts to wake up to our world changing role. And after the Bomb, certainly after Hiroshima, we could not see ourselves, with our world-changing technology, the same again.
DG: I have heard differing opinions on whether or not the sixth great extinction is assured at this point, but either way it is obvious we are having a significant impact on the evolution of life on this planet and many species have not, will not, survive our presence here. Our impact will be detectable for the rest of time on this planet. For example, it is clear that the existing coral reefs on the planet will not survive our impact. We are going to lose them. This is inevitable now because of ocean acidification even in the best case scenario. It is slightly comforting that the reefs have disappeared before, due to past episodes of acidification, and they have returned. So they may be back in the future but there will be a time of no coral reefs in Earth history that will forever be traceable to the actions we are taking now.
Q: Do you believe Anthropocene should be classified as a new geological epoch within the Quaternary period, or does it stand for a larger time-scale? Might the establishment of the Anthropocene geological time period include the present-known Holocene epoch?
DG: One interesting question about the Anthropocene is how long it might last. Geologically, will it be an event like the K/T boundary, an epoch like the Paleocene, or a transition like the origin of life? I think it will either be a brief event recording the failed experiment of our so-called civilization, or it will be a transition to an entirely new planet in which intelligent life has a permanent role in managing the planet. But if we call it an epoch it represents an ambition for our species that is somewhere between these two extremes, and maybe that is OK for now.
DG: I don’t know. To be honest I haven’t been following this too closely. It’s really not that interesting to me whether or not it becomes formally adapted as part of the geological time scale. What I’m interested in is the conversations going on about the Anthropocene and what it means to view ourselves as a part of Earth’s geological history. These conversations will continue regardless of what this Commission decides.
Q: We can now observe the role of exotic species in many habitats around the world, usually disrupting the local ecology of where they were introduced by man. Do you see the growth of development and usage of transgenic organisms, nano-robots and even artificial (synthetic) life as possible key factors to influence the near-future of Earth’s biota?
DG: Yes, certainly. As you’ve pointed out we have already become an unprecedented kind of disruptive force in biological evolution, through our purposeful and inadvertent transport of species around the planet. With these new technologies we will have the capacity to much more dramatically affect the mechanics of evolution.
Q: If humanity was extinct (or reduced to nearly that point) today, what could be the large scale effects to Earth in a future of no more maintenance on all of our nuclear facilities, biological warfare and disease-control laboratories?
DG: The breakdown of the nuclear facilities would lead to some local disturbances for a long time but I don’t believe there would be any large global effects from this. I think the biggest signature would be the perturbation to the carbon cycle which will take tens of thousands of years to repair itself. The ocean will be acidified for a similar timescale with massive effects on reefs and other biomes. The hydrological cycle will gradually return to normal as dams break down.
Q: How do you see the possibility of the Anthropocene marking a period when humankind not only became a geological force in Earth, but also began to reach the other bodies in the Solar System as a first step to largely expand its zone of influence?
This article has been translated into Portuguese.