Wednesday, 26 October 2011

Are we living in the Anthropocene?

Human influence on the environment is undeniable. Among other things, we introduce chemicals into, and change the pH of, the water; we fragment and reduce habitat; we persecute species to the point that they go extinct; and we introduce invasive species that reconfigure local ecosystems. As a result of all these things and more, many scientists have begun calling our current epoch the "Anthropocene," or the time of humans. The popularity of the term is such that geologists are not debating whether this is an accurate designation, but rather when, exactly, this era began.

However, not everyone is on board with this concept--in terms of both its accuracy and its usefulness. In an essay in the scientific journal Conservation Biology, collaborators from two departments at the University of California--Davis (the Department of Wildlife, Fish, and Conservation Biology, and the Department of Animal Science) argue that it is wrong to believe that there are no longer any places on earth that are "natural"--or, in other words, untouched and/or unaltered by humans. They acknowledge that humans are "undoubtedly" the dominant species on Earth, but stress that there are many specific regions/ecosystems that are still intact. These are areas in which the majority of native species are still present and active in the same functional role they performed prior to the appearance of humans, where nutrient flows have not been drastically altered by pollution, and where there are not many human residents. The authors classify these into 5 broad categories: places that are unexploited by humans, wilderness areas, ecoregions with little or no human presence, local sites little influenced by human activity, and biodiversity hotspots.

 (The Cameroon mountains, listed by the authors as a relatively untouched "site of extraordinary species richness.)

Using these areas as evidence, the scientists argue that, despite popular belief, humans have not changed everything. For instance, there are "gaps" in the human footprint (a blanket concept covering population density, land-cover and land-use changes, accessibility to humans, and the availability of electrical power) at equatorial, subtropical, temperate, and palearctic latitudes. In other words, the bulk of human disturbance is concentrated within particular geographic areas, leaving other regions intact--or, at least, under less pressure. Further, the authors state that, while climate change has led to overall increases in global temperature, locally, these have been recorded mostly in the northern and southern latitudes and at high elevations, leaving the lowland tropics--where most of the world's species occur--in a much more "natural" condition. Finally, the scientists point to the fact that there are many areas where humans do not live, or only live at low densities. In these places, there are many ecological elements--species diversity, the presence and activity of top predators, food webs, nutrient cycles, and overall ecosystem function--that have not been dramatically altered by the rise of humans.

(Greenland--one of the 4 ecoregions identified by the authors as having "virtually no human presence")

All of these points are not advanced purely as a rhetorical and philosophical exercise, however. The authors stress that the intact regions listed in their paper should immediately receive management support so that we can ensure their continued ecological health. Further, the scientists worry that acceptance of the Anthropocene concept will lead to the adoption of unhealthy and dangerous attitudes towards wildlife and conservation. For instance, people may be tempted to "open the floodgates to human manipulation of species assemblages," falsely believing that the only way to preserve wildlife is to engage in potentially damaging (and currently controversial) practices such as assisted migration and Pleistocene rewilding. In order to set more appropriate conservation goals, it is important to have intact areas that can be used as baselines and targets; if we fail to recognize the existence of such "natural" areas, it will be very difficult to understand how humans have impacted ecosystems, or to create logical and useful conservation goals. In fact, people may be less inclined to support conservation efforts at all--monetarily, emotionally, or with contributions of time and effort--if they feel that they are only fighting a losing battle. At that point, the authors argue, a defeatist attitude may lead people to feel that they might as well do even greater damage--such as building more dams, exploring for oil in new locations, razing forests for lumber--rather than continuing to seek sustainable methods of coexisting with wildlife.

(Gran Chaco, also known as the "last frontier in South America." It was identified by the authors as one of several intact "wilderness areas.")

Overall, the scientists state, we have a duty to future generations to consider these scientific, practical, public relations, and ethical reasons against the Anthropocene mindset. They feel that if we wish to preserve the environment for ourselves and our descendants--a decision that will enhance quality of life "by providing...the opportunity to observe the wonders of nature"--we should focus on developing appropriate conservation and restoration objectives. Rather than advocating the idea that "humans have altered everything," we should believe that humans can achieve anything--even those conservation goals that may, at first, seem unobtainable.

For supplementary images associated with this post, please visit the Anthrophysis pin board at Pinterest.

Caro, T., Darwin, J., Forrester, T., Ledoux-Bloom, C., Wells, C. 2011. Conservation in the Anthropocene. Conservation Biology, online advance publication.

Thanks to the following websites for providing the images used in this post:

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