Adventures in the Anthropocene

Adventures in the AnthropoceneAdventures in the Anthropocene:  A Journey to the Heart of the Planet We Made is, indeed, a journey. (1) Its author, Gaia Vince, traveled the globe for two years to witness first-hand the impact of human civilization on the planet.  It is an even-handed account, in which grim realities are described but are balanced with optimistic predictions of the innovations that will ultimately enable us to cope with them.

Ms. Vincent takes us to remote corners of the Earth where undeveloped communities are further impoverished by climate change and related changes in the environment.  Rising temperatures and reduced rainfall have forced many agricultural communities off their ancestral lands and into a more marginal existence.  In Bolivia, for example, former farmers have been displaced into brutal mines where life span is typically shortened by health and safety hazards.  Some Pacific and Indian Ocean islands have been drowned by rising sea levels, forcing mass evacuations onto those that remain.  Their protective reefs are dissolving in the increasingly acidic ocean.

Meanwhile, enterprising people are responding to threats their communities are facing.  In the Indian Himalayas, for example, artificial glaciers are being created to replace those that are melting.  Glaciers were the irrigation system that enabled agriculture in marginal conditions.  Torrential downpours caused by climate change are frozen on dammed, flat plains to create artificial glaciers that perform the same function.  In a remote village in Nepal, a villager returns from his Western education to bring his impoverished community into the 21st century by creating a wi-fi network that provides internet access.  The internet brings education to a village that could not afford teachers.  It is powered by a small hydroelectric generator in a glacial stream.  The stream is expected to disappear when the glacier melts in a decade or two, a problem yet to be solved.

These stories and a multitude of others are both sobering and inspiring, but we will focus on the issues relevant to Million Trees.

Harvesting fog with trees

The coast of Peru is one of the driest places on the earth.  There are places in Peru where no rain has been recorded.  The city of Lima is near the coast and its climate is similar to San Francisco.  There is little rain, but there is a great deal of fog.  Lima, like many cities in undeveloped countries, is surrounded by shanty towns in which poor people build make-shift shacks and live without modern services such as water, power, and sewage systems.

Demonstrating once again, that poverty is sometimes the mother of invention, the people of one of these shanty towns are attempting to grow a forest on their sand dune.  The trees are being irrigated with water harvested by huge fog nets, which are also supplying the community with drinking and washing water.  Within four years, the community expects the trees to be large enough to harvest the fog without the help of the fog nets, “producing a self-sustaining run-off that will replenish ancient wells and provide water for the community for the first time in 500 years.” (1)

Sutro forest on a typical summer day. Courtesy Save Sutro Forest.
Sutro forest on a typical summer day. Courtesy Save Sutro Forest.

This is a familiar scenario to the readers of Million Trees.  Fog drip in the eucalyptus forests in San Francisco has been measured at over 16 inches per year.  In the driest months of the year, soil moisture in San Francisco’s eucalyptus forest has been measured at over 10%, while soil moisture in grassland was only 2% and 4% in shrubs.  (2)

The value of forests and the dangers of deforestation

Each chapter of Adventures in the Anthropocene is devoted to a different ecosystem.  Each ecosystem is introduced with a description of the importance of that ecosystem and the way in which is it being compromised by the activities of humans in the Anthropocene.  Here are a few excerpts from the chapter about forests, which will be familiar to the readers of Million Trees.

  • “Forests play an important role in local and global climate. The world’s forests absorb 8.8 billion tonnes of carbon dioxide each year through photosynthesis—about one-third of humanity’s greenhouse gas emissions.”
  • “…their canopies provide shelter from the sun and wind, making forests much wetter, cooler environments than surrounding treeless areas. This nurtures streams and rivers, provides habitat for a range of amphibians and other life, helps cool the regional and global atmosphere, and recycles water.”
  • “Although forests help create the climate, they are also exquisitely sensitive to it—and the smaller a forest gets, the less resilient it is. When trees are chopped down, sunlight enters in the gap and dries the soils. Drought upsets the forests’ delicate water cycle—trees start to die and the entire ecosystem can tip from rainforest to grass-dominated savannah.”
  • “Deforestation emits carbon dioxide from soils and decaying plant matter, and is responsible for around 20% of all carbon dioxide emissions.”

One point bears repeating because it is relevant to our local version of deforestation.  In some cases, native plant advocates have succeeded in their demand to destroy 100% of our urban forest because it is predominantly non-native.  In other cases, they have only been able to convince land managers to “thin” the forests, although “thinning” does not seem an accurate description of destruction of 90% of the trees.  In any case, we should all understand that the ultimate likely outcome of the “thinning” strategy is an eventual clear-cut because “when trees are chopped down, sunlight enters in the gap and dries the soils….trees start to die and entire ecosystem can tip” from forest to grassland.  The drying of the soil is only one factor in this prediction.  The remaining trees also will be vulnerable to wind throw.  And the herbicides used to prevent the destroyed trees from resprouting are mobile in the soil and are likely to damage the trees that remain.  Plans to “thin” the forest are either based on ignorance or are a strategy designed to achieve the same goals as a clear-cut with less public opposition.

Are invasive species a problem?

We were gratified that there was barely a mention of “invasive” species in the detailed accounts of the impact of human civilization on the planet.  The conventional wisdom that “invasive” species are one of the primary causes of species extinction is waning and this book reflects that fact. 

Galapagos Islands
Galapagos Islands

The pros and cons of introduced plant species are debated in the context of the Galapagos Islands, where biodiversity is worshipped because it was instrumental in Darwin’s theory of evolution.  Ms. Vince interviewed the conservationist who has been battling invasive plant species on the Galapagos for 20 years.  He recently decided that attempts to eradicate introduced plants are futile and he now calls them native plants.  His surrender to this reality is controversial, but he is resolute.  He is supported in this decision by scientists who have studied novel ecosystems and find ecological value in them.  The rebuttal to such defense of novel ecosystems is that the globalization of ecosystems is homogenizing the world’s biota.

Ms. Vince concludes that proponents of eradicating non-native plants are losing the battle against the “McDonaldization” of nature:  “From the Galapagos to Hawaii, conservationists are switching tack and starting to embrace the introduced species of Anthropocene ecosystems…” because “In some places, invasives have enhanced the landscapes, reducing erosion, providing handy cash crops or food and habitat for other wildlife.”

We can only hope that our local version of “conservation” in the San Francisco Bay Area will catch up with this new realistic perspective in time to save our urban forests from being needlessly destroyed.


The final chapter of Adventures in the Anthropocene is an epilogue, which takes place in 2100 in London.  The author’s son muses at the age of 87 about which of his mother’s many predictions occurred in the 21st Century.  As we would expect, it was a tumultuous century, one in which drastic changes were made to accommodate the changing climate.

We notice that 22nd Century vegetation of London is tropical:  “Now, carpets of sedges and mosses fill the spaces, interspersed by grasses grazed by capybara, and the planted fig and mango trees, noisy with wild birds.”     We marvel that people claiming to be environmentalists are blissfully unaware of the fact that the native plants they are demanding we restore are not adapted to current climate conditions, let alone the climate foreseen in the near future.

We conclude with the final paragraph of Adventures in the Anthropocene, because it is the most optimistic prediction in this excellent book:

…the world has become a kinder place.  The terrible wars, the famines, the terrorism, extremism and hate, the drownings and deaths of hundreds of thousands of migrants the humanitarian crises…they seem to be over now…The great global mix-up of people that has occurred as a result of climate migration, urbanization, and online networks has produced a new, socially mobile, egalitarian society.  The world’s giant cities force people to live together in close but diverse communities, and it has generated a spirit of cooperation.”

We look forward to a time of greater equality for humanity as well as for the natural world, when the meaningless and unnecessary distinction between native and non-native will be retired from our vocabulary.


(1) Gaia Vince, Adventures in the Anthropocene:  A Journey to the Heart of the Planet We Made, Milkweed Editions, 2014

(2) Kevin M. Clarke, et. al., “The influence of urban park characteristics on ant communities,” Urban Ecosyst, 11:317-334, 2008

Climate Change vs. Biodiversity: NOT!!

A new study reported changing public and scientific interest in biodiversity compared to climate change.  Using reports in the media and scientific journals in the United Kingdom and the US, as well as funding of scientific studies by the World Bank and the National Science Foundation, the study reports that the interest in climate change has increased and the interest in biodiversity has decreased in the past 25 years.

This analytical approach seems to suggest that these two environmental issues are mutually exclusive, that the interest in one is at the expense of the other.  We find this both unfortunate and unnecessary because we consider these two issues intimately related.  Climate change is increasingly the biggest threat to biodiversityIf plants and animals are unable to adapt to climate change, they are doomed to extinction. 

Therefore, we believe that science should study these topics together.  In fact, the study on which we are reporting acknowledges the relationship between these topics:  “Dual-focus projects are being funded more often, but… ‘this is relatively small and does not mitigate the plateauing expenditure on biodiversity research.’” (1)

Conservation in a changed climate

As long as conservation and “restoration” projects are devoted to replicating historic landscapes, they are likely to be unsuccessful.  The climate, atmosphere, and soil conditions are no longer suited to a landscape that existed hundreds of years ago, particularly in urban environments.  Therefore, if biodiversity is to be preserved by conservation and restoration, such projects must look forward, not backwards. 

We have been watching the Nature Conservancy closely for signs that it is adapting to climate change.  We look to the Nature Conservancy to lead the way because they employ hundreds of scientists.  In contrast, many mainstream environmental organizations employ more lawyers than scientists.

We have reported that the Conservancy’s Chief Scientist, Peter Kareiva, is at least paying lip service to an approach to conservation that takes into consideration the profound changes in the environment caused by the activities of man.  This acknowledgement of the irreparably altered environment is encapsulated by the proposal to name a new geologic era, the Anthropocene.

Unfortunately, the old guard of conservation biology has engaged in a vigorous campaign to silence the Conservancy’s new approach.  This conflict between the old guard and scientists who have proposed a more realistic approach to conservation was recently reported by the New Yorker. (2)  According to that article, Peter Kareiva has made a commitment to the old guard to quit publishing anything regarding the Anthropocene and its implications for conservation practices.

The Nature Conservancy has responded to the article in the New Yorker in its on-line blog.  It doesn’t explicitly address the question of whether or not a commitment has been made to quit advocating for a more realistic approach to conservation.  However, it implies that the Conservancy plans to continue on a course of scientific innovation and experimentation, which it describes as “practical.”  Here is a specific choice made by the Conservancy that typifies this approach:

Monarch butterflies roosting in eucalyptus tree.
Monarch butterflies roosting in eucalyptus tree.

“We know it was worth spending millions of dollars to rid Santa Cruz Island of non-native pigs.  But we are pretty sure it would not be worth spending what could be hundreds of millions of dollars to rid California of non-native Eucalyptus trees (which also happen to harbor wildlife and monarch butterflies.)” (3)

Although the Nature Conservancy’s Chief Scientist may have agreed to “shut up,” we see signs of the Conservancy’s new approach in its latest magazine.  In a brief article entitled “Forests of the Future,” the magazine reports that they are no longer planting the species of trees that existed in the past in one of their properties in Minnesota, because they don’t believe that species is adapted to current or predicted future conditions.  Instead they are actively engaged in reforestation of the land with new species:

Over the past two springs, the team planted 88,000 tree seedlings across 2,000 acres in the northeastern corner of the state.  The seedlings consisted of species that should survive better in a warmer and drier climate—trees, such as red oak, found in higher numbers just south of the area. For a team accustomed to restoring forests to match historical landscapes, helping the North Woods [of Minnesota] adapt to a predicted future climate is a new but necessary idea.  [The Conservancy’s science director in Minnesota] says, ‘All of our modeling is saying the same thing,’ she adds, ‘We needed someone to actually go out and start trying some of this stuff.’” (4)

Looking forward not back

We are very encouraged by the Conservancy’s new approach and we hope that other land managers will be inspired by it.  We are also reminded of a recent visit to a nature reserve near San Luis Obispo managed by the local chapter of the Audubon Society.  We reported about this reserve in a recent article because the land managers had planned to destroy all eucalyptus trees on that property but were forced to scale back their plans in response to a noisy negative reaction from the public.

Dying oak tree, Sweet Springs Nature Reserve
Dying oak tree, Sweet Springs Nature Reserve

On our recent visit, we learned that this was a wise choice because many of the oak trees that were planted on this reserve by those who wish to “restore” it are quite dead despite the fact that the reserve has an extensive irrigation system.  These land managers looked back and the result of that retrospective thinking is a landscape of dead native trees.

Irrigated native plant garden, Sweet Springs Nature Reserve
Irrigated native plant garden, Sweet Springs Nature Reserve

Climate change requires land managers to wake up to the realities of what will grow where.  Land managers in the San Francisco Bay Area appear to be blind to that reality.  They repeatedly plant species where they grew hundreds of years ago and we are forced to watch the plants die repeatedly. 



(1)    “Climate change beats biodiversity as a press, scientific, and funding priority,” Science Daily, June 11, 2014

(2)    D.T. Max, “Green is Good,” New Yorker, May 12, 2014

(3) Mark Tercek and Peter Kareiva, “Green is Good:  Science-Based Conservation in the 21st Century,” May 5, 2014

(4)    “Forests of the Future,” Nature Conservancy, June/July 2014

Anthropocene: The Sixth Extinction

There have been five major episodes of massive extinctions in the 4.5 billion years that our planet has existed.  All occurred within the past 500 million years because there was little known as “life” prior to that time.  We are now experiencing the sixth massive extinction episode which began approximately 50,000 years ago with the dispersal of humans around the world.  The causes of prehistoric extinctions are not fully known, unlike the current episode.  We know that we are the cause of the sixth extinction, but we seem to be incapable of preventing it.

Prehistoric extinctions

The fifth and most recent massive extinction event occurred about 65 million years ago. It brought the age of dinosaurs to an abrupt end.  There were no humans or even our primate ancestors at that time.  The cause of that extinction was only recently discovered in the 1980s and even more recently accepted by most scientists.  There is now general agreement that the entire environment of the planet was radically and suddenly altered by the impact of a huge asteroid that landed on what is now the Yucatan peninsula in Mexico.  The impact raised a huge dust cloud that engulfed the earth and precipitated the equivalent of a nuclear winter, killing most vegetation and the animals adapted to a much warmer climate.  As with all massive extinctions, it took many millions of years for the environment to recover from that event and for plants and animals to slowly evolve adaptations to the new environment.

Update:  There is an alternate theory about the cause of the fifth extinction.  Huge volcanic eruptions in India may have been the cause, or perhaps a contributing factor.  Explained HERE.

Scale of dinosaurs compared to human. Creative Commons - Share Alike
Scale of dinosaurs compared to human. Creative Commons – Share Alike

The third and biggest extinction event occurred about 250 million years ago at the end of the Permian geologic period.  Paleontologists tell us that about 90% of all living plant and animal species died as a result of that extinction event.   Like the fifth extinction, the End-Permian extinction was precipitated by a sudden and radical alteration in the climate.  However, less is known about what caused that change in the climate.  Like our current round of climate change, there was a massive release of carbon into the atmosphere with a related drop in oxygen.  These changes caused temperatures to soar and the chemistry of the oceans to acidify.  Although there is not yet consensus amongst scientists, current speculation in the scientific community is that the changes in atmospheric conditions were the result of huge volcanic eruptions in what is now Siberia that emitted carbon dioxide into the atmosphere. (2)

The first massive extinction occurred about 450 million years ago just 50 million years after the first land plants began to emerge on the planet.  In fact, the plants may have been a factor in the climate change that caused the extinction at the end of the Ordovician geologic period.  The cooling of the climate that caused the extinction was associated with a sharp drop in carbon dioxide levels which may have been partially the result of plants that convert CO₂ to oxygen.  The movement of the continents is also thought to have been a factor in the cooling because the breakup of the unified continent, Pangaea, changed the circulation of ocean currents which affect the climate on land.

All of the massive prehistoric extinctions were associated with sudden changes in climate, although human perception of time should not be imposed on the word “sudden.”  These events occurred over thousands of years and are only “sudden” when compared to the 4.5 billion years of the existence of our planet.

Extinctions of the Anthropocene

Genus Homo evolved into its only surviving species, Homo sapiens, about 200,000 years ago.  That’s us…humans.  However, we didn’t begin to extinguish plant and other animal species until our population grew and dispersed throughout the world.  And when we did, the first victims of our ability to hunt cooperatively with weapons were the megafauna, now largely gone from the world.

Megafauna are the huge animals now known primarily from their fossil remains that were so large they had no predators until humans brought their intelligence to the task of hunting which was previously limited by size and speed.  Megafauna reproduction wasn’t capable of keeping up with the pace of human hunting because they had long gestation periods, many years to sexual maturity, and small numbers of offspring.

Humans reached the Australian continent about 50,000 years ago.  When they arrived, Australia had its own megafauna:  giant kangaroos and other enormous herbivores.  Within 10,000 years the megafauna were gone and the landscape changed as grazing was significantly reduced:  “With no more large herbivores around to eat away at the forest, fuel built up, which led to more frequent and more intense fires.  This, in turn, pushed the vegetation toward fire-tolerant species.”  (1) Conversion to grassland savanna was also accelerated by the frequent fires intentionally set by humans to facilitate their hunting.

Eurasian Mammoth on left; American Mastodon on right. Creative Commons -dantheman9758
Eurasian Mammoth on left; American Mastodon on right. Creative Commons -dantheman9758

The same shift in vegetation occurred in North America when humans arrived about 13,000 years ago and American megafauna such as mastodons and giant sloths were hunted to extinction.  Grassland found in North America when Europeans arrived thousands of years later in the 16th century was therefore not adapted to heavy grazing and was largely destroyed by domesticated animals brought by early settlers.  Native Americans did not have domesticated animals. 

Similar scenarios played out around the world as humans arrived, most recently on the Pacific Islands where Polynesians arrived as recently as 1,500 years ago.  Huge flightless birds were found on New Zealand until they were hunted by humans just 500 years ago.

The second wave of extinctions caused by humans occurred during the age of exploration, beginning in the 16th century.  Humans wiped out many species of animals all over the world to feed their explorations and early settlements.  Huge turtles were brought on board ships to feed the crew on long voyages.  Passenger pigeons and American bison were killed by early settlers for food, leather, and sport.

As humans developed agriculture and domesticated animal-herding, hunting wild animals decreased.  In developed countries, extinctions today are largely by-products of western civilization, through mechanisms such as climate change and global exchange of diseases and pathogens…all equally deadly to other living things.

Modern Extinctions

There are no longer any physical barriers to the exchange of pathogens and pests.  Invasion biology is based on the fiction that such exchanges can be prevented or even reversed.  The most deadly invasions prove otherwise:

  • Amphibians, especially frogs, are being wiped out all over the world by a fungal disease that is traveling fast.  It is now known to exist in Central, South, and North America, as well as Australia.  The means of transmission is not yet known.
  • Bats are dropping dead by the tens of thousands primarily in New England as they succumb to a different fungal disease.  Nothing is known about how this disease is transmitted.  We should probably assume that it will also spread beyond its current range.
  • Insects, such as the emerald ash borer that is killing millions of ash trees in the United States, have been accidentally introduced as a result of global trade.

We should expect the loss of these species to reverberate throughout the food web, although little is known about the secondary effects of the loss of species.  For example, when bats are no longer available to eat insects, what will those insects eat?  And what will the animals that ate frogs eat when the frogs are gone?  These animals may be playing roles about which we know little and therefore cannot predict the consequences of their loss.

The spread of pathogens and insects that prey on plants could be related to climate change.  For example, the pine bark beetle is a native insect that has become a serious problem in the forests of North America because mild winters associated with global warming are not cold enough to cause an annual die-back of the insects.  The range of the pine bark beetle has expanded and is killing millions of acres of forests in North America.

Ecosystems are being fragmented by agricultural development.  Much of the Amazonian rainforest has been reduced to isolated fragments which are not large enough to support the diverse plants and animals that occupied intact ecosystems.

Climate change…the silent killer

When we look to the distant past, we can see how levels of carbon dioxide in the atmosphere have caused massive extinctions of plant and animal species.  Low levels of carbon dioxide have been associated with a cooling phase and high levels of carbon dioxide have caused temperatures to rise.  We are now in a period of a huge increase in carbon dioxide levels caused by the activities of humans, particularly emissions associated with the burning of fossil fuels and deforestation.  There is scientific consensus that the climate has changed and will continue to change as well as about the causes of those changes.  However, we still know little about the long-term consequences of climate change.

Coral reef. Creative Commons - Share Alike
Coral reef. Creative Commons – Share Alike

One consequence of increased levels of carbon dioxide is well known and that is the acidification of the oceans.  The laws of chemistry tell us that when carbon dioxide dissolves in water it forms carbonic acid.  Carbonic acid dissolves shells and coral.  Aquatic animals such as mussels, clams, oysters, crabs, and lobsters will be incapable of building the shells that protect their bodies when levels of carbonic acid increase.  Australian scientists report that coral cover of the Great Barrier Reef has decreased 50% in the past 30 years.  A paper published in 2008 predicted the imminent extinction of one-third of 800 reef-building species as a result of increased water temperature and acidity of the oceans.  An estimated one-half million to 9 million species “spend at least half their lives on coral reefs.” (1)

So why are we destroying trees?

As disturbing as it is to witness the death of plants and animals which are innocent by-standers to the choices made by humans, we have some sympathy and understanding for why our political system has been incapable of the fundamental changes needed to stop the process.  We burn the fossil fuels that emit carbon dioxide and other greenhouse gases to keep us warm in the winter and cool in the summer, to transport us to work and play, to power our industrial processes and many other vital functions.

But, we cannot understand why we continue to destroy millions of healthy trees (that we planted) essentially because they are out of fashion. These trees are storing tons of carbon that will be released into the atmosphere when the trees are destroyed and we will lose their ability to store carbon in the future.

We loved these trees as recently as 50 years ago.  Now many people have decided that they “don’t belong” because they aren’t native.  Eucalyptus is only one of many targets of this fad.  Norway maples are being destroyed in communities in eastern United States for the same reason.  And most of the trees being destroyed in the Midwest (because people wish to “restore” the prairie artificially maintained by Native American fires) are even native to the Midwest.

In the case of eucalyptus, the trees are expected to live in California for several hundred more years.  How will the climate have changed in 300 years?  Will any of the plants presently considered “native” even exist?  On our present climate trajectory, the answer to that question is clearly “no.”


Most information in this post is from these two sources:

(1)    Elizabeth Kolbert, The Sixth Extinction, An unnatural history, Henry Holt and Company, 2014

(2)    “Where have all the species gone?” University of California Museum of Paleontology, short course, March 1, 2014

The Anthropocene vs. The Doomed Earth

On Saturday, September 14, 2013, The New York Times published an op-ed by Erle C. Ellis entitled, “Overpopulation Is Not the Problem.”  Professor Ellis challenges the conventional wisdom that the future of the Earth is threatened by an inexorably increasing human population.  He tells us that emerging knowledge of the history of human civilizations should reassure us that humans have altered ecosystems for 200,000 years to meet their needs and there is no reason to believe there is a limit to the ability of humans to continue to manipulate our environment as needed to support a growing population.   


Little of human history is recorded.  Therefore, only recent discoveries of archaeologists have informed us of the many technological advances of human civilization that increased food production.  Irrigation and agriculture, for example, is a relatively recent human accomplishment.  In the Old World, humans have supplemented their diets by raising domestic animals in the past 6,000 years.  This knowledge only reached the New World with Europeans in the 16th century. 

Professor Ellis suggests that our appreciation of human adaptability is based on our knowledge of the history of human accomplishment.   That knowledge is not only relatively new, but is not yet widely known by the public.  He admits that he, himself, did not comprehend human adaptability until studying agriculture in China, where human ingenuity has managed to keep pace with the growth of the most populous country on Earth.  His work is now as informed by archaeology, geography, and economics as it is by his original discipline, biology.

We introduced Professor Ellis (University of Maryland, Baltimore) to our readers in an article about the globalization of ecology by humans.  He is one of the proponents of naming a new geologic era, the Anthropocene, to acknowledge the fact that the activities of humans have altered the Earth in significant and profoundly important ways.  He does not find reason to despair about our impact on the Earth:

“The only limits to creating a planet that future generations will be proud of are our imaginations and our social systems.  In moving toward a better Anthropocene, the environment will be what we make of it.”  (1)

At the opposite extreme:  The viewpoint of Jake Sigg

At the opposite extreme of Ellis’ rosy view of the future of the Earth and its human occupants, we turn to Jake Sigg’s “Nature News.”  Regular readers of “Nature News” will find the following example of Sigg’s pessimistic view of the future of the Earth typical of his viewpoint:

“My vision for the world is increasingly apocalyptic.  Lest you think I’m being overly dramatic, with the type of economic/political system we have, things can only get worse, not better, and the horror and chaos of Syria, Egypt, et al could be easily foreseen–not in detail, but in general, as the result of too many competing for space and resources.  I expect lots of horror stories in the future, and I hope I’m dead by the time it hits me directly.  At the pace things are moving, I may not be that lucky.”  “Nature News,” September 7, 2013.

Jake Sigg’s concern about over-population also motivates his extreme opposition to immigration, including legal immigration. 

Finding Common Ground

As diametrically opposite as these viewpoints seem on the surface, they actually share common ground.  As Professor Ellis says, “The science of human sustenance is inherently a social science.”  In other words, the famines that humans have experienced were as much a failure of the social system as they were of the physical limitations of the planet to provide adequate food.  Jake Sigg agrees that “our economic/political system” is at least partially to blame for the failure to compensate for inadequate resources. 

For example, the current round of climate change has been caused by the activities of humans, but our social, political, and economic systems are preventing us from responding to it effectively.  Hunger in America will be exacerbated if conservative politicians are successful in their effort to drastically reduce the availability of food stamps to the poor.     

Professor Ellis is confident that human social systems will accommodate population increases.  Mr. Sigg predicts the opposite outcome.  The more likely outcome is probably somewhere in between.  We will probably muddle through with occasional catastrophic famines where physical shortages cannot be mitigated by competent social/political structures. 

Admittedly, this topic is a digression for Million Trees.  It is intended as a reminder that the ecological “restorations” being demanded by native plant advocates should be a public policy decision and the failure to treat it as such has resulted in irreparable harm to our environment.  It is therefore an example of how environmental problems and their resolution are ultimately failures of human social systems.

Update:  Our readers might be interested in Jake Sigg’s very different reaction to Erle Ellis’ op-ed in his latest newsletter (September 17, 2013), available here.  Here is an excerpt from it:

“One of the most discouraging developments of our time is the elevation of opinion to equal status with knowledge in the minds of large numbers.  People who have spent their lives studying and working in a field are on equal footing with someone who hadn’t thought about the matter five minutes ago, and their vote counts just as much.  Not exactly a way to build a lasting, self-perpetuating society.”

In other words, problems are caused by too much democracy, in Sigg’s opinion.  He believes that “experts” should be in charge, of which he—a retired gardener in the Recreation and Park Department– is apparently one and Erle Ellis—Associate Professor of geography and environmental systems at University of Maryland, Baltimore—is not.  In contrast, Million Trees values expertise, but considers the alteration of our public parks a political decision which must be made democratically.  More democracy is needed to resolve these conflicts, not less. 


Erle C. Ellis, “Overpopulation Is Not the Problem,” New York Times, September 14, 2013.

The Globalization of Ecology by Humans

Humans have had a profound impact on our planet wherever they have lived.  Since the industrial age man’s impact on the environment has even extended beyond where he lives as atmospheric changes impact remote places such as the polar regions. Humans are a particularly restless species of animal, forever fleeing whatever conditions threaten existence or seeking a better life ahead.  Because we are an adaptable species with the capacity to alter conditions, we have a wider range of movement than other animals. 

Wherever humans have gone they have taken with them the seeds of plants, at first unwittingly and then purposefully after the advent of agriculture.  Edward Salisbury, a 19th Century British horticulturalist, reported raising 300 plants of 80 different species from the debris in his trouser cuffs despite wearing spats.(1)

The impact of Native Americans on the landscape

Native Americans arrived in North America about 13,000 years ago and slowly migrated to South America.   The megafauna that Native Americans found when they arrived disappeared soon after they arrived.  Although not all scientists agree, there is strong evidence that the megafauna, such as enormous buffalo and mastodons were hunted to extinction by the first human inhabitants of the New World.  The loss of these huge herbivores was a factor in the development of grasslands that were not adapted to heavy grazing.(2)

Native Americans setting grass fire, painting by Frederic Remington, 1908

The most profound alteration of the ecology of the New World by Native Americans was their use of fire to assist their hunting and gathering activities.  Burning grassland to the ground encourages the growth of new sprouts that improve grazing and attract the animals the Native Americans hunted.  And burning grassland funneled the animals into the hunt.  These frequent burns prevented the succession of grassland to shrubs and forest, maintaining prairies that were essentially manmade. 

The arrival of Europeans in the New World

This process of transplanting plants around the globe was greatly accelerated by the age of exploration which began in earnest in the 15th century.  When Columbus arrived in the New World in 1492, he found a land that had already been radically altered by Native Americans, though he had no way of knowing that. 

The Europeans that eventually settled the New World were ignorant of the impact of Native Americans on their new home until the advent of archaeology in the 20th century.  Their ignorance was based on their mistaken perception that the Native American population was small.(3) 

In fact, the population of Native Americans was decimated by the time the Europeans settled the New World nearly 200 years after the early explorers arrived at the end of the 15th century.  The early explorers introduced European diseases to which they were immune, but the Native Americans were not.  From just a few localized contacts with Europeans these diseases–such as measles, smallpox, and syphilis–spread quickly through Native American communities, sometimes reducing the population by as much as 90%.  These deadly epidemics were largely unwitnessed by the tiny population of early explorers.

Alfred Crosby speculates in Ecological Imperialism that Native Americans were particularly vulnerable to these diseases because they had virtually no domesticated animals.  He gives us a fascinating explanation of how Europeans developed their immunities by living in close proximity with animals for centuries.

The history of Native Americans was initially recorded by the European settlers who arrived in numbers nearly 200 years after initial contact in the 15th century.  Their perception that they found a pristine wilderness, largely untouched by human hands, has persisted to this day in the public’s mind.   It is that perception that has led native plant advocates to the conclusion that the pre-European landscape should be the goal of restorations.

The impact of Europeans on the landscape

As much impact as Native Americans had on our landscape it pales in comparison to that of Europeans.  The importation of domesticated animals—such as cattle, pigs, horses, and sheep—changed the ecology of the New World quickly.  Because the population of early settlers was small and the grazing resources vast, these animals quickly became huge herds of feral animals, roaming places such as the pampas of Argentina and the prairies of the mid-west of North America.  The native grasses were quickly replaced by the non-native grasses spread by these wandering herds. (4)

Herd of sheep, Mono County, CA. Creative Commons

Likewise, the agricultural practices of European settlers have introduced virtually everything we eat today in North America.  Nearly all of our fruits, vegetables, and cereals are not native to North America.  If non-native food were to be banished from California, we would be reduced to a diet of game, acorn mush and a few species of nuts and berries.   The diet of Europeans would be equally impoverished if they lost the potatoes, corn, tomatoes, etc. that came to them from the New World.

USDA photo

The Anthropocene:  The geologic age of humans

The Earth’s ecology is in a constant state of change.  Humans are not the source of much of that change.  The continents shift.  The climate oscillates.  Plants are moved by the wind and tide.  Animals move without the assistance of humans, often taking plants with them.  But change has been accelerated by the restless movements and activities of humans. 

Scientists have recently begun to advocate for the naming of a new geologic era, the Anthropocene.   The Anthropocene would officially acknowledge that the environment has been altered by humans.  Although the beginning of this era is still being debated by scientists, Erle Ellis (University of Maryland, Baltimore) believes that an appropriate beginning would be about 6,000 years ago, when humans domesticated animals. 

Why are we suddenly afraid of change?

Changes in the ecology of North America resulting from the movement of humans have been going on for thousands of years and have greatly accelerated in the last 500 years.  Until very recently, these changes were broadly perceived as improvements.  We enjoy a more varied diet than our ancestors and we are shielded from famine by our access to food from anywhere in the world.  We find the products of the New World useful in other ways, such as the rubber that is essential to transportation.

Suddenly, for little apparent reason, we are afraid of everything new in our environment.  The media is full of panic-stricken reports of alien “invasions.”  Most of these panic attacks eventually prove to be baseless.  The newcomers are eventually absorbed into the landscape or they disappear without a trace.  Or scientists eventually explain that the newcomers are better adapted than their predecessors to the climate, water, and soil conditions created by the activities of man. 

We asked a scientist who advises us occasionally this question:  Since new species of plants and animals have been introduced to our landscape for hundreds, if not thousands of years, why the sudden panic?  His reply was:  “It’s trendy. It’s ‘cutting edge.’ It’s ‘hot.’ It’s…fundable.”   

In the service of a scientific fad that has spread into the popular culture, introduced species of plants and animals are being needlessly destroyed.  Many of these new species are better adapted to present conditions than their predecessors.  Many are essential to our way of life and the animals with which we share the planet. 

(1) Richard Mabey, Weeds:  In Defense of Nature’s Most Unloved Plants, Harper-Collins, 2011

(2) Alfred Crosby, Ecological Imperialism. Cambridge University Press, 2004

(3) Charles Mann, 1491, Random House, 2005

(4) Crosby