“Men still live who, in their youth, remember pigeons; trees still live who, in their youth, were shaken by a living wind. But a few decades hence only the oldest oaks will remember, and at long last only the hills will know.”
–Aldo Leopold, “On a Monument to the Pigeon,” 1947
It is hard to imagine how plentiful a species the passenger pigeon was. In the 19th century, it was likely the single most abundant bird in the world. Their huge flocks would block out the sun. Their sheer numbers discouraged natural predation. They ate literally everything in their path leaving behind, in the words of Aldo Leopold, “a world plated with pigeon ejecta”
The passenger pigeon disappeared in a very short time because of human predation. The impression of the people at the time was that the population was infinite. But in less than 30 years passenger pigeons were reduced from an estimated 136 million breeding adults to a dozen or so flocks. The last known passenger pigeon died in captivity at the age of 29 in 1914. Last year was the 100th anniversary of the extinction of this species.
Last year a group of scientists gathered to discuss whether or not the earth has entered a new epoch called the Anthropocene. This epoch is the time period where human activity is the primary cause for large scale changes that are taking place on the earth.
The current epoch is called the Holocene. It began with the retreat of the glaciers 12,000 years ago and continued with the spread of humans across the globe. The Holocene represents a period of general warming of the earth.
In connection with all of the research being conducted to understand how human activity is affecting our climate, there is some new research attempting to measure more specifically what this human activity is.
The basic challenge is that humans have the same expectations of the earth’s capacity today that they had 100 years ago. Our aspirations are infinite but the earth’s resources are finite.
The result has been a “Great Acceleration” of human activities starting in the 1950’s that decrease the earth’s resources. These activities range from population, to water use, to GDP growth, to international tourism. All of these activities change the earth’s resources from greenhouse gases, to surface temps, to ozone loss, to ocean acidification, to tropical forest loss.
The authors of the study summarize their findings in the following quote.
Of all the socio-economic trends only construction of new large dams seems to show any sign of the bending of the curves – or a slowing of the Great Acceleration. Only one Earth System trend indicates a curve that may be the result of intentional human intervention – the success story of ozone depletion. The leveling off of marine fisheries capture since the 1980s is unfortunately not due to marine stewardship, but to overfishing.
A related study examined how this activity has pushed four key areas past core boundary values where continued activity would drive the affected systems into a new unstable state. Two are entering a zone where the affected system is already unsustainable and the damage may already be irreversible. Extinction is an example of irreversible damage.
The two areas where we are in danger are loss of biosphere diversity and alteration of biogeochemical cycles (overuse of phosphorus and nitrogen). The two areas where continued human activity will start to cause changes, but those changes may still be reversible are climate change and land use.
The problem is that even though scientists are raising the alarm on a number of fronts, humans haven’t changed their behavior.
Here are just a few examples of items in the news over the last month.
Even with all of this information, climate science in this country is politicized and most just aren’t that much concerned that we are reducing the time until everyone on the planet will experience serious changes in their lives. People in coastal areas will likely be affected first. Rising sea level and loss of barrier reefs combined with more intense storms means severe irreversible damage. The government of Kiribati has purchased land in Fiji for their 110,000 inhabitants to move to when their island disappears. The Marshall Islands invested in a sea wall which was overtopped by a heavy storm last year. The massive flood damaged the only airport and contaminated fresh water resources that were already in short supply.
If the bee population continues to collapse, the fruit industry will not be far behind. In China, humans have been forced to take over the job of pollinating fruit trees because they inadvertently killed off their wild bee population. In their rush to expand fruit production, they killed the bees with pesticides and destroyed the natural habitat that wild bees needed to recover.
Forests are stressed around the world because of climate change and deforestation. The remaining trees are more susceptible to disease. Invasive species have already wiped out Elm, Ash, and Chestnut trees in this country. We are also losing Beech, Redwood, and Sequoia.
The Asian Carp is perilously close to the great lakes, which would dramatically change the ecology of the biggest single source of freshwater in the world. The lakes are also threatened by algae pollution from excess fertilizer run off.
Our challenge as a species is that we are myopic. We care about our own survival first. We are wired to think locally. The problem is that there are seven billion of us now on the planet and our combined local actions threaten all of us globally. We are collectively “taking” more from the earth than the earth is able to sustain. The result is that systems which have operated reliably for millennia are starting to break down. When those systems ultimately fail, NOTHING replaces them. Instead the earth dies just like the carrier pigeon.