Archive for the 'Carrying Capacity' Category

Realize the Tragedy of Demographic Entrapment

Sunday, March 4th, 2012

Last month’s column was on the “tragedy of the commons”—when people use more than their share of a common resource, leading to the resource’s destruction. An example is overgrazed fields, where unpalatable weeds replace nourishing plants. Overgrazing is a disaster for shortsighted ranchers, because depleted fields can support very few animals.

Can a similar calamity happen to humans?

Yes, that is exactly what devastated Somalia recently. That country in the Horn of Africa is generally arid, and rainfall has been made scarcer by climate change. Human actions make the situation even worse, because cutting firewood leads to deforestation that reduces rainfall.

During the region’s frequent droughts, food production drops below what is necessary for human survival. Tens of thousands died in Somalia during 2011 from starvation.

Unstable politics in Somalia make the situation much worse. Gangs victimize the poor, robbing them of what little food they have. The Somali government is too weak to enforce any sort of rule of law.

Can we help by sending food? That sounds like the compassionate thing to do, but there is a hitch. Food aid arrives at distribution centers in cities so hungry people must leave their land to collect food. Their fields are abandoned and crops die. With no reason to return to their fields, these destitute people are forced into a cash economy. When the short-term food aid ceases these now landless peasants are caught with no money, no skills to make money, and (once again) no food.

This sad situation is made worse by the rapid growth rate of Somalia. Its Total Fertility Rate is 6.4—the average woman will bear more than six children. Only one country in the world has a higher TFR! In a wet year the harvest is good enough to feed all mouths, but not when the monsoon rains don’t come.

But, you might say, what about countries that far exceed their human population carrying capacity? For example the island of Singapore has the world’s highest population density and little land to grow food. Singapore imports its food, paying with money from manufacture and trade.

There are historical examples of human populations that outgrew the land’s ability to support them. I am part Irish, and suspect that my ancestors came to the USA to escape the Great Potato Famine in the mid 19th century. Ireland had become dependent on a single crop—potatoes—for most of its sustenance. This New World tuber allowed the population of Ireland to expand significantly—until a crop failure (from potato blight) caused an estimated million people to starve to death. Another, luckier million were able to emigrate from Ireland—many to the USA.

“Demographic entrapment” is the term applied to human overuse of their land’s carrying capacity. Dr. Maurice King, a British physician who has spent many years working in Africa, has tried to warn people about this tragedy.

Demographic entrapment occurs when a country has a population larger than its carrying capacity, when the country exports too little to be able to import food and when emigration is impossible. Dr. King suspects that much of sub-Saharan Africa will become entrapped soon.

An example of entrapment occurred in Rwanda in 1994. The genocide is generally blamed on tribal conflict, but starvation may have been the real reason. James Gasana, a former Minister in the Rwandan government, has excellent support for this theory. He found that, before genocide, ethnic strife was most likely to happen in areas where people were famished. Violence only occurred where people consumed less than 1500 calories each day. For comparison, the average person in the USA eats more than 2500 calories daily.

“Collapse”, Jared Diamond’s book, gives other examples of societies that outgrew their resources—the Romans, Mayas and Ancestral Puebloans. An intriguing video of Collapse can be found on YouTube in seven parts.

What is the best way to prevent demographic entrapment? There are very few under-populated countries, so massive emigration is unlikely. The poor countries of Africa are unable to compete on the world market, so exports cannot save them. The best way to head off violence similar to Rwanda’s is with small families.

Dr. King has not made friends by publicizing the concept of demographic entrapment. It is so frightening that many people are not willing to contemplate it. To ignore demographic entrapment, however, will not solve the problem. Sticking our heads in the sand could have tragic consequences, sentencing millions of people to death by starvation or by violence.

© Richard Grossman MD, 2012

Tragedy of the Commons

Sunday, March 4th, 2012

“In every deliberation, we must consider the impact on the seventh generation….”
Great Law of the Iroquois


            “They know that they shouldn’t fish closer than 500 meters from the coast, but I’ve seen these boats with their nets out just 200 or 300 meters offshore. The officials don’t enforce the laws.”

We were visiting the Greek island of Mykonos while on tour with the Durango Choral Society. We walked along the harbor with our guide, David, admiring the many small fishing boats. He explained facets of the failing Greek economy as well as the ancient and modern sites on this beautiful island. The Aegean Sea around Mykonos was so overfished, David said, that there were few fish left to catch.

We found proof that David was correct when we sat down to eat. Restaurants, even those overlooking the beautiful blue Aegean, had menus that listed few seafood dishes. Any seafood was prohibitively expensive since it had been caught in distant seas.

The situation that we encountered in Greece is a good illustration of the “tragedy of the commons”. That tragedy can occur when a limited resource is open to uncontrolled use by many people. Any one user may think he can benefit from taking as much of the resource as possible. This behavior is rational only in the narrow sense of self-interest. Regrettably, unbridled use of a resource is likely to lead to its depletion.

The term “commons” referred to pastureland that was available for everyone to graze his sheep in old England. Now it includes many different vital resources such as the air we breathe, the water we drink and the fish in the Aegean.

Most of us learned to share in kindergarten. Unfortunately, some adults never mastered that lesson or have forgotten it.  When there are many people using the same resource, any person who takes more than his share may deprive others of their fair share. Even worse, selfish people can deplete the resource, so eventually no one benefits from it.

In the case of fishing off Mykonos, there had been plenty of seafood for centuries. In the past the boats and fishing techniques only allowed small, sustainable catches, so the small proportion of sea life that ended up in nets was quickly replaced. Now, with more fishermen and more effective fishing techniques and many more mouths to feed, the fish supply has been exhausted. The Greek government has tried to prevent depletion by having a “no fish” zone, with poor results. People don’t seem to pay attention to the law, or the reason that it is needed.

Human population growth is one factor leading to the tragedy of the commons: more people using the same resource means less for all.

Ironically, some of the pollutants we have unintentionally added to drinking water may serve as a feedback mechanism to slow human population growth. Endocrine disruptors are chemicals that have unintended hormonal effects. They are found in much of our country’s drinking water. Some come from insecticides and other agricultural chemicals. Many plastics contain BPA, which has undesirable effects. Another source is the waste of women taking hormones. These chemicals have been shown to produce fish and other animals with sexual aberrations. It is possible that endocrine disruptors will lead to decreased human fertility.

The amount of fresh water on the planet is limited and, in some cases, is very slow to be replenished. The Ogallala aquifer is an example of a resource that is being used in an unsustainable manner. Much of the food grown in our country’s midwestern breadbasket depends on water from this aquifer. Tragically, there are some places in eastern Colorado (and in other states) that rely on the Ogallala where the water table has dropped 40 feet in just 15 years!

As our human population has grown, the apparent size of the commons has shrunk. Although the first few wells in the Ogallala made little difference to the water table, now we seem to be sucking it dry. Dumping waste into a river or the atmosphere made little difference with few people and fewer factories, but these resources have become toxic in our populous, industrialized nation. We are learning the problems that can be caused by abusing the commons.

The people who will suffer the most may be those who come after us, the “seventh generation” in the Iroquois law. Unless we think and plan ahead, our progeny will not have the use of many of the resources that we have enjoyed.

© Richard Grossman MD, 2012

Beware of Technology

Tuesday, August 10th, 2010

Beware of Technology—6-2010

© Richard Grossman MD, 2010

The chief cause of problems is solutions.

(Eric Sevareid)

I once sat on an airplane next to an engineer specializing in failure analysis. I told him about my “rip-stop” condom invention, which I hoped would be less likely to tear. “I’ve never had a condom break,” he said. Then his face clouded and he added: “Well, just once. In Thailand.”

As a physician I am used to things not working out as planned. There is so much variability among people it’s unreasonable to anticipate the same level of success with every patient. However, people’s faith in technology is such that we expect a perfect cell phone connection every time and spill-free offshore drilling. We are shocked when our expectations are disappointed.

I will not write about how BP grossly underestimated the amount of crude oil spilled into the Gulf of Mexico with the Deepwater Horizon disaster. Neither will I dwell on the executives’ culpability in this catastrophe, nor the dishonesty that allowed industry and watchdogs to make an incestuous agreement about safety. Nor will I highlight BP’s reckless decisions and actions. I will write about the risk of our overdependence on technology.

I know a few of the local BP executives. They are intelligent, well meaning and honest. Like you and me, they are just trying to earn a living. It is not their fault that BP has taken advantage of our social and legal structure that allows large corporations to run roughshod over the environment and the rights of people.

Engineers don’t assume that their projects won’t fail. Rather, they estimate the “time to failure.” For some highly refined mechanisms, that may be many years. For complex new technologies it may be impossible to estimate the time to failure. Don’t ever believe a claim that anything is entirely reliable.

One of the ways to increase safety is to have redundant systems. This is a bit like what we have in a car. There are brakes to avoid an accident. If the brake fails (or if you fail to use it in time) the seatbelt will keep you from going through the windshield. Air bags offer a second level of safety.

Every gas well drilled in La Plata County has redundant systems in case of a blowout. There are annular valves to squeeze the pipe, and rams if the annular systems fail. If any one valve type were perfect, a second set wouldn’t be needed.

There were valves at the Deepwater Horizon drilling site that failed. Perhaps the failure was because the explosion cut the control cables—we don’t know yet what caused the problem.

BP won’t tell me if there was an “acoustic switch” on this drill rig. This type of valve is triggered to shut not by wires but by an acoustic signal. It is required in some areas, but apparently not for rigs in the Gulf. An acoustic switch has the advantage that it can still be closed if the wires to the drilling platform are cut.

This oil spill is a tragedy, but I can think of much worse. What if there were a nuclear accident instead of one with petroleum? As bad as crude oil is to the environment, it is far better than spreading highly toxic radioactive isotopes over the Atlantic!

I view the Deepwater Horizon tragedy as a wake up call: any technology can fail. Large, complex technology can fail disastrously. Even with “failsafe” precautions, disasters happen.

Coal and petroleum fueled the industrial revolution and revolutionized the way we live. Fossil fuels have also allowed our population to grow enormously over the past two centuries. Regrettably, growth cannot continue indefinitely. Continued growth and dependence on fossil fuels are major issues that our society is just beginning to examine.

Renewable energy is one way to avoid large disasters. Most of the electricity for our home comes from solar panels on our roof. Our generating system is small, safe and doesn’t burn fossil fuels. We depend, however, on natural gas to cook and keep us warm.

I draw several conclusions from the Deepwater Horizon experience. We shouldn’t allow any more nuclear power plants. Consideration of drilling in the Arctic Ocean must be stopped. Any further offshore drilling must be carefully supervised by governmental agencies that are also carefully monitored. There must be contingency plans laid out ahead of time for dealing with an emergency such the Horizon’s blowout. Perhaps the most powerful lesson is that we must become less dependent on fossil fuels.

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Creative Commons Attribution 3.0 United States
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