external image ehrlich_400px.jpgPaul R. Ehrlich

He was born in Philadelphia de 29 of May of 193, he is an American entomologist at the University of Stanford, in 1968 he became one of the best known scientists of the environmental branch, after writing his bookthe population bomb which sold many books ,

Ehrlich theory resumes in the equation I=PAT , I is the product of three terms

1- population (P)

2- affluece (A)

3- Technology (T)

I = P x A x T or I=PAT.

IPAT has been chosen by many scholars in both the social and natural sciences as a starting point for investigating interactions of population, and technological change. It has also been used for climate change.

Some supporting quotes

“Our theory of evolution has become, as Popper described, one which cannot be refuted by any possible observations. Every conceivable observation can be fitted into it. It is thus "outside of empirical science" but not necessarily false. No one can think of ways in which to test it. Ideas, either without basis or based on a few laboratory experiments carried out in extremely simplified systems, have attained currency far beyond their validity. They have become part of an evolutionary dogma accepted by most of us as part of our training.”

"I see harm reduction as a way of engaging people as part of that path to recovery."

"The National Academy of Sciences would be unable to give a unanimous decision if asked whether the sun would rise tomorrow."

"To err is human, but to really foul things up you need a computer."

"We're one of the most highly regulated industries, and we have to pay attention to what government is doing."

"Among the knowledgeable people there is no more conversation about whether the danger is re "Civilizations have collapsed before: the question is whether we can avoid the first time entire global civilization has given us the opportunity of having the whole mess collapse."

~ Paul Ehrlich

Ehrlich is famous for positing three key factors that determine sustainability: population, affluence and technology, and this has been summarized in the equation I PAT.

Population "Problem" is a localized, economic and culturally dependent phenomenon:

The world population was estimated to be 6.96 billion by the United States Census Bureau as of July 1, 2011 and is supposed to have crossed 7 billion on 31st October according to the UN. Latest predictions from the UN estimate a higher population growth than previously of 9.3 billion by 2050 and over 10 billion by 2100 with higher rates possible. These are discussed below.

2002 figures showed a drop in fertility from the explosive figures of the 1980s. Current trends suggest a population in 2050 around 9.2-9.3 billion. To everyone's surprise in 2002 a very significant drop was detected in the fertility rates of a broad spread of diverse countries spanning the developed and developing world comprising half the world's population and with little in common between their governments and social attitudes. In 1950, worldwide the average woman had five children. Today she has just 2.3. Although in many countries there are still a large number of people at or below child-bearing age and actual birth rates will remain very high for some years to come, this fall has already led to a downgrading of future population predictions and fears of a population crash with societies full of the elderly unable to support their own services. However 2004 predictions have increased again from around 8.9 to 9.2 billion.


•Ehrlich’s theory is that there will be a disaster for humanity due to over population.

•10 million people will be starving during each of the years in the 1970′s.

•“The battle to feed all of humanity is over. In the 1970s and 1980s hundreds of millions of people will starve to death in spite of any crash programs embarked upon now. At this late date nothing can prevent a substantial increase in the world death rate…”

•A minimum of ten million people, most of them children, will starve to death during each year of the 1970s. But this is a mere handful compared to the numbers that will be starving before the end of the century”

Proof:•“Compare the end of the 20th century with the end of the 19th century. Twenty

to twenty-five million people died of famine related causes from 1875 to 1901, in a world whose population was only one-half to one-third as large. If the world had remained at 19th century levels in comparable food production, Ehrlich’s prediction would have come true. Unfortunately for Ehrlich (but not for the world) humanity learned a little about agriculture and other resources in the intervening 100 years.”

•United States population is more than double the 150 million that Ehrlich proposed