The group "World Overpopulation Awareness" states on their website:
Unfortunately, with exploding population growth, excessive consumption on
the part of the more well-off people in the world, errant technology, and
corrupt governments, the environment is in trouble and the sustainability of the
people of our planet is threatened. The solutions seem simple: empower and
enable women to have fewer children, develop simpler lifestyles, tax pollution
of any kind, and set up government programs to enable the other three
solutions.
Overpopulation is a serious problem getting worse every year: if we continue at the current rate, population will double to over 11 billion by 2035. Overpopulation is the root of most, if not all, environmental and many economic issues, timber overharvesting, loss of arable land, ocean depletion, food shortages, water shortages, air pollution, water pollution, flooding, plant and animal habitat loss, global warming and immigration.
That sounds pretty serious. They also claim on the same website that "1/3 of the population growth in the world is the result of incidental or unwanted pregnancies." A quick perusal of their website would have you believe that increased contraceptive use would solve most of the world's problems. As they said, one of the "simple solutions" is to "empower and enable women to have fewer children." But is that true?
Obviously, many unwanted pregnancies contribute to population growth. The very definition of population growth requires new people to be born. However, according to a study by the Guttmacher Institute, in 1994 "28% [of women aged 15-44] had had one or more unplanned births." Farther down on the same page they note "[a]n earlier study based on the 1982 NSFG [National Surveys of Family Growth] concluded that 46% of women aged 15-44 at the time of the survey had experienced one or more unintended pregnancies." That is a drop of more than a third in the number of women having unintended pregnancies, which would seem to indicate an increase in "contraceptive use" (including abstinence, condoms, birth control, abortions, etc.). NSFG data collected in 2002 shows 14% of women reported having an unwanted birth, again a significant drop. So, we would assume that from 1982 to 1994, and through to 2002, we would see a significant drop in the population growth rate.
Using U.S. census data, the population growth rates for 1980, 1990, and 2000 respectively were 11.5%, 9.8%, and 13.2%. So, while unwanted pregnancies (and lack of contraceptive use) can contribute to growth rate increases, they apparently are not a major cause of current trends.
Perhaps it's our complicated lifestyles that are causing overpopulation, and we need to "develop simpler lifestyles." However, the U.S. census data also shows that population growth significantly decreased from the 19th to the 20th century, when life became less simple.
Okay, so their solutions to overpopulation may not be correct, but overpopulation is still a problem right? The current population of the world is around 6.7 billion according to UN estimates. Using some simple math, 7 billion people living in single family homes could fit inside the state of Alaska. (Assume 4 people per house, .2 acre lots, 1.48 million km² of land) Now, obviously everyone is not going to move into single family homes in Alaska, but the point is that they could and the population density would only be 4070 people/km², a little less than Philadelphia, Pennsylvania. For comparison, Manhattan has a population density of 25,850 people/km².
Indisputably, if the population continues to grow, eventually (many, many years from now) the earth will become overcrowded. But, as World Overpopulation Awareness tells us, "the sustainability of the people of our planet is threatened." Doesn't it stand to reason that if the world becomes overcrowded enough to affect the sustainability of humans that the population will decrease? It seems to be a self-correcting problem.
Besides, by the time the population grows that much, we'll be living in outer space.