answer: If a population has a constant birth rate through time and is never limited by food or disease, it has what is known as exponential growth. With exponential growth the birth rate alone controls how fast (or slow) the population grows.
While humans may eventually define a logistic growth curve ; currently there is no evidence that this is the case. The only think that is demonstrable, as shown below, is that the rate of growth of the world's population is decreasing, but it's still exponential in nature. here is the data
In other words, the population doubling time is increasing, but there still is a characteristic doubling time. (70/n).
Often times exponential growth is plotted as a straight line on a semi-log plot. The Y-axis is logarithmic and the X-axis is linear.
ln (ex) = ln y
ln y = x3. answer:
“Under the densification scenario we assumed that in the first instance areas with suburban levels of housing would become dense urban housing. This would greatly reduce the amount of new land needed for housing,” he says.
The study team, from the University of Sheffield and the Centre for Ecology and Hydrology, in Wallingford, explored the effect of these two different scenarios on threeecosystem services – flood mitigation, agricultural production and carbon storage.
Felix says: “If a city expands then that land is no longer useful for agriculture so production goes down and when you construct new houses you disturb the soil, which removes the stored carbon.
“However, if you reduce expansion of cities by increasing high density housing, you tend to have much less green space so the water will run off quicker and contribute to flooding, whereas in suburban areas there will be a lot of gardens and parks where the water can drain into the soil and not create floods.”
4.answer We face many environmental challenges, but the foremost is the risk for a severe climate change due to CO2 emissions from fossil fuels.
I meet so many that think population growth is a major problem in regard to climate change. But the number of children born per year in the world has stopped growing since 1990. The total number of children below 15 years of age in the world are now relatively stable around 2 billion. The populations with an increasing amount of children born are fully compensated by other populations with a decreasing number of children born. A final increase of 2 billion people is expected until the world population peaks at about 9 billion in 2050. But the increase with 2 billion is comprised by already existing persons growing up to become adults, and old people like me (+60 years). So when I hear people saying that population growth has to be stopped before reaching 9 billion, I get really scared, because the only way to achieve that is by killing.
So the addition of another 2 billion in number constitutes a final increase of less than 30%, and it is inevitable. Beyond 2050 the world population may start to decrease if women across the world will have, on average, less than 2 children. But that decrease will be slow.
The original goal of the policy was to keep China's population to 1.2 billion in the year 2000, according to Cai Yong, a sociology professor at University of North Carolina, and a fellow at the Carolina Population Center. In fact, China's population reached a level of 1.26 billion in 2000, meaning they were over the mark by 60 million people.
But the underlying motivation for that goal of 1.2 billion people was to increase GDP per capita — and China's GDP grew much more quickly than the pessimistic predictions in 1980 had expected. So the GDP per capita was way above target , even though the population also grew more quickly than intended.
No. The one-child policy (or, translated from the Chinese name, "policy of birth planning") only to 40% to 63% of the population, depending on whether you're talking to China's National Population and Family Planning Commission or American academics. Specifically, the policy applies to urban married couples who are part of the nation's Han ethnic majority
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