How many people can the earth bear?

We don't know whether the population of 7 billion today is sustainable, otherwise where is its upper limit?

Overpopulation, a word that makes politicians blush, is often described as "? The elephant in the room. "

You often hear people mention that overpopulation is the biggest threat to the earth. But is it necessary for us to list the problem of population growth separately? Are there really too many people on earth?

Obviously, the earth will not get bigger. Such a large living space, not to mention the population supported by various resources-food, water and energy. In this way, isn't population growth harmful to the well-being of the earth?

that this is not the important question.

The earth will not get bigger.

"The number of people on earth is not the problem-the number of consumers and the scale and nature of consumption are the problems," said David, a senior researcher at the Institute for International Environment and Development in London. Satterthwaite said. He quoted Gandhi as saying: "The earth provides enough to meet everyone's needs, but not enough to meet everyone's desires."

Modern humans (Homo? For a long time, the number of Homo sapiens was relatively small. About 10? 000 years ago, they had only a few million. /kloc-only broke through the 10 billion mark in the 0/8th century. It didn't rise to 2 billion until the 1920s of 19.

At present, the world population has exceeded 7.3 billion. According to the prediction of the United Nations, by 2050, this figure will be rewritten to 9.7 billion, and by 2 100, it will exceed 1 100 billion.

The rapid growth of population is unexpected, and we don't even have a precedent for reference to predict the possible consequences. In other words, by the end of this century, the earth needs to feed more than 1 1 100 million people, and our current cognitive level is not enough to imagine whether it can survive at that time.

Even so, judging from the areas where the population growth is expected to be the fastest in the next few years, we still have a trail to follow.

Satterthwaite believes that in the next 20 years, the population growth will mainly come from the current central cities of low-and middle-income countries.

On the surface, the global impact of adding billions of people to these cities is negligible. Because the historical consumption level of urban population in low-and middle-income countries is low.

The emission of carbon dioxide and other greenhouse gases is an index to measure the consumption level of a city.

Satterthwaite said: "We know that cities in low-income countries emit less than 65,438+0 tons of carbon dioxide equivalent per capita every year." "In high-income countries, it is as high as 6 to 30 tons."

Residents in rich countries have a much greater impact on the earth than those in poor countries-but there are exceptions. Copenhagen, the capital of Denmark, and Porto Alegre, a high-income city in Brazil, have high living standards, but their per capita emissions are relatively low.

Copenhagen: high income, low emissions

Satterthwaite went on to say that if we look at individual lifestyles, the differences between the rich and the non-rich groups are also very different. The consumption level of residents in many low-income cities is very low, which makes little contribution to greenhouse gas emissions.

In that case, a society with a population of 1 1 100 million should put as little pressure on the earth's resources as possible. But times are changing. Low-income cities may no longer follow the low-carbon development track.

What is really worrying is that once people in these areas are bent on living in a high-income country and reaching their consumption level, all they have to discuss is fairness. Therefore, the impact of urban population growth is much greater.

This general rule has been put forward for more than a century, and will, honorary professor of Finner College of Environment and Society of Australian National University? Steffen said. The problem is not the population growth itself, but the sharp rise in global consumption (of course, not everywhere).

The implication is quite unpleasant: when the society is facing population pressure, people in rich countries must play their due role. Only when the rich begin to accept a low-carbon lifestyle and allow their governments to support such a seemingly unpleasant move can we alleviate the pressure of global climate, resources and waste.

An article published in the Journal of Industrial Ecology 20 15 looks at the impact on the environment from the perspective of the family and resolutely puts the consumption problem on the table.

According to data analysis, the greenhouse gas emissions of household consumption account for 60% of the global total emissions and 80% of land, materials and water resources. In addition, the researchers found that the ecological footprint of different places is large and small, and the influence of rich countries is greater.

The author of the article, Diana of Norwegian University of Science and Technology in Trondheim? Ivanova said that the conclusion is that we should change the concept of who is responsible. "We always like to blame others, the government or enterprises," she said.

For example, western consumers will think that some consumer goods producing countries, such as China, should be responsible for emissions because they are produced. Ivanova and her colleagues believe that consumers themselves should take responsibility. "If we change our consumption habits, it will also have a huge impact on the ecological footprint."

In this sense, it is necessary for developed countries to make some fundamental changes in their core values: not overemphasizing material wealth and putting personal and social well-being first.

Our society depends on manufacturing.

Even so, the earth may not be able to bear 1 1 100 million people. Therefore, steffen suggested stabilizing the global population, preferably around 9 billion. Then gradually reduce the population over a period of time. That is, reducing the fertility rate.

These measures have begun to show signs, although the number is still rising. The growth rate of population began to slow down in the 1960s. According to the world fertility model of the United Nations Population Agency, the global average fertility rate of women dropped from 4.7 in 1970-75 to 2.6 in 2005- 10.

However, it is also possible that there will be no meaningful decline for centuries. Corey from the University of Adelaide, Australia? Bradshaw said.

The huge population base makes the growth trend hard to shake, he said, even a disaster will not help. In a report in 20 14, bradshaw concluded that even if 2 billion people died the next day-or every government adopted a controversial family planning policy, such as the one-child policy recently abolished in China-the population would only be much larger by 2 100 than it is now.

The urgent task is to speed up the reduction of fertility rate. Steffen said that a relatively simple way is to improve women's social status, especially their opportunities in education and employment.

According to the statistics of the United Nations Population Fund, women in 350 million poor countries don't want their last child, but they can't get pregnant. If their demands are met, it will have a great impact on the global population growth trend. In this sense, for the sustainable growth of population, promoting women's rights means reducing resource consumption.

Maybe? 1 10 billion people really can't live. So theoretically, how many people can the earth bear?

Bradshaw said that it is almost impossible to get an exact figure, because the population that society can bear depends entirely on the development of agricultural technology, power generation and transportation-it depends on how many of us complain about poverty and hunger.

Shantytowns in Mumbai, India

Considering the lifestyle we choose and are unwilling to make changes, many people think that the population today has far exceeded the sustainable population. Because we are facing climate change, biodiversity reduction and large-scale marine pollution, 654.38 billion people in the world are starving and 654.38 billion people are malnourished.

A report of the United Nations in 20 12 summarized 65 kinds of estimated maximum sustainable population size, and the most common estimate was 8 billion, only a little more than the current population. But these numbers range from 2 billion to a staggering 10? 24 billion.

Because they are based on many assumptions, it is hard to say which is closer to the truth.

The ultimate determinant is how this society works. If some or all of us are extravagant, the maximum sustainable population will be very low. If we are careful, we'd better not reduce our material comforts, then the earth can accommodate more people.

The development of science and technology is often unpredictable and will also affect the maximum sustainable population.

In the early 20th century, the fertility of land was as much a problem as the fertility rate of women. 1928, George? In his book The Shadow of the Future World, Dick Knibbs suggested that if the population reaches 7.8 billion, the land should be used as efficiently as possible.

Just three years later, Carl? Bosch won the Nobel Prize in Chemistry for his contribution to the development of chemical fertilizers. In the 20th century, nothing can promote the rapid change of population more than chemical fertilizer.

Fertilizer promotes population growth.

In the distant future, if we don't live on the earth, science and technology will bring a larger number of sustainable population.

It is only a few decades since man first set foot in space. We are not satisfied with looking up at the starry sky, but determined to leave the earth and emigrate to another planet. Many outstanding thinkers, including the famous physicist Hawking, believe that space migration is the ultimate way out for mankind in the future.

However, although NASA's Kepler program has discovered many terrestrial planets, we still know very little about them and it is difficult to reach them, so emigrating to aliens can't solve the current problem.

In the foreseeable future, the earth will still be our home, and we should also find a sustainable way of living. Obviously, we should save money, especially turning to a low-carbon lifestyle and improving women's social status. Only by doing this can we estimate the sustainable population that the earth can bear.