By World Population Day this year, which fell on July 11, the population on earth had reached somewhere between 7.5 and 7.6 billion people.

According to a report released by the United Nations (UN) last year, the world population is expected to reach 9.8 billion in 2050, and then 11.2 billion in 2100.

The report, covering demographic information from 233 countries and regions, said that around 83 million people are born each year. From now until 2050, half of all population growth will take place in only nine countries: India, Nigeria, the Democratic Republic of the Congo, Pakistan, Ethiopia, Tanzania, the U.S., Uganda and Indonesia.

The 2017 revision of the UN World Population Prospects noted that the birth rate in most countries has declined despite the growing general population.

The population will stay unchanged when a couple has two children that live to child-bearing age. However, more and more countries today are witnessing a lowering birth rate. From 2010 to 2015, 83 countries had a birth rate lower than this, with their population accounting for 46 percent of the world’s total.

The lowering birth rate is coupled with an aging population that continues to grow. Daily Mail on Wednesday cited Reuters, saying the number of people aged 60 and above will more than double from 962 million today to 2.1 billion in 2050, and more than triple to 3.1 billion in 2100.

Apart from a lowering birth rate, the growing population is bringing huge pressure to our planet environmentally. Decreasing non-renewable resources pose a major challenge for human beings.

The situation is worsened by the imbalance of resource consumption in developed countries. Every person needs 1.9 hectares of land to live, but in the U.S. every person has an average of 9.7 hectares. If everyone in the world lived by the U.S. standard, the earth would only support 1.5 billion people, or about a fifth of today’s global population.

According to the World Health Organization, the earth has a total fresh water volume of 91,000 cubic kilometers. However, safe and clean drinking water is still inaccessible for about 210 million people, with 450 million people having no access to sanitary facilities.

Human-driven climate change is an overriding threat that is further accelerated by population growth. The Intergovernmental Panel on Climate Change noted that economic and population growth continues to be the most important factor that drives up carbon emissions through fossil fuel consumption.

Though the future of human beings is unpredictable, one thing is certain: water and food are living necessities to us all. Each of us is a part of this world, and we should save energy as much as possible.