1. In 1955 there were fewer than one billion children (aged 0-14) in the world. By 2015 there were two billion. About how many children do UN experts estimate there will be in 2100?
The Nature article quoted an answer of Two billion. The number of children in the world is no longer increasing.
However, the population projections are widely variable for 2100 and have been trending higher. However, the estimate for the number of children (0-14) is still 2 billion despite an overall boost in the middle of the medium estimate going up 350 million.
World population projections have increased in recent years because the birthrate in Africa is not decreasing as quickly as projected
The population levels projected in the medium variant are an outcome of the substantial projected declines in fertility. According to the medium variant of the 2015 Revision, global fertility is projected to fall from 2.5 children per woman in 2010-2015 to 2.4 in 2025-2030 and 2.0 in 2095-2100. Steep reductions are projected for the least developed countries, from 4.3 in 2010-2015 to 3.5 in 2025-2030 and 2.1 in 2095-2100. However, for countries with high fertility there is significant uncertainty in the projection of fertility, even in the 15-year horizon of the post-2015 development agenda, and more so in the long-term projection to 2100. Slower-than-projected fertility declines would result in much higher population totals in all subsequent time periods. For example, a scenario in which all countries had a fertility rate that was consistently half a child higher than in the medium variant would produce a population of 16.6 billion in 2100, more than 5 billion higher than the medium-variant projection.
According to the 2015 Revision, the world today has 7.3 billion inhabitants and a 95-percent chance of having between 9.5 billion and 13.3 billion in 2100. Furthermore, there is just a 23-percent chance that the world population may peak and start declining before 2100. The median projected population for 2100 is 11.2 billion, meaning that there is a 50/50 chance that the population at century’s end may actually be higher or lower than that number.
The 2015 estimate for 2100 is 350 million more than the 2012 estimate.
Population of 13-17 billion in 2100 is not impossible. It depends upon what happens with fertility in Africa and Asia. This would mean answers of 3 billion or 4 billion people aged 0-14 could happen. But is would likely require 2100 population of 13.5 billion to get to 3 billion children and 17 billion to get to 4 billion.
2. The life expectancy at birth in the UK is 81 years. What is the life expectancy at birth in the world as a whole?
The Nature article quoted an answer of 70 years. There has been a 10-year rise in life expectancy in the past 50 years.
From the UN 2015 population revision - Globally, life expectancy at birth is projected to rise from 70 years in 2010-2015 to 77 years in 2045-2050 and to 83 years in 2095-2100. Africa is projected to gain about 19 years of life expectancy by the end of the century, reaching 70 years in 2045-2050 and 78 years in 2095-2100. Such increases are contingent on further reductions in the spread of HIV, and combating successfully other infectious as well as non-communicable diseases. Both Asia and Latin America and the Caribbean are projected to gain 13-14 years of life expectancy by 2095-2100, while Europe, Northern America and Oceania are projected to gain 10-11 years.
3. Globally, men aged 25 and older have spent about 8 years in school on average. How many years have women in the same age group spent in school?
The Nature article quoted an answer of - Between 1970 and 2009, the number increased from 3.5 to 7.1 years.
4. Roughly what percentage of the world's one-year-old children is vaccinated against measles?
The Nature article quoted an answer of -The World Health Organization calculates that about 85% of children have been vaccinated against measles. We gave you the points if you rounded up or down.
5. Roughly what percentage of the world’s population has electricity at home?
The Nature article quoted an answer of - Again, nearly 85% of homes have electricity worldwide.
6. Roughly what percentage of the girls in the world attend primary school (first 4-6 years of school)?
The Nature article quoted an answer of 90%. The number of children who never have the benefits of primary education fell steadily between 2000 and 2007. The proportion has continued to fall since then, but much more slowly. In 2014, the out-of-school rate was 9%.
7. In the past 20 years, the proportion of the world population living in extreme poverty has roughly…
The Nature article quoted an answer of Decreased by half. According to the most recent estimates, 10% of the world’s population lives on less than US$1.90 per day, down from 35% in 1990.
8. In 1965, the number of babies born per woman in the world, on average, was five. What do you think the number is today?
The Nature article quoted an answer of -2.5. The world’s declining fertility rate is one of the most astounding shifts in recent history.