Maps illustrate world population changes

31 October 2011

Maps illustrate world population changes

A series of maps demonstrating the distribution and changing trends of the world´s population have been created at the University of Sheffield.

The three maps were developed by Benjamin Hennig and Professor Danny Dorling from the University of Sheffield´s Department of Geography as part of a project funded by the Leverhulme Trust. They illustrate the most recent global population shifts between 1990 and 2015. The declaration of the 7th billion person living on the planet marks a significant milestone within that dynamic development.

With recent estimates from the United Nations stating that the world´s population will rise to over 10 billion by 2100, the maps show where the world´s population is growing and declining as well as growth patterns within individual countries.

Hennig said: "It is important to reflect on the global population development beyond the issue of mere growth and the national-level trends, but to look at the diverse patterns that happen within countries. These tell us so much more than the current focus on either growth or decline within a country and reveal more complex patterns of changing populations."

The first map is an equal population projection which shows the land area of the world resized according to the total number of people living in each country. It reflects the current distribution of people in the world. The map is based on a novel technique, called gridded cartograms, which allows seeing the dimensions in an unprecedented level of detail.

Superimposed on the map is information about changing population trends in the 25 years that have been analysed by the researchers, allowing the growth and declines rates to be seen in those areas where people live, and where these trends therefore matter most.

Each cell is coloured just one of four shades and the area of each cell is in proportion to current population. Areas shaded blue such as in Eastern Europe are declining most quickly in terms of people dying or leaving, and areas shaded red such as large parts of Africa are places with the highest current rates of births and/or migration.

Two additional maps show this data split into the dimensions of growth and decline, depicting only those areas that contain these two contradictory trends using the same gridded cartogram technique.

The map of population growth shows where the extra people in 2015 will be compared to those living in 1990. The more extra people expected, the larger the areas of each grid cell on the map. The map of decline is the opposite picture that shows only those spaces where there are expected to be fewer people in the very near future, proportionate to that population loss.

Many countries contain areas where population is currently falling and others where it is growing, and this explains why different parts of China appear on both cartograms.

As the currently largest country, China´s diverse patterns are particularly striking on a global perspective. There is considerable growth in the Pearl River Delta region, the factory of the world, where many essentials of our postmodern lifestyles are made. Elsewhere in China, a more mixed pattern of growth and decline is found, with the hinterland of the most productive regions losing out considerably on population because of complex internal migration patterns. Many countries are expected to soon show similar kinds of diverse patterns of coexisting growth and decline exhibited by China and much of Europe.

In the United Kingdom for instance, the South of England is getting the majority of growth, while the North, and even more the rural areas in the north including Scotland, are seeing significant decline rates that stand in contrast to the overall growing population.

The UK is one of the few countries with a moderate increase in an overall shrinking role of Europe in the global population distribution. Despite the repeated focus of growth and overpopulation, the declining trend is as relevant here from a demographic perspective as it is for most parts of Europe.

The researchers also produced a time series showing the change in population trends between 1950 and 2100 based on United Nations population projections.
The map animation demonstrates changing distribution of people ranging from the 2.5 billion people that lived in the middle of the last century to the present population of nearly 7 billion, moving the gravitational centre of people considerably from the wealthier regions in Europe and North America towards Asia.

This has now started turning towards the African continent. Africa has not only been a considerable part of the global population growth over the last quarter of a century, but is expected to outnumber Asian population growth considerably in the decades to come.

Europe will continue to lose large shares of its population in total as well as in relation to the rest of the world. The dominance of Asia slowly starts to be relativised by the increasing population shares on the African continent, making changes in the Americas almost insignificant from a global perspective.