(Excerpts and some figures ... full article here.)
The world's population surpassed 6.8 billion in early 2009, with no significant slowing in the pace of growth in recent years.1
(See Figure 1.) Estimates by the United Nations Population Division
indicate that humanity has been consistently gaining more than 79
million people-a population almost the size of Germany's-each year
since 1999.2 During the 1990s, annual additions fell from
nearly 90 million people to less than 80 million, feeding optimism that
world population might peak not long after the middle of this century.3
But the recent stability of annual population increments adds to the
uncertainty and when-and how-world population growth will end.4 (See Figure 2.)
U.N. demographers currently offer eight variant projections for the
future, with the median and most cited one placing world population
slightly above 9.1 billion in 2050.5 Non-demographers often
misinterpret this number, however, as an expert prediction or forecast
of what population will be. Rather, all projections are conditional
assessments based on current numbers, age structure, and trends and
reasonable assumptions about the future.6 Thus the
projections the United Nations offers produce a range of 2050 world
population from slightly less than 8 billion to slightly more than 11
billion.7 The Washington-based Population Reference Bureau
(PRB) recently released its own projections, suggesting a population at
mid-century of slightly more than 9.4 billion.8
The recent leveling out of annual population growth increments, which
no demographer had predicted, helps illustrate that there is no way to
be sure that population is "likely" or "expected" to peak at roughly 9
billion people at mid-century, or indeed at any particular time in the
future.
[End Notes, etc.: From world Watch: Complete
trends will be available with full endnote referencing, Excel
spreadsheets, and customizable presentation-ready charts as part of the
to-be-introduced subscription service of the World Watch institute, Vital Signs Online, http://www.worldwatch.org/vsonline, slated to launch this fall. (Not available here)]
