Future Development of World Population

• Projections of future development of world population are published by the statistics department of the UN. These projections are updated roughly every two years. Three variants are projected, where the medium variant is typically used in many studies for their evaluations of possible future scenarios.

• The medium projection has been systematically modified in upward direction in succesive publications during the last decades. Reasons are:

• child mortality has globally decreased faster than previously assumed,

• birth rate in sub-Saharan countries decreased more slowly than originally assumed,

• the influence of HIV is smaller than originally thought.

• As a consequence, all earlier studies are systematically too otptimistic.

• If the systematic upward shift is extrapolated, it can be shown that development will not follow the medium variant but instead very probably the high variant.
  

• Thus, there will possibly be 11.6 billion people instead of expected 9.7 billion in 2050 and more than 16 billion instead of 11 billion in 2100. As a consequence, in 2100 the pressure on the resources will be higher by a factor of 1.5 than projected in most of the scenarios developed.

• This is fatal, because policies build on the results of such studies.

The discussion presented here is based on a publication in ChemBioEng Reviews:
Pfennig, A.: Sustainable Bio- or CO2-Economy: Chances, Risks, and Systems Perspective.
ChemBioEng Reviews (2019) 6(3), 90-104.