World Population imbalance between the sexes

[Klaus]

Not really. You are overlooking the compounding of change. You are arguing on the basis of a linear model, but the better model is exponential.

Why? Growth is exponential. Decline is not. More people are born as a consequence of past births. But fewer people die as a consequence of past deaths, not more.

Using numbers for world population distribution that I found here:
http://www.census.gov/cgi-bin/broker

and mortality rates for the US, which I found here:
http://www.data360.org/dsg.aspx?Data_Set_Group_Id=587

(I did no due diligence on the validity of either data set), I wrote a little simulation to calculate total population by year. Additional simplifying assumption: Nobody lives to be 101 years old, and population within each age bracket is evenly distributed (so, if the range was 20-24 years old and the chart said there were 100 people in that bracket, I put them in as 20 for each age). The output:

Code:

2011, pop 6817058007
2012, pop 6780947321
2013, pop 6743420887
2014, pop 6704654628
2015, pop 6664799512
2016, pop 6623965248
2017, pop 6580863349
2018, pop 6536365484
2019, pop 6490646673
2020, pop 6443857022
2021, pop 6396125182
2022, pop 6345931078
2023, pop 6294327848
2024, pop 6241428235
2025, pop 6187334701
2026, pop 6132236077
2027, pop 6074793053
2028, pop 6015883666
2029, pop 5955653466
2030, pop 5894230835
2031, pop 5831729226
2032, pop 5766880188
2033, pop 5700474675
2034, pop 5632656642
2035, pop 5563553686
2036, pop 5493309282
2037, pop 5420672094
2038, pop 5346373353
2039, pop 5270597102
2040, pop 5193504635
2041, pop 5115237519
2042, pop 5034929397
2043, pop 4953123232
2044, pop 4869969448
2045, pop 4785601594
2046, pop 4700274299
2047, pop 4612919077
2048, pop 4524297722
2049, pop 4434567588
2050, pop 4343866337
2051, pop 4252314568
2052, pop 4158859732
2053, pop 4064282383
2054, pop 3968715974
2055, pop 3872279361
2056, pop 3775421253
2057, pop 3677473877
2058, pop 3578963068
2059, pop 3479997498
2060, pop 3380672244
2061, pop 3281070604
2062, pop 3180354190
2063, pop 3079139025
2064, pop 2977500322
2065, pop 2875509885
2066, pop 2773909639
2067, pop 2672030740
2068, pop 2570426329
2069, pop 2469173531
2070, pop 2368338580
2071, pop 2267978271
2072, pop 2167206766
2073, pop 2066393181
2074, pop 1965634311
2075, pop 1865024424
2076, pop 1766270310
2077, pop 1669280788
2078, pop 1574158861
2079, pop 1480899571
2080, pop 1389493103
2081, pop 1299925584
2082, pop 1211126581
2083, pop 1123494972
2084, pop 1037050593
2085, pop 951831884
2086, pop 871106744
2087, pop 794234247
2088, pop 721419516
2089, pop 652450052
2090, pop 587124292
2091, pop 525251086
2092, pop 465472888
2093, pop 407832128
2094, pop 352359962
2095, pop 299100992
2096, pop 253246323
2097, pop 213781326
2098, pop 179801113
2099, pop 150543516
2100, pop 125352281
2101, pop 103662349
2102, pop 84948759
2103, pop 68836343
2104, pop 54963640
2105, pop 43019421
2106, pop 32735702
2107, pop 22620255
2108, pop 13912123
2109, pop 6415742
2110, pop 0

Population drops to 5 billion in 32 years. This is really simple (mortality rates in other countries are obviously different than the US, and overall are going to be higher), but you can see that the decline is pretty linear until the bulk of the population moves into the higher age ranges.