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Overpopulation is indeed an elephant, but the medical profession's responses have not, perhaps, the memory of an elephant.
Back in the late 1960s a pressure group was set up called "Doctors and Overpopulation". It produced a long report published in "The Ecologist" and prophesied many of the issues that are now obvious today. Sadly it was ignored, and died. However its original activities were reported in the BMJ - see George Morris's letter (Br Med J 1973;2:717).
There is another elephant - landscape manipulation. The destruction of tropical rainforests in Brazil and Indonesia, the deforestation in the Himalayas and the diversion of rivers away from the Aral Sea are three such. These are not directly related to population growth but have materially affected the rate of global warming.
I doubt that any action will be taken on these issues, or on overpopulation, until it is too late. However the eruption of a supervolcano somewhere (the one in the Canaries is a likely candidate) will not only wipe out populations along many coasts but will also throw out a huge ash cloud that will rapidly cause global cooling. Nature has its checks and balances...