Fertility Decrease and Rising Volcanic Activity Can Stop Global Warming

The possibility of achieving carbon neutrality of the global economy is studied taking into account alternative demographic scenarios that assume depopulation; estimates of global net emissions of greenhouse gases are made given account their absorption by the world’s forests and the development of technologies for carbon dioxide capture and sequestration. The probable dynamics of the most important climate factor, volcanic activity, is examined; its change in the 21st–22nd centuries is assessed. Using a set of global climate system models, the global average temperature for the proposed scenarios is simulated, and the simulation results are compared with other works. It is shown that the combination of rapidly falling birth rates in all countries of the world and the expected increase in global volcanism are capable of keeping changes in the global average temperature within relatively safe limits even at the current low rates of decarbonization of the global economy.