World Population and the Climate Changes
The world population data from 1 AD to 2017 and the temperature variations of the North Hemisphere from 1 AD to 1979 have been analyzed. Possible data errors have been estimated. The population index is introduced as the relative difference between inverse numerical data and its parabolic approximation. The index occurs to be a bounded function; its average value is close to zero; its error level occurs to be nearly uniform. The index describes variations of the world population in the past. The population index has been compared with the North Hemisphere temperature variations. During the last millennia climate warming stimulates the world population growth while cooling leads to decrease of growth and sometimes even to decrease of population number. However, the population response to temperature variations occurred with a significant delay of about 100 years. Possible reasons for this delay are discussed against the background of known historical events. The historical analysis and the found climate–population correlation could give a principal possibility to forecast the world population behavior approximately up to year 2080. However, the actual forecast occurs to be reliable to years 2060–2065 only.