Calculating sum of all pixel values of world population map without defining area of interest in Google Earth Engine

Question

I would like to know the world population in the year 2015 according to WorldPop data without bounding the calculation of the sum to a specific region or area of interest.

What is the function for doing this?

var worldPop = ee.ImageCollection("WorldPop/GP/100m/pop");

var WP_2015  = worldPop
  .filter(ee.Filter.equals('year', 2015))
  .select('population');

https://code.earthengine.google.com/393e834ade64a583c840444cb7547afb

Answer 1

You cannot aggregate pixels without specifying some region, either implicitly or explicitly. Just specify the whole world (as a non-geodesic polygon) and use it as a region in the reduceRegion call.

var WORLD = ee.Geometry.Polygon([-180, 88, 0, 88, 180, 88, 180, -60, 0, -60, -180, -60], null, false)