This is due to the difference between a measurement in degree and a measurement in meters (nothing that you can do about that) and maybe to the projection of the map (all projections induce distortions of the reality, your choice of a projection will depend on what you try to do).
If you assume that the Earth is a sphere, one degree along NS direction will ...
From the first few lines at your link it looks like it is KML 2.2:
<?xml version="1.0" encoding="UTF-8"?>
-<kml xmlns="http://www.opengis.net/kml/2.2" xmlns:atom="http://www.w3.org/2005/Atom" xmlns:kml="http://www.opengis.net/kml/2.2" xmlns:gx="http://www.google.com/kml/ext/2.2">