During the ice age 20 thousand years ago, the Earth became a planet 'slim'. During the period of long-term reduction of geological and surface temperature of Earth's atmosphere, the weight of ice sheets in the Earth's crust and mantle change the shape of the Earth causes the Earth's bulge at the center.
Not completely spherical shape of Earth as reported Dailymail. This can be seen from kilometers stretch of the North Pole is closer than the planet's core line of the Equator. Fattening effect is believed to occur after the Ice Age that made the Earth more spherical.
According to National Geographic, the bulge at the Equator to shrink less than one millimeter per year. However, looking at satellite measurements of the Gravity Recovery and Climate Experiment (GRACE), this effect was reversed.
"There are other things happening (depreciation circumference of the Earth)," said geophysicist John Wahr at the University of Colorado.
Melting rate of ice at the North Pole and South which amounted to 382 billion tons of ice a year turned out to fight these slimming effect.