During what event was the earth covered by 10% ice? How high were sea levels at this time?

There are two distinct Cryogenian ice ages called Sturtian glaciation between 750 and 700 million years ago, followed by the Varanger (or Marinoan) glaciation, 660 to 635 million years ago which covered the earth ice. Also the Global sea level has fluctuated widely in the recent geologic past.

Explanation:

Cryosphere is the part of the earth' surface where the land areas exits in the solid form when the warming temperature low. The snow and ice covers the 10% of the earth permanently in the ratio of 60% in northern hemisphere and less than in snow in southern hemisphere.

Its is formed due to lesser warm temperature. snow and the ice covered on the surface it store the fresh water under the floating ice, most of the fresh water is present in the two major ice sheets Antarctica and Greenland.

Melting ice does not cause any impact on sea because it was already floating on the sea surface. If the temperature become warm, its melt on the ocean itself.