So much ice is melting at the Earth's poles that it's affecting the rotation of the planet, scientists say. Its spin is slowing down slightly, causing days to get longer.

Geologists rely on tiny crystals of the mineral zircon to understand the timing of key events in Earth's early days, like the rising of continents and the emergence of oceans.

Global temperatures are on track to rise 3-5 degrees by the year 2100 , according to the United Nations Meteorological Organization. That level of...