Enlarge / Loads of lava: Kasbohm with a few solidified lava flows of the Columbia River Basalts. (credit: Joshua Murray) As our climate warms beyond its historical range, scientists increasingly need to study climates deeper in the planet’s past to get information about our future. One object of study is a warming event known as the Miocene Climate Optimum (MCO) from about 17 to 15 million years ago.