From the article:..."
"The historical pattern of warming is that most of the warming has occurred over land, in particular over the northern hemisphere," said Cristian Proistosescu, Ph.D. '17, and first author of the paper. "This pattern of warming is known as the fast mode -- you put CO2 in the atmosphere and very quickly after that, the land in the northern hemisphere is going to warm."
But there is also a slow mode of warming, which can take centuries to realize. That warming, which is most associated with the Southern Ocean and the Eastern Equatorial Pacific, comes with positive feedback loops that amplify the process. For example, as the oceans warm, cloud cover decreases and a white reflecting surface is replaced with a dark absorbent surface.
The researchers developed a mathematical model to parse the two different modes within different climate models."