Beneath their still surfaces, the lakes of some Arctic islands may hide the story of the rise and fall of Viking chiefdom.

Historians still aren’t sure exactly what led to the centuries of Viking raiding and expansion, a period politely known as the Scandinavian Diaspora that ran from the late eighth century to the mid-11th. Population pressures and political rivalries probably played a role, but changing climate around the North Atlantic may also have given the Scandinavians a push.

So far, paleoclimate researchers have mostly focused on warmer climates in the Vikings’ destinations, like Iceland, which might have drawn people to settle there. But those who set sail may have been facing trouble with the crops back home thanks to changing temperatures. A team of researchers hope to find some answers in a new series of sediment cores from ancient lakebeds in a remote Norwegian island chain.