The Centre for Ice and Climate is one of the leading institutes for climate research based on information stored in ice cores from ice sheets and glaciers. The past atmospheric composition is also recorded in ice cores as bubbles of old air. During the last glacial with lower temperatures methane as well as temperature in the northern hemisphere show rapid increases so called Dansgaard-Oeschger events. The underlying reason for both is circulation changes in the Atlantic Ocean i.e. the formation of deep water. During Dansgaard-Oeschger events, the emission of CH4 increases by roughly 100%. In this project, we want to understand what sources increase during Dansgaard-Oeschger events and where they are located. That information is important for projecting emissions of the potent greenhouse gas methane in a warming world scenario with potential rapid climate change.