My grandma just found out I’m headed to Uganda, and she asked me what the trip was about, so I told her I’m going to the Rwenzori Mountains near the equator in Uganda (border with the Congo) to learn about tropical glaciers and their changes during and since the last ice age (20,000 years ago). Just like in the northern and southern hemispheres, glaciers in the tropics grew to be much larger in the last ice age and we can collect samples from the boulders they transported and dropped at the glacier edge (think of the glacier as a conveyor belt and boulders melt out at the end and drop to the ground to form a ridge of rock debris that outlines where the glacier once was). We take samples from these boulders and do some fancy chemistry work to figure out how long that boulder has been sitting there, exposed to cosmogenic radiation that penetrates through the earth’s atmosphere. It’s important to know WHEN the glaciers advanced/were larger so then we can look at the timing of other glacier advances and climate events around the world at that time and figure out how a climate ‘signal’ moves around the world. For example, the ice sheets that covered Canada and Scandinavia were huge and white and reflected a lot of sunlight back into space. If our tropical glaciers did not grow until after the large northern hemisphere ice sheets grew, maybe the tropical glaciers are responding to a global (rather than local) cooling. Alternatively, the glacier advances could relate to changes in wind direction, ocean temperatures, global CO2, or changes in the gradient of cooling with elevation.