Climate Change Write down everything you can think of that might change the earth's atmosphere. When you have 10 ideas, go back and circle the ones you think have the most impact. Now underline the ones that result from human activity. In the Land of 10,000 Lakes, our scientists have access to special clues about the climate of the past. Through the years, pollen falls into a lake.
Algae settles to the bottom.
Dust, with distinct chemical signatures from the environment, drifts into the water. On the lake bottom, these bits of evidence are covered by mud and preserved. These clues can reveal what plants grew near a lake at different times in the past. Plant and tree types vary greatly depending on whether the climate is warm or cool, wet or dry. From lake sediment samples showing what plants thrived, scientists can construct a picture of ancient climates and learn how they've changed.