Scientists have evidence that climate change is not just something that will happen in the future—it is happening now. Such evidence relies upon accurate records of climate variables dating back well before people thought humans could alter the climate. These records are not common, but the ice cover data for lakes in Madison, WI provide a good example of a valuable dataset for identifying these trends. As University of Wisconsin-Madison lakes researcher John Magnuson says, “We can recall the past and sense change only when we keep records.”