Measurements from Listvyanka reveal some interesting trends related to the timing of ice break-up; most notably that it is occurring earlier now than in the past. In the 1870s, thawing began around May 10; today, it often begins in late April. One study by a Swiss researcher calculated that the thawing date had moved by half a day per decade between 1869 and 1999. However, the most rapid change (about 3 days earlier per decade) occurred between 1869 and 1920. Since 1920, the date of ice breakup has remained fairly constant at Listvynaka. Ice formation, however, has occurred later in the winter, so the overall ice cover doesn’t last as long as it once did.
