Declining observations of lake and river ice in the Arctic
Most of the information about long-term changes in lake and river ice comes from surface-based observations. These usually record dates of ice formation and break-up, and sometimes also ice thickness. Since the mid-1980s, the number of these surface-based observation systems has been in serious decline.
The chart above shows the number of sites included in three different databases of ice observations since 1800. The abrupt change is partly due to weather stations becoming automated and partly due to financial cutbacks. The effect is a discontinuity in the information on lake and river ice dynamics, which makes it very difficult to track long-term change.
Remote sensing from satellites has not yet replaced these surface observations at any national scale. The capability to monitor river and lake ice across the Arctic from satellites is expected to emerge in the future.