Direct observations of ice seasonality reveal changes in climate over the past 320-570 years.
Lake and river ice seasonality (dates of ice freeze and breakup) responds sensitively to climatic change and variability. We analyzed climate-related changes using direct human observations of ice freeze dates (1443-2014) for Lake Suwa, Japan, and of ice breakup dates (1693-2013) for Torne River, Finland. We found a rich array of changes in ice seasonality of two inland waters from geographically distant regions: namely a shift towards later ice formation for Suwa and earlier spring melt for Torne, increasing frequencies of years with warm extremes, changing inter-annual variability, waning of dominant inter-decadal quasi-periodic dynamics, and stronger correlations of ice seasonality with atmospheric CO2 concentration and air temperature after the start of the Industrial Revolution. Although local factors, including human population growth, land use change, and water management influence Suwa and Torne, the general patterns of ice seasonality are similar for both systems, suggesting that global processes including climate change and variability are driving the long-term changes in ice seasonality.
Department of Biology, York University, Toronto, Ontario, M3P1J3, Canada.
Sapna
S
Sharma
Center for Limnology, University of Wisconsin-Madison, Madison, Wisconsin, 53706, USA.
John J
JJ
Magnuson
Center for Limnology, University of Wisconsin-Madison, Madison, Wisconsin, 53706, USA.|Department of Ecology, Evolution, and Natural Resources, Rutgers University, New Brunswick, New Jersey, 08901, USA.
Ryan D
RD
Batt
Center for Limnology, University of Wisconsin-Madison, Madison, Wisconsin, 53706, USA.|Center for Integrated Data Analytics, United States Geological Survey, 8505 Research Way, Middleton, Wisconsin, 53562.
Luke A
LA
Winslow
Freshwater Centre, Finnish Environment Institute, Helsinki, FI-00260, Finland.
Johanna
J
Korhonen
Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Osaka, 599-8531, Japan.
Yasuyuki
Y
Aono