Shorter Ice Duration and Changing Phenology Influence Under-Ice Lake Temperature Dynamics.

Area of Science:

• Environmental Science
• Limnology
• Climate Change Research

Background:

• Temperate lakes globally are experiencing reduced ice cover.
• The effects of changing ice phenology on under-ice thermal dynamics are not well understood.

Purpose of the Study:

• To investigate trends, variability, and drivers of ice phenology and under-ice temperatures in a temperate lake.
• To analyze the implications of altered ice cover duration on lake thermal structure.

Main Methods:

• Analysis of a 92-year record of ice phenology (ice formation and ice-off dates).
• Examination of under-ice temperature profiles over 36 years.
• High-frequency under-ice observations during two recent winters.

Main Results:

• Ice formation onset decreased by 23 days per century, linked to rising air temperatures.
• Ice-off dates showed increased variability, explained by spring air temperatures and snowfall.
• Total ice duration decreased by one month and its interannual variability more than doubled.
• Shorter ice duration reduced winter inverse stratification and prolonged spring mixing.

Conclusions:

• Changing ice phenology significantly alters temperate lake thermal dynamics.
• Relying on discrete ice clearance dates can misrepresent under-ice thermal conditions.
• Climate change impacts on ice cover have profound consequences for lake ecosystems.