4. Conclusions
This study assesses trends of year-over-year variability in both
observed Laurentian Great Lake levels and net basin supply components.
Our analysis found definitive statistical evidence of robustly
increasing interannual variability in both the levels of individual
Great Lakes – outside of well-regulated Lake Ontario – as well as in
the individual hydrologic components of lake levels across all basins.
These rises in variability coincide with a period of observed
intensification of the hydrologic cycle due to anthropogenic-driven
changes in climate (IPCC, 2021).
Other potential factors
contributing to the trends we observe here include changes in
precipitation caused by evolving aerosol concentrations, changes in land
use and urbanization, shifts in historical measurement availability and
accuracy, and, in the case of lake level variability, changes in water
level management and regulation (REF). Regardless of cause, our
characterization of trends in interannual variability necessitates
future work to determine if these increasing trends in hydrologic
variability will persist in future climate states, as well as how this
shift in the physical climate system will impact society and the
environment.