Understanding the response of Great Lakes ice coverage to climate change using a threshold model

Session: Large Lakes’ Response to Climate: Past, Present, and Future (1)

Stephanie Nummer, University of Toledo, [email protected]
Song Qian, University of Toledo, [email protected]
Andrew Gronewold, University of Michigan, [email protected]

Abstract

Historically, global average temperatures have stayed rather steady, but has experienced an upward climb in more recent years. This change in temperature impacts the ice coverage of important freshwater systems and associated biodiversity. For example, lake whitefish (Coregonus clupeaformis) -- an important fishery in the Great Lakes -- rely on winter ice coverage in their spawning areas for recruitment. As the long-term average temperature change pattern can be described by the hockey stick model, variables that respond to temperature, such as ice coverage duration, may also be modeled in the same manner. We present a multilevel hockey stick model that is applied to Great Lakes ice coverage data to model the change in peak ice coverage over time. Using the multilevel nature of the model, we can quantify the year that peak ice coverage started to decline and the magnitude of decline for each lake and for the whole region. As a whole, the Great Lakes experienced a shift toward a shorter duration of ice coverage in 1981 (1974/1995) with a shift of 0.8 days less per year (-0.3/-1.3 days). This information can assist managers in deciding the allocation of resources for habitat restoration and other management.

Twitter handle of presenter
@NummerStephanie