[Ed. – I hope our scientists aren’t seriously so blind that they consider only the possibility of warming induced by surface conditions. It seems at least as likely that influences from under Earth’s mantle are also in play. The Great Lakes are the size of inland seas and deep in places.]
“These changes may seem very small, a couple tenths of a degree per decade, but this has been going on for several decades now, perhaps longer than is reflected in our monitoring,” said Craig Stow, a NOAA Great Lakes Environmental Research Laboratory scientist and author of the study. …
“We’ve known for a while now based on surface temperatures — not just in Lake Michigan but smaller lakes and large lakes worldwide — that the surface temperatures seem to be increasing,” Stow said.
Lake Michigan surface temperatures are estimated to be warming at a rate of as much as a third to a fourth of a degree Celsius per decade.
But the story of what’s going on as far as 460 feet below the surface is sparse. Deep water understandings had previously relied on translating surface data or limited observations.