We know the actual numbers are slight, but I've seen an incremental change on the water. We know it's gotten a bit warmer(the water) and that has changed several dynamics we're well aware of.
On the plus side, swimming. The last two seasons have seen us in the water more times than the last 15-20 all together. A few degrees of seawater rise seems slight, but that rise changes many of the ocean current flow patterns up here.
Seawater temperatures reaching the upper 60's and low 70's were not uncommon in several places like here, Perry Creek last summer. I've 'tested' this water for years as only kids would brave it.
For the sailboat cruising in Maine, anchored on a summer day that will see the air temperatures rise into the low 80's, this-new to us trend, is not such a bad thing.
What will this summer bring? Not as easy to say, the water temperature is a bit less predictable today.