A subjunctive "were"

"Nor will they want to put their efforts and money into projects that don’t yet have proven financial track records, like many clean energy innovations – which, not incidentally, might have enabled us to meet our targets under the Paris climate accords, were we still part of the Paris accords." (The Guardian.)

Is "were" a subjunctive one in the above? Could it be replaced by "should we be still..." with the same meaning?