A $2.3 billion bond issue from one of the major banks is fairly common, almost run-of-the-mill and, so far this month, there has been at least six $1 billion plus bond sales from the majors. However, the latest Westpac bond sale is a little different from the regular everyday bond sale; of the two tranches, one is "green". Green bonds, also known as climate bonds, are a relatively new innovation...