Global interest rates have only been this low 3 times since 1522

Global bonds have been selling off.

As demand for them has waned and their prices fallen, yields have shot up.

Eurozone yields, notably the German 10-year bund, surged on Wednesday. It touched 0.79%, a roughly 1200% appreciation in just a few weeks.

US Treasury yields followed, with the benchmark 10-year note yielding as much as 2.25%, its highs for the year.

In a note Wednesday, Gluskin Sheff's David Rosenberg takes a massive look back at yields. As in a 500-year look back.

"We have global bond yields going back to the 16th century and only in the 1570s and 1930s have yields been as low as they have been in recent months," Rosenberg wrote.

Even with the recent spike in Treasury yields, Rosenberg points out through this chart just how close they are to turning negative.

Some analysts have argued that's not going to happen, especially with a Fed rate hike in view.

Still, we're right on the edge:

"All it takes is a 50 basis point backup in the 10-year yield and it generates a -2% total return; go back 10 years, and there was still enough of a cushion that the total return in a year's time even with a yield spasm like that would have kept investors in the black. Two decades ago, the coupon was enough to still keep the total return at over +3% with a 50 basis point increase in the yield while a similar move 30 years ago would still result in roughly an 8% total return."

Gluskin Sheff