For the likes of Paul Krugman, the Riksbank provides a cautionary tale for central banks wary of committing so-called "policy mistakes."

Back in 2010, the bank started to hike rates. That decision halted a decline in unemployment and shortly thereafter, it became apparent that "the rock star of the recovery had turned itself into Japan." Or so Krugman says.

He went on to blame the "error" on "Sadomonetarism," which he hilariously described as "an attitude, common among monetary officials and commentators, that involves a visceral dislike for low interest rates and easy money, even when unemployment is high and inflation is low."

If these "sadomonetarists" are indeed "common among monetary officials," then it's news to us because everywhere you turn, DM central bankers have plunged headlong into the Keynesian abyss as NIRP proliferates and QE continues unabated in Europe, Japan, and yes, in Sweden, where the Riksbank made a U-turn in 2011 on the way to pushing rates deeply into negative territory.

Here's where the world stands as it relates to NIRP.

The question one might fairly ask Krugman is why the world is still stuck with a stubborn deflationary impulse 8 years after Ben Bernanke mustered the "courage" to print. Central banks have eased, and eased, and eased and yet inflation is still below target (and that's putting it nicely) while global growth and trade remain stuck in the doldrums.

It could be that the competitive nature of the rate cuts and QE expansion ultimately mean that no one gets to enjoy the benefits - or at least not for long. One round of easing simply offsets another in an endless race to some lunatic bottom or, ultimately, towards the abolition of cash. Or it could simply be that this isn't the answer when it comes to juicing aggregate demand. But whatever the case, it's pretty clear that what the global central banker cabal is doing simply isn't working. What's not clear - and this is the scary part - is what the consequences of these policies will ultimately be.

On Monday, we got a look at minutes from the latest Riksbank meeting and Deputy Governor Martin Floden is getting concerned. "The Riksbank has started to approach limit to how much it can cut rate without weakening impact or problems arising," he warned. "Monetary policy tools are becoming increasingly difficult to use," he continued, adding that "it's likely that interest rate cut won't have full impact on lending rates to households and companies."

In the same vein, Denmark's central bank governor, Lars Rohde says monetary policy has reached its limit. "We have reached a point where monetary policy no longer has a big overall impact,'' he said on Monday. "[It's] overstreched [and] there's a limit to what more one can do'."