The chart below compares the yield on the U.S. Treasury's 10-year zero coupon with the 10-year zero coupon inflation swap rate. The difference is the implied 10-year zero coupon real rate, which is becoming increasingly negative. We are not yet in a stagflation environment, but the indicator is certainly starting to point in that direction.
Just to put things into perspective, the CRB Commodity Index broke through 300 today and is now up 14% from its lows. As inflation expectations pick up (due to increasing rents and rising commodity prices), this push into negative real rate territory is only going to get worse.