Those are warmings at the strat level - and that warm is going out to space. The blocking and reversal effects are what cause the cold at lower levels. Are we watching burps of heat going to space?
Ah, but the warming is caused by compression of air rather then a radiative effect. They also occur approx every 2 years (although if this one comes off itll be the 4th since feb 2018...) since first observed in '54 (?) They are therefore part of the natural energy balance at a standard frequency.