Global warming appears to have shifted into a faster gear. After removing the effects of El Niño, volcanic eruptions, and solar cycles, researchers found that the planet has warmed at roughly 0.35°C per decade over the past ten years, compared with just under 0.2°C per decade from 1970 to 2015. The acceleration, which becomes visible around 2013 to 2015, appeared across five major global temperature datasets with more than 98% statistical certainty.
I don’t think that last bit is right, see my other comment to FireRetardant’s reply. I think the increase in warming rate is basically instantaneous (maybe a few months for atmospheric mixing), it’s the peak of temperature/heat that is delayed (agreeing with your 3rd paragraph)