Trenberth writes that the recent Karl et al paper skimped on trends by using 1950 as a starting date:
and notes that global surface temperature rises in a step-by-step fashion instead of a monotonic increase:
and that, now that the PDO (Pacific Decadal Oscillation; data here) has flipped to its positive phase, we may be stepping up again.
"There is speculation whether the latest El Niño event and a strong switch in the sign of the PDO since early 2014 (see the figure) mean that the GMST is stepping up again. The combination of decadal variability and a trend from increasing greenhouse gases makes the GMST record more like a rising staircase than a monotonic rise. As greenhouse gas concentrations rise further, a negative decadal trend in GMST becomes less likely (13). But there will be fluctuations in rates of warming and big regional variations associated with natural variability. It is important to expect these and plan for them."Which means, I guess, that after this temperature step increase levels off, we get to do the hiatus all over again. Deniers, save your posts for reuse.