A good deal of air has been let out of what remained of the "no global warming" argument.
As far as I can tell from the article and from a conversation with my meteorologist officemate, it goes like this:
One of the most important disagreements between observations and climatology models has been the daytime upper-atmosphere temperatures, which have been nonintuitively trending *downwards* since the Seventies, while everything else has been trending upwards, including *nightime* upper-atmosphere temperatures. What these guys from California are arguing is that this anomalous cooling trend is an artifact of improvements in weather-balloon technology.
The sensor-packages get warmed by direct sunlight, and the heat shielding technology before the mid-Seventies weren't good enough to keep this from biasing the temperature results. Whenever they introduced better shielding in the weather balloons used by a station or service, a discontinuity resulted in the data-stream. Since weather satellites' remote-sensing results were directly calibrated to the weather-balloon direct-sensing data, this bias was also present in pre-improvement satellite data as well, and if the re-calibration was done eventually against the new weather-balloons, the satellite data would no doubt have had something of a delay discontinuity, as they trumbled along on their own, only later being re-calibrated to the "new" standard temperatures. As my officemate notes, this should have been detected in the initial testing of the new technology, and probably can be demonstrated by running both sets of sensor packages off of the same weather-balloon, if you can still find the old models.
As far as I can tell, though, it seems as if authors of previous studies knew about the discontinuity effect, and had adjusted for it in some fashion. From some rather cryptic comments in the last third of the linked article, it sounds as if the authors of the new study are of the opinion that the previous corrections were incorrectly done, and that the discontinuity wasn't properly removed by the method used. Essentially, it's the same story as the infamous "hockey-stick", except it's biting against the anti-warming case this time. I can't go any further on that line without knowing more than what we're given in this article, and it's almost certain that I wouldn't understand the math specifics if I had them.
My officemate said that he never really credited the "no warming" argument, and points to significant Arctic icemelt and Alaskan permafrost melting as more important signifiers anyways. But he's not generally a "hair-on-fire" kind of guy, so YMMV.
HT to the guys at Rantburg, even if they don't seem to understand why an erroneously warmer Seventies and normal Eighties-to-the-present would give a false-positive cooling trend appearance.