As usual with these things, the past has been cooled and the present warmed.
http://www.woodfortrees.org/plot/rss/from:1998/to:2016/plot/rss/from:1998/to:2016/trend
As we know, RSS have been a real thorn in the side of the climate establishment in recent years. Their satellite measured temperature trends have failed to back up claims of rising global temperatures and record years.
This has also been a huge embarrassment to Carl Mears, who is responsible for the dataset.
Well, if you don’t like the data, adjust it!
No doubt under great pressure from above, RSS have now brought out a new version, starting with the Mid Troposphere temperatures, TMT, which in the words of their paper says:
The new dataset shows substantially increased global-scale warming relative to the previous version of the dataset, particularly after 1998.
Let me stress again, this only applies at this stage to the mid troposphere, rather than the lower troposphere which we usually pay attention to. Nevertheless, Mears has made it clear that the latter will be similarly adjusted in due course.
As usual with these things, the past has been cooled and the present warmed.
Although Mears states that this (diurnal adjustments) is the most important change, and leads to substantially more warming during the 1999-2005 period when the NOAA-15 satellite was drifting rapidly, it is apparent that substantial adjustments have been made since 2012 as well. This is often a tell tale sign that adjustments keep accumulating in one direction, rather than making one step change, something we have regularly seen with GISS.
The most recent figure for February 2016 actually increases the old version by 0.178C.
The effect of the change since 1998 in particular is startling. An essentially flat trend has been replaced by 0.74C/C.
All datasets are continually refined, but until now changes to RSS have been much, much smaller, just a few hundredth degrees.