Frank Lansner writes via email:
I just want to make sure that people are aware of this little maybe-oddity regarding argumentation for ERSSTv4 data changes due to the shift from ship measurements to buoys.
We are all focusing on the data changes ERSSTv3b to ERSSTv4 after year 2003 as these affect the pause.
And so the argument goes, that it’s the shift to buoys that makes warm-changes necessary in ERSSTv4.
But if so, what about the period 1986 to 2003 ? In this period we have an increase from around 8% to 50% use of buoys.
So why is it not necessary to warm adjust 1986-2003, just like 2003 – 2016 ?
I’m aware that this may have been addressed many times, but I just have not noticed.
Data of buoy fractions In % are estimates from this article:
Until 2006 percentage values are read from the graphic in the article. And in addition they write that the fraction of buoys after 2006 is above 70%. Thus the 2007-2016 number are just reflecting that we are over 70 % in 2015.
But the point remains, buoy fraction when up to 50% in 2003 but was only accompanied by still colder temperature adjustments.
So, there “should” be a very important reason to cold adjust around 1986-2000 – that dominates over the “necessary” warm adjustment due to buoys.