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Guest Post by Willis Eschenbach

Over in the Tweeterverse I saw that someone said:

NASA GISSTEMP Global Mean went above 1.5C for 2 months in 2016.

Hmmm, sez I … why not since then?

So I thought I’d take a look at the major global surface temperature estimates for the 21st Century.

The datasets that I used are the surface temperature datasets of the Goddard Institute for Space Science (GISS), Hadley Climate Research Unit (HadCRUT), Berkeley Earth, and Japan Meteorological Agency (JMA), along with the Earth’s Radiant Energy System (CERES), University of Alabama Huntsville Microwave Sounding Unit (UAH MSU), and the Remote Sensing Systems Microwave Sounding Unit (RSS MSU) satellite-based datasets.

I’ve done a structural change breakpoint analysis for each one. I have not chosen the breakpoints. They are selected, and their uncertainties estimated, by the Bai & Perron algorithm implemented in the R computer language package “strucchange”.

Here they are, in no particular order:

Surface Station Datasets

Satellite Based Datasets

Clearly, there has been a sea-change in the surface temperature changes in the 21st century. For most of the last half of the 20th century, temperatures were rising on the order of 0.15°C per decade. But this century, for a good part of the period from 2000 to the end of 2014, the rate of rise of most of the datasets was much less than that.

And in all seven of the datasets, since the breakpoint before the 2015/16 El Nino, the temperatures have either been level or dropping …

Hmmm …

One interesting note. The records fall into two groups—the CERES, JMA, RSS and UAH data have very little change up until ~ 2015. But three of the ground-station-based datasets, GISS, HadCRUT, and Berkeley Earth, have a distinct trend change around 2005. Why? Dunno … but it doesn’t increase my confidence in the ground-based data. My guess is that those three ground datasets, GISS, HadCRUT, and Berkeley Earth, are contaminated by the Urban Heat Islands or excessive “homogenization”. However, that’s only a guess.

My very best wishes to all,

w.

PS—Please do us all a favor, and when you comment, QUOTE what you’re talking about. This avoids endless misunderstandings.

PPS—Please be clear that I am not predicting the future—I am reporting on the past …

via Watts Up With That?

May 11, 2022