What does "hottest year' really mean, by Ken Haapala

Source:
http://www.sepp.org/twtwfiles/2021/TWTW%201-916-21.pdf

Last week’s TWTW carried the report of the Earth System Science Center, UAH (satellite), stating: 

 “2020 ended up as 

the 2nd warmest year  

with a departure from the 1981-2010 average 

of +0.49 °C (+0.88 °F) 

... just behind 2016  

with +0.53 °C (+0.95 °F) and 

... just ahead of 1998  

which had +0.48 °C (+0.86 °F). 

Considering the uncertainty of the measurements, these three years could be considered as tied for the warmest year of the 42-year record.”

 

This week ... the Wall Street Journal screamed: “2020 Ties for Hottest Year on Record, NASA Says.”

 

(Ken) Haapala (SEPP President) objected to the article stating:
“You write: ‘In a new climate study, the National Aeronautics and Space Administration ranked 2020 in a dead heat with 2016 as the warmest year since official record-keeping began in 1880.’ 

 

 
What percentage of the globe was covered in 1880?

2%, 3%?

“It is only since September 2002 that we have had comprehensive surface skin temperature trends with the Atmospheric Infrared Sounder, or AIRS.

 

Only since 1978 have we had comprehensive coverage of the atmosphere giving data to estimate temperature trends.

“Before WWII, the global coverage was poor with best coverage for the US.

 

However, the changes to the 1930s US temperatures (lowering) are highly questionable.

“Your readership deserves to be so informed.”

The response was:
“Thank you for your note. 

As you may appreciate, the article concerned the formal public announcements of 2020's annual global land and sea surface temperatures calculated by NASA and NOAA. 

It's important for our readers to have timely information about expert assessments of temperature trends and climate change so that they can make their own well-informed judgements.

In this instance, the article cited 4 independent assessments by 3 different governments. 

The historical issues with the various data sets used by NASA and NOAA that you mention are well-documented publicly, well-debated and, as you note, constantly improved as techniques and new sensors become available. 

In any historical empirical endeavor, you have to use the data you have, as I'm sure you appreciate.” [Boldface added]

Interpret this as you wish. 

UAH (satellite) measurements show 1998 temperatures were comparable to those of 2016 and 2020.

In 1998 the annual average of measurements of CO2 at the observatory in Mauna Loa were 367 parts per million (ppm). 

In 2020 the preliminary annual measurements were 414 ppm, an increase of 47 ppm or 12.8%. 

If CO2 is the control knob of earth’s temperatures, as the director of NASA-GISS has claimed, it is a very sloppy control knob."