Last updated by The POOG on January 10, 2021.

Global temperature is a surprisingly difficult concept to quantify by measurement. Traditional methods using thermometers have only been in use since the seventeenth century[1].

Historical Data

Significant temperature risks to our society are all related to global cooling. That mammoths have been found flash frozen with stomach material undigested suggests that extreme and rapid cooling events may be possible. In any case, another grand solar minimum (GSM) with reduced temperatures over a decade or several decades means reduced harvest with starvation and increasing disease. Indeed past such minima have correlated with the fall of empires (see Figure 1). On the other hand, during warming periods, civilizations flourished.

Figure 1. Source: Ice Age Now.

Figure 3 of the Vostock ice core data in our article CO2 shows a cyclical pattern of glaciation lasting roughly 100,000 years. If the pattern continues then we are near the en of an inter-glacial warm period and should be expecting a relatively steep drop of temperature in geological time scale, of 10 degrees Kelvin (Celsius).

Determinations of solar minima are based on sunspot cycles. We are beginning solar cycle 25 having reached the bottom of the last cycle in 2019-2020. There is a wide range of estimation of the strength of cycle 25. The average estimate is that it will be about the same strength as cycle 24 before descending into the next GSM.

Satellite Data

The original means of measuring temperature was the mercury thermometer. In 1979, the National Oceanic and Atmospheric Administration (NOAA) launched the first of a series of satellites to measure atmospheric temperature. Satellite data is a more accurate measure of global temperature because the satellites cover most of the globe. Thermometers are not arranged to give good geographic coverage and can’t give consistent ocean coverage.

Dr. Roy Spencer and his colleagues produce a monthly temperature figure, available at At the time of this writing in October, 2020, the most recent data is:

Figure 2. Source: Roy Spencer, UAH.

The graph shows the important distinction between weather data (blue) and climate data (red). Climate is the longer-term average of weather data, in this case a 13-year simple moving average.

Fudging the Data

Tony Heller explains how NOAA falsifies temperature records to warm them up.

Figure 3. Source: Tony Heller.

An important observation which has been made by others in the past is that large areas of the globe have no thermometers for official data recording, while other vast areas have at most a handful. To get a “global” record one must make gross assumptions and manipulate the data extensively. Heller in the video, references the decline in the number of US thermometers and this is true globally. So why not use satellite measurements that do give a global data set?

So let’s go to the source of the land temperature data, NOAA:

Figure 4. Source: NOAA>

Heller also has a three-part video series showing how NOAA fudges US Temperature data:

Figure 5. Source: Tony Heller.
Figure 6. Source: Tony Heller.
Figure 7. Source: Tony Heller.

Sea Surface Temperature

NOAA measures and publishes global Sea Surface Temperature (SST) Contour Charts.

Figure 8. Sea Surface Temperature (SST) Contour Chart. NOAA.



  1. Mary Bellis. The History of the Thermometer. ThoughtCo., May 07, 2019.