Was 2024 the Hottest Year on Record?
We are often reminded that 2024 was the hottest year on record and that 2023 was the second hottest. The World Meteorological Organization, NOAA, and Copernicus (the European Union equivalent to NOAA) all report this.
Given the considerable amount of expertise that these agencies represent, it would be natural and reasonable to accept their claims. How could anyone say otherwise? But not everyone agrees.
Before I explain, it’s fair to say that 2024 was a hot year by several metrics and the hottest in at least 47 years. The University of Alabama in Huntsville Global Temperature Report nicely illustrates that 2024 was indeed very warm on our planet.
Since 1978, Earth has had satellites capable of measuring microwave radiation coming from the atmosphere. Using that data, Dr. John R. Christy and Dr. Roy Spencer — each with over 40 years experience with temperature datasets — calculate the Monthly Global Lower Troposphere Anomaly. What does that mean? The lower troposphere is our atmosphere from the ground up to about 5 miles in altitude. The anomaly is the difference between the global average air temperature for a particular month and the global average air temperature for the same month from 1991–2020. Dr. Christy explained to The American Spectator that this metric is “far more capable of responding to rising greenhouse gasses than surface temperature, which is influenced by many non-greenhouse gas issues, including poor geographic coverage for large regions of the globe.”
Just below is their latest graph. The increasing temperatures from 2023 to 2024 followed by an overall decrease — with some upward fluctuations — to December 2025 are evident.
Image courtesy of John R. Christy of the University of Alabama in Huntsville
There are several global temperature datasets used by scientists to analyze climate change. Although they probably have more in common than not, they are not identical and each one is managed according to the standards established by the controlling agency. For example, the Copernicus ERA5 dataset has data going back to 1940. Therefore, any high temperature event before 1940 will obviously be excluded in determining the hottest year when using ERA5. The NOAA Merged Land Ocean Global Surface Temperature Analysis (NOAAGlobalTemp) dataset begins in 1850, providing us with a much wider timeline. This is a monthly dataset composed of inputs from the Global Historical Climatology Network (land stations), Extended Reconstructed Sea Surface Temperature (ocean surface temperatures), International Comprehensive Ocean-Atmosphere Data Set (surface marine data), and the International Arctic Buoy Program (Arctic buoy data) that create a comprehensive, gridded global temperature dataset.
NOAA’s map of global temperature trends from 1994–2023
Most pertinent to our question is the fact that NOAA, like most weather agencies, calculates the average temperature (TAVG) of the daily maximum temperature (TMAX) and the daily minimum temperature (TMIN). This average is then fed into the NOAAGlobalTemp dataset that produces its Global Mean Surface Temperature (GMST). NOAA uses TAVG to create temperature trends diagrams such as this one below.
Why is this relevant? According to Dr. Christy, TAVG is influenced by urbanization. This means that higher temperatures found in urban centers relative to their surroundings can distort the true temperature profile. For that reason, he and colleague Dr. Spencer focus on TMAX because it is less influenced by urbanization.
By using TMAX instead of TAVG, the Christy–Spencer team revealed a very different temperature profile for the contiguous 48 states over time, as illustrated in the graph just below. They built this graph by comparing the temperature data for each weather station in one year to the same station in all other years from 1898 to 2025.
Image courtesy of John R. Christy of the University of Alabama in Huntsville
It is obvious that many more TMAX records were set in 1936 compared to 2024 by a wide margin, revealing 1936 as the hottest year on record since 1898 in the U.S.
The Christy–Spencer graph agrees with the Warm Spells and Heat Wave Magnitude Index graphs (shown below), which were published in the Climate Science Special Report Fourth National Climate Assessment, Vol I.
Image published by NOAA
If we widen our perspective even further, the answer changes yet again.
We have temperature data going back 600 million years. In the relatively recent past, we know that the Minoan, Roman, and Medieval warm periods were all warmer than today, as shown in the diagram below.
Image courtesy of William Happer at Princeton University
In southern Greenland, the ruins of about 620 farms from the Medieval period have been discovered. Thousands of hectares were likely farmed at these sites. Farming was mainly animal-based, but evidence of barley grains has been found at several locations. Today, there are about 40 commercial farms in Greenland, and these are mainly focused on sheep farming, although there is some small-scale vegetable production enabled by recent warming and advanced greenhouse technology.
TAVG or TMAX, you decide, but as far as I’m concerned, based on the data that I’ve seen, 2024 wasn’t the hottest year on record in the USA. That honor should belong to 1936.
READ MORE:
Two Retractions Raise the Question: Is Climate Science Really Settled?
The Welcome Demise of Climate Change Catastrophism
Bill Gates Has Discovered Something More Profitable Than the Climate Apocalypse