Hottest Days Ever? Don’t Believe It

The global-warming industry has declared that July 3 and 4 were the two hottest days on Earth on record. The reported average global temperature on those days was 62.6 degrees Fahrenheit, supposedly the hottest in 125,000 years. The claimed temperature was derived from the University of Maine’s Climate Reanalyzer, which relies on a mix of satellite temperature data and computer-model guesstimation to calculate estimates of temperature.

One obvious problem with the updated narrative is that there are no satellite data from 125,000 years ago. Calculated estimates of current temperatures can’t be fairly compared with guesses of global temperature from thousands of years ago.

A more likely alternative to the 62.6-degree estimate is something around 57.5 degrees. The latter is an average of actual surface temperature measurements taken around the world and processed on a minute-by-minute basis by a website called temperature.global. The numbers have been steady this year, with no spike in July.

Moreover, the notion of “average global temperature” is meaningless. Average global temperature is a concept invented by and for the global-warming hypothesis. It is more a political concept than a scientific one. The Earth and its atmosphere is large and diverse, and no place is meaningfully average.

Average global temperature also changes on seasonal basis: Temperatures are higher globally during the Northern Hemisphere’s summer because of more sunlight-trapping land. In this case, the Climate Reanalyzer’s estimated temperatures in early July were skewed by a heat wave in the Antarctic, where areas may have warmed some Antarctic temperatures by as much as 43 degrees. This is likely the explanation for the difference between the 62.6-degree and 57.5-degree estimates.

Another problem is that our temperature data are imprecise. It has been estimated that 96% of U.S. temperature stations produce corrupted data. About 92% of them reportedly have a margin of error of a full degree Celsius, or nearly 2 degrees Fahrenheit. The lack of precision of reported temperatures, whether estimated or measured, is not reassuring.

Temperature stations also tend to be limited to populated areas. Much of the Earth’s surface isn’t measured at all. Although the National Oceanic and Atmospheric Administration likes to present global temperatures starting in 1880, regular temperature collection in places such as the north and south poles began much later.

It isn’t plausible to characterize Earth’s warming in a single average number, especially when we don’t really know what that number is today, much less from 125,000 years ago.

Mr. Milloy is a senior legal fellow at the Energy and Environment Legal Institute.