From Dr. Roy Spencer's Global Warming Blog
Dr. Roy Spencer
Key points:
- For years, some commentators have believed that the highest temperature ever recorded in the world was 134 degrees Celsius. The F recorded in Death Valley, California on July 10, 1913 is physically incredible.
- Here I show quantitatively that a temperature of 134 degrees Fahrenheit is on the high side, about 10 degrees Celsius. F.
- William T has conducted extensive historical research. Reed suggested that those making temperature observations at the Greenland pasture might replace the official measurements from the thermometer in Stevenson's screened shed with other measurements taken next to the adobe settlement.
background
The “official” world record high near-surface temperature is 134 degrees. F, recorded at Greenland Ranch, California, on July 10, 1913, in Death Valley, California, a remote location with no stations of similar location to compare to. Greenland Ranch is a man-made oasis created by the Borax people in the early 20th century, with water piped in from nearby mountains. It's rich in history, but always coupled with summer heat that few visitors (or even workers) can endure.
As part of my new analysis of GHCN's daily high and low temperatures, John Christie suggested I look at temperature data for Death Valley, and its record high of 134 degrees Celsius. The temperature is extremely high. Over the years, some have expressed concerns about 134 degrees. The read rate is incredibly high, but hard to prove. The World Meteorological Organization and NOAA National Weather Service continue to recognize 134 degrees. F is the world record. Death Valley may well still be the hottest place in North America; the world record values in question are here.
To my knowledge, the most extensive meteorological and historical arguments against the record come from a series of blog posts by storm chaser William T. Reid, which was reposted here at Weather Underground until I I didn’t read the article until I had figured out the calculations. I have since read some of what Bill has written and I encourage anyone interested in history to read his extensive summary (along with old photos) of Greenland Ranch, the place where world record temperatures were recorded. He did extensive research in the library and discovered a letter from the ranch foreman expressing disappointment that the 1911 gauge shelter measurements provided by the U.S. Weather Bureau were much lower than the measurements he took under his balcony. Bill suspects (and I agree) that the values reported over time are most likely not from instrumented shelters.
The method I will use to demonstrate that high bias is almost certain is also included in a limited way in Reed's blog post (which contains various meteorological arguments). I will apply this method to all years since 1911 and prove 134 degrees. F records about 10 degrees. Higher than it should be. The analyzes I present are based on NOAA GHCN daily temperatures and apply basic NOAA quality control procedures, so they are from “official” sources. The GHCN data set includes 134 degrees. F records the highest temperature in Death Valley.
How to quality check the world record highest temperature?
The main reason why the world record hottest temperature cannot be easily “fact-checked” is that there were no other weather stations in Death Valley at the time, and the low altitude (below sea level) of Greenland pastures is usually dozens of degrees F is hotter than in mountain stations, which are dozens of miles away and thousands of feet above sea level.
However, from a meteorological perspective, Death Valley in the summer is the best place to quality check the heat from a remote mountain station. Before explaining why, let's take a look at how temperatures in Death Valley compared to temperatures at higher altitude stations this July (in 2024, when temperatures were near record highs) and in July 2013. Plot of mean July high temperature (Tmax) for all stations within 100 miles of the former “Greenland Ranch,” now known as Death Valley National Park (Figure 1) [NP] station). Importantly, I plotted these average temperatures versus station elevation:
Figure 1. Average July maximum temperatures at weather stations within 100 miles of Furnace Creek, California, in 2024 (top) and 1913 (bottom), plotted against station elevation. Regression line applies to all weather stations near Greenland Ranch/Furnace Creek/Death Valley NP
Note the close relationship between site elevation and temperature, also noted by William Reed. It is worth noting that the temperatures at the two lowest elevation stations (Death Valley) in 2024 are very close to the regression line related to how the average July high temperature changes with station height (the two Death Valley stations are below sea level and are not included in the regression middle).
Regression lines can also be calculated in other years and used to statistically estimate the temperatures that should be measured at the Furnace Creek Observatory in Death Valley, based on surrounding high-altitude observatories. This approach allows us to estimate annual Death Valley temperatures, as shown in Figure 2.
Figure 2. Annual estimate of mean July temperature in Furnace Creek, California, based on all available GHCN weather stations within 100 miles of Furnace Creek. Each annual estimate is based on station data for that year. The estimate for July 10, 1913 (the date the world record reading of 134 degrees Fahrenheit was reported) was 10 degrees lower than the world record reading of 124 degrees Fahrenheit. F. This 1-day estimate is based only on surrounding stations on that date. Note that the value in 2024 is about 0.5 degrees. F is higher than the 1931 value.
Meteorological justification for the method
For reliable meteorological reasons, one can check Death Valley temperatures in July using fairly distant high-altitude stations. (Keep in mind, my formal training is as a meteorologist…I only work in climate because it pays better. I actually measured GHCN while interning at the National Weather Service office in the summer of the late 1970s Some temperature measurements included in the data set.
In short, during the warm season of dry, semi-desert, or desert climates, daytime temperatures vary with altitude in a predictable and repeatable manner, with little variation over considerable distances. Figure 1 shows evidence of this. This makes Death Valley in July one of the best places on Earth to fact-check very warm temperature values. This applies very well to the American Southwest in the summer (at least before the monsoon rains arrive), where a semi-permanent ridge of high pressure forms every May through July, and the slowly sinking (sinking) air creates mostly clear skies. This weather feature has a large, uniform regional extent (unlike a trough of low pressure, which changes sharply with strong horizontal temperature changes; this is related to the so-called “Rosby radius of deformation.”)
Briefly, the stable warm high-pressure air mass over the southwestern United States in July is spatially homogeneous, with strong daytime vertical mixing producing temperature lapse rates approaching dry adiabatic values. This makes it possible to compare temperatures at a site 100 miles away, for example. Therefore, large differences in temperature between adjacent sites are primarily due to altitude. In dry climates, summer daytime temperatures decrease rapidly with altitude (see image above), providing the perfect meteorological conditions for making the comparisons I describe here.
Greenland Ranch/Furnace Creek/Death Valley National Park Estimate Bias for July
Finally, we can examine the difference between Death Valley mean July temperatures reported by GHCN data and estimates from surrounding sites (Fig. 3).
Figure 3. Estimated deviations from the official GHCN July mean temperature in Death Valley, California, based on comparison with estimates for Death Valley from all weather stations within 100 miles of Furnace Creek. 1-2 degrees. Most of the recorded F-mean deviations are most likely not actual deviations in the official measurements, but deviations in the described methods.
Note that there was a significant warm bias in reported temperatures in Greenland pastures during the first 10-15 years after the USWB installed instrumented shelters. As Bill Reid speculated, the ranch foreman was most likely reporting the value of another poorly exposed thermometer next to the building. Also shown in green is data from a nearby site called Cow Creek (5 miles away, essentially the same elevation). Note that for nearly a decade, temperature estimates from observatories around Death Valley are consistent with current measurements from observatories in Death Valley National Park.
Bottom line, I believe there is enough quantitative evidence to suggest 134 degrees. F The world record hottest temperature is as high as 10 degrees, which is still recognized by WMO and NWS. F is too hot, possibly due to observer error. Again, for those interested in the history of Greenland's pastures, including the stories of those who died trying to escape the sweltering summer heat, start here to read the fascinating history revealed by Bill Reed.
Relevant
