Phoenix’s Record Summer Warmth Not Reflected In Surrounding Weather Station Data

A man named Luke Howard was the first to document the urban heat island (UHI) effect, 190 years ago (The Climate of London).

Cities have expanded substantially since 1833, replacing the native landscape with high heat capacity surfaces like buildings, pavement, and sources of waste heat. This leads to UHI warmth today of +10F or more, mostly at night.

The UHI effect, along with “record warm” temperatures it delivers, would exist even if humans didn’t emit a single pound of carbon dioxide into the atmosphere. Yet, we are routinely told through media reports that anomalous city warmth shows ‘the fingerprints of climate change’ and wouldn’t have occurred if we humans had never burnt any coal.

As caterwauled by the Miami Herald, the summer of 2023 experienced some record heat in cities across the South:

Conflating the urban heat island with ‘global boiling’ is an easy win for the MSM, and it is demanded that they do so.

As the Herald’s report dutifully adds: “Prominent scientific institutions around the globe including the National Oceanic and Atmospheric Administration agree that the warming is caused mainly by human-caused greenhouse gas emissions, NASA said.

“See how that works?,” writes former NASA scientist Dr Roy Spencer. “A city has record warmth, so it must be due to global warming caused by burning fossil fuels.”

The southern U.S. had an unusually hot summer, particularly in August — nobody is arguing that.

According to Dr Spencer’s analysis –which used urbanization-adjusted average summer temperatures (based upon NOAA homogenized GHCN surface air temperatures) across all available stations in the Lower 48 states– the summer of 2023 was the 13th warmest on record (since 1895):

Lower-48 (CONUS) summer temp variations, 1895-2023, computed from GHCN “adj” (homogenized) data, versus those data adjusted for the UHI warming estimated from population density.

The media cherry-picks urban reporting stations, or at least airports serving major urban areas, and for good reason — this is where the heat is. Staying in Phoenix, the city’s “record hot summer” doesn’t show up at the surrounding weather stations.

As part of Dr Roy Spencer’s research project –where his team at the University of Huntsville are quantifying the average urban heat island effect and its growth over time as a function of population density– he looked at the official NOAA GHCN monthly surface temperature data at Phoenix Sky Harbor Airport (red curve in the below graph) versus at all rural stations (0 to 100 persons per sq. km) within 10 to 100 km of Phoenix (blue curve below). Spencer also applied a small urbanization adjustment correction at the rural (or nearly-rural) stations based upon their individual histories of population growth.

The result? The summer of 2023 was only the city’s 11th warmest summer on record.

“We see that the urban heat island effect was the dominant cause of the summer of 2023 being a record warm year in Phoenix,” writes Dr Spencer. Clear as day, the surrounding rural and nearly-rural stations held far cooler.

Alarmists will likely point to the blue line and protest that even the rural stations still show a strong warming trend.

“Well,” continues Spencer, “that is partly because I have used only ‘homogenized’ temperature data, which NOAA has already adjusted to some extent leading to all nearby station temperature trends being more or less equal to one another.”

Dr Spencer says he is still trying to determine if he can use the ‘raw’ data to make such comparisons, since there are other data adjustments made in NOAA’s homogenization of the data that I’m not privy to.

One final point: The legacy media routinely parrots NOAA’s claim that these new high temperature records are based upon data extending back to 1895. In general, this is not true, notes Dr Spencer. Most of these station records don’t go back nearly that far. For the Phoenix Sky Harbor location, for example, the data starts in 1933. A few of 2023’s other “record hot cities” start dates are Miami, FL (1948), Houston, TX (1931), and Mobile, AL (1948).

Cities are hotter than their rural surroundings, and increasingly so — this is an undisputed yet rug-swept fact.

Spurious correlations and unsupportable conclusions, however, continue to be front and center of MSM rounds.

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