A recent article from the climate desk at Philadelphia’s WHYY news titled “‘Fingerprint of climate change’: April heat wave could break a record in Philadelphia,” claims that warm temperatures in the Mid-Atlantic this week are evidence of long-term global warming. [some emphasis, links added]
This is false.
While it is true that average, long-term global temperatures have modestly increased since the Industrial Revolution, heatwaves like those forecast for the East Coast are not evidence of any emergency, and also are not becoming more frequent or severe.
A high-pressure ridge in the Atlantic Ocean is causing warmer air to sweep up the Southeastern United States and Mid-Atlantic states, bringing a springtime heatwave.
That’s a short-term meteorological event, which is normally referred to as weather, not a long-term change in the average temperature and prevailing conditions for a region, which is climate.
WHYY News says “climate analysts say these hot temperatures fit into a trend of warming spring weather,” quoting a researcher at the climate action advocacy group Climate Central, saying the heatwave has a “fingerprint of climate change,” as proof.
Indeed, some data indicate that spring weather conditions are arriving a few days earlier in recent years than they did a hundred-plus years ago in some locations; however, this does not mean that severe spikes in temperature are the drivers of those changes.
In fact, it is a less severe cold driving the trend, not more severe warmth.
For example, the article and Climate Central point to Philadelphia, PA, as one of the regions expected to see unseasonal warmth this spring, saying, “Since 1970, Philadelphia’s average spring temperatures have risen roughly 3 degrees, according to Climate Central.”
They say that climate change is what “makes this week’s high temperatures in Philadelphia twice as likely, according to the organization’s Climate Shift Index, which uses models to compare today’s world to a world without human-caused carbon pollution.”
There are major flaws and bad science in this reasoning.
Data show that temperatures for the entire state of Pennsylvania have only increased on average by around 2 °F since 1900, meaning that Philadelphia’s 3 ° F of warming since 1970 (if we assume Climate Central is correct) is higher over the past half-century than the average for the state as a whole over the past 125 years.
This is actually not a surprise, and it has nothing to do with “human-caused carbon pollution.”
The higher warming rate in a city like Philly, like with other highly urbanized regions around the country, has everything to do with increased population density and associated development, producing the urban heat island (UHI) effect.
This UHI effect was recently described by both an analysis of urban temperature stations in extremely hot places like Reno, Nevada, by meteorologist Anthony Watts, as well as broader, summertime satellite-based measurements of temperatures by Dr. Roy Spencer, who found between the years 1895 and 2023:
[f]or the average “suburban” (100-1,000 persons per sq. km) station, UHI is 52% of the calculated temperature trend, and 67% of the urban station trend (>1,000 persons per sq. km). This means warming has been exaggerated by at least a factor of 2 (100%).
This analysis was for summertime temperatures, but what’s true of summer is true of spring because the built-up, heat-retaining environment is the same.
Additionally, data from the National Oceanic and Atmospheric Administration’s (NOAA) state climate summaries show that heat spikes are not getting more common.
Rather, the slight, long-term rise in temperatures is due to days and nights with extremely low temperatures becoming less common, and nighttime temperatures (which are particularly influenced by UHI) are modestly warmer than they were a few decades ago.
Indeed, data indicate that instances of extreme warmth are actually less prevalent today than they were in the mid-twentieth century:
Climate Central and WHYY fail to reference any real-world data, opting instead to simply assert without providing proof that it is warming in general.
Instead of data, they point people to an attribution study that compares two models of the world—both fictional, both loaded with assumptions on the part of the researchers and other climate scientists—to prove climate change is causing heatwaves.
Models are not data, and, as such, attribution studies don’t provide evidence of warming.
Climate Realism has discussed many times why it is invalid to use a model that assumes what it is setting out to prove: that climate change is responsible for any given weather event.
Base models, which these attribution studies rely on, have failed to accurately predict real-world temperature change, and the vast majority of supposed extreme weather trends they predict have failed to materialize.
Just as a single month’s unusual cold is not proof that the planet is cooling, a single month’s unusual warmth is likewise not some “fingerprint” of a climate emergency.
It is shameful that WHYY and other media outlets do not undertake some basic research before publishing alarming climate stories. Referencing long-term data would result in a fact-based and nuanced scientific view of weather.
Instead of harming their audience, they produce hyperbolic stories based on fearmongering grounded in unscientific attribution modeling done by groups like Climate Central.
A week of warm weather after months of dreary early spring cold is hardly alarming and certainly provides no evidence that catastrophic climate change caused by humans is underway.
Read more at Climate Realism
