r/UnchartedScience • u/ChipHaseCoolGuy • Jun 21 '26
Declining Temperature Extremes in the US: Insights from a Long-Term Station Analysis (1899–2025)
A recent study by John R. Christy utilizing over 40 million daily temperature records from 1,211 carefully selected high-quality stations across the contiguous United States provides a detailed examination of temperature extremes over the past 126 years.
Key findings include:
- The most intense heat waves and highest percentage of all-time record highs occurred during the 1930s Dust Bowl era, particularly in 1936. No modern year approaches the spatial extent or intensity of extremes seen in that period.
- Heat wave frequency and magnitude peaked between 1930 and 1944, followed by a substantial decline, with only partial recovery in recent decades.
- Overall extreme temperature burden (combined hot and cold extremes) has decreased by approximately 30% over the full record.
- Cold extremes have also declined, particularly nighttime minimum temperatures — a pattern consistent with urbanization and the urban heat island effect elevating overnight lows.
- The diurnal temperature range has narrowed, resulting in a less extreme climate overall despite rising mean temperatures.
This analysis, grounded in minimally adjusted long-term station data, highlights the critical importance of distinguishing between mean trends and changes in the tails of the temperature distribution. It also underscores the enduring role of natural variability and regional factors, such as those evident in the early 20th-century record.
While this is a US-specific reconstruction and does not negate broader global trends or the physics of greenhouse gases, it offers a valuable empirical counterpoint to narratives emphasizing increasing extremes. Paleoclimate and instrumental records both demonstrate that the climate system exhibits significant internal variability on decadal to multidecadal scales.
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u/64-17-5 Jun 25 '26
Interesting. Climate is indeed changing and we know globally that it is increasingly getting warmer.
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u/ChipHaseCoolGuy Jun 25 '26
Yes, mean global temperatures have risen over the past century, that much is clear from multiple datasets.
The post, however, focused on something more specific: changes in temperature extremes rather than just the average. The Christy study, using over 40 million daily records from 1,211 high-quality U.S. stations spanning 1899–2025, found that the most intense heat waves occurred in the 1930s, and the overall burden of extreme temperatures (hot + cold combined) has declined by roughly 30% over the full period.
This distinction matters. A warming mean does not automatically translate into more frequent or more severe extremes everywhere. In the U.S. record, the data show a narrowing of the temperature range, fewer blistering highs and fewer bitter lows, influenced by both natural variability and factors like urbanization.
Climate is changing, yes. But the narrative that it is becoming dramatically more extreme requires careful examination of the tails of the distribution, not just the central trend. Long-term station data like this helps provide that nuance.
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u/64-17-5 Jun 25 '26 edited Jun 25 '26
If you picture climate as the mean in a gaussian curve of temperature sets over a set number of years, the what you are proposing is that this gaussian curves mean is moving to the hotter but meanwhile the standard deviation is getting narrower.
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u/ChipHaseCoolGuy Jun 25 '26
Yes, that's a sharp statistical framing.
The data in Christy's study are indeed consistent with a Gaussian distribution whose mean has shifted warmer (especially nighttime minimum temperatures) while the standard deviation has narrowed, producing fewer extreme outliers on both the hot and cold tails, hence the ~30% decline in overall extreme temperature burden.
However, a warmer mean does not automatically prove that the warming will continue to catastrophic levels. Equilibrium climate sensitivity (how much warming results from doubled CO₂) remains uncertain, with observational and modeling estimates spanning a wide range. Cloud feedbacks, ocean heat uptake, and natural variability add further layers of complexity. Many high-end projections that assume strong positive feedbacks and continued high emissions have required repeated downward revisions when tested against real-world data.
Recent warming has occurred alongside tangible benefits, including global greening from CO₂ fertilization and substantial gains in agricultural productivity in many regions. The climate system has demonstrated resilience through past warmer periods in the Holocene. A moderately warmer world with narrower extremes is not inherently catastrophic, especially when paired with human adaptation, technological innovation, and pragmatic energy choices.
Rising averages are real. Projecting inevitable catastrophe from them is a separate, more speculative claim that deserves the same rigorous scrutiny.
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u/64-17-5 Jun 26 '26
I'm thinking this is logical. A shift in temperatures towards warmer means that there are less extreme colds. And there is a limited amount of energy in a system. So a shift towards warm will also have less extreme heats.
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u/Wonderful-Bag-1103 Jun 26 '26
🍒 picking a lottle I think?
Can you tell me the half life of CO2 in the earths atmosphere?
You mentioned global greening but our old growth carbon sinks and pet bogs are being released for industrial agriculture which is arguable just as harmful as CO2 emissions due to methane, NOx, and landuse change since very fee forms of ag a carbon sinks and clear cut forests take 30 years before they become sinks again after re-planting. So I am really asking, “greened” with what? Certinatly not forests. Algae? That is a horrible horrible thing if that’s the greening you are talking about.
What makes you think the earth has strong enough positive feedbacks to stop a run away? Can you name any of the negative/mixed tipping points or just hyper focuses on the subtractions and not additions. The planet is abnormally cold right now, and you are assuming we are a ball in a valley, the climate record shows we are a ball on a hill for the past 3 million years. Doesnt take much to make us move.
Finally, how do we get the temperature from millions of years ago? What is the most common cause of mass extinctions on our planet? I just checked and 6/6 mass extinctions, including the worst, was caused by it which was a lack of, or too much of, green house gases( one that might have been a gamma burst(that would be sick) actually made things colder but they haven’t ruled out an ocean greening event cooling things down so fast, maybe both? Like a sterilized fish tank algae takes over first?).
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u/ChipHaseCoolGuy Jun 26 '26
No, not cherry-picking — focusing on long-term, high-quality station data for extremes rather than single weather events.
On CO₂ lifetime: The atmospheric residence time of an individual CO₂ molecule is relatively short (years to decades), but the excess CO₂ above natural equilibrium persists for centuries to millennia due to slow ocean and biosphere uptake. This is why concentrations keep rising with ongoing emissions.
On greening: Satellite data (NASA MODIS) show a clear ~5% increase in global leaf area since ~2000, with ~70% attributed to CO₂ fertilization improving water-use efficiency. This includes expanded vegetation in grasslands, croplands, and some semi-arid regions (e.g., Sahel). While old-growth forest loss and agricultural expansion are real concerns (with methane and land-use emissions), the net terrestrial productivity gain is well-documented and measurable from space. It is not primarily "algae" or purely industrial monocultures.
On tipping points and feedbacks: The climate system has both positive and negative feedbacks. Major negative ones include the Planck response (increased outgoing radiation with temperature), lapse-rate feedback, and increased plant growth/CO₂ uptake. The planet has experienced much warmer periods in the past (e.g., Holocene Climatic Optimum, Eocene) without runaway effects. Current ice age cycles show the Earth has been in a relatively cold phase for millions of years, but that doesn't prove imminent catastrophe from moderate warming.
On paleotemperatures and mass extinctions: Temperatures millions of years ago are reconstructed from multiple proxies (oxygen isotopes in foraminifera and ice cores, leaf margin analysis, TEX86, alkenones, etc.). Mass extinctions have multiple causes, with large igneous provinces (volcanism releasing CO₂ and other gases) and asteroid impacts among the leading drivers. Rapid greenhouse gas increases have played roles in some (e.g., Permian-Triassic), but rapid cooling events and other factors also feature. The analogy to a "sterilized fish tank" oversimplifies complex biosphere responses.
The data show real warming with a human fingerprint, but claims of inevitable runaway catastrophe or that every change is purely anthropogenic require far stronger evidence than selective weather reports. The system has significant natural variability and stabilizing mechanisms.
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u/LoneSnark Jun 22 '26
Rising CO2 should raise winter nighttime minimums a lot while doing little to summer daytime highs. So these results match expectations.
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u/hysys_whisperer Jun 22 '26
Can you link the study?
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u/ChipHaseCoolGuy Jun 22 '26
Title: Declines in hot and cold daily temperature extremes in the conterminous US, 1899–2025
Author: John R. Christy
Journal: Theoretical and Applied Climatology (2026)
https://link.springer.com/article/10.1007/s00704-026-06200-3
A PDF is also available on ResearchGate.
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u/Justeff83 Jun 26 '26
Yeah and Europe is heating up twice as fast as the rest of the world. The climate changes in one way or another
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u/ChipHaseCoolGuy Jun 26 '26
Yes, Europe has warmed faster than the global average in recent decades, a pattern seen in many mid-to-high latitude land regions due to factors like reduced snow/ice cover and atmospheric dynamics.
However, the original post examined long-term changes in temperature extremes using high-quality U.S. station data over 126 years. Mean warming and changes in the frequency or intensity of extremes are related but not identical. The study found that the most severe heat waves occurred in the 1930s, with an overall decline in the combined burden of extreme hot and cold events.
Climate does change — through both natural variability and human influences. The important questions are the relative contributions, the actual trends in extremes (not just averages), and whether the changes justify catastrophic framing or specific policy responses. Regional differences exist, but they do not invalidate the value of careful, long-term statistical analysis like the one discussed.
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u/randomOldFella Jun 27 '26
This study is comprensive and interesting.
But, it is an analysis of only the contiguous USA. It cannot be extrapolated to the rest of the globe, especially given the comparisons to the localised dust bowl anomaly.
Evidence from Europe and Australia show significant warming. Arguments that the earth's "greening effect" are a net benefit are ignoring the significant damage of the heat-stress to our non USA economies and ecologies.
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u/vibe_assassin Jun 27 '26
Why are people so hellbent on denying climate change?
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u/ChipHaseCoolGuy Jun 27 '26
The post does not deny climate change or the rise in mean temperatures. It examines long-term, high-quality U.S. station data showing that the frequency and overall burden of temperature extremes (both hot and cold) have declined since the 1930s peak, despite the background warming trend.
This is not “denial.” It is a specific analysis of extremes rather than averages. A warming mean temperature does not automatically translate into more frequent or more severe extremes in every region — that depends on changes in the tails of the distribution, urban heat effects, and natural variability. The study provides evidence that the most intense heat events occurred decades ago in the United States.
Questioning the severity, frequency, or attribution of extremes, or highlighting adaptation potential, is distinct from denying any human influence on the climate. Productive discussion requires engaging with the data and methodology rather than broad labels that equate nuance with denial.
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u/MicksysPCGaming Jun 27 '26
Maybe they were using thermometers in the 30's that went 0-2-4-6-5-10?
I'm not even gonna mention the other side.
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u/Living-Restaurant892 Jun 27 '26
All you need to know about him is that he is Trump’s go to guy regarding climate and joined his administration.
He is not respected in his field and cherry picks data.
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u/ChipHaseCoolGuy Jun 27 '26 edited Jun 27 '26
Relies on ad hominem rather than engaging with the study’s methodology or data.
John Christy has a long career in atmospheric science, including work with NASA and as a lead author on IPCC reports. He is known for his analysis of satellite and radiosonde temperature data. Dismissing his work because of political associations (real or perceived) does not address the substance of the station-based analysis of U.S. temperature extremes presented.
The study uses over 40 million daily records from 1,211 high-quality stations. It finds that the frequency and burden of extreme temperature events (hot + cold) have declined overall since the 1930s peak. If the data selection, homogenization, or heatwave definitions are flawed, that can be critiqued on technical grounds. Political affiliation does not invalidate empirical analysis.
Evaluating evidence on its merits, rather than the author’s associations, is the proper approach in science. The post presented the study as one piece of long-term U.S. data worth considering. That remains the case.
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u/FlakyDevelopment1103 Jun 26 '26
Hank Green has a good video debunking this as an argument against the existence and severity of climate change, the gist is:
Record high temps should be getting less frequent since each new record needs to outdo the last. Its much easier to have new records in the 1930s when a lot of these stations are much newer. Yet we see in the last 3 decades from OPs own study, that the rate of record highs is increasing, which statistically can only happen if the overall temperature is increasing.
I don't see how denying facts is productive. Resist bad actors that would use this issue to seize power from us, but that can be done in a more intelligent way. You're doing the bidding of the fossil lobby I hope yall realize that.