This week on Climate Change Roundtable, host Anthony Watts and panelists Linnea Lueken and H. Sterling Burnett will talk about the big white elephant in the climate room: UHI.
The Urban Heat Island effect (UHI) has been known for decades, but it is routinely dismissed by climate advocates as being either insignificant or “we adjust for it” when they really don’t.
We will be joined by Dr. Roy Spencer on the University of Alabama, Huntsville who will talk about his new UHI dataset, which shows clearly that the effect is not just strong in the United States, but elsewhere in the world. He’s found some amazing things that we’ll illustrate with maps.
Join us on Climate Change Roundtable #87. URBAN HEAT ISLAND EFFECT – Dramatic New Findings! We’ll also cover the crazy climate news of the week and take your questions.
Climate Change Roundtable is live every Friday at 12pm CT/1PM ET. Make sure to join the live show and leave your questions for our panelists. And if you want to be sure your question is answered, leave your question as a super chat and we’ll guarantee we will cover your question.
Watch live here:
I first became properly acquainted with the urban heat island effect about 15 years ago when I got my first car that displayed the outside temperature.
I was living 10 miles outside Edinburgh at the time and the difference between home and the city centre was consistently between 3° and 5°C depending on weather conditions and time of day.
Nobody should be in any doubt that it exists and to shrug it off as insignificant is simply dishonest. But then …….
Everybody accepts it exists.
But the climate enthusiasts need to accept that UHI is not temperature – it’s a measure of urban activity. By mixing UHI and temperature readings in the same datasets they have hopelessly contaminated them to the point where they are completely useless. An arbitrary ‘adjustment’ is worse than useless as each UHI area is different and changes at different times and different seasons – the only way to ensure ‘clean’ readings is to take temperature readings away from UHI areas. To keep using the same contaminated datasets with the information we have now is knowingly dishonest or fraudulent.
Or you could tip all of the readings from all the weather stations around the world and satellites into one gynormous spreadsheet column, total the rows, then divide by the number of entries, and hey presto – you have an “average global temperature” that you can use as a basis for making decisions that impact energy policies for the next 70 years.
(or is that like mixing one cup of paint from every color and hue in the spectrum and calling the result “average global surface color”?)
That’s not a global average. That’s a station average.
Why don’t we try it anyway?
Gotta be better then anything that’s being used at the moment 🙁
You can certainly do that, but 1) you won’t like the result and 2) it would not be the global average.
It is however, what the alarmists do.
Who are these “alarmists” that compute a trivial station average and present it as a global average? I ask because I track most of the major global average temperature dataset and not a single one of them takes a trivial station average and presents it as a global average.
Global Average Temperature has no basis in Physics.
I’ll let you pick that fight with Dr. Spencer, Dr. Christy, and Anthony Watts on your own.
All three would agree with Graemethecat.
Now you can argue with yourself, budgerigar.
If all 3 think the global average temperature has no basis in physics then why are all 3 promoting it?
Very glad you finally realise that the surface data sets CANNOT give a true representation of whole of globe temperatures.
Well Done !
Especially when said data set is a total mess…
https://robert-boyle-publishing.com/product/audit-of-the-hadcrut4-global-temperature-dataset-mclean-2018/
“The overall conclusion (see chapter 10) is that the data is not fit for global studies. Data prior to 1950 suffers from poor coverage and very likely multiple incorrect adjustments of station data. Data since that year has better coverage but still has the problem of data adjustments and a host of other issues mentioned in the audit.
Calculating the correct temperatures would require a huge amount of detailed data, time and effort, which is beyond the scope of this audit and perhaps even impossible. The primary conclusion of the audit is however that the dataset shows exaggerated warming and that global averages are far less certain than have been claimed.
One implication of the audit is that climate models have been tuned to match incorrect data, which would render incorrect their predictions of future temperatures and estimates of the human influence of temperatures.”
I’ve looked at 40 stations on the NOAA dataset in the state of New York, that claim to have contiguous daily temperature high and low for the last 100 years. Nine of those stations actually have data with fewer than 5% of the records missing. The rest are useless. Averaging those 40 stations would result in gibberish.
Alarmists accept that it exists, however they deny that it is increasing.
What is it about alarmists and their ability to tell, at best, only half truths.
My heating bill would be a lot higher without UHI…
I live in a medium sized town in Southern California. The town is split by a modest mountain range with 66,000 people on one side and 3-4000 on the other (my) side. Uniformly 5-10° cooler in the low population low density side.
Using Dr. Spencer’s dataset I estimated the effect on the global average temperature at about 0.02 C.
Did you publish a paper or is it just a bad guess ? 😀
It’s an appallingly bad guess. He’s undershot by a factor of (my guess) 50 to 100. The effect on the global temperature would be somewhere in the region of 1-2°C
1-2 C isn’t even remotely close to what Dr. Spencer’s data shows.
Well if you average out the cream-coloured area that’s about right, bdgwx. However, if you look at how high the urban spikes go and take into account the homogenisation bias in the datasets you get a much higher figure, much higher. Given that the overwhelming majority of temperature stations are land-based and the majority of those are in urban expansion areas, you’ve undercooked the goose.
The yellow area is 0.05-0.10 C. The cream colored area is 0.01-0.05 C. The grey area is 0.00-0.01 C. The ocean is 0.00 C. That is the vast majority of the surface area. That is no where close to a 1-2 C global average.
It is from Dr. Spencer’s dataset. The data can be found here.
Well, there you go.
ROTFLMAO.
What value do you get using Dr. Spencer’s data?
I looked at the figures that Dr. Spencer gave in the previous articles where he estimates 22% to 55% (or 57%) of the warming to be due to UHI and the fact that 70-80% or so of the global temperature stations are represented by urban land-based stations and then extrapolated to other areas, thus magnifying the UHI contamination to a far higher degree. The, frankly, poor to awful methodology of the climate enthusiasts has resulted in datasets that magnify and increase the UHI contamination in almost every single regional reading in an abysmal mess that is simply unuseable junk.
He says no such thing. What he said is that 22% of the US warming trend can be attributed to UHI and that in urban locations it is 57%.
He did NOT say that “22% to 55% (or 57%)” warming globally can be attributed to UHI. And why would he say that since his dataset would falsify that hypothesis.
Not even remotely close. Only about 10% of the land area or 3% of the total area is represented by urban stations.
And I think you are confusing the UHI effect with the UHI bias. Those two different concepts. The effect is the real warming that results from land use changes. The bias is the result of deficiencies in the spatial average step. The effect is always positive. The bias can be either positive or negative depending on the specific circumstances. The most intuitive and obvious scenario where the bias is negative is when urban stations move to rural grid cells or when the ratio of rural-to-urban stations increases. And according to [Rohde et al. 2013] the bias (not the effect) is close to zero after WWII, but if anything is more likely to be negative than positive.
Furthermore many datasets deal with the bias (not effect) by removing the effect. By removing the effect you remove the possibility of the bias. This comes with a cost though. The result is that global average temperature dataset underestimate the warming because they intentionally removed some of it.
Then don’t use the adjusted versions of the datasets and instead accept that the overall warming trend is HIGHER than it is compared to the raw versions [Hausfather]. My suspicion is that you aren’t as convicted against these adjustments as you let on here though since it necessarily requires the belief that the warming trend is higher than what the consilience of evidence shows and which climate scientists report.
Horsefather compares one “adjusted” set against another “adjusted” data set. It is meaningless.
Nothing he compares is remotely “raw” data.
Anyone that falls for his CON is an extremely gullible and mindless fool.
You know me on here, bdgwx. You and I have crossed swords on this numerous times in the past and no doubt will again. You know how long I’ve been hammering this same damn point post after post, year after year. I don’t give a good godamn what your microanalysis of fractions of a degree in each published dataset tell you. Unless we move the temperature stations outside of the UHI bubbles and stop this stupid homogenisation of temperatures across areas that we have no data for then we do not have any idea whatsoever what temperatures are doing regionally or globally. You can trot out “x month was the nth warmest by 0.01°” to your hearts content but it is completely and utterly meaningless because all of the datasets are unuseable junk. This should never have been done in the first place, the methodology used is very bad – the best thing we can do is start over with new stations, free from UHI contamination. I know it’ll cost billions but probably less than the latest crappy green boondoggle or COPfest junket – skip one for a year and this will pay for itself.
Macquarie Island has not changed in 40 years and probably much longer knowing what the BoM does.
( Yes bmx, I know it’s only one station but it’s in the middle of a very big ocean. It is a good representative station for a good part of the southern Hemisphere.
Macquarie Island has a warming trend of +0.10 C/decade which is about 0.7 C of warming. According to the GISTEMP that is actually slightly higher than areas along the same latitude which average 0.58 C. If the intent is to criticize global average temperature datasets using a single cherry-picked station then I would not have picked that one.
From when to when?
No change AT ALL between 1970 and 2015. 45 years.
Pretty close. +0.01 C/decade.
1950 to 2020…the same as the graph you posted.
Did you just say that? Ha ha ha ha.
You made bdgwx cry.
If all datasets are “unusable junk” then why did you put stock in Dr. Spencer’s dataset?
I didn’t. Dr. Spencer’s using published datasets which are hopelessly contaminated to show how badly they are contaminated. You wouldn’t hold up a healthy human body as an example of the spread of disease, so you take a contaminated dataset and show just how badly it’s been corrupted with bad methodology and UHI magnification.
You want to keep using that crap then go right ahead, that’s between you and your conscience, but I’ll keep labelling it as useless junk.
Here and here
He created his own dataset. It does not show “how badly” other datasets are contaminated. It shows the effect of the UHI.
I think it’s a stretch to call Dr. Spencer’s work “crap”. In fact, I actually found it to be insightful and useful. But if you truly take issue with it then take it up with Dr. Spencer. I’m just the messenger here.
Rampant DENIALISM is all you have left, isn’t it, beeswax !
You really think urban warming doesn’t contaminate a LARGE PROPORTION of surface data.
You must walk around with your eyes and mind , totally closed to reality.
Dr. Spencer did not create his own dataset out of thin air. He used published datasets and isolated some of the UHI contamination to show as a comparison. As you know perfectly well and, as you are also well aware, I was referring to the published datasets. No you are not a ‘messenger’, you are a voice of unreason, a statistician that cannot comprehend how to deal with real world data and thinks it’s all just ‘a numbers game’ but it’s late and I’m straying back onto familiar ground so I’ll just stop there.
He did not isolate UHI contamination. He isolated the effect. Those are two different concepts. If you don’t understand what the difference is then ask questions and I’ll help as best I can.
A lot.
Can you post what it is and where/how you got that value?
Why didn’t Macquarie Island’s temperature show any trend for 45 years? (at least) Where is the co2 (which increased by 80ppm during that time) signal?
The trend at Macquarie Island over the last 45 years is +0.05 C/decade.
This is what the CO2 signal looks like.
The model is a load of absolute NONSENSE.
It is as FAKE as you can get. You cannot prove anything by using FAKED models that rely on FAKE anti-science assumptions.
Oh and Thanks for showing , YET AGAIN
that warming ONLY comes at major El Nino events…
Showing that there is absolutely ZERO EVIDENCE for CO2 warming of the atmosphere in the last 45 years
“+0.05 C/decade.”
LOL.. totally INSIGNIFICANT and totally NOT A PROBLEM
Admitting that global warming is an insignificant 0.05ºC/DECADE…
You have to be a particularly mindless zealot to be SCARED by that. !
You just destroyed climate alarmism in one stupidly ignorant post !.
WELL DONE.!
If the error bounds were included the result is total
bovinegallus nada.Fake model!
🤣 😂 🤣 😂 🤣 😂 🤣 😂 😂 🤣 😂 🤣 😂
I can attest it is real. I’m the one that created it.
Yes, I can.
A self taught lawyer? Would you please do so?
No.
And you’re keeping it a secret because?
It is far better for me to know than you.
Ok, I get it. I’ve been duped. Don’t let it be said that I didn’t give you the benefit of the doubt.
As if . . . ahhh . . . that matters to me at all?
One has to wonder how climate science can not adequately deal with UHI. I have seen folks claim that UHI dispersion only occurs via diffusion so doesn’t affect much area and then turn around and claim that wind blows a good deal of the time. Cold fronts and warm fronts don’t move by diffusion. Why should UHI temperature increases not move with the wind also.
Because the source of the UHI doesn’t move with the wind and the built-up areas often form an ‘air pocket’ near ground level rather than allowing every gust of wind to blow through.
The unnatural continental heat islands impact isotherms, circulation, and cloud well beyond local circumstances. One cannot account for this with local “adjustments”. The entire global signal is awash in its influence.
Lightly off topic, but there are several new posts at
https://climateaudit.org/ that worth al look 😀
Stephen McIntyre is back 😀
UHI is the only measurable affect on temperature that can be attributed to humans and it’s regional. Does it add to AGW? Yes, but considering the dilution it’s minimal, but still there. The importance of UHI is that most weather collecting stations in urban areas have been overtaken by human intrusion over time and their veracity has been compromised and can be proven by Anthony’s work …. but ignored because it doesn’t fit their narrative. Once again, it’s politics, not science.
Over 80% of temperature stations are land-based and the vast majority of those (75-85%) have been swallowed up by urban expansion. Given that and the fact that UHI can easily range from 2-7°C, I dispute your claim that the effect on the 1.5°C of global warming is minimal.
I’m with mles on this one – The area warmed by UHI is small compared to the whole. I’m wondering if you mean that UHI contamination of “reported” 1.5C of global warming is not minimal?
Ah I see your point – we are talking at cross purposes here. I was talking about the effect on the temperature datasets collected by the climate scientists where the effect of them smearing UHI elevated readings all over the world has resulted in most of the reported increase in ‘global temperatures’ being due to UHI.
Obviously, in the real world the UHI will have a minor role in the temperatures outside of the built-up urban areas with lower populations and activity.
Good point.
Any discussion of this subject must make clear the distinction between the effect of UHI and the so-called “adjustments” made to purportedly compensate for it, and the actual role urbanization and such has on the overall heat content of the atmosphere.
In many ways though, the actual UHI effect is huge, albeit limited in scope.
It is so large in fact, that tropical plants have survived many decades of being planted in the ground, out of doors, in locations far outside the tropics. Places like cities in the Northeast US and New England.
But even in rural locations far from any cities or towns, every building, and even small slabs of concrete, create microclimates that vary hugely from areas even a few feet away.
It’s not really the rise in temps that is important, it’s that a large number of thermometers are affected by it. Adding a few degrees to a small area is no big deal, but adding those degrees to 3/4 of the thermometers you are monitoring drives your “average” way up.
Keep an eye on mainstream media efforts to spin the UHI effect into something it is absolutely not. I keep an overall count of the sheer bias of the PBS NewsHour on climate issue reporting (here), and in my count so far, they’ve had had three instances now where they’ve spun UHI as being isolated ‘island’ areas within cities, and predictably enough, they attribute those little areas to ……. wait for it ……… racism. I kid you not, as seen in their most recent spin effort on Sep 30, 2023:
That’s pretty damn disgusting. Dishonest racist media manipulation.
Poor people plant fewer trees. When the left runs out of excuses, they always reach for the race card.
The Northern Hemisphere is warming, and the Southern Hemisphere is cooling.
I wonder if UHI is the difference? There is much more land area in the Northern Hemisphere, so there is much more UHI in the Northern Hemisphere.
If we subtracted UHI warming from the Northern Hemisphere warming, would the Northern Hemisphere actually be cooling, like the Southern Hemisphere?
About 11% of the global population live in the Southern Hemisphere.
No. The peak solar intensity has been shifting northward for a few centuries now. The warming trend in the NH is baked in until the snowfall overtakes the snow melt again.
Warming northern oceans means more snowfall on northern land. Snowfall records will be a feature of weather reports for the next 9,000 years. This November is already close to setting a global high for modern records:
This is consistent with record global surface temperature in September. Northern oceans have a lot more warming to go before the snowfall overtakes the melt. Once that starts, the average temperature of the land drops because ice is hard to shift above 0C and the ice mountains gain elevation over the oceans; the former going up and latter going down. But ocean surface temperature will continue to climb for a few thousand years.
The cooling trend in the SH is also baked in but so far only south of 40S has cooled during the satellite era.
No. The peak solar intensity has been shifting northward for a few centuries now. The warming trend in the NH is baked in until the snowfall overtakes the snow melt again.”
What about the 60-year (or so) warming and cooling cycle that we have experienced since the end of the Little Ice Age?
The sun’s intensity has been increasing all during that time, yet we still have temperatures warming and cooling within a range of about 2.0C from warmest to coolest during that time of increasing sun intensity.
I’m not saying you are wrong in your longterm forecast, but the recent past shows the climate can vary quite a bit in the current environment, and a steady increase in solar intensity in the Northern hemisphere does not explain the cooling part.
Global temperature measurement before satellites was hit and miss So what was measured before satellites was not global.
Central England has the longest instrumented record and there is no 60 year cycle evident in that:
http://www.climate4you.com/CentralEnglandTemperatureSince1659.htm
The rise in sea level is probably best indicator of global surface temperature trends and long term records indicate an increasing trend for about 200 years.
Climate can never be steady. Earth’s orbit varies from year-to-year and the sun output varies from day-to-day. Then there are volcanoes, asteroids and a myriad other unpredictable events that will effect climate.
Although Earth’s orbit precession is predictable and enables accurate calculation of solar intensity at the top of the atmosphere, the mix of land and water at each latitude changes and land responds differently to solar input than oceans. Land can get to temperature above 50C but open ocean surface cannot sustain more than 30C.
Anyone hoping for a sustained cooling trend in average surface temperature will be disappointed until the snow begins to accumulate again. There will be a continuing warming trend in the NH and more of the SH will shift to a cooling trend. Also look for new snowfall records in the NH because that is a consequence of warmer ocean surface.
“Central England has the longest instrumented record and there is no 60 year cycle evident in that”
There is a 60-year cycle in the United States:
Hansen 1999:
And it can be shown that if was just as warm in the Early Twentieth Century as it is today.
And it can be shown that climate scientists were wringing their hands over a possible new ice age in the 1970’s, after cooling significantly from the 1940’s.
If your theory can’t explain the U.S. temperature profile, then it is missing something, because the U.S. temperature profile is reality.
The chart does not display a repeating cycle. It shows a peak in the 1930s.
I could point to 1931 as having one of the closest aphelion of the 20th century but it is not close enough to cause the increase in temperature observed across the USA in 1930s:
http://astropixels.com/ephemeris/perap/perap1901.html
The more likely cause is farming practice that created the historic dust bowl conditions across the USA. That is explained here:
https://www.history.com/topics/great-depression/dust-bowl
Vegetation is vital to maintaining a temperate climate. Remove vast amounts of vegetation and you decertify a region resulting in more extreme temperature.
As I wrote above, there was no global temperature measurement before the satellite era. Picking one region and inferring it is global trend is not valid.
I guess you missed the fact that the 1880’s were as warm as the 1930’s. And the 1910’s were as cold as the 1970’s.
You may have missed the 1880’s highpoint since it doesn’t show on Hansen 1999, but I can provide you with Tmax charts from all over the world that show it was just as warm in the 1880’s as it was in the 1930’s, as it was in 1998, and beyond.
And here are 600 Tavg regional charts from around the world that show the same general temperature profile as does Hansen 1999, which shows a 60-year cycle of warming and cooling.
https://notrickszone.com/600-non-warming-graphs-1/
How much corroboration do you need?
If your theory (which I support) doesn’t account for the 60-year cycle, then the theory is incomplete.
What has been made transparently clear is that the so-called UHI adjustments, which purported to correct for UHI, did exactly the opposite.
They exaggerated (IOW invented) warming even more than before the “adjustment”!
They cooled past temps, which is exactly the opposite of what any honest effort would do, to account for increasing urbanization.
“In Las Vegas over the last 40 years, nighttime temperatures have risen 10 degrees Fahrenheit, due solely to the urban heat Island effect.”
Dr. Roy Spencer, July, 2014, Las Vegas, Nevada.
In Las Vegas’ case I would probably say there’s more night-time activity (and bright lights) than day-time activity!
No,
But, the size of the city and the size and height of it’s buildings have doubled several times.
Here is one new 2023 study that says that depending on the surface temperature and solar irradiance datasets that one uses, one can show anything from mostly human-caused warming to mostly natural warming.
‘Challenges in the Detection and Attribution of Northern Hemisphere Surface Temperature Trends Since 1850’
https://iopscience.iop.org/article/10.1088/1674-4527/acf18e
The datasets are historical so there is not much that can be done about them.
Story tip . . . as well as question directed to Dr. Spencer and Anthony Watts:
I believe that beyond UHI effect, there is potentially greater effect (on reporting “global temperature” changes) that I have dubbed HAME . . . Human-caused Albedo Modification Effect. This encompasses the fact that areas of Earth’s surface have had their natural surface albedos modified over time by human cultivation of lands, including massive deforestation on most continents and especially over the last 200 years.
There is certain to be a change in the albedo of, say, natural historic Amazon rain forest compared to that land being cleared and then planted with, say, nice rows of cultivated corn:
“The mean forest albedo, 0.134, is slightly higher than the value that has generally been used in GCM deforestation simulations, while the mean ranch land albedo, 0.180, is slightly lower than the value usually used.”
(source: https://www.researchgate.net/publication/253452031_The_Albedo_of_Amazonian_Forest_and_Ranch_Land
Similarly, an albedo difference would be expected between previous open prairie land in the US midwest compared to, for example, expanses of cultivated wheat.
Another clear cut example, pardon the pun, would be mankind’s utilization of rice paddies in India and throughout the Far East that have displaced natural dry land vegetation that used to cover such areas:
“The albedo value of bare soil is 17%, whereas the albedo is more than 20% over mature rice field”
(source: https://www.worldwidejournals.com/indian-journal-of-applied-research-(IJAR)/recent_issues_pdf/2015/September/September_2015_1492582725__184.pdf )
Exposed dirt and water characteristically have lower albedo (i.e., absorb more sunlight) than does green vegetation. However, cultivated croplands typically have higher albedo compared to native forests, as document in the paragraphs above. Here are some typical albedo values for comparison:
Open ocean = 0.06
Conifer forest, summer = 0.08 to 0.15
Deciduous forest = 0.15 to 0.18
Bare soil = 0.17
Green grass =0.25
(source: https://en.wikipedia.org/wiki/Albedo )
Tundra = 0.2
(source: http://www.climatedata.info/forcing/albedo/ )
Crops = 0.15 to 3.0
(source: https://iopscience.iop.org/article/10.1088/1748-9326/aab650 )
So, the bottom line questions to you:
a) To what extent has HAME around the Earth caused a net increase or net decrease in “distilled down” global temperature anomaly reporting over the last 12,000 or so years (the Holocene)?,
and
b) What, if any, adjustments for HAME have been undertaken vis-a-vis separating out this forcing on net “global warming” from other factors such as atmospheric CO2 levels and UHI effects?
Any time someone tells me they made adjustments to the data for something, I always say – “I want to see the raw and adjusted data in a side-by-side comparison.” The responses to my request have always been – entertaining.
Here is the comparison. Notice how the net effect of all adjustments actually reduces the overall warming trend.
[Hausfather]
But they’re adjusting spurious readings to start with.
Don’t you ever consider the qualitive properties of the temps numbers rather than just the dubious hundreds-of-a-degree quantitative values offered?
The blue line is the raw (unadjusted) data. The label is right there in the graph.
What’s actually wrong with you?
Hausfather’s datasets are not raw data, bdgwx, and you should know that. If you don’t know that then there is probably little hope for you, you’re a lost cause.
The graph doesn’t even show Hausfather’s datasets. And it is clearly labeled. Blue is raw. Red is adjusted.
All wrong! Here: I’ll fix it for you:
“Notice how the net effect of all adjustments
actuallyapparently reduces theoverall warming trendtotal range of the numerical values (expressed as anomalies) that some people actually believe can represents Earth’s global temperature as reduced to a single value at any moment in time.”UHI there in front of our eyes.
We live in rural Somerset, England. A little village in a natural bowl, it’s a frost pocket in the winter. 14 miles away is Bath. What we see every year is that our Stellata Magnolia blooms two to three weeks later than those in Bath.
And I have clocked a five degree drop between out out of town Supermarket, tarmac central and the tree-lined village we live in.
Yep. It’s a bigger margin of difference than many people realise and certainly that climate enthusiasts will ever admit to. Keep a log of those temperature differences and see if they change much between the different seasons or times of day, it’d be really interesting to see that.
Same here in SW Surrey. I can tell where I am on my commute by the air temperature. It’s usually 1 to 2 degrees warmer in town in summer and 3 to 4 degrees warmer in winter. In winter there are two frost hollows where temperature drops by 1 degree and a steady increase in the reading over the last 3 miles as the road drops down into the built up area.
This interactive map attempts to display all Urban Heat Island “clusters” globally:
https://yceo.users.earthengine.app/view/uhimap
A while back I compared the average temperature for four days – the equinoxes and the solstices, over a 100 year period, for Geneva NY and for Central Park in NYC.
These two locations are 300 miles apart, one is rural and the other is arguably urban. Geneva is getting colder, NYC warmer. Can this be UHI? Geneva in blue, Central Park in red.
Obvious question: do you believe the accuracy of measuring (atmospheric) temperature 100 years ago was the same as it is today?
Your answer to that question will say much regarding the inferred temperature trends.
I keep hearing “ hottest year etc etc on record “
However I’d like to know if these are real global records as most of the world was unknown 200 years ago, so do they mean just the hottest in the known world at the time?