UAH Global Temperature Update for May 2021: +0.08 deg. C

Reposted from Dr Roy Spencer’s Blog

June 1st, 2021 by Roy W. Spencer, Ph. D.

The Version 6.0 global average lower tropospheric temperature (LT) anomaly for May, 2021 was +0.08 deg. C, up from the April, 2021 value of -0.05 deg. C.

REMINDER: We have changed the 30-year averaging period from which we compute anomalies to 1991-2020, from the old period 1981-2010. This change does not affect the temperature trends.

The linear warming trend since January, 1979 remains at +0.14 C/decade (+0.12 C/decade over the global-averaged oceans, and +0.18 C/decade over global-averaged land).

Various regional LT departures from the 30-year (1991-2020) average for the last 17 months are:

2020 01 0.42 0.44 0.41 0.52 0.57 -0.22 0.41
2020 02 0.59 0.74 0.45 0.63 0.17 -0.27 0.20
2020 03 0.35 0.42 0.28 0.53 0.81 -0.96 -0.04
2020 04 0.26 0.26 0.25 0.35 -0.70 0.63 0.78
2020 05 0.42 0.43 0.41 0.53 0.07 0.83 -0.20
2020 06 0.30 0.29 0.30 0.31 0.26 0.54 0.97
2020 07 0.31 0.31 0.31 0.28 0.44 0.27 0.26
2020 08 0.30 0.34 0.26 0.45 0.35 0.30 0.24
2020 09 0.40 0.41 0.39 0.29 0.69 0.24 0.64
2020 10 0.38 0.53 0.22 0.24 0.86 0.95 -0.01
2020 11 0.40 0.52 0.27 0.17 1.45 1.09 1.28
2020 12 0.15 0.08 0.22 -0.07 0.29 0.44 0.13
2021 01 0.12 0.34 -0.09 -0.08 0.36 0.49 -0.52
2021 02 0.20 0.31 0.08 -0.14 -0.66 0.07 -0.27
2021 03 -0.01 0.12 -0.14 -0.29 0.59 -0.78 -0.79
2021 04 -0.05 0.05 -0.15 -0.28 -0.02 0.02 0.29
2021 05 0.08 0.14 0.03 0.06 -0.41 -0.04 0.02

The full UAH Global Temperature Report, along with the LT global gridpoint anomaly image for May, 2021 should be available within the next few days here.

The global and regional monthly anomalies for the various atmospheric layers we monitor should be available in the next few days at the following locations:

Lower Troposphere:
Lower Stratosphere:

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June 1, 2021 2:16 pm

This makes May 2021 the equal 10th warmest May in UAH history, the coldest since May 2018.

Using the 1981:2010 base period, this would be +0.20°C, compared with last month’s +0.07°C.

The Monckton Pause now starts in April 2015, making it 6 years and 2 month old.

Reply to  Bellman
June 1, 2021 2:42 pm

the coldest since May 2018.” reminds me Simpsons
“2 days without accident”

Reply to  Alex
June 1, 2021 4:04 pm

The Media spent all last weekend gushing over “RECORD TRAVEL!!!!” while they showed empty beaches and empty boardwalks with live reports.

The “Record Travel” was a record for 2021 travel.

john harmsworth
Reply to  UNGN
June 2, 2021 9:21 am

Bore-der line between pathetic and sensationalist reporting. Isn’t the media just the worst?

Reply to  Bellman
June 2, 2021 11:13 am

The Monckton Pause now starts in April 2015, making it 6 years and 2 month old.

That will give us a chance to ask his Lordship to explain why he thinks it is that the full global temperature trend in UAH up to April 2015 is +0.11C per decade; but now, up to May 2021, following his 6 years 2 months of ‘no warming’, it has risen to +0.14C per decade! Should be fun.

By the way, +12 positives for Bellman at WUWT (at time of writing)?? Must be a record. There’s hope for us all!

Last edited 18 days ago by TheFinalNail
Carlo, Monte
Reply to  TheFinalNail
June 2, 2021 11:21 am

Where is the hockey stick?

Reply to  Carlo, Monte
June 2, 2021 12:45 pm

Who mentioned a hockey stick?

Perhaps you have some explanation for why the last 6 yrs 2mths of no warming has caused the long term UAH trend to rise from +0.11C per decade to +0.14C per decade.

There is an reason and it’s quite simple: but something tells me you won’t like it.

Carlo, Monte
Reply to  TheFinalNail
June 2, 2021 2:52 pm

Statistically they are the same number, oops.

This is what you call an emergency?

dodgy geezer
June 1, 2021 2:26 pm

I am hoping to see a downward trend as the AMO enters a downward phase.

Chris Hanley
Reply to  dodgy geezer
June 1, 2021 2:53 pm


Pillage Idiot
Reply to  Chris Hanley
June 1, 2021 3:51 pm

So poor people will be allowed to lift themselves out of poverty using inexpensive energy sources.

OTOH, if your premise is that the current temperature is less than the optimum temperature for humans and the rest of the biosphere, then I fully support your premise.

Chris Hanley
Reply to  Pillage Idiot
June 1, 2021 4:16 pm

So poor people will be allowed to lift themselves out of poverty using inexpensive energy sources …

That will continue to happen whatever the supposed global temperature trend.
The GAT obsession is confined to the temporarily relatively wealthy West.

Last edited 18 days ago by Chris Hanley
Pillage Idiot
Reply to  Chris Hanley
June 1, 2021 4:33 pm

In my experience, the Left in the U.S. and Europe are not about to allow inexpensive fossil fuels or GMO crops for Africans, Asians, or South Americans that live in extreme energy and food poverty.

Chris Hanley
Reply to  Pillage Idiot
June 1, 2021 4:53 pm

The global geopolitical balance is changing rapidly, much faster than the climate.

Dave Fair
Reply to  Pillage Idiot
June 1, 2021 11:09 pm

China will.

Reply to  Pillage Idiot
June 1, 2021 4:46 pm

There’s no money in that for some, reasons against it for others.
Those who would help find themselves in conflict with both of the above.
Most poor people don’t get out of poverty by getting electricity to run their tv’s.

Reply to  Chris Hanley
June 1, 2021 5:22 pm

Smart move.

Walter Horsting
Reply to  Chris Hanley
June 2, 2021 5:48 am

China just completed a 2 million ton a year coal railroad.

AGW is Not Science
Reply to  Walter Horsting
June 2, 2021 7:39 am

Me thinks that’s understated, or that China runs some pretty light coal trains. US coal trains typically run 10,000 tons or more each (100 cars, 100 tons per car), which would require just 200 trains per year to hit 2 million – not even one train per day.

john harmsworth
Reply to  AGW is Not Science
June 2, 2021 9:22 am

The Chinese wouldn’t give out false information, would they?

Reply to  AGW is Not Science
June 2, 2021 4:03 pm

The statement is not understated. They are adding one new railroad to their export lines, period. It says nothing about total coal railroads in, into or out of China. China exports around 10 million a year, a very small amount of total coal use. They import about 10 times that much. And they consume over 4 billion tons a year. The addition of one new track increased their exports by 20%,.
We don’t know the specifics of what the route requires and limits and what the new track is capable of sustaining. Perhaps a billion tons a year. The report could only indicate the increased amount of exports limited by market demand or political reasons, not to China running “light coal trains”.
The story also does not reflect on China’s use of coal. The US alone exports around 70 million tons a year.

June 1, 2021 2:28 pm

The global number derived from polling the worlds reporting stations since January 2015 shows a -.26C anomaly. Pretty consistent with UAH

Reply to  rbabcock
June 1, 2021 3:05 pm


Roy Martin
Reply to  Mike Smith
June 1, 2021 4:49 pm

Thought “global” was doubled, but the first part is actually a link:

Solomon Green
Reply to  Roy Martin
June 2, 2021 4:44 am

I am sure that there must be something wrong with this site and the data that appears. But I am not capable of figuring it out for myself.

Can anyone help me. You don’t have to be an alarmist.

Ron Long
June 1, 2021 2:30 pm

It’s colder where I am…where was it warmer?

Reply to  Ron Long
June 1, 2021 5:19 pm

Not here.

Carlo, Monte
Reply to  Scissor
June 1, 2021 6:15 pm

This is certain.

Reply to  Ron Long
June 1, 2021 10:46 pm

March weather in April and May in Southern Ontario!

Joseph Zorzin
Reply to  Ron Long
June 2, 2021 3:53 am

Everywhere else is warming twice as fast as everywhere else.

Clyde Spencer
Reply to  Joseph Zorzin
June 2, 2021 2:01 pm

And, all the children and temperatures are above average.

Reply to  Ron Long
June 2, 2021 6:24 am

Not at my house. Still running the furnace. It’s June, and the furnace is running. What’s wrong with this picture?

Carlo, Monte
Reply to  Sara
June 2, 2021 11:23 am

Was 39F here yesterday morning.

john harmsworth
Reply to  Ron Long
June 2, 2021 9:31 am

The Alarmists check thermometers with a heat lamp

Reply to  Ron Long
June 2, 2021 10:52 am

The UAH chart should be published in a day ot two. Central Asia up to N Russia looked very warm on most of the May daily charts on Climate Reanalyzer.

Remember folks, UAH is a global average (over land and ocean) of lower troposphere temperatures. It is not the average temperature of your local region at ground level.

Carlo, Monte
Reply to  TheFinalNail
June 2, 2021 11:24 am

And it totally meaningless, does not represent “climate’.

Reply to  Ron Long
June 2, 2021 6:04 pm

Allegedly the Arctic, Northern Siberia, Antarctic and Crapifornia.

June 1, 2021 2:49 pm

Just eyeballing it, if we used the Super El Nino as the starting point, we could claim that we’ve been in a cooling trend for the entire current millennium. 🙂

Rory Forbes
Reply to  davidmhoffer
June 1, 2021 3:05 pm

If we used all data and proxies, covering the whole Holocene,the planet has been cooling steadily since the Holocene Thermal Optimum, ~ 8000 ago. We’ve warmed slightly since the LIA ended in the 18th century. CO2 has increased beneficially over the past ~50 years. There’s really nothing much else of importance. Earth will be just fine.Weather is uncannily stable.

John Tillman
Reply to  davidmhoffer
June 1, 2021 3:08 pm

Super El Niño of 1997-98 was a tiny fraction less warm than Super El Niño of 2015-16, but since the latter, Earth’s average temperature has been in a pronounced downtrend. It was flat between Super Los Niños.

john harmsworth
Reply to  John Tillman
June 2, 2021 9:32 am

I believe 15-16 el Nino temps were “adjusted”.

June 1, 2021 3:18 pm

File this under “anecdote is not data”.

New England these last two weeks saw temps both higher and lower than Isee all year in my SoCal home. Yesterday May 31st was the second day in a row of a new all time record maximum temperature low temperature reading. May 30th broke a record set in 1917. If temperature is a climate change indicator then the signal is longer than a Century.

Reply to  Rob_Dawg
June 1, 2021 6:08 pm

Some of Mark Twain’s description of similar observations: “Gentlemen: I reverently believe that the Maker who made us all, makes everything in New England—but the weather. I don’t know who makes that, but I think it must be raw apprentices in the Weather Clerk’s factory, who experiment and learn how in New England .”
“There is a sumptuous variety about the New England weather that compels the stranger’s admiration—and regret. The weather is always doing something there; always attending strictly to business; always getting up new designs and trying them on the people to see how they will go.”
But it gets through more business in spring than in any other season. In the spring I have counted one hundred and thirty-six different kinds of weather inside of four and twenty hours.”

-This was in 1876, so alarmists may claim the 1% change in CO2 was already throwing the climate off balance.

Rud Istvan
June 1, 2021 3:36 pm

I got to thinking about the significance of the 0,14C UAH decadal trend newly again reported here relative to the three independent ways ECS can be estimated at about 1.7C per doubling: Callendar’s 1938 curve (McIntyre has a good analysis at Climate Audit, or see essay Sensitive Uncertainty in ebook Blowing Smoke), energy budgets (e.g. Lewis and Curry), and Lindzen’s Bode feedback method (a recent guest post, noting here that the correct Lindzen formalism is 1/(1-f) not f/1+f) [which is also correct but for a different model than Bode, my bad]—but which text goof makes no difference to the guest post analysis that imported and used only the correct Lindzen Bode curve).

So here is a back of the envelope math reconciliation. At the time UAH started (Jan 1979) the Mauna Loa CO2 concentration was 336 ppm. Last month it was 419. ECS is relative to a CO2 doubling. 2*336=672, and 419/672=0.624, so after 4 UAH decades a bit over a third (0.624/1.7) of the way to doubling. 0.624 relative rise to doubling/1.7 ECS/4 decades = 0,156C implied rise per decade.

Now since ECS is reached many years AFTER doubling is reached, the ‘instantaneous’ decadal UAH rise must be lagged something a bit less, and it is! 0.14/0.156=0.9, or about 90% of the ultimate expected ECS.

This also ‘reconciles’ to energy budget TCR ~1.35/ ECS ~1.7 = ~0.8, because TCR is defined as CO2 increasing 1%/yr, so doubling in ~70 years, which is faster that what is observed, resulting in a bigger lag to ECS.

All in the same ballpark, showing yet another way that the climate models can be shown to run hot so their ECS is almost twice ‘reality’.

the energy budget

Rud Istvan
Reply to  Rud Istvan
June 1, 2021 5:39 pm

Sorry, all. There are a number of typos /missing error corrections in this comment. I hurried it because was simultaneously cooking dinner for my (mild cognitive impairment from almost fatal anaphylactic shock, since disabled by PTSD) Patricia. Came back to edit, and by that got done had timed out of revisions due to dinner double duty. Well, maybe next time.

Reply to  Rud Istvan
June 1, 2021 7:06 pm

Sorry to hear about that Rud.

Also, remember that if the logarithmic relationship holds at these levels, then the first half of the logarithmic curve is faster than the second half.

I still have a problem with ECS of a doubling of CO2. Wouldn’t it be better named as ECS to a doubling of CO2 if all else was equal? … which, by definition makes it irrelevant, as other things aren’t all equal. Even if the doubling occured over 150 years from here, that’s two and a half 60-year climate cycles, a shitpile of El Ninos and La Ninas equilibrating the temperature, as can be observed in the above graph, and throw in a few volcanic eruptions and several more climate parameters, and CO2 ECS probably doesn’t actually exist in our real world.

Last edited 18 days ago by philincalifornia
AGW is Not Science
Reply to  philincalifornia
June 2, 2021 7:50 am

Thank you! I’ve said the same a thousand times – ALL claims to climate “sensitivity” to atmospheric CO2 levels are based on the assumption “all other things held equal.” Once you recognize that this critical and central caveat has never, is not, and will never occur here in the real world, and that the “feedbacks” are overwhelmingly negative, offsetting feedbacks (otherwise the Earth would have a wildly unstable climate), you can deduce quite easily that the “ECS” is not distinguishable from ZERO.

Smart Rock
Reply to  Rud Istvan
June 1, 2021 7:16 pm

Rud: Not trying to be picky, but I think you got the calculation wrong and ended up with almost the right answer by chance. I had to read your comment several times before I saw the error. The relationship between δCO2 and δT is exponential.

The way I read it, if n = number of doublings to go from 336 ppm to 419 ppm, it would be represented by (419/336) = 2^n, which gives n = 0.32, so if ECS δT per doubling is 1.7°, then δT over the 1979-2021 period would be 1.7*0.32 = 0.54° or 0.13° per decade. Close enough for climate work!

I’m still not sure I really believe in this ECS and TCR stuff. Theoretical calculations of ECS and TCR have to assume that everything else stayed the same and only the CO2 content changed. This would seem to be very unlikely in a natural world. where everything is related to everything else.

That said, it is possible that by putting a great deal of CO2 in the atmosphere over a very short time, humans have succeeded in doing an almost-controlled experiment. I.e. changing only one variable (CO2) while not giving any of the other input variables time to respond.

Rud Istvan
Reply to  Smart Rock
June 2, 2021 4:47 pm

Not disagreeing. My first early draft included the ln correction, even incorporating Callendar’s 1938 curve. Then thought, nope, can do a first order ‘bracketed’ approximation. Since the goal was to prove the models off by half, not my ball parks by less than 10%, sufficed.
I am really rethinking useful level or argumentation. Used to think had to explore every nuance of the other side. Like Steve McIntyre did with paleoclimate.
I now think we were addressing the wrong audience. It isn’t countering Warmunists in their minutia. It is addressing yhe general public exposing the big picture. Two means: ridicule (my recent Koonin inspired post on Alinsky Rules), and big picture mess ups, as here.

Martin Cropp
Reply to  Rud Istvan
June 1, 2021 9:09 pm

Hi Rud
Well you have got ECS and then you have this chart below.
The warmth is in the coldest latitudes, and this is mainly caused by wind direction changes.

Until the atmospheric dynamics that cause the distribution of heat and cold in the chart below, posted by Willis are identified, global ECS calculation is virtually pointless in my opinion.

And what about the reported 15% slower wind speeds = longer dwell.


comment image?w=680&ssl=1

Last edited 18 days ago by Martin Cropp
Joel O'Bryan
June 1, 2021 4:05 pm

The March and April drop, driven mostly by the SH readings, was so dramatic that May was likely to rebound a bit.

Pillage Idiot
Reply to  Joel O'Bryan
June 1, 2021 4:37 pm

We have slipped back to neutral ENSO conditions. However, the Earth Institute forecast has La Nina becoming more likely than Neutral beginning with the Sep-Oct-Nov period of 2021.

Reply to  Pillage Idiot
June 1, 2021 4:45 pm

BOM stopped showing NASA ENSO forecasts as they disagreed with the rest of the assembles the compare to.
NASA showed that they expected La Nina to continue after a small drop.
Sadly current BOM estimates do show neutralish at the moment and we have to wait for the will of the gods.

Joel O'Bryan
Reply to  angech
June 1, 2021 6:39 pm

Yep. ENSO state is the most important weather factor affecting most of the Globe’s temperatures and even Sea Ice extents. The best science today cannot tell us what ENSO state the tropical Pacific will be next December with any certainty. Yet we are supposed to believe climate science’s temperature projections for 80 years from now have credibility in order to restructure the entire global energy economy and the welfare of billions. Most of those climaate charlatans should be put in jail, just like Italy tries to jail earthquake seismologists. Vast numbers of people are going to die in the coming decades as a direct result of scientific-fraud based climate policy, not climate change itself.

Gordon A. Dressler
June 1, 2021 6:23 pm

I have science-based faith (yeah, you gotta think about THAT for a minute or so) that the next short-term trendline will nose-dive for August 2021 to Feb 2022.

To paraphrase a common adage: just follow the Sun.

Reply to  Gordon A. Dressler
June 1, 2021 10:59 pm

Will the next decade see a rise of around 0.14°C? Seems likely.

donald penman
Reply to  Loydo
June 2, 2021 1:42 am

No I do not think that it is certain that it will increase by 0.14c in the next decade. Temperature goes up and down and drawing a line through a set of points does not determine anything this is just extrapolation. The straight line through the points gives a misleading view of global temperature as does splitting the globe into northern hemisphere, tropics and southern hemisphere it supports the view of those doing this.

Reply to  Loydo
June 2, 2021 5:10 am

It does seem likely as the temperature record is constantly adjusted upward from the real values.

Carlo, Monte
Reply to  Loydo
June 2, 2021 11:26 am

Does your body know if the ambient temperature rises by 0.14C?

Gordon A. Dressler
Reply to  Carlo, Monte
June 2, 2021 4:59 pm

Equally—perhaps even more important—does it care?

Reply to  Gordon A. Dressler
June 3, 2021 3:03 pm

That’s just what the frog said.

Matthew Sykes
June 2, 2021 12:34 am

As expected, but there is a clear line going from – 0.3 C to + 0.2 C right through the middle of that graph. It is still warming.

spangled drongo
Reply to  Matthew Sykes
June 2, 2021 2:14 am

But wouldn’t it be great to have had a similarly smart satellite measurement for a similar period prior to that.

AGW is Not Science
Reply to  Matthew Sykes
June 2, 2021 7:57 am

When you start the “trend” in a period cold enough that the onset of another ice age was a concern, it’s not hard to show a “warming trend.”

As in, “Pick your period, pick your trend.” Doesn’t tell you a damn thing about causation nor about what will happen in the future.

And for planet Earth, currently in an “interglacial” period during an ice age, “warming” is what sane and numerate individuals call “good news.”

Gordon A. Dressler
Reply to  Matthew Sykes
June 2, 2021 4:57 pm


I have looked and looked at the graph in the above article and just cannot find a “clear line” going “right through the middle of that graph”.

Therefore, I have to question your assertions “as expected” and “It is still warming”.

Then again, maybe your planet has two moons?

john harmsworth
June 2, 2021 9:19 am

Broke the zero line in 1987. Still able to get back to the zero line 37 years later. That’s either an awful lot of heat to reject or else it’s pretty iffy measurement. Either way, hold the panic, please.

Martin Cropp
Reply to  john harmsworth
June 2, 2021 1:12 pm

The difference in the satellite era is that all of the surface area is recorded.

The satellite era cannot be accurately and reliably compared to any period prior, that used simplistic small area coverage data recording.

Heat transport, and polar amplification identified in my comment above are not understood, and yet they play a major part in current AGW scenarios.

Accurate records started in 1979. Prior to that we have a global indication only. End of story.

Last edited 17 days ago by Martin Cropp
Aleksandr Zhitomirskiy
June 2, 2021 10:06 am

 Since we are talking about the results of statistical processing of temperature values, it is useful to recall the basic rules of statistics. 1. Rule of significant digits. For any arithmetic operation (in this case, addition and division to average the result), the number of significant digits in the result cannot be more than in the original values. The accuracy of temperature measuring instruments is 0.2-0.33 ° C ( Taking into account the temperature fluctuations within the region represented by this meteorological station, the accuracy of the initial temperature value is unlikely to be higher than 0.5 ° C, so in the end result the values of tenths of a degree, not to mention hundredths, are doubtful. 2. It makes no sense to discuss any results of statistical calculations without assessing their reliability. The statistical error is usually characterized by the value of the standard deviation (σ)and the error in the confidence interval of 95% ( ε). For example, NOAA takes as the base (zero) value of the temperature anomaly its average value over 100 years (1900 — 1999).( The calculation of the statistical error of this value gives: σ = 0.09 оС, ε = 0.06 о. In light of this, how reliable is the value of 0.08 ° C in the title of the article? 3. The reliability of the linear trend in the value, along with the slope itself, is characterized by the correlation coefficient. By the way, the values of the global temperature deviation given in the article for 17 months show a decrease in temperature from January 2020 to May 2021: the slope coefficient is -0.027, the correlation coefficient is -0.805.

Reply to  Aleksandr Zhitomirskiy
June 2, 2021 11:04 am

The accuracy of temperature measuring instruments is 0.2-0.33 ° C…

Your link refers to surface temperatures measured by thermometers. The UAH satellite data sets don’t show measured temperatures directly. They infer them from radiances measured in wavelength bands.

Taking into account the temperature fluctuations within the region represented by this meteorological station, the accuracy of the initial temperature value is unlikely to be higher than 0.5 ° C…

It’s not a region and it’s not a single station. These figures are derived from irradiances measured in the global lower troposphere as measured by several satellites and interpreted (using a model) by UAH.

Aleksandr Zhitomirskiy
Reply to  TheFinalNail
June 2, 2021 12:28 pm

Your remark does not clarify the issue of measurement accuracy. It is also unclear how the results of measurements at meteorological stations (thermometers, thermistors) and on satellites (measurements of radiation) agree. These measurements give two independent data sets, since the surface temperature always differs from the air temperature at an altitude of 1.5 (1.2-1.8) m.

Clyde Spencer
Reply to  Aleksandr Zhitomirskiy
June 2, 2021 2:22 pm

Rule of significant digits. For any arithmetic operation (in this case, addition and division to average the result), the number of significant digits in the result cannot be more than in the original values.

Actually, the rule is that the final answer should not retain any more significant figures than the multiplicand or divisor with the least number of significant figures. Although, one might make a case for doing a weighted-average where the weighting is proportional to the number of significant figures.

“When adding numbers, the rules of significant figures dictate that the sum should be rounded to the same place as the least significant place of the number, with the least number of places after the decimal point”.

June 2, 2021 12:25 pm

Makes you wonder what the turn down of the AMO will do to this short-term trend on the graph. That is the emergency for the con men, if one can be found.

June 3, 2021 11:50 pm

Are meteorological thermometers accurate to a hundredth of a degree?

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