COVID-19 lockdowns temporarily raised global temperatures

Reductions in aerosol emissions had slight warming impact, research shows

NATIONAL CENTER FOR ATMOSPHERIC RESEARCH/UNIVERSITY CORPORATION FOR ATMOSPHERIC RESEARCH

Research News

The lockdowns and reduced societal activity related to the COVID-19 pandemic affected emissions of pollutants in ways that slightly warmed the planet for several months last year, according to new research led by the National Center for Atmospheric Research (NCAR).

The counterintuitive finding highlights the influence of airborne particles, or aerosols, that block incoming sunlight. When emissions of aerosols dropped last spring, more of the Sun’s warmth reached the planet, especially in heavily industrialized nations, such as the United States and Russia, that normally pump high amounts of aerosols into the atmosphere.

“There was a big decline in emissions from the most polluting industries, and that had immediate, short-term effects on temperatures,” said NCAR scientist Andrew Gettelman, the study’s lead author. “Pollution cools the planet, so it makes sense that pollution reductions would warm the planet.”

Temperatures over parts of Earth’s land surface last spring were about 0.2-0.5 degrees Fahrenheit (0.1-0.3 degrees Celsius) warmer than would have been expected with prevailing weather conditions, the study found. The effect was most pronounced in regions that normally are associated with substantial emissions of aerosols, with the warming reaching about 0.7 degrees F (0.37 C) over much of the United States and Russia.

The new study highlights the complex and often conflicting influences of different types of emissions from power plants, motor vehicles, industrial facilities, and other sources. While aerosols tend to brighten clouds and reflect heat from the Sun back into space, carbon dioxide and other greenhouse gases have the opposite effect, trapping heat near the planet’s surface and elevating temperatures.

Despite the short-term warming effects, Gettelman emphasized that the long-term impact of the pandemic may be to slightly slow climate change because of reduced emissions of carbon dioxide, which lingers in the atmosphere for decades and has a more gradual influence on climate. In contrast, aerosols – the focus of the new study – have a more immediate impact that fades away within a few years.

The study was published in Geophysical Research Letters. It was funded in part by the National Science Foundation, NCAR’s sponsor. In addition to NCAR scientists, the study was co-authored by scientists at Oxford University, Imperial College, and the University of Leeds.

Teasing out the impacts

Although scientists have long been able to quantify the warming impacts of carbon dioxide, the climatic influence of various types of aerosols – including sulfates, nitrates, black carbon, and dust – has been more difficult to pin down. One of the major challenges for projecting the extent of future climate change is estimating the extent to which society will continue to emit aerosols in the future and the influence of the different types of aerosols on clouds and temperature.

To conduct the research, Gettelman and his co-authors used two of the world’s leading climate models: the NCAR-based Community Earth System Model and a model known as ECHAM-HAMMOZ, which was developed by a consortium of European nations. They ran simulations on both models, adjusting emissions of aerosols and incorporating actual meteorological conditions in 2020, such as winds.

This approach enabled them to identify the impact of reduced emissions on temperature changes that were too small to tease out in actual observations, where they could be obscured by the variability in atmospheric conditions.

The results showed that the warming effect was strongest in the mid and upper latitudes of the Northern Hemisphere. The effect was mixed in the tropics and comparatively minor in much of the Southern Hemisphere, where aerosol emissions are not as pervasive.

Gettelman said the study will help scientists better understand the influence of various types of aerosols in different atmospheric conditions, helping to inform efforts to minimize climate change. Although the research illustrates how aerosols counter the warming influence of greenhouse gases, he emphasized that emitting more of them into the lower atmosphere is not a viable strategy for slowing climate change.

“Aerosol emissions have major health ramifications,” he said. “Saying we should pollute is not practical.”

###

About the article

Title: “Climate Impacts of COVID-19 Induced Emission Changes”
Authors: A. Gettelman, R. Lamboll, C. G. Bardeen, P. M. Forster, D. Watson-Parris
Journal: Geophysical Research Letters

This material is based upon work supported by the National Center for Atmospheric Research, a major facility sponsored by the National Science Foundation and managed by the University Corporation for Atmospheric Research. Any opinions, findings and conclusions or recommendations expressed in this material do not necessarily reflect the views of the National Science Foundation.

On the web: news.ucar.edu

On Twitter: @NCAR_Science

From EurekAlert!

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Mark Pawelek
February 3, 2021 2:09 am

If global temperatures were temporarily “raised” why is the global temperature anomaly (UAH – satellite, lower troposphere average temperature) down to only an eighth of a degree Celsius?

http://www.drroyspencer.com/wp-content/uploads/UAH_LT_1979_thru_January_2021_v6.jpg

Loydo
Reply to  Mark Pawelek
February 3, 2021 3:07 am

raised…”than would have been expected with prevailing weather conditions”.

This is not a surprising result of reduced aerosols. The aerosol masking effect is nothing new and it is estimated to be cooling the surface by as much as 1C. Unlike CO2 they wash out quickly – in the order of a few weeks – so the removal of the masking effect is rapid.

Reply to  Loydo
February 3, 2021 3:36 am

Nevertheless, Aerosol particles cool the climate less than we thought“The impact of atmospheric aerosols on clouds and climate may be different than previously thought. That is the conclusion of cloud researcher Franziska Glassmeier from TU Delft. The results of her study will be published in Science on Friday, January 29th.”


Sulfate Aerosols Cool Climate Less Than Assumed
“The life span of cloud-forming sulfate particles in the air is shorter than had been assumed due to a sulfur dioxide oxidation pathway which has been neglected in climate models so far.”

Last edited 3 months ago by Krishna Gans
Bryan A
Reply to  Krishna Gans
February 3, 2021 10:59 am

Hmmm Kimosabe
pollution bad … causing climate warming
Lack of pollution bad … causing climate warming

Loydo
Reply to  Krishna Gans
February 3, 2021 2:59 pm

From your Franziska Glassmeier link:
Our conclusion is that the cooling effect of aerosols on clouds is overestimated when we rely on ship-track data,” says Glassmeier. “Ship tracks are simply too short-lived to provide the correct estimate of cloud brightening.”

None of that conflicts with what I wrote and I am definitely not speaking about the weather. Sulphate aerosol cooling is a climatic forcing phenomena.

Latitude
Reply to  Loydo
February 3, 2021 5:41 pm

this is bullcrap…..china increased it’s emissions

china doesn’t exist in this global warming world

Reply to  Loydo
February 3, 2021 4:32 am

Btw, remember, you speak about weather 😀

Gerald Machnee
Reply to  Loydo
February 3, 2021 7:31 am

**They ran simulations on both models, adjusting emissions of aerosols and incorporating actual meteorological conditions in 2020, such as winds.**
Enuf said here Loydo. “SIMULATIONS”. They never measured a thing. Sat at a computer collecting money for fiction.

Loydo
Reply to  Gerald Machnee
February 3, 2021 3:01 pm

Isn’t that what the authors of this post did?

MarkW
Reply to  Loydo
February 3, 2021 7:32 am

Most of the post 70’s warming was caused by the Clean Air Act.

Notice how none of the climate models that Loydo is paid to worship, include any of this pollution reduction in their tuning. They all assume that all warming was caused by CO2.
One of the many reasons why all of the models run very hot.

Loydo
Reply to  MarkW
February 3, 2021 3:01 pm

Why do you say they don’t include it?

Bryan A
Reply to  Loydo
February 3, 2021 8:15 pm

How about because, in all the reports/papers/MSM articles, CO2 increase is the ONLY source mention of a cause/control temperature mechanism and no mention of aerosol reduction induced warming is made

Meab
Reply to  Loydo
February 3, 2021 8:47 am

You do realize, LoyD’oh, that you just argued that CO2 has a minor effect on temps, don’t you? Since aerosols wash out quickly, they must have risen much more quickly at the start of the industrial age than CO2, causing a rapid decline in temps over a century ago, especially as little was done to control particulate emissions from early industry. If, as you claim with no evidence, that aerosols cause 1 C of cooling, they must be responsible for causing much of the apparent warming seen in the last century. I’m always stunned by the things that you brain-dead alarmists say without thinking things through.

fred250
Reply to  Meab
February 3, 2021 10:52 am

You do realize, LoyD’oh, that you just argued that CO2 has a minor effect on temps.

.

Loy-dumb has made it a point of PROVING that there is no evidence of warming by atmospheric CO2,…

…. let alone the small fraction that humans are responsible for.

That is, in fact, the ONLY contribution he/she/it makes to the blog.

Lrp
Reply to  Meab
February 3, 2021 2:36 pm

He’ll need to be awake first

Loydo
Reply to  Meab
February 3, 2021 3:06 pm

 “If, as you claim with no evidence, that aerosols cause 1 C of cooling,”

I didn’t, I said “as much as” 1C”. Estimates vary. But we get a clear example each time a large volcano goes off.

These studies shows that the temperature anomaly after Pinatubo is about 0.4 to 0.6 K cooler than average over a large part of the Earth”
https://pubs.usgs.gov/pinatubo/self/#:~:text=These%20studies%20shows%20that%20the,13).

commieBob
Reply to  Mark Pawelek
February 3, 2021 5:48 am

The baseline has been changed so that reduces the anomaly a bit.

Look at the temperature record though. It’s a mess. Doing statistics based on a short period of messy data is bogus and meaningless.

eck
Reply to  Mark Pawelek
February 4, 2021 5:58 pm

Models, dear boy. Models.

David Guy-Johnson
February 3, 2021 2:13 am

This strikes me as absolute rubbish.

Peta of Newark
Reply to  David Guy-Johnson
February 3, 2021 4:29 am

yes

Rick C
Reply to  David Guy-Johnson
February 3, 2021 7:07 am

Yup. Whenever you see, “Teasing out the impacts”, that’s climate speak code for pure speculation and confirmation bias.

Matthew Sykes
February 3, 2021 3:02 am

Flying. Temperatures rose after 9/11 when flights were banned for a week or so.

THose contrails reflect a lot of the suns energy,

Craig from Oz
Reply to  Matthew Sykes
February 3, 2021 4:08 am

But only when you are flying in a private jet to a conference to ‘Raise Awareness’.

If you are flying economy to visit your family you are a CO2 Monster that is Roasting the Planet(tm).

Geoffrey Moore
Reply to  Matthew Sykes
February 3, 2021 7:06 am

I agree, my solar panels made record amounts of power last year. We live on the southern tip of Lake Huron under a major air corridor into the USA. Noticeably less cloud and con trails.

Michael S. Kelly
Reply to  Matthew Sykes
February 4, 2021 4:00 am

I’ve read the same stories, but am not sure I believe that the effect was really that big. I lived in Redlands, CA on 9/11/2001. We were directly under the LAX/ONT pattern, though we never noticed it until all flights stopped. Then the situation was eerie. I still can’t recall any flight noise during normal times, but I strongly recall the lack of noise – and contrails – when flights were stopped. But there was no perceptible difference in temperature.

I contrast that with brushfire situations. I vividly recall driving from Rocketdyne in Canoga Park back to Redlands, along the I-210 and then Baseline Drive (before the 210 to San Bernardino was complete) during a particularly bad brush fire to the north. It was a hot day by Valley standards, in the upper 90s. But as soon as I passed under the smoke cloud of the brushfire, my car’s outside thermometer reading dropped a full 20 F. I found that rather astonishing, but it was very real.

As an aside, we had an interesting occurrence in Redlands in 2005. There were two weeks in December of that year where the skies were completely clear at night, and air temperatures dropped as low as (but no lower than) 38 F. On five of those nights, the air at ground level was absolutely still. Those nights, our swimming pool froze to a depth of 3/8 of an inch. The implication is that the dominant heat transfer effect was radiative, and it was very powerful. I estimated the view factor (given that our pool had our house on one side, and tall trees on the remaining three sides), and calculated the sky temperature required to produce that amount of ice in 8 hours of darkness. It was -60 F. That’s when I became a skeptic of CO2 induced global warming.

JeffC
February 3, 2021 3:52 am

So the increase in temperature since the 1970s was down to the removal of pollutants in the atmosphere by most industrial nations and was nothing to do with CO2?

Alan Watt, Climate Denialist Level 7
Reply to  JeffC
February 3, 2021 4:39 am

JeffC: Thank you; I was going to make the same point.

Amazing how “startling findings” from one study can directly contradict “startling findings” from other stories and nobody notices (well, not officially).

Carl Friis-Hansen
Reply to  JeffC
February 3, 2021 4:51 am

You stated the obvious.
One just have to be thinking a bit logic here, think about pictures from the past and a London that in the past saw no sun, because everyone were heating and cooking with coal, firewood and the like.

Crab aside, the global temperature is a raw indicator at best, the system is complex and a thousand human parameters influence the weather to a lesser degree.

In reality we saw surprisingly little weather effect due to Lock-Down, but rising human suffering far worse than bad weather.

Only Isle of Man government seem to make sense in Western Europe.

Greg61
Reply to  JeffC
February 3, 2021 7:44 am

Collapse of the Soviet Union, drastic improvements in pollution reduction in India, the acid rain effort, etc, etc etc.

Matthew Sykes
Reply to  JeffC
February 4, 2021 1:14 am

Yes, that has been my thoughts precisely, so although the suns increased activity peaked in the 70s, the removal of pollution in the west caused temperatures to continue increasing after.

In the UK in London in the 1950s we had such bad smog you couldnt see more than ten feet! Thats how bad pollution was, way way worse than Beijing.

ozspeaksup
February 3, 2021 4:07 am

oh thats funny
pollution cools isnt unknown at all
and they utterly avoided China?Indias massive pollution reductions shown by the cleaner air and Indians seeing the Himalayas again
if theyd banned ALL heating n cooling machinery used in homes as well as having cars off rd and most all planes grounded thereby reducing waste heat emissions I betcha UHI woulda dropped a decent bit of a degree too
roflmao

Paul C
February 3, 2021 4:13 am

These are true climate scientists who ignore the DATA “temperature changes that were too small to tease out in actual observations” in favour of computer games “simulations on both models, adjusting…” until they got whichever result they wanted.

Dave
February 3, 2021 4:21 am

The volcano rumbles and only the high priests know why. We must do what the high priests tell us. Bacause only the high priests know the secrets of the deep.

I pray for an Ice Age. Just to watch how these priests will explain how humans warming the planet has caused the Atlantic to freeze

Peter W
Reply to  Dave
February 3, 2021 6:45 am

Given the way the winter has been going, looks like your prayers might be getting an answer.

2hotel9
February 3, 2021 4:34 am

And just how much of our tax money was pissed away on this crap?

Cynic
February 3, 2021 7:02 am

Today on the Worldometers site the weekly trend lines show ~142K daily new cases and ~3K daily deaths for a 2.2% death rate. It looks like in about another month there will be about 1 death for every 20 new cases or a 5% death rate. That’s estimating 40K new daily cases and 2K daily deaths. I suppose there would be a change in the methods for counting covid deaths to prevent that from happening.

andy in epsom
Reply to  Cynic
February 3, 2021 11:34 am

How is this relevant to the cooling effect?

GregK
Reply to  Cynic
February 4, 2021 7:40 pm

A somewhat cynical observation….3000 deaths per day. Each human produces about 100W so that’s 3000 by 100 = 300,000 W less per day. That doesn’t include whatever other energy/power producing activities they might have been involved in. Got to contribute to global cooling.

Gerald Machnee
February 3, 2021 7:28 am

**Although scientists have long been able to quantify the warming impacts of carbon dioxide**
Another fable. Only on paper.

Steve Z
February 3, 2021 7:30 am

During practically the entire year 2020, the ENSO meter on the WUWT site has been steady around -0.7, indicating a fairly strong La Nina for the entire year. Precipitation was very low across the western USA starting around May 2020, while there was a very active Atlantic hurricane season. How much of the apparent “temperature rise” was due to lower aerosol emissions, and how much to La Nina?

Also, the Covid lockdowns also reduced CO2 emissions from transportation, particularly planes and cars. If global-warming theory is correct, wouldn’t that tend to reduce temperatures?

Paul C
February 3, 2021 7:30 am

I just have a suspicion that this is an attempt at giving a pre-emptive excuse for a planned downwards adjustment to last year’s temperatures. With the Glasgow boondoggle coming up, the “most hottest year evah” that was tried out in 2020 could prove inconvenient if it is trending cooler this year, especially if Glasgow has normal weather. A special lockdown adjustment to the already mangled temperature record may be deemed necessary to create a false appearance of warmth in 2021.
At least the Scots can be a friendly bunch. There is even a special welcome called a “Glasgow kiss” which the many deserving delegates are unfortunately likely to miss out on with all the social distancing rules.

Ab Mix-O'Lydian
Reply to  Paul C
February 3, 2021 10:37 am

Is that “Gleska kiss” anything like a “Govan grin”? May more than a few be conferred on delegates.

Paul C
Reply to  Ab Mix-O'Lydian
February 3, 2021 1:16 pm

In Britain, a Glasgow kiss is known as the action of the forehead being applied (with extreme prejudice) to the interloper’s nose. Often accompanied by the verbal greeting “Hey you Jimmy, who you looking at?”. Jimmy being a Scottish approximation of John Doe in American English. The native performing the greeting will normally have consumed large quantities of alcohol to create the required ambience. The traditional response of the recipient of the greeting is to bleed profusely from the nose and mouth (spitting out teeth is optional) and roll about on the floor moaning incoherently. Failure to respond appropriately may invoke the ire of any of the greeter’s compatriots who may enforce the appropriate response by administering a good kicking.
As you can see in the article linked below, just as the Inuit have many words for describing snow as it is so important in their culture, so the Scottish have a colourful and rich description of drunkenness, it being so central to their culture.
https://www.scotsman.com/heritage-and-retro/heritage/50-scottish-slang-words-translated-funniest-and-best-sayings-and-slang-phrases-scotland-and-what-they-mean-english-2539426

Chaswarnertoo
February 3, 2021 7:52 am

So how come there has been no measurable reduction in CO2? Could it be that CO2 has no measurable effect…..

Clyde Spencer
Reply to  Chaswarnertoo
February 3, 2021 9:19 am

The really interesting thing is that studies have been able to document decreases in the atmospheric concentrations of NOx and particulates, and increases in ozone. Anthropogenic emissions of CO2 decreased, yet, there was no discernible decrease in atmospheric CO2 concentrations, or even the rate of increase, at any of the monitoring stations during the time that the CO2 sinks in the northern hemisphere were inactive.

That raises the uncomfortable question of whether it is reasonable to expect the rate of CO2 increase to decline if we take drastic measures to curtail the use of fossil fuels! An alternative hypothesis to the prevailing paradigm is that anthropogenic emissions are so small, compared to the annual turnover of the Carbon Cycle, as to be negligible! Yet, politicians who have no expertise in science, claim to “believe science” and are willing to risk a major disruption in the economy to support their ‘belief.’ I’d rather see a detailed cost/benefit analysis with estimates of the time necessary to accomplish the steps in the revolution, taking into consideration the availability of essential resources such as copper and Rare Earth Elements. Beliefs are only useful until it becomes obvious that the beliefs are “baseless.”

Matthew Sykes
Reply to  Clyde Spencer
February 4, 2021 1:17 am

Quite, there has to be a carbon cycle so big that it dwarfs out output. Lockdown has been a very interesting experiment, and it has thrown a huge spanner in the works.

There is literally no point cutting CO2 production, it has no impact at all on global CO2 levels.

Randy Stubbings
February 3, 2021 8:38 am

“This approach enabled them to identify the impact of reduced emissions on temperature changes that were too small to tease out in actual observations, where they could be obscured by the variability in atmospheric conditions.”

To produce results that cannot be teased out of actual observations I can write a mean little random number generator. Please send money and I will forward the code.

Joel O'Bryan
February 3, 2021 9:23 am

“models”….”This approach enabled them to identify the impact of reduced emissions on temperature changes that were too small to tease out in actual observations, where they could be obscured by the variability in atmospheric conditions.”

Complete Emperor’s New Clothes stuff… masquerading as some semblance of science.

Last edited 3 months ago by joelobryan
February 3, 2021 10:05 am

Temperatures over parts of Earth’s land surface last spring were about 0.2-0.5 degrees Fahrenheit (0.1-0.3 degrees Celsius) warmer than would have been expected with prevailing weather conditions, the study found. The effect was most pronounced in regions that normally are associated with substantial emissions of aerosols, with the warming reaching about 0.7 degrees F (0.37 C) over much of the United States and Russia.

The above conclusion is directionally correct, but 0.1-0.3C of aerosol cooling from the lockdown looks too large. In this 15June2019 paper, I show that the cooling impact of a century-scale VEI6 volcano like Pinatubo is only about 0.5C.
 
https://wattsupwiththat.com/2019/10/27/the-real-climate-crisis-is-not-global-warming-it-is-cooling-and-it-may-have-already-started/#comment-2836262

Major volcanoes (some VEI5 eruptions like El Chichon 1982 and most VEI6 events like Pinatubo 1991+) cause significant (~0.5C) global cooling – but industrial emissions and smaller volcanoes don’t have much impact. Even Mt. St. Helens (VEI5, 1980) did not have much cooling impact because it blew mostly sideways, not up into the stratosphere.

Supporting evidence is in Section 5 of this paper.

CO2, GLOBAL WARMING, CLIMATE AND ENERGY
by Allan M.R. MacRae, B.A.Sc., M.Eng., June 15, 2019 
https://wattsupwiththat.com/2019/06/15/co2-global-warming-climate-and-energy-2/
Excel: https://wattsupwiththat.com/wp-content/uploads/2019/07/Rev_CO2-Global-Warming-Climate-and-Energy-June2019-FINAL.xlsx

 

Last edited 3 months ago by ALLAN MACRAE
Reply to  ALLAN MACRAE
February 3, 2021 1:14 pm

 

Although scientists have long been able to quantify the warming impacts of carbon dioxide…

 
Nope! Most climate-alarmist scientists have over-estimated the warming impacts of increasing atmospheric CO2 by a factor of at least 3 and probably 10 or more, in order to create false alarm.
 
I know, picky picky – but I’m tired of all the warmist BS!
 
Je suis completement “fed-up”, tabarnac! 🙂

February 3, 2021 1:28 pm

When the Global Warmists start to advocate an increase in the level of pollution as a solution to the supposed temperature increase caused in their imagination, by manmade CO2 since the 1970s they are beginning to look very inappropriate and harmful.

menace
February 3, 2021 1:57 pm

Reminds me of analysts on TV that try to explain a cause for every little glitch in the stock market. It can’t just be “noise in the system” everything has to have some cause to explain it.

We thought temp should go down but it went up instead – someone quick explain it for me!

Walter Sobchak
February 3, 2021 2:38 pm

“To conduct the research, Gettelman and his co-authors used two of the world’s leading climate models:”

Sorry, that is not research. No actual data was gathered.It is just computer games. He could have played Call of Duty instead. It would be just as meaningful.

Greg
February 3, 2021 11:19 pm

The counterintuitive finding highlights the influence of airborne particles, or aerosols, that block incoming sunlight. When emissions of aerosols dropped last spring, more of the Sun’s warmth reached the planet, especially in heavily industrialized nations, such as the United States and Russia, that normally pump high amounts of aerosols into the atmosphere.

Oh, the US and bad,bad Russia.

Please do NOT mention the greatest producer of REAL pollution on the planet. Hunter Biden’s “investments” may be negatively affected !!

Last edited 3 months ago by Greg
Andy Pattullo
February 4, 2021 8:30 am

Drivel. This is just more pretending to understand weather, climate and the exact causative role of human activity or inactivity. It seems 95% of “research” in this area is self-justifying claims of relevance with no actual test of an hypothesis.

niceguy
Reply to  Andy Pattullo
February 4, 2021 5:27 pm

The same way they are pretending to model Corona.

Ulric Lyons
February 4, 2021 4:17 pm

In the UK, which I am sure is not unique, we have higher surface temperatures when there are high levels of low altitude air pollution. Like with the record high temperatures in 21-27 February 2019, and in Easter 2011, both with heavy air pollution which drifted across from Europe. And the hot summer of 1783, with low altitude volcanic fumes and dust from the Laki eruption in Iceland. The Moscow 2010 summer heatwave was exacerbated by forest fire smoke.

eck
February 4, 2021 6:02 pm

“carbon dioxide and other greenhouse gases”. Don’t you just love how the “hive” phrases things? How about “water vapor and other greenhouse gases”.

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