Australia Bushfire Smoke Now Warming the Lower Stratosphere?

From Dr. Roy Spencer’s Blog

March 4th, 2020 by Roy W. Spencer, Ph. D.


Fig. 1. Bushfire smoke flowing eastward from SE Australia on January 4, 2020 as seen from the International Space Station (NASA).

John Christy pointed out to me that our UAH lower stratosphere (“LS”) temperature product which has peak sensitivity at about 17 km (70 hPa pressure) has increased in the last 2 months to its warmest value since the post-Pinatubo period of warming (1991-93). This can be seen in the following plot of global average anomalies.

Fig. 2. UAH Version 6 global-average lower stratospheric (LS) temperature anomalies for January 1979 through February 2020.

At first I though we might be seeing warming from the mid-January eruption of Taal volcano in the Philippines, but even the much more massive mid-June 1991 eruption of Pinatubo did not show up in the LS temperatures until the month following the eruption, while we see evidence of warming in Fig. 2 in the same month as the Taal eruption.

NASA had previously reported that the smoke from the Australian bushfires had been detected in January as as high as 20-25 km, well into the stratosphere (see here, here, and here). The measurements come from the CALIPSO spacecraft which has a lidar instrument capable of accurate altitude measurements of aerosols.

The mechanism for the warming of the lower stratosphere by the smoke is some combination of direct solar heating of the smoke particles, and infrared (“greenhouse”) warming of the smoke layer, the latter being the mechanism that caused the warming after the eruptions of El Chichon and Pinatubo. The aerosol layer is very cold, and it intercepts infrared radiation from below and so warms slightly.

I will try to examine the specific latitude band (30S-60S) being affected in more detail, including temperature measurements from higher up (which we do not produce official products for). The difficulty is that there is considerable natural variation in the tropical and extra-tropical temperatures in the stratosphere which have a see-saw behavior due to variations in the strength of the Brewer-Dobson circulation. As a result, these stratospheric aerosol effects on temperature tend to show up best in global or nearly-global averages (Fig. 2, above) where such circulation induced changes average out.

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March 5, 2020 2:09 am

Holy smoke!

Komrade Kuma
March 5, 2020 2:10 am

As an Australian I sincerely and profoundly apologise for the opportunity this phenomenon will gift the climate alarmists in postulating some sort of catastrophic feedback between climate change – bushfires and further climate change. We really should have sorted out that Indian Ocean Dipole thing much earlier. We were slack and still pissed ( i.e. drunk) from the football season finals. Sorry about that.

March 5, 2020 2:57 am

So the Lower Strat. cooling trend seems to be an inverse of of the Troposphere warming. Does that mean that we should now see some cooling of the Troposphere over the next few months ?

Roy W. Spencer
Reply to  ggm
March 5, 2020 4:33 am

ggm, it appears the smoke is causing warming in the troposphere as well. I’m investigating that now with Metop AMSU data from all of its channels, and the main tropospheric channel (AMSU5) is considerably warmer (by about 0.4 deg C) than it should be given the values of AMSU channels 1,2,3 averaged over the latitude band 25S-55S. So, some of the strong global lower tropospheric warmth in February 2020 could be from the radiative effects of the smoke.

Joel O’Bryan
Reply to  Roy W. Spencer
March 5, 2020 7:27 am

Do you monitor what is going on under the hood on the instruments controlled by the operator. Firmware and bus software updates?
I know you compensate for platform drift over time, but what about keeping an eye on voltages on the receiver antennas LNAs? things like that that the technicians control?

Roy W. Spencer
Reply to  Joel O’Bryan
March 5, 2020 10:01 am

There are no changes made to these instruments on-orbit unless there is a failure say in a local oscillator and it’s one of the channels that has redundant hardware. Since the instruments are externally calibrated through the entire RF path, such changes “shouldn’t” affect calibration. The 2 satellites we are currently using both show the LS warming.

Greg Goodman
Reply to  Roy W. Spencer
March 5, 2020 8:45 am

and infrared (“greenhouse”) warming of the smoke layer, the latter being the mechanism that caused the warming after the eruptions of El Chichon and Pinatubo.

That is interesting but as ggm says that would seem to suggest there should have been TLT warming after Mt Pinatubo, yet the orthodox view is volcanic cooling at the surface.

How does this relate to persistent 0.5 deg C cooling which of TLT which see after both El Chichon and Mt P. Doesn’t this imply that once the aerosols had been removed by natural processes, the lower stratosphere was notable less opaque than before the eruption.

My personal interpretation of this was a) ozone destruction by sulphate aerosols; b) likely the processes which removed them also removed other pollutants ( probably aircraft derived ) at the same time. This also leads to the conclusion that major eruptions have a long term warming effect beyond the initial cooling which modellers use.

I’ve been waiting for the next VEI5/6 to test this hypothesis.

Reply to  Greg Goodman
March 5, 2020 9:00 am

Oops, that was a bit garbled.

How does this relate to the persistent 0.5 deg C cooling of TLS which is seen after both El Chichon and Mt Pinatubo eruptions? Doesn’t this imply …..

Reply to  Roy W. Spencer
March 5, 2020 6:02 pm

And are you able to geographically map it out from SAT data?

Ben Vorlich
March 5, 2020 3:59 am

So now the fires are out, how long will this last and what are the knock on effects?

March 5, 2020 4:04 am

“In the case of Mount Pinatubo, the result was a measurable cooling of the Earth’s surface for a period of almost two years.” link

Samuel C Cogar
March 5, 2020 4:04 am

Excerpted: “the smoke is some combination of direct solar heating of the smoke particles, and infrared (“greenhouse”) warming of the smoke layer,

I assume that the incoming solar energy would not only cause “direct solar heating of the smoke particles” …… but an additional percentage of the incoming solar energy is being reflected away from the earth via the smoke particulate.

So, my question is, …. given the above absorption and refection, …. has anyone measured the reduction in the energy density at the surface, which is normally or approximately 1,000 W/m2?

Roy W. Spencer
Reply to  Samuel C Cogar
March 5, 2020 4:35 am

Samuel, I don’t think anyone knows the answer to that question yet.

Greg Goodman
Reply to  Roy W. Spencer
March 5, 2020 9:12 am

You may find this article I wrote goes someway to answering that question.

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An essential step is first work out the climate response curve rather than just taking the AOD data directly. The AOD effect peaked about 7mo after the eruption, but the surface climate response peaks at more like 13mo. This fits with a simple relaxation response. It is similar to the fact that NH peak solar occurs in mid June but temps peak in August.

Ben Santer et al 2014 noted a mismatch when using AOD to fit temperature data but failed to realise why it occurred. To their credit they did document the discrepancy in an appendix.

This all relates to untangling the in phase and and the orthogonal response, something I think Dr Spencer has commented on on his blog, several years back.

Reply to  Greg Goodman
March 5, 2020 9:35 am

Incidentally, this is quite important since, if you use AOD and not the climate response, you get the peaks misaligned and this leads to an incorrect scaling of AOD ( the measured Dobson optical density ) and the radiative forcing you need for you climate models and multivariate regression attempts.

That is why my calculations fit better with Lacis et al’s original physics based models of El Chichon (x30 W/m2), than Hansen et al’s later attempts at arbitrary fudge factor twiddling to match model hindcasts (x21 W/m2).

They are happy to chop 50% of volcanic forcing but the rest is all settled science.

Craig from Oz
Reply to  Roy W. Spencer
March 5, 2020 3:48 pm

Sorry Roy, but why not?

Are people honestly claiming that there has NEVER been bushfires before and by extension NEVER been smoke at these levels? We have been hearing for years how mankind may be forced to spray particles in the air to block some of that nasty warming sunlight (because it may already be too late and it is worse than we thought etc etc) but now people are claiming they haven’t even studied the processes?

Reply to  Craig from Oz
March 5, 2020 7:31 pm

Don’t worry, if the green idiots manage to drastically reduce or cancel commercial air travel, they will stop our efforts to pollute the lower stratosphere. That means less condensation nuclei, it will become less opaque and more solar energy will make it to ground level.

Then they will get the opposite effect of what they hoped for. Yet another piss-pot world saving idea that they do not understand, have not though through and will hit be back with the law of unintended consequences.

Samuel C Cogar
Reply to  Roy W. Spencer
March 6, 2020 3:51 am

Well now, I was simply pondering why, ….. given the fact they can measure the energy density at the surface on a clear bright sunshiny day to be approximately 1,000 W/m2, ……. why hasn’t someone measured the energy density at the surface on a “brushfire” smokey hazy day?

Then ya take the “energy density” difference between the two, ……. times the number of “brushfire smokey hazy days”.

Iffen the “experts” can calculate exactly how much CO2 is being emitted by humans, ….. then calculating that “energy density” difference ought to be ‘duck soup’ easy.

March 5, 2020 4:27 am

If the spacing of the samples is any indication, the curve is rising about half as fast as it did after Pinatubo.

Greg Goodman
Reply to  commieBob
March 5, 2020 8:55 am

Mt P. was quite close to the equator which made dispersal pretty much global and hemisphere symmetric.
I proposed a model based on rate processes, one the production of aerosols, the other removing them.

This fits the data much better than the usual attempts to use a single decaying exponential.

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The climate response lags about a year behind the AOD measurements of opacity. ( This is not a fixed lag, that’s a lazy description, it’s phase response ).

The fire pollution may work differently since it direct pollution not conversion of SO2in to sulphate aerosols.

March 5, 2020 4:42 am

The article links suggest that Aussie brush fires are responsible for unprecedented stratospheric pollution (esp. the third ‘here‘ link below)

NASA had previously reported that the smoke from the Australian bushfires had been detected in January as as high as 20-25 km, well into the stratosphere (see here, here, and here). The measurements come from the CALIPSO spacecraft which has a lidar instrument capable of accurate altitude measurements of aerosols.

So, what effect does this have on the troposphere, where most of us live?

Using the on-line interactive weather tool, you can see tropospheric global air quality conditions in real time. For example, here is satellite-observed ‘dust mass’ for Africa, Asia and Australia:—add-more-layers/overlays?dustsm,-14.491,96.270,3

Try changing the target layer parameter (Dust mass, Aerosol, SO2, PM2.5, CO, NO2, etc) from the menu on the right side of the screen. You will see that tropospheric air quality conditions are generally far worse now in Africa and Asia than Australia.

Is this a political ‘smoke job’ on Australia? What lasting impact do these stratospheric smoke intrusions have on our climate?

Reply to  Johanus
March 5, 2020 5:41 am

According to the NASA link, the smoke may be with us a bit:

In that case [Canadian fire’s smoke], satellites detected the smoke for eight months before it dissipated.

March 5, 2020 4:45 am

Very interesting. A number of posts on this blog have convincingly made the point that while the 2019/20 fire season was high, it was not exceptional. Could one expect a similar signal after other big fire years or was there something special about this season (height of smoke column, prevailing atmospheric conditions, etc)? Is Australia uniquely positioned globally for this TS warming phenomenon or would we expect similar warming from big fire years on other continents (e.g. NA in the late 19th and early 20th centuries)?

Reply to  MJB
March 7, 2020 10:55 am

The season was not at all exceptional in terms of area burned, but it may well have been exceptional for the quantity of burned organics, since it affected areas where burns had been prevented/prohibited for a long time. This may also have been true for fire intensity, which affects the altitude to which the smoke rises.

A thought in this context. Has anyone tried to investigate if the very considerable fires in the northern hemisphere 1942-45 affected climate?

March 5, 2020 4:58 am

Does the fact that last year had over 25 stratospheric eruptions by various volcanoes have any impact?

Taal is just one volcano that did this earlier this year, but Shiveluch had several stratospheric eruptions last year alone. That may be something to look into. Temperatures have been higher for any months now.

March 5, 2020 5:37 am

And there’s me thinking stratospheric aerosols from volcanoes cause cooling, according to IPCC climate models.

Reply to  ThinkingScientist
March 5, 2020 7:10 am

That was a different computer model silly. Do keep up.

Reply to  ThinkingScientist
March 6, 2020 7:55 am

Aerosols are shiny, soot is dark.

Joel O’Bryan
March 5, 2020 5:41 am

What is the trend in stratospheric ozone over this spike (January-February)? The Brewer-Dobson circulation hypothesis posits ozone circulation from the tropics to the polar stratosphere. At least in this NH winter we have seen no polar vortex outbreaks since November which would disrupt that re-distribution. The Arctic has stayed cold this winter and locked up with no excursions.

Randall Harris
March 5, 2020 5:58 am

Just looking at the graph it seems to me that the takeaway is that the temp over the long term is decreasing and occasionally has a bump up with volcanic eruptions. Is that not better news than global warming?

Loren Wilson
Reply to  observa
March 5, 2020 10:06 am

I hypothesize that there are an infinite number of tipping points but as we pass them, the climate doesn’t actually tip. Several billion years of weather tends to support my hypothesis, but I need some funding in order to study it a bit more.

Joel O'Bryan
Reply to  Loren Wilson
March 5, 2020 2:03 pm

The overland mid-latitudes and tropics atmospheric systems go through 2 energy input forced tipping points every 24 hours.

Surface air temps coldest just before dawn, then rapidly increasing SW radiation forcing after sunrise moves the atmosphere to a shift to convective control by local noon, then through the afternoon surface winds are strongest.

Just after sunset a rapid reconfiguration past another tipping point occurs. Convective controls diminish and radiative cooling mechanism in the troposphere predominate except where localized cumulonimbus storms are convecting, but then these die-off too as the night cooling continues and surface heat that fueled the original convection burst diminishes.

Same happens over the oceans but to a much smaller degreee due to SST thermal inertia to depth.

The land-ocean interface is the complex part with shifting on-shore (daytime) and offshore (night time) breeze systems signaling these two atmospheric state regime shifts.

Old Woman of the North
Reply to  Loren Wilson
March 5, 2020 3:19 pm

Good one, Loren, I hope you find some!

Reply to  Randall Harris
March 5, 2020 9:22 am

Just looking at the graph it seems to me that the takeaway is that the temp over the long term is decreasing and occasionally has a bump up with volcanic eruptions.

Firstly, note this TLS, not lower climate. Second, don’t fall for the lazy habit of trying to draw straight line “trends” though everything. That will tell you nothing and will probably mask any real info.

There are two 0.5deg C STEPS in that data. Not a “trend”. Apart from the initial humps after each eruption the net long term effect is sizeable downward step event. The step nature is recognised and is at least in part due to ozone destruction by the sulphate aerosols. Once the aerosols clear, the lower stratosphere blocks less incoming SW due to less ozone. The implication is it should cause lower climate warming.

Also drawing a straight line though this data is excuse for pretending ozone depletion was all caused by man made CFCs and that flat later section is the amazing success of the Montreal Protocol. That is a lie, it is just that there were not more major eruptions on the scale of Mt P.

Reply to  Greg
March 5, 2020 9:41 am

“At the time of maximum aerosol development, up to 20% depletion in ozone was measured over Colorado and Hawaii ”

Lee Alison
March 5, 2020 6:23 am

Any chance that months of huge fires might have warmed the air a bit?

March 5, 2020 6:39 am

How does the smoke get up there? I can understand the power of a big volcano launching ash up that high, but forest fires seem to have columns of smoker less towering.

Robert W Turner
Reply to  Caleb Shaw
March 5, 2020 7:04 am

That’s my question exactly. Not even all volcanoes eject smoke that high.

My guess is the smoke got wrapped up into a very powerful low pressure system – where most stratospheric water vapor comes from. But how enough of it got into the stratosphere to make a difference is odd.

Plain Jane
Reply to  Robert W Turner
March 6, 2020 6:03 pm

I just thought of something a friend told me. He described his son as a conservative sort of fellow not prone to exaggeration. His son was on the coast, about 30 km downwind of those fires. There are burnt leaves landing huge distances from the fires, but that is expected. His son said that a burnt stick about 8 inches long and almost as thick as his finger landed near him – remember this is 30 km or more from the fire. So the updrafts around those huge fires have an enormous amount of energy.

Reply to  Caleb Shaw
March 5, 2020 7:35 am

I wonder about that too. Yeah I know, convection, but part of the cause of the fires was high pressure in that regional area, which is subsidence.

Plain Jane
Reply to  beng135
March 5, 2020 7:01 pm

My imperfect understanding from having to live with these huge fires less than 10 km away for about 6 weeks, is that the high pressure cells cause high temps from inland and are followed by low pressure fronts with very high winds, like 80 to 120 km per hour, that last 12 hours or so (I am so tired of them). So its low fronts that follow the highs that cause the catastrophic days, like the 4th January, not the highs themselves. There are things that people describe from those catastrophic fires that I dont think science understands yet. Some other sort of physics and meterorology takes over, things like massive wind shear effects (that brought down the american water bomber near here and also picked up and flipped over and over a 16 ton water tanker). There are anecdotal descriptions of “descending fireballs” that are common, but have no scientific explanation that I know of. The power of the heat and wind is doing things that might get it high enough into the atmosphere. I can pick where I live in the picture at the top of this post from the shape of those plumes and I know which fires they were. It went blacker than midnight by 4pm on the 4th Jan from a fire that I knew was over 80 km away. I am so glad I had the internet and weather radars to show me where the smoke was. The smoke showed like rain on airport weather radars but with a different pattern and was the most reliable judge for me as to how worried I should get and how close bad fires were.

Reply to  Plain Jane
March 6, 2020 8:46 am

Thanks for your reply & so sorry about the misfortune…

March 5, 2020 6:56 am

Just today, CBC in Canada is still using the Australian bush fires to promote climate change alarmism:

Dave Eserhut
March 5, 2020 6:58 am

If smoke from the Australian fires is indeed causing LT warming, wouldn’t we expect to see more of an effect in the southern hemisphere? The February data shows the northern hemisphere with a considerably larger anomaly.

Izaak Walton
March 5, 2020 9:46 am

I am confused. First numerous people here have claimed that the Australian bushfires were nothing out of the ordinary and that less of Australian burned than usual. See for example an article by a Dr. Roy Spenser:

but now they were so severe they are changing the temperature of the entire planet. Which I thought was due to Russian collusion:

I just wish I knew which one to believe.

Jeff Alberts
Reply to  Izaak Walton
March 5, 2020 10:18 am

“I am confused.”

Tell us something we don’t know.

Robert W Turner
Reply to  Izaak Walton
March 5, 2020 10:27 am

I’m confused because you linked to the same article as if they were two different articles with opposing conclusions.

P.S. The stratosphere is not the whole planet.

Izaak Walton
Reply to  Robert W Turner
March 5, 2020 11:09 am
Reply to  Izaak Walton
March 5, 2020 2:09 pm

Izaak, I suggest that they didn’t have the same technology for previous severe fires events, some of them go back quite some time. It’s likely our fires added to warming then to but we just didn’t know it.

Izaak Walton
Reply to  Megs
March 5, 2020 4:09 pm

I think it is unlikely. If you look at the temperatures that Dr. Spenser posted for February they
2020 02 +0.76 +0.96 +0.55 +0.76 +0.38 +0.02 +0.30

It is clear that the above average warmth last month was concentrated in Europe. And indeed
all the ground based measurements agree that it was an exceptionally warm winter in Europe. See:
for details.

Now what I want to know is how smoke from Australia makes only Europe warm without making a similar rise in temperatures around the globe.

Reply to  Izaak Walton
March 6, 2020 7:58 am

When you have to lie about what others are saying, you know you have already lost the debate.

What others have been saying is that the big fires of last year weren’t unusual, not because their are big fires every year, but because there have been big fires in the past.

Izaak Walton
Reply to  MarkW
March 6, 2020 9:01 am

Can you show me any data correlating Australian bush fires with sudden
increases in temperature a month later? There is monthly satellite data from
1979 available so it should be fairly easy to do if it were the case.

March 5, 2020 10:04 am

The increase in temperature in the lower stratosphere results from the increase in ionization in these layers during very low solar activity (solar minimum).
The highest rate of carbon-14 production takes place at altitudes of 9 to 15 km (30,000 to 49,000 ft) and at high geomagnetic latitudes.
Vertical soundings of the atmospheric ion production rate have been obtained from Geiger counters integrated with conventional meteorological radiosondes. In launches made from Reading (UK) during 2013–2014, the Regener–Pfotzer ionisation maximum was at an altitude equivalent to a pressure of (63.1±2.4) hPa, or, expressed in terms of the local air density, (0.101±0.005) kg m−3.

Reply to  ren
March 5, 2020 11:01 am

An increase in temperature in the lower stratosphere can cause an increase in water vapor in the stratosphere, which explains such a rapid increase in temperature in the upper troposphere and the lower stratosphere.

Farmer Ch E retired
March 5, 2020 10:13 am

Can we attribute a portion of the lower stratospheric warming to smoke generated by arson and accidental ignitions?

Reply to  Farmer Ch E retired
March 5, 2020 10:51 am

The number of fires in tropical areas, e.g. in Africa, was larger than that in southern Australia.

Farmer Ch E retired
Reply to  ren
March 5, 2020 11:27 am

What’s that got to do with my arson question?

Reply to  Farmer Ch E retired
March 5, 2020 11:46 am

I would argue the fires were caused by build up fuel resulting from discontinuing control burns. Forests are going to burn one way or another – fire is part of their natural cycle. Think of the smoke as plant fertilizer and the charcoal left on the ground as carbon capture. I would predict the troposphere will cool because of reflection and the ozone may or may not break down. The net result of the ozone will depend on the frequency content of the sunlight in a solar minimum – there are (high) UV frequencies which break down ozone – and (low) UV frequencies with produce ozone in the stratosphere . And most doomers belief the ozone hole over Antarctica in the SH spring is a result of refrigerants but then hole heals itself every SH summer.

March 5, 2020 10:13 am

In January and February 2020 ionizing radiation in the lower stratosphere was maximum in this solar ycle.
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March 5, 2020 11:52 am

Don’t forget the volcanic eruptions
Violent lightning storm of Calbuco Electric Volcano in Chile.

Reply to  Vuk
March 5, 2020 4:35 pm

Cool photo,

embutler butler
March 5, 2020 3:09 pm

in the 1970s, smoke was claimed to be the cause of climate cooling..
The 1970’s Global Cooling Compilation – looks much like …

March 6, 2020 7:51 am

The fact that CO2 is not the cause of the recent warming is just going to break poor Simon’s heart.

Ulric Lyons
March 8, 2020 7:45 pm

According this there was a stronger 70hPa warming 25S-65S last Sept-Oct when the tropics at 70hPa went colder, but both have warmed during Jan-Feb. Is that bushfire smoke in the tropics?

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