The Science of Aerosols

[kassy]

Earth is way dustier than we thought. That may be a problem for climate forecasts.

...

Dust in the upper atmosphere interacts with clouds, oceans and even radiation, or heat, from the sun. It can affect weather, precipitation and even has an impact on climate change. In a new study, scientists from the University of California Los Angeles (UCLA) found that there is four times as much coarse dust in our planet's atmosphere than has previously be seen in climate models.

There is more than one type of dust. In Earth's atmosphere, there is fine dust that is easily picked up by winds in dry areas, as well as coarser dust made of larger grains often from desert regions_ that can actually contribute to global warming in a similar way to greenhouse gases, according to a statement from UCLA. These large, coarse particles absorb radiation coming in from the sun and leaving the Earth, trapping that radiation on our planet. So, it's important for researchers to understand how much dust, especially course dust, is floating around in the atmosphere.

...

This team analyzed dozens of dust observations made by aircraft and compared them to how much dust current climate models predict should be in the atmosphere. And, while climate models predict only about 4 million metric tons, the team found that there is closer to 17 metric tons of coarse dust in our atmosphere.

"When we compared our results with what is predicted by current climate models, we found a drastic difference," study co-author Jasper Koka, a UCLA associate professor of atmospheric and oceanic sciences, said in the statement.

he team also found that dust particles also stay in the air longer than expected. This could mean that, since they're in the atmosphere for longer, they fall back to Earth much farther from the location where they were first picked up by the wind. So dust from a desert could affect ocean ecosystems and even increase how much carbon dioxide oceans absorb, according to the statement.

https://www.space.com/earth-atmosphere-dustier-thought-climate-models.html

Climate models miss most of the coarse dust in the atmosphere
https://advances.sciencemag.org/content/6/15/eaaz9507/

[interstitial]

<snip>
This team analyzed dozens of dust observations made by aircraft and compared them to how much dust current climate models predict should be in the atmosphere. And, while climate models predict only about 4 million metric tons, the team found that there is closer to 17 metric tons of coarse dust in our atmosphere.
<snip>

I assume that is 17 million metric tons

[kassy]

I just autocompleted that. 

Abstract
Coarse mineral dust (diameter, ≥5 μm) is an important component of the Earth system that affects clouds, ocean ecosystems, and climate. Despite their significance, climate models consistently underestimate the amount of coarse dust in the atmosphere when compared to measurements. Here, we estimate the global load of coarse dust using a framework that leverages dozens of measurements of atmospheric dust size distributions. We find that the atmosphere contains 17 Tg of coarse dust, which is four times more than current climate models simulate. Our findings indicate that models deposit coarse dust out of the atmosphere too quickly. Accounting for this missing coarse dust adds a warming effect of 0.15 W·m−2 and increases the likelihood that dust net warms the climate system. We conclude that to properly represent the impact of dust on the Earth system, climate models must include an accurate treatment of coarse dust in the atmosphere.

[kassy]

The study into Southern Ocean clouds is in.

Scientists just sampled the most pristine air on Earth. Here's what they found.

...

But due to how remote the Southern Ocean is, there have been very few actual studies of the clouds there. Because of this lack of data, computer models that simulate present and future climates overpredict how much sunlight reaches the ocean surface compared to what satellites actually observe. The main reason for this inaccuracy is due to how the models simulate clouds, but nobody knew exactly why the clouds were off. For the models to run correctly, researchers needed to understand how the clouds were being formed.

To discover what is actually happening in clouds over the Southern Ocean, a small army of atmospheric scientists, including us, went to find out how and when clouds form in this remote part of the world. What we found was surprising — unlike the Northern Hemisphere oceans, the air we sampled over the Southern Ocean contained almost no particles from land. This means the clouds might be different from those above other oceans, and we can use this knowledge to help improve the climate models.

Ice clouds and liquid clouds
Clouds are made of tiny water droplets or ice crystals, or often a mixture of the two. These form on small particles in the air. The type of particle plays a big role in determining whether a liquid droplet or ice crystal forms. These particles can be natural — like sea spray, pollen, dust or even bacteria — or from human sources like cars, stoves, power plants and so on.

To the untrained eye, an ice cloud and a liquid cloud look much the same, but they have very different properties. Ice clouds reflect less sunlight, precipitate more and don't last as long as liquid clouds. It matters to the weather — and to climate models — what kinds of clouds are around.

...

This was the mystery: Why are there more liquid clouds than the models think there are? To solve it, we needed to know what kinds of particles are floating around in the atmosphere around Antarctica.

Before we went down there, we had a few clues.


Previous modeling studies have suggested that the ice–forming particles found over the Southern Ocean may be very different from those found in the Northern Hemisphere. Dust is a great ice cloud seeder, but due to the lack of dusty land sources in the Southern Hemisphere, some scientists have hypothesized that other types of particles might be driving ice cloud formation over the Southern Ocean.

...

Bacterial maps

...

The atmosphere is full of microorganisms that are carried hundreds to thousands of kilometers on air currents before returning to Earth. These bacteria are like airborne license plates, they are unique and tell you where the car — or air — came from. Since scientists know where most bacteria live, it's possible to look at the microbes in an air sample and determine where that air came from. And once you know that, you can predict where the particles in the air came from as well - the same place the bacteria usually live.

...

Ocean bacteria alone
In most ocean regions around the world, especially in the Northern Hemisphere where there is a lot of land, the air contains both marine and terrestrial particles. That's what we expected to find down south.

With the frozen filters safely back at our lab in Colorado, we extracted DNA from the bacteria and sequenced it to determine what species we had caught. Much to our surprise, the bacteria were essentially all marine species that live in the Southern Ocean. We found almost no land-based bacteria.

If the bacteria were from the ocean, then so were the cloud-forming particles. This was the answer we were looking for.

https://www.livescience.com/most-pristine-air-on-earth-bacteria.html

Airborne bacteria confirm the pristine nature of the Southern Ocean boundary layer

We found that the summer airborne bacterial community in the marine boundary layer over the Southern Ocean directly south of Australia is dominated by marine bacteria emitted in sea spray, originating primarily from the west in a zonal band at the latitude of collection. We found that airborne communities were more diverse to the north, and much less so toward Antarctica. These results imply that sea spray sources largely control the number concentrations of nuclei for liquid cloud droplets and limit ice nucleating particle concentrations to the low values expected in nascent sea spray. In the sampled region, the sources of summer cloud-active particles therefore are unlikely to have changed in direct response to perturbations in continental anthropogenic emissions.

https://www.pnas.org/content/117/24/13275

[kassy]

Soot particles influence global warming more than assumed

...

Burning wood, petroleum products or other organic materials releases soot particles into the atmosphere that consist mainly of carbon. This soot is considered the second most important anthropogenic climate forcing agent after carbon dioxide. In the atmosphere or as deposits on snow and ice surfaces, soot particles absorb the short-​wave radiation of the sun and thus contribute to global warming.

In the atmosphere, soot particles also have an indirect effect on the climate by altering the formation, development and properties of clouds. A research team led by Ulrike Lohmann, professor at the Institute for Atmosphere and Climate at ETH Zurich, has now for the first time investigated how two specific types of soot particles influence clouds and, in turn, the climate: on the one hand, soot aerosols that age due to ozone and, on the other, those that age due to sulfuric acid.

Soot chemistry changes cloud formation

"Until now, it was assumed that these two types of soot ageing had little effect on cloud formation and climate," says David Neubauer, scientific programmer in Lohmann's research group. However, the results of the simulations now carried out on the CSCS supercomputer "Piz Daint" paint a different picture.

...

Simulations of ozone-​aged soot show that when the carbon dioxide content of the atmosphere doubles compared to the pre-​industrial era, fewer low clouds form. Considerably more cloud droplets are initially formed by ozone ageing of soot. However, their high concentration leads to more cloud top cooling causing more dry air being mixed in from above.  "These clouds then evaporate more quickly, especially in a warmer climate," explains Lohmann. "In a warmer climate, the air mixed in also has a lower relative humidity". Due to the faster evaporation, less low-​lying clouds remain, and more short-​wave radiation reaches the earth and warms it.

The soot particles aged by sulfuric acid, on the other hand, cause more ice crystals to form and make cirrus clouds optically thicker, i.e. they are less permeable to radiation. They extend as far as the tropopause, which is located at an altitude of 10-​18 kilometres, and also linger longer in higher regions of the atmosphere. As a result, cirrus clouds absorb more of the long-​wave thermal radiation emitted by the Earth and allow less of it to escape into space. The warming effect of cirrus clouds increases and exacerbates global warming: When the carbon dioxide content of the atmosphere doubles compared to pre-​industrial times, both types of soot ageing together lead to a 0.4 to 0.5 ºC increase in global warming. As a result, the water cycle will further accelerate and global precipitation will further increase, the researchers write.

..

https://ethz.ch/en/news-and-events/eth-news/news/2020/11/soot-particles-influence-global-warming.html

[vox_mundi]

Aerosols Add a New Wrinkle to Climate Change In the Tropical Pacific Ocean
https://phys.org/news/2021-07-aerosols-wrinkle-climate-tropical-pacific.html

A new Yale study suggests that aerosols in the atmosphere may be temporarily holding down ocean temperatures in the eastern equatorial Pacific.

The findings, published in the journal Nature Climate Change, are an indication that the surprisingly modest warming observed in the tropical Pacific in recent decades may be short-lived, with more dramatic changes yet to come. The results also may help climate scientists make better predictions for how global warming will affect weather patterns, ecosystems, and storm impacts throughout the Pacific rim.

If the eastern Pacific warms at a faster rate than surrounding oceans, it signals a slowing of atmospheric tropical circulation known as the Walker circulation—which manifests in a reduction of both the trade winds and the amount of cold water rising from the ocean depths.

"A slowdown of tropical circulation would mean changes to the El Niño events and the tropical rain belt," Fedorov said. "These changes would affect societies across the tropics and beyond."

"It is known that aerosols arising from air pollution and combustion have a cooling effect on the Earth's climate, and that aerosols have partially canceled out some warming effects from greenhouse gases since pre-industrial time," Heede said. "We show in our study that aerosols are likely contributing to the delay in eastern Equatorial warming and the slowdown of tropical circulation, which would have otherwise occurred."



Heede added, "It is important to keep in mind that this delay is temporary. In the future, as greenhouse gas emissions increase further, they will become the dominant factor for tropical Pacific climate, likely leading to enhanced eastern Pacific warming."

It is likely that the delay in eastern Equatorial warming will continue for several decades, the researchers said.

Heede and Fedorov said there may also be a thermostat-like mechanism operating in the tropical Pacific that is contributing to the delay in warming. Cold water upwells in the eastern equatorial Pacific due to the trade winds. With global warming, the deeper ocean warms slower than the surface waters, and this contributes to a delay in warming of the eastern equatorial Pacific, while temperature in the western equatorial Pacific keeps rising. These two factors strengthen the trade winds—as these winds critically depend on the east-west ocean temperature contrast—and maintain the upwelling of relatively cooler waters until the deeper ocean warms enough to overcome this effect.



Ulla K. Heede et al, Eastern equatorial Pacific warming delayed by aerosols and thermostat response to CO2 increase, Nature Climate Change (2021)
https://www.nature.com/articles/s41558-021-01101-x

[anthropocene]

Posting by James Hansen on July 2021 temperatures.

Indicates that the first evidence may be coming in on increased warming due to reduction in aerosols due to enforcement of new standards on shipping. Possibility of warming at rate of 0.36degC/decade in the next 20 years.

So sad that the satellite intended to provide critical measurements is now on the ocean floor. 

http://www.columbia.edu/~mhs119/Temperature/Emails/July2021.pdf

[jai mitchell]

Posting by James Hansen on July 2021 temperatures.

Indicates that the first evidence may be coming in on increased warming due to reduction in aerosols due to enforcement of new standards on shipping. Possibility of warming at rate of 0.36degC/decade in the next 20 years.

So sad that the satellite intended to provide critical measurements is now on the ocean floor. 

http://www.columbia.edu/~mhs119/Temperature/Emails/July2021.pdf

The Glory Satellite was an orbital spectrographic detector that would focus toward the sun and take multiple cross sections of the earth's atmosphere as it orbited, measuring the absorption of the sunlight by each atom's cross section.  In doing so it would have provided unparalleled revelations of what exactly constitutes trace elements in our atmosphere.

This satellite technology was first proposed by James Hansen when he became head of the Goddard Institute in the 1980s. 

It was soundly rejected until 2010 and then approved, launched in 2014, the fairing failed to open, causing it to return back to earth.

Years later an Oregon firm would be sued for falsification of quality control checks and fraud for providing metal to the project that was horribly below specifications and the cause of two Taurus rocket failures (one of NASA's most reliable orbital vehicles)

https://www.nasa.gov/mission_pages/Glory/main/index.html

Hansen wrote about his proposal in "Storms of My Grandchildren"

[jai mitchell]

Cross post from NASA & NOAA - Rapid Rising Earth Energy Imbalance  Thread in the Science Section of ASIF

It is my assertion that this change in albedo was subsequent to a shift in the Pacific Decadal Oscillation (PDO) to positive in 2014 and was the result of air pollution mitigation in China.  We recently had a return to a negative PDO that was coincident to ramping up production post covid.

While it seems clear that the additional forcing is based in the Eastern South Pacific and is causally linked to a shift to Positive PDO and it also appears very clear that the PDO cycle is not a natural variability but is rather aerosol driven.

It has yet to be concluded that this change in ocean wind patterns-ocean surface temperature patterns driving large changes in earth albedo (positive forcing) can then be consisdered a third term in aerosol emissions.

If so, it could lend itself to a targeted global dimming activity, especially if this effect is regionally localized delivery.

more + graphics here:  https://forum.arctic-sea-ice.net/index.php/topic,3535.msg323179.html#msg323179

[kassy]

While it seems clear that the additional forcing is based in the Eastern South Pacific and is causally linked to a shift to Positive PDO and it also appears very clear that the PDO cycle is not a natural variability but is rather aerosol driven.

If that is the case then why did it change in 1925 or 1947? We did not have the current pollution changes then.

I do think that it is possible that the aerosols influence (a region/part of) the PDO.

[jai mitchell]

There is a growing body of evidence that suggests volcanic aerosols are driving PDO

However, your observation about 1925 and 1950 are correct.

Here is a graphic from https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019MS001978

Historical (1850–2014) Aerosol Evolution and Role on Climate Forcing Using the GISS ModelE2.1 Contribution to CMIP6  27 May 2020



you can see a fairly large proportional drop in 1924 or so due to the global great depression.  At that point the GHG forcing was quite low so the aerosols had a higher influence - also it is not clear what difference the lower temperature furnace activity at that time, in proportional to the decline in high temperature processes impacted total forcing and this effect.

More clearly is the ramp up in aerosol forcing using high temperature (steel) processes post WWII and then the global aerosol emissions reductions in 1980.

I note the SOx curve (red) on the right 3 blocks.

[jai mitchell]

I would also note that the PDO does appear to be dropping back down to negative after the brief ramp up.  This may be an indication that the pdo has more to do with the rate of change of aerosols than absolute loading. (if it is causally linked to aerosol emissions).

[vox_mundi]

Large Effect of Solar Activity On Earth's Energy Budget
https://phys.org/news/2021-10-large-effect-solar-earth-energy.html

Researchers have traced the consequences of eruptions on the Sun on aerosols, clouds and Earth's energy balance.

"We tested cosmic ray effects on the atmosphere for about two weeks. When solar explosions reduce the cosmic ray flux reaching Earth, they temporarily reduce the production of small aerosols. The aerosols are molecular clusters in the air that normally grow to seed the water droplets of low-level clouds. This, in turn, reduces the cloud cover, which is known to affect climate," says senior researcher. Henrik Svensmark, lead author of the study published in Nature's Scientific Reports.

The breakthrough is that the effect on the Earth's energy budget has been quantified directly using detailed satellite observations from the CERES instrument on NASA's Terra and Aqua satellites. The observation is that Earth absorbs almost 2 W/m2 extra energy within 4 to 6 days of the cosmic-ray minimum.

This research connects observable variations in clouds and Earth's energy budget to Danish laboratory experiments and theory. It shows how cosmic rays help make the all-important aerosols and accelerate their growth to cloud condensation nuclei.

Previous research by the team predicted that the effects should be most noticeable in low altitude liquid clouds over the oceans is confirmed with the new study. Spatial maps verify that the dominating net radiative forcing changes are from low liquid clouds over the pristine seas.



"The solar effects in this study are too short-lived to have a lasting effect on the climate."

Henrik Svensmark et al, Atmospheric ionization and cloud radiative forcing, Scientific Reports (2021).
https://www.nature.com/articles/s41598-021-99033-1

[AbruptSLR]

The linked reference, and associated linked article, indicate that that less than half of the sulfur marine plankton released as dimethyl sulfide (DMS) can help nucleate clouds.  As consensus climate change model currently do not account for this reduced rate of cloud formation (and possible reduction in net cloud brightness); this is yet another example of where consensus climate change science (including AR6) has erred on the side of least drama.

Gordon A. Novak, G.A., et al. (11 October 2021), “Rapid cloud removal of dimethyl sulfide oxidation products limits SO and cloud condensation nuclei production in the marine atmosphere”, Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.2110472118

https://www.pnas.org/content/118/42/e2110472118

Significance
Ocean emissions of dimethyl sulfide (DMS) are a major precursor for the production and growth of aerosol particles, which can act as seeds for the formation of cloud droplets in the marine atmosphere with the subsequent impacts on Earth’s climate. Global aircraft observations indicate that DMS is efficiently oxidized to hydroperoxymethyl thioformate (HPMTF), a previously unrecognized molecule, which necessitates revisiting DMS oxidation chemistry in the marine atmosphere. We show through ambient observations and global modeling that a dominant loss pathway for HPMTF is uptake into cloud droplets. This loss process short circuits gas-phase oxidation and significantly alters the dynamics of aerosol production and growth in the marine atmosphere.

Abstract
Oceans emit large quantities of dimethyl sulfide (DMS) to the marine atmosphere. The oxidation of DMS leads to the formation and growth of cloud condensation nuclei (CCN) with consequent effects on Earth’s radiation balance and climate. The quantitative assessment of the impact of DMS emissions on CCN concentrations necessitates a detailed description of the oxidation of DMS in the presence of existing aerosol particles and clouds. In the unpolluted marine atmosphere, DMS is efficiently oxidized to hydroperoxymethyl thioformate (HPMTF), a stable intermediate in the chemical trajectory toward sulfur dioxide (SO2) and ultimately sulfate aerosol. Using direct airborne flux measurements, we demonstrate that the irreversible loss of HPMTF to clouds in the marine boundary layer determines the HPMTF lifetime (τHPMTF < 2 h) and terminates DMS oxidation to SO2. When accounting for HPMTF cloud loss in a global chemical transport model, we show that SO2 production from DMS is reduced by 35% globally and near-surface (0 to 3 km) SO2 concentrations over the ocean are lowered by 24%. This large, previously unconsidered loss process for volatile sulfur accelerates the timescale for the conversion of DMS to sulfate while limiting new particle formation in the marine atmosphere and changing the dynamics of aerosol growth. This loss process potentially reduces the spatial scale over which DMS emissions contribute to aerosol production and growth and weakens the link between DMS emission and marine CCN production with subsequent implications for cloud formation, radiative forcing, and climate.

See also:

Title: " Massive Flying Laboratory Uncovers Secrets of How Marine Life Influences Cloud Formation"

https://scitechdaily.com/massive-flying-laboratory-uncovers-secrets-of-how-marine-life-influences-cloud-formation/

Extract: "From the flight data, the team discovered that HPMTF readily dissolves into the water droplets of existing clouds, which permanently removes that sulfur from the cloud nucleation process. In cloud-free areas, more HPMTF survives to become sulfuric acid and help form new clouds.

Led by collaborators from Florida State University, the team accounted for these new measurements in a large, global model of ocean atmospheric chemistry. They discovered that 36% of the sulfur from DMS is lost to clouds in this way. Another 15% of sulfur is lost through other processes, so the upshot is that less than half of the sulfur marine plankton release as DMS can help nucleate clouds.

“This loss of sulfur to the clouds reduces the formation rate of small particles, so it reduces the formation rate of the cloud nuclei themselves. The impact on cloud brightness and other properties will have to be explored in the future,” says Bertram.

[jai mitchell]

https://www.nature.com/articles/s41467-021-23888-1

Significant underestimation of radiative forcing by aerosol–cloud interactions derived from satellite-based methods

Published: 15 June 2021

Abstract
Satellite-based estimates of radiative forcing by aerosol–cloud interactions (RFaci) are consistently smaller than those from global models, hampering accurate projections of future climate change. Here we show that the discrepancy can be substantially reduced by correcting sampling biases induced by inherent limitations of satellite measurements, which tend to artificially discard the clouds with high cloud fraction. Those missed clouds exert a stronger cooling effect, and are more sensitive to aerosol perturbations. By accounting for the sampling biases, the magnitude of RFaci (from −0.38 to −0.59 W m−2) increases by 55 % globally (133 % over land and 33 % over ocean). Notably, the RFaci further increases to −1.09 W m−2 when switching total aerosol optical depth (AOD) to fine-mode AOD that is a better proxy for CCN than AOD. In contrast to previous weak satellite-based RFaci, the improved one substantially increases (especially over land), resolving a major difference with models.

This value pushes RFaci just oustide of the AR6 results for combined total aerosol forcing.  Which is why the 2014 end date for selection bias of historical performance of model outputs was the wrong decision.

[RoxTheGeologist]

....

[This value pushes RFaci just outside of the AR6 results for combined total aerosol forcing.  Which is why the 2014 end date for selection bias of historical performance of model outputs was the wrong decision.

Jai - could you please explain this? It was a real teaser at the end of your post!

[jai mitchell]

I would refer you to this thread on twitter.

https://twitter.com/RisetoClimate/status/1411745141644201991

[kassy]

But twitter is always so messy. Rox´ question could be translated to how does this metric or the selection bias work and it could be answered here if it is important.

[jai mitchell]

The selection bias (really an artifact of the covid impact making the original SSP work done (supposed to be used in) AR5 to be used in the AR6.  The SSP work was only extended through 2014 and so when AR6 was done the check for consistency with historical warming trends stopped at 2014.

At 2014 the aggressive reduction in Chinese aerosols took place.  It is also the point when a sharp increase in GMST happened.  It is also shown now (from CERES cloud data) and modeling work by Dessler and Zhou) that this correlated to both a shift to a positive PDO - the historic period with the most warming) and cloud regime pattern shifts in the South Eastern Pacific and the Western Pacific warm pool.

Since this new data shows that the aerosol impact is currently higher than we thought.  This would show that the models with the higher aerosol cloud effect and regional pattern warming impacts, the same models that had a higher Equilibrium Climate Sensitivity, were actually performing better than the models with lower ECS.  By changing the study period we would include some of the higher ECS models and drop the lower ones (like the one that currently has an ECS of 2.0K, a ridiculously low value) from the sample.

This modeling work would show that our current committed warming is over 2C and that the 90% ECS range is 2.5K to 5.0K   It would also show that we will require much more than simple market-based solutions to global warming and that if we do not act immediately we have a near certitude of a total collapse in global population and modernity by 2065, which is the truth.

[RoxTheGeologist]

Jai,

I really appreciate the time taken to reply - yes - I think we all have a dirty hope that the CMP 6 ECS range is correct, but that the reality is much, much worse.

I sit here, in a meeting, (ARGUS meeting on the LCFS and Cap&Trade in California) and they are discussing the 2045 net-zero goal, with the disconnect between what is wanted and its feasibility growing. There are artifacts in the regulations, which will have to be rethought. The neighboring states are only just considering small increments. Washington with its brand new shiny policy steps up at 1% per year from 2023, Canada is the same. California is trail-blazing the way in the US, but even then it looks like it's too little too late. I can't see a reduction below 20% in the eight blue states considering LCFS programs before 2035. A total of 150 million tonnes by 2035 out of the 3 Gtonnes in the US that is emitted by the transportation sector just from burning the fuels

Thanks again

Roxby

[interstitial]

California often claims to be doing better than Washington on CO2 but I do not count aspirations I count emissions. The simple truth is California emitted 50.8 kg CO2 per MBTU of energy. Washington emitted 34.8 million metric tons CO2 per MBTU of energy. This result is further skewed because California imports about 20-30% of its electricity from out of state. (mostly hydroelectricity from Washington/Oregon). Further due to the efficiency losses of converting natural gas to electricity compared to hydro electricity California creates more energy to do the same amount of usable work further diluting the 50.8 kg CO2 per MBTU of energy. We still have a ways to go but stop with we are better than you crap.

data from 2018 (most recent) energy related CO2 emissions from EIA.

[interstitial]

I am not talking about Washington state to say we are better just to say loose the attitude.

My utility gets less than 4.85% other sources which may or may not be fossil fuels the other 95% are low carbon sources. A 1% reduction for a grid with less than 5% is much harder than a 10% reduction for a grid with much higher percentage emissions. 

[morganism]

Emission reductions from pandemic had unexpected effects on atmosphere

"First, while the 5.4% drop in emissions was significant, the growth in atmospheric concentrations was within the normal range of year-to-year variation caused by natural processes. Also, the ocean didn't absorb as much CO2 from the atmosphere as it has in recent years - probably in an unexpectedly rapid response to the reduced pressure of CO2 in the air at the ocean's surface.

Air Pollutants and Methane
Nitrogen oxides (NOx) in the presence of sunlight can react with other atmospheric compounds to create ozone, a danger to human, animal, and plant health. That's by no means their only reaction, however. "NOx chemistry is this incredibly complicated ball of yarn, where you tug on one part and five other parts change," said Laughner.

As reported earlier, COVID-related drops in NOx quickly led to a global reduction in ozone. The new study used satellite measurements of a variety of pollutants to uncover a less-positive effect of limiting NOx.

That pollutant reacts to form a short-lived molecule called the hydroxyl radical, which plays an important role in breaking down long-lived gases in the atmosphere. By reducing NOx emissions - as beneficial as that was in cleaning up air pollution - the pandemic also limited the atmosphere's ability to cleanse itself of another important greenhouse gas: methane.

Molecule for molecule, methane is far more effective than CO2 at trapping heat in the atmosphere. Estimates of how much methane emissions dropped during the pandemic are uncertain because some human causes, such as poor maintenance of oilfield infrastructure, are not well documented, but one study calculated that the reduction was 10%.

However, as with CO2, the drop in emissions didn't decrease the concentration of methane in the atmosphere. Instead, methane grew by 0.3% in the past year - a faster rate than at any other time in the last decade. With less NOx, there was less hydroxyl radical to scrub methane away, so it stayed in the atmosphere longer.

    
FROTH AND BUBBLE
Emission reductions from pandemic had unexpected effects on atmosphere
by Carol Rasmussen for JPL News
Pasadena CA (JPL) Nov 10, 2021

Worldwide restrictions during the COVID-19 pandemic caused huge reductions in travel and other economic activities, resulting in lower emissions. Seen here, almost-empty highways in Colombia during the pandemic.

The COVID-19 pandemic and resulting limitations on travel and other economic sectors by countries around the globe drastically decreased air pollution and greenhouse gas emissions within just a few weeks. That sudden change gave scientists an unprecedented view of results that would take regulations years to achieve.

A comprehensive new survey of the effects of the pandemic on the atmosphere, using satellite data from NASA and other international space agencies, reveals some unexpected findings. The study also offers insights into addressing the dual threats of climate warming and air pollution.

"We're past the point where we can think of these as two separate problems," said Joshua Laughner, lead author of the new study and a postdoctoral fellow at Caltech in Pasadena, California. "To understand what is driving changes to the atmosphere, we must consider how air quality and climate influence each other."

Published Nov. 9 in the Proceedings of the Natural Academy of Sciences, the paper grew from a workshop sponsored by Caltech's W.M. Keck Institute for Space Studies, led by scientists at that institution and at the Jet Propulsion Laboratory in Southern California, which is managed by Caltech.

Participants from about 20 U.S. and international universities, federal and state agencies, and laboratories pinpointed four atmospheric components for in-depth study: the two most important greenhouse gases, carbon dioxide and methane; and two air pollutants, nitrogen oxides and microscopic nitrate particles.

Carbon Dioxide
The most surprising result, the authors noted, is that while carbon dioxide (CO2) emissions fell by 5.4% in 2020, the amount of CO2 in the atmosphere continued to grow at about the same rate as in preceding years.

"During previous socioeconomic disruptions, like the 1973 oil shortage, you could immediately see a change in the growth rate of CO2," said David Schimel, head of JPL's carbon group and a co-author of the study. "We all expected to see it this time, too."

Using data from NASA's Orbiting Carbon Observatory-2 satellite launched in 2014 and the NASA Goddard Earth Observing System atmospheric model, the researchers identified several reasons for this result.

First, while the 5.4% drop in emissions was significant, the growth in atmospheric concentrations was within the normal range of year-to-year variation caused by natural processes. Also, the ocean didn't absorb as much CO2 from the atmosphere as it has in recent years - probably in an unexpectedly rapid response to the reduced pressure of CO2 in the air at the ocean's surface.

Air Pollutants and Methane
Nitrogen oxides (NOx) in the presence of sunlight can react with other atmospheric compounds to create ozone, a danger to human, animal, and plant health. That's by no means their only reaction, however. "NOx chemistry is this incredibly complicated ball of yarn, where you tug on one part and five other parts change," said Laughner.

As reported earlier, COVID-related drops in NOx quickly led to a global reduction in ozone. The new study used satellite measurements of a variety of pollutants to uncover a less-positive effect of limiting NOx.

That pollutant reacts to form a short-lived molecule called the hydroxyl radical, which plays an important role in breaking down long-lived gases in the atmosphere. By reducing NOx emissions - as beneficial as that was in cleaning up air pollution - the pandemic also limited the atmosphere's ability to cleanse itself of another important greenhouse gas: methane.

Molecule for molecule, methane is far more effective than CO2 at trapping heat in the atmosphere. Estimates of how much methane emissions dropped during the pandemic are uncertain because some human causes, such as poor maintenance of oilfield infrastructure, are not well documented, but one study calculated that the reduction was 10%.

However, as with CO2, the drop in emissions didn't decrease the concentration of methane in the atmosphere. Instead, methane grew by 0.3% in the past year - a faster rate than at any other time in the last decade. With less NOx, there was less hydroxyl radical to scrub methane away, so it stayed in the atmosphere longer.

Lessons From the Pandemic
The study took a step back to ask what the pandemic could teach about how a lower-emissions future might look and how the world might get there.

Notably, emissions returned to near-pre-pandemic levels by the latter part of 2020, despite reduced activity in many sectors of the economy. The authors reason that this rebound in emissions was probably necessary for businesses and individuals to maintain even limited economic productivity, using the worldwide energy infrastructure that exists today.

"This suggests that reducing activity in these industrial and residential sectors is not practical in the short term" as a means of cutting emissions, the study noted. "Reducing these sectors' emissions permanently will require their transition to low-carbon-emitting technology."

https://www.terradaily.com/reports/Emission_reductions_from_pandemic_had_unexpected_effects_on_atmosphere_999.html

https://ocov2.jpl.nasa.gov/

[jai mitchell]

Also, the ocean didn't absorb as much CO2 from the atmosphere as it has in recent years - probably in an unexpectedly rapid response to the reduced pressure of CO2 in the air at the ocean's surface.

[Freegrass]

Also, the ocean didn't absorb as much CO2 from the atmosphere as it has in recent years - probably in an unexpectedly rapid response to the reduced pressure of CO2 in the air at the ocean's surface.

That's the biggest problem, isn't it? People keep thinking that the oceans will just keep absorbing all our CO2. But all they do is create equilibrium. If we want the oceans to keep absorbing more CO2, we'll have to give it the tools to do so. And those tools are mangroves, phytoplankton, and minerals on the beaches...

[morganism]

Desert dust’s iodine destroys ozone

 In one image, for example, “iodine seemed to correlate with dust … but not absolutely clearly,” he said. Everywhere, dust seemed to destroy ozone, but why? “Iodine and ozone clearly connect, but there weren’t any ‘photos’ of both with dust,” said Koenig, who is now an air pollution researcher at Peking University in China.

The data from TORERO (the “Tropical Ocean Troposphere Exchange of Reactive Halogens and Oxygenated Hydrocarbons,” a field campaign funded by the National Science Foundation) captured those three characters together, finally, in one image he said, and it was clear that where desert dust contained significant levels of iodine—like dust from the Atacama and Sechura deserts in Chile and Peru—the iodine was quickly transformed into a gaseous form and ozone dropped to very low levels. But how did that dust-based iodine transform?  “The mechanism still remains elusive,” Volkamer said. “That’s future work.”

https://scienceblog.com/527448/desert-dusts-iodine-destroys-ozone/

paper in science advances

[NotaDenier]

Major eruption in Tonga. I can find the size of the Magma reservoir in cubic km though.

https://en.wikipedia.org/wiki/Hunga_Tonga

Sounds like it’s not especially sulfur rich. So less sulphuric dioxide to block out the sun.

https://pacific.scoop.co.nz/2022/01/tonga-undersea-eruption-and-tsunami-expert-reaction/

[Sciguy]

The eruption in Tonga didn’t have enough SO2 to significantly impact the climate.  However, there may be more eruptions in the next few weeks.

https://www.seattletimes.com/nation-world/pacific-volcano-erupts-with-explosive-force-heard-5000-miles-away/

Simon Carn, a professor at Michigan Tech, tweeted that “so far, the [sulfur dioxide] columns do not appear to be extreme.” It would need to be five to 10 times more dense to begin to have a measurable climate impact.

Alan Robock, a professor in the Department of Environmental Sciences at Rutgers, noted that the amount of sulfur dioxide needed to cool the Earth would be immense.

“Only if the eruption injects a lot of SO2 into the stratosphere, at least 1000 [kilotons, or thousands of tons] or more, will there be a climate impact,” he wrote via email. “The 1980 Mt. St. Helens eruption had a [volcano explosive impact] of 5 (very large), but no climate impact because of little SO2.”

Satellite measurements show SO₂ is 400 kilotons. Robock said the eruption will “produce about 1/50 of the impact of the 1991 Pinatubo eruption,” or about 0.02 degrees (0.01 degree Celsius) average cooling.

While initial estimates peg the low amounts of released SO₂, experts point to continued eruptions as something to monitor.

[NotaDenier]

NASA scientists estimate Tonga blast at 10 megatons
https://www.mtpr.org/2022-01-18/nasa-scientists-estimate-tonga-blast-at-10-megatons

But for all its explosive force, the eruption itself was actually relatively small, according to Poland, of the U.S. Geological Survey. Unlike the 1991 eruption of Mount Pinatubo, which spewed ash and smoke for hours, the events at Hunga Tonga-Hunga Ha'apai lasted less than 60 minutes. He does not expect that the eruption will cause any short-term changes to Earth's climate, the way other large eruptions have in the past.

In fact, Poland says, the real mystery is how such a relatively small eruption could create such a big bang and tsunami.

"It had an outsized impact, well beyond the area that you would have expected if this had been completely above water," he says. "That's the thing that's just a head-scratcher."

Garvin says that scientists want to follow up with additional surveys of the area around the volcano's caldera. Satellite imagery analysis is already underway and may soon be followed with missions by drones. He hopes the volcano will be safe enough for researchers to visit later in the year.

Poland says he believes researchers will learn a lot more in the days and months to come, as they conduct new surveys of the area.

"This is just a horrible event for the Tongans," he says. But "it could be a benchmark, watershed kind of event in volcanology."

[kassy]

AE12A-02 - How will lightning change during the pollution-reduced COVID-19 pandemic period? A data study on the global lightning activity

Abstract
Lightning activity has been shown to be responsive to both thermodynamic and aerosol effects. During the pollution-reduced COVID-19 pandemic period, the satellite-based aerosol index Aerosol Optical Depth (AOD) manifests a reduction (e.g., Sanap, Atmos. Res., 2021) over much of the inhabited land regions and also the remote oceanic regions. In the meantime, the global warming has continued largely unabated. This circumstance offers a valuable natural experiment to study the response of lightning activity with a global scope. Taking advantage of the global lightning data from both the GLD360 Network and the World Wide Lightning Location Network (WWLLN), both continuously operational through the COVID pandemic period, results have shown a global reduction in levels of lightning stroke activity during the 3-month “lockdown” period March to May, 2020, over four years of inter-comparison (2018-2021). Reductions of 10-20% are evident, depending on how the lightning is counted. The regional variations in lightning are generally consistent with the AOD satellite analysis, with aerosol/lightning reductions over Africa/Europe and Asia/Maritime Continent, and lesser increases over much of the Americas. Consistent with the VLF network findings, the intensity of the Schumann resonances within the Earth-ionosphere cavity is reduced at ELF receivers in the multi-station HeartMath network, also supporting a weaker global lightning vigor during the pandemic. This paper explores spatiotemporal correlations between lightning activity and AOD deviations from multi-year averages, and uses this relationship to support a causal effect between regional reductions in aerosol content and lightning activity.

https://agu.confex.com/agu/fm21/meetingapp.cgi/Paper/917688

This is an interesting find.
Can we also conclude from this that cleaning up a large part of our pollution will then result in less lightning strikes overall so that via this mechanism less fires start?

[kassy]

Updrafts crucial: Clouds in the southern hemisphere more precisely understood

Clouds in the southern hemisphere reflect more sunlight than those in the northern hemisphere. The reason is a more frequent occurrence of liquid water droplets, which results from an interplay between updrafts and a cleaner environment. In a study published in the journal Atmospheric Chemistry and Physics, a team of researchers led by the Leibniz Institute for Tropospheric Research (TROPOS) found a stronger influence of updrafts than expected. The new results were made possible by long-term measurements in Leipzig (Germany), Limassol (Cyprus) and Punta Arenas (Chile).

Covering three years, the measurements in Punta Arenas are the longest dataset on cloud properties obtained with ground-based lidar and radar in the Southern Ocean. From 2018 to 2021, an international team from University of Magallanes (UMAG), TROPOS and University of Leipzig had conducted extensive observations of aerosols, clouds, wind and precipitation in the very south of Chile as part of the DACAPO-PESO field experiment. The researchers used two datasets from the northern hemisphere locations of Leipzig and Cyprus to put their findings into global context. Data from the CyCARE field campaign on Cyprus were collected in the years 2016 to 2018 in collaboration with researchers from the Cyprus University of Technology and the ERATOSTHENES Centre of Excellence in Limassol.

The main objective of the measurements in the pristine environment at the southern tip of South America was to study the atmosphere and to learn more about the interactions between aerosols and clouds in a region where there is hardly any long-term data available so far. To address the lack of observations, TROPOS brought the two containers of the LACROS mobile atmospheric observatory together with instrumentation of the University of Leipzig to Punta Arenas. There, the observations were conducted together with UMAG's Laboratory for Atmospheric Research. The instrumentation of LACROS consists of multiple lidars, radars, radiometers, sun photometers and others. These measurements were supplemented by aerosol filter samples from Cerro Mirador, a 600 m high hill close by.

Originally, the measurements were planned for one year as a contribution to the "Year of Polar Prediction in the Southern Hemisphere" (YOPP-SH). But due to the global COVID-19 pandemic and the resulting travel restrictions, the measurements were extended by two years and only finished at the end of 2021. "Scientifically, this delay was of great benefit," says Kevin Ohneiser, PhD student at TROPOS. Because the huge "Black Summer" wildfires of 2019/20 occurred in Australia during this period. Their smoke was transported more than 10,000 kilometres across the Pacific to South America and could be observed there up to heights of 25 km with the laser-based investigations until the measurements were completed at the end of 2021. Since the air in southern Chile is usually very clean, this type of air pollution was immediately noticeable and underlines the global influence of the large forest fires on climate.

...

Due to a high percentage of oceans covering the Earth in the southern hemisphere, the atmosphere in this region is cleaner, i.e. contains fewer aerosol particles. This difference is especially strong in the free troposphere -- the air masses at higher altitudes, unaffected from local pollution sources. "Fewer particles mean fewer ice nuclei in the atmosphere. But it is precisely these that are needed to cause cloud droplets to freeze into ice crystals at temperatures between 0 and -40°C. Therefore, clouds ice up much less in the mid-latitudes of the southern hemisphere and contain more liquid water at the same temperatures. This means that they influence the incident sunlight and also the thermal radiation emitted from the Earth's surface differently than in the north. This is one explanation why global climate models are still not able to represent the radiation balance of the southern hemisphere with sufficient accuracy," summarises Dr Patric Seifert from TROPOS. In the temperature range between -24 and -8°C, the lack of ice nuclei caused the clouds over Punta Arenas to form ice on average 10 to 40 percent less often than the clouds over Leipzig. The ice mass produced by the liquid water clouds is also reduced by at least a factor of 2.

However, contrary to previous studies, differences in atmospheric pollution are not the only cause of the observed contrasts, especially at even lower temperatures. The investigations in southern Chile showed that the clouds are often influenced by so-called gravity waves. The strong westerly wind from the Pacific collides with the Andes mountains, is displaced upwards and creates these gravity waves. "By measuring the up- and downward winds within the clouds, we were able to detect clouds that had been influenced by these waves and filter them out of the overall statistics. This allowed us to show that these gravity waves, and not the lack of ice nuclei, are mainly responsible for the excess of cloud droplets at temperatures below -25°C," explains Dr Martin Radenz from TROPOS, who recently obtained the Phd degree for his work on this subject. " However, it is currently unclear whether this phenomenon only influences clouds in southern Chile. How important are gravity waves for the formation of clouds and precipitation in other regions of the Southern Ocean? How often do gravity waves occur over the open ocean, which covers most of the Earth's surface between 30 and 70 degrees south and is currently only observed by satellites? Further measurements of air motion in clouds are needed to further constrain the role of ice nuclei in the apparent excess of liquid water in clouds. In the near future, we plan to work with our partners to investigate these questions at other locations in the Southern Hemisphere, such as Antarctica and New Zealand, and ideally also from aboard research vessels. Because from space those observations are not possible at the moment."

...

https://www.sciencedaily.com/releases/2022/01/220126144156.htm

[jai mitchell]

Drivers of Recent North Pacific Decadal Variability: The Role of Aerosol Forcing
Dittus, Andrea J; Hawkins, Ed; Robson, Jon I; Smith, Doug M; Wilcox, Laura J.Earth's Future; Bognor Regis Vol. 9, Iss. 12,  (Dec 2021). DOI:10.1029/2021EF002249
https://www.proquest.com/openview/5810a60fd5f518afbeaba5044dd117d2/1?pq-origsite=gscholar&cbl=2034575

There are individual realizations in the CMIP6 ensemble that have a cooling pattern of Pacific SATs similar to those observed. Two individual ensemble members are shown in Figure 2b that look the most and the least like observations, based on pattern correlations over the Pacific, respectively. This is done to illustrate the range of patterns seen across CMIP6 only and is not indicative of model performance. However, members that have similar SAT patterns to observations are infrequent and, in most cases, the cooling is weaker than observed (not shown). This discrepancy could suggest a bias in the forced response or errors in the representation of internal variability in many CMIP6 models. However, it is also possible that the real world was in an unusual phase of internal variability during this time, and the models are consistent with observations when internal variability is considered (Olonscheck et al., 2020). In the following sections, the role of anthropogenic aerosols in driving this cooling pattern in the Pacific is investigated by revisiting the question of whether anthropogenic aerosols played a role as a driver of a negative PDO

. . .

As expected, a stronger aerosol forcing is associated with a larger relative decrease in global temperatures in all time periods. The strongest cooling occurs in the period from 1951 to 1980, corresponding to the period where changes in global aerosol burden are largest across the ensemble, while the changes are weakest in the period from 1921 to 1950. Importantly, however, this figure highlights that the responses to anthropogenic aerosol forcing during the 1981–2012 period differ from earlier periods. In particular, it is the period with the strongest (and most significant) atmospheric circulation responses to anthropogenic aerosol over the Pacific, while the preceding periods are dominated by global cooling but seemingly weaker circulation responses. As the globally averaged aerosol forcing over the most recent time period is approximately constant, it is likely the regional changes in aerosol emissions that are important in explaining the changes over 1981–2012. Indeed, while European and North American aerosol emissions have been declining over this period, Asian emissions have been at their highest levels and with the most rapid growth since 1850 (Figure 1), suggesting that Asian aerosol emissions are a plausible driver of the changes seen in this period. This hypothesis is consistent with results from a previous study that has shown a Rossby-Wave response with a similar structure to increases in Asian aerosol emissions over the same time period in a predecessor of this model, HadGEM3-GC2 (Wilcox et al., 2019).

. . .

Recent papers have argued that climate projections from high climate sensitivity models are unrealistic, as the rapid warming seen in those models is inconsistent with recent historical trends (Brunner et al., 2020). Studies have also suggested that the transient climate response (TCR) to greenhouse gases is unrealistically high by using the period since the 1980s to constrain the transient climate response (Dittus et al., 2020; Nijsse et al., 2020; Tokarska et al., 2020). These conclusions rely on the assumption that internal variability and the responses to anthropogenic aerosols and volcanoes are all simulated realistically over this period. Therefore, it is imperative that future work address this question, as the interpretation of projections from high sensitivity models relies upon knowing which of the above hypotheses is correct. Regardless of the cause of the observed negative PDO in the real world, a reversal of this trend would be expected to lead to enhanced near-term warming, potentially amplified by cloud and lapse-rate feedbacks becoming more positive (Andrews & Webb, 2018).

[morganism]

Air lasing: A new tool for atmospheric detection

 When air lasing encounters coherently vibrating molecules, it will effectively produce coherent Raman scattering. By recording the frequency difference of Raman signal and air lasing, the molecular "identity information" can be known. Thus, such a Raman scheme combines the advantages of the femtosecond laser and air lasing, it thus can meet the needs of multi-component measurement and chemical specificity.

Some specific designs used in this work, especially the optimization of pump-seed delay and the choice of perpendicular polarization, ensure a high detection sensitivity and signal stability. It was shown that the minimum detectable concentrations of CO2 and SF6 can reach 0.1% and 0.03%, respectively.

The minimum signal fluctuation reached the level of 2%. The research team also demonstrated that the technique can be applied for simultaneous measurement of CO2 and SF6. More importantly, the measured Raman spectrum can well distinguish 12CO2 and 13CO2.

The simultaneous measurement of various pollutants, greenhouse gases as well as the detection of CO2 isotopes are of great significance for tracing the sources of air pollution and studying the carbon cycling. This is a significant advantage of the proposed technique as compared to traditional remote sensing methods.

However, for realistic application of trace gas remote detection, it is necessary to improve the detection sensitivity to the ppm or even ppb level, as well as extend the detection distance from the laboratory scale to the kilometer scale. It is expected that such a goal can be realized in the near future with the development of high-repetition, high-energy femtosecond laser technologies."

https://www.spacedaily.com/reports/Air_lasing_A_new_tool_for_atmospheric_detection_999.html

High-Sensitivity Gas Detection with Air-Lasing-Assisted Coherent Raman Spectroscopy

https://spj.sciencemag.org/journals/ultrafastscience/2022/9761458/

Remote or standoff detection of greenhouse gases, air pollutants, and biological agents with innovative ultrafast laser technology attracts growing interests in recent years. Hybrid femtosecond/picosecond coherent Raman spectroscopy is considered as one of the most versatile techniques due to its great advantages in terms of detection sensitivity and chemical specificity. However, the simultaneous requirement for the femtosecond pump and the picosecond probe increases the complexity of optical system. Herein, we demonstrate that air lasing naturally created inside a filament can serve as an ideal light source to probe Raman coherence excited by the femtosecond pump, producing coherent Raman signal with molecular vibrational signatures. The combination of pulse self-compression effect and air lasing action during filamentation improves Raman excitation efficiency and greatly simplifies the experimental setup. The air-lasing-assisted Raman spectroscopy was applied to quantitatively detect greenhouse gases mixed in air, and it was found that the minimum detectable concentrations of CO2 and SF6 can reach 0.1% and 0.03%, respectively. The ingenious designs, especially the optimization of pump-seed delay and the choice of perpendicular polarization, ensure a high detection sensitivity and signal stability. Moreover, it is demonstrated that this method can be used for simultaneously measuring CO2 and SF6 gases and distinguishing 12CO2 and 13CO2. The developed scheme provides a new route for high-sensitivity standoff detection and combustion diagnosis."

[morganism]

Atmospheric pollution from rockets

We address the impact of rocket exhaust gases on atmospheric pollution through high-resolution computational fluid dynamics simulations.
We have modeled the exhaust gases and developing plume at several altitudes along a typical trajectory of a standard present-day rocket, as a prototypical example of a two-stage rocket to transport people and payloads into Earth’s orbit and beyond. The modeled rocket uses RP-1 as the propellant and liquid oxygen as the oxidizer to generate 6806 kN of thrust via a total of nine nozzles, matching—as closely as possible based on available data—the specifications to the Thaicom 8 launch mission of the Falcon 9 rocket manufactured by SpaceX. We have used
high-order discretization methods, 11th-order accurate, in conjunction with implicit large eddy simulations to model exhaust gas mixing, dispersion, and heat transfer into the atmosphere at altitudes up to 67 km. We show that pollution from rockets should not be underestimated as frequent future rocket launches could have a significant cumulative effect on climate. The production of thermal nitrogen oxides can remain considerable up to altitudes with an ambient atmospheric pressure below but of the same order of magnitude as the nozzles exit
pressure. At the same time, the emitted mass of carbon dioxide in the mesosphere is equivalent to that contained in 26 km3 of atmospheric air at the same altitude."

https://aip.scitation.org/doi/pdf/10.1063/5.0090017

[NeilT]

I had a thought about the impact of a sea borne volcanic VLE6 eruption and went looking for articles which talked about the aerosol impact of the volcano from both water and SO2


It made quite interesting reading but it was mostly to do with the impact of the water on the SO2 and the longevity in the atmosphere.  It doesn't really talk much about the impact of pushing so much water vapour into the mesosphere.

Abstract The January 2022 Hunga Tonga-Hunga Ha'apai (HTHH) volcanic eruption injected a relatively small amount of SO2 , but significantly more water into the stratosphere than previously seen in the modern satellite record. Here we show that the large amount of water resulted in large perturbations to stratospheric aerosol evolution. Our Community Earth System Model simulation reproduces the enhanced water vapor observed by the Microwave Limb Sounder at pressure levels between 10 and 50 hPa for three months. Compared with a simulation without a water injection, this additional source of water vapor increases OH, which halves the SO2 lifetime. Subsequent coagulation creates larger sulfate particles that double the stratospheric aerosol optical depth. A seasonal forecast of volcanic plume transport in the southern hemisphere indicates this eruption will greatly enhance the aerosol surface area and water vapor near the polar vortex until at least October 2022, suggesting that there will continue to be an impact of the HTHH eruption on the climate system

https://assets.researchsquare.com/files/rs-1647643/v1/aede369c-205b-4216-b59f-795f47c91681.pdf?c=1652373632

[kassy]

In a paradox, cleaner air is now adding to global warming

Satellites capture fall in pollution that helps cool the planet


t’s one of the paradoxes of global warming. Burning coal or gasoline releases the greenhouse gases that drive climate change. But it also lofts pollution particles that reflect sunlight and cool the planet, offsetting a fraction of the warming. Now, however, as pollution-control technologies spread, both the noxious clouds and their silver lining are starting to dissipate.

Using an array of satellite observations, researchers have found that the climatic influence of global air pollution has dropped by up to 30% from 2000 levels. Although this is welcome news for public health—airborne fine particles, or aerosols, are believed to kill several million people per year—it is bad news for global warming. The cleaner air has effectively boosted the total warming from carbon dioxide emitted over the same time by anywhere from 15% to 50%, estimates Johannes Quaas, a climate scientist at Leipzig University and lead author of the study. And as air pollution continues to be curbed, he says, “There is a lot more of this to come.”

“I believe their conclusions are correct,” says James Hansen, a retired NASA climate scientist who first called attention to the “Faustian bargain” of fossil fuel pollution in 1990. He says it’s impressive scientific detective work because no satellite could directly measure global aerosols over this whole period. “It’s like deducing the properties of unobserved dark matter by looking at its gravitational effects.” Hansen expects a flurry of follow-up work, as researchers seek to quantify the boost to warming.

...

The new study, submitted as a preprint to Atmospheric Chemistry and Physics in April and expected for publication in the next few months, grew directly out of last year’s U.N. climate assessment. It included studies showing aerosol declines in North America and Europe but no clear global trends. Quaas and his co-authors thought two NASA satellites, Terra and Aqua, operating since 1999 and 2002, might be able to help.

The satellites tally Earth’s incoming and outgoing radiation, which has enabled several research groups, including Quaas and his colleagues, to track the increase in infrared heat trapped by greenhouse gases. But one instrument on Aqua and Terra has also shown a decline in reflected light. Models suggested a decrease in aerosols is partly responsible, says Venkatachalam Ramaswamy, director of the National Oceanic and Atmospheric Administration’s Geophysical Fluid Dynamics Laboratory. “It’s very hard to find alternate reasons for this,” he says.

Quaas and his co-authors have now taken things a step further with two instruments on Terra and Aqua that record the haziness of the sky—and therefore its aerosol load. From 2000 to 2019, haze over North America, Europe, and East Asia clearly declined, although it continued to thicken over coal-dependent India.

Aerosols don’t just reflect light on their own; they can also alter clouds. By serving as nuclei on which water vapor condenses, pollution particles reduce cloud droplet size and increase their number, making clouds more reflective. Reducing pollution should undo the effect—and using the same instruments, Quaas and his team found a clear decrease in cloud droplet concentrations in the same regions where aerosols declined.

The evidence in the paper is clear, says Joyce Penner, an atmospheric scientist at the University of Michigan, Ann Arbor. “It’s remarkable that we’re seeing this already,” she says. “This is contributing a lot to the climate changes we’re seeing in the current era.”

Just how much this declining reflectivity has boosted recent warming is hard to quantify, says Stuart Jenkins, a doctoral student at the University of Oxford who is also studying the aerosol decline. In forthcoming work, Jenkins will show there’s just too much natural variability in the past 20 years to pick out the effect of clearer skies.

...

https://www.science.org/content/article/paradox-cleaner-air-now-adding-global-warming

[kassy]

Ice formation in water does not involve aerosols so i removed a story about that, but it is interesting so see here:

'IcePic' Algorithm Outperforms Humans In Predicting Ice Crystal Formation

[vox_mundi]

Ice formation in water does not involve aerosols so i removed a story...

Bullshit!

Do you just make stuff up off the top of your head?

This is Dunning–Kruger effect pure and simple.

Did you even read the article?

... Their model accurately predicts the ice nucleation ability of materials. Deep learning techniques enable an easy, cheap, and rapid method that requires just an image of room temperature water in contact with a substrate as input. Remarkably, the model shows that the interfacial structure of water alone is sufficient to determine nucleation.

Crystal nucleation is one of the most fundamental processes in the physical sciences and almost always occurs heterogeneously with the aid of a nucleating substrate. No example of nucleation is more ubiquitous and impactful than the formation of ice in clouds, vital to a field such as climate science.

In the atmosphere, ice affects cloud albedo, lifetime, and composition. This in turn makes it vital to Earth’s radiation budget and the modeling of future changes in climate

----------------------------------------------------------

Aerosols Acting as Ice Nucleating Particles, ETHZurich Institute for Atmospheric and Climate Science, (2018)
https://iac.ethz.ch/group/atmospheric-chemistry/research/aerosols/aerosols-acting-as-ice-nucleating-particles.html

The formation of ice in mixed-​phase clouds occurs in the presence of aerosol particles with the ability to nucleate ice on their surface (heterogeneous freezing). These ice-​nucleating particles (INPs) represent a small fraction of particles in an atmospheric aerosol. One main particle type which acts as INPs are mineral dusts such as clay minerals, feldspars, and quartz. Different factors influence the ice nucleation ability of such mineral dust particles. Besides the obvious factor of temperature, semivolatile substances that accumulate on the particle surface or electric fields and charges carried by the particles or by cloud droplets may increase or reduce the ice nucleation activity. Furthermore, the freezing mode plays an important role.

-------------------------------------------------------------

Radiative forcing of anthropogenic aerosols on cirrus clouds using a hybrid ice nucleation scheme, EGU Atmospheric Chemistry and Physics, (2020)
https://acp.copernicus.org/articles/20/7801/2020/

Anthropogenic aerosols impact cirrus clouds through ice nucleation, thereby changing the Earth's radiation budget. However, the magnitude and sign of anthropogenic forcing in cirrus clouds is still very uncertain depending on the treatments for ice-nucleating particles (INPs), the treatments for haze particle freezing, and the ice nucleation scheme. In this study, a new ice nucleation scheme (hereafter the HYBRID scheme) is developed to combine the best features of two previous ice nucleation schemes, so that global models are able to calculate the ice number concentration in both updrafts and downdrafts associated with gravity waves, and it has a robust sensitivity to the change of aerosol number.

-----------------------------------------------------------

Annual cycle observations of aerosols capable of ice formation in central Arctic clouds, Nature Communications, (2022)
https://www.nature.com/articles/s41467-022-31182-x

... Specifically, aerosols called ice nucleating particles (INPs) remain understudied yet are necessary for cloud ice production and subsequent changes in cloud lifetime, radiative effects, and precipitation. Here, we report observations of INPs in the central Arctic over a full year, spanning the entire sea ice growth and decline cycle. Further, these observations are size-resolved, affording valuable information on INP sources. Our results reveal a strong seasonality of INPs, with lower concentrations in the winter and spring controlled by transport from lower latitudes, to enhanced concentrations of INPs during the summer melt, likely from marine biological production in local open waters. This comprehensive characterization of INPs will ultimately help inform cloud parameterizations in models of all scales.

----------------------------------------------------------

Ice nucleation by aerosols from anthropogenic pollution, Nature Geoscience, (2019)
https://www.nature.com/articles/s41561-019-0389-4

... Our model simulations suggest that this positive correlation is explained by enhanced heterogeneous ice nucleation and prolonged ice particle growth at higher aerosol loading, indicating that polluted continental aerosols contain a considerable fraction of ice nucleating particles. Similar aerosol–ice relationships are observed for dust aerosols, further corroborating the ice nucleation ability of polluted continental aerosols. By catalysing ice formation, aerosols from anthropogenic pollution could have profound impacts on cloud lifetime and radiative effect as well as precipitation efficiency.

----------------------------------------------------------

The Role of Organic Aerosol in Atmospheric Ice Nucleation, ACS Earth Space Chemistry, (2018)
https://pubs.acs.org/doi/10.1021/acsearthspacechem.7b00120

... Among atmospheric ice formation processes, heterogeneous ice nucleation proceeds on aerosol particles ranging from a few nanometers to micrometers in size, commonly referred to as ice nucleating particles (INPs). Research over the last two decades has demonstrated that organic matter (OM) is ubiquitous in the atmosphere, present as organic aerosol (OA) particles or as coatings on other particle types. The physicochemical properties of OM make predicting how OM can contribute to the INP population challenging.

---------------------------------------------------------

Sea spray aerosol as a unique source of ice nucleating particles, PNAS, (2015)
https://www.pnas.org/doi/10.1073/pnas.1514034112

[kassy]

Did you even read the article?

Sorry only the quote and a bit of the article and i somehow got it very wrong. Please accept my apology. I really misinterpreted the water part.

[kassy]

Cloud study demystifies impact of aerosols

Aerosol particles in the atmosphere have a bigger impact on cloud cover -- but less effect on cloud brightness -- than previously thought, new research shows.

Aerosols are tiny particles suspended in the atmosphere, and they play a key role in the formation of clouds.

With aerosols increasing due to human activities, numerous assessments by the Intergovernmental Panel on Climate Change (IPCC) have suggested they could have an important impact on climate change because clouds reflect sunlight and therefore keep temperatures cooler.

However, this cooling impact of aerosols on clouds is difficult to measure, and this has led to significant uncertainty climate change projections.

The new study -- led by the University of Exeter, with national and international academic partners and the UK's Met Office -- used the 2014 Icelandic volcano eruption to investigate this.

"This massive aerosol plume in an otherwise near-pristine environment provided an ideal natural experiment to quantify cloud responses to aerosol changes, namely the aerosol's fingerprint on clouds" said lead author Dr Ying Chen.

"Our analysis shows that aerosols from the eruption increased cloud cover by approximately 10%.

"Based on these findings, we can see that more than 60% of the climate cooling effect of cloud-aerosol interactions is caused by increased cloud cover.

"Volcanic aerosols also brightened clouds by reducing water droplet size, but this had a significantly smaller impact than cloud-cover changes in reflecting solar radiation."

Previous models and observations suggested this brightening accounted for the majority of the cooling caused by cloud-aerosol interactions.

Water droplets usually form in the atmosphere around aerosol particles, so a higher concentration of these particles makes it easier for cloud droplets to form.

However, as these cloud droplets are smaller and more numerous, the resulting clouds can hold more water before rainfall occurs -- so, more aerosols in the atmosphere can lead to more cloud cover but less rain.

The study used satellite data and computer learning to study cloud cover and brightness.

It used 20 years of satellite cloud images from two different satellite platforms from the region to compare the periods before and after the volcano eruption.

The findings will provide observational evidence of aerosols' climate impacts to improve the models used by scientists to predict climate change.

Jim Haywood, Professor of Atmospheric Science at the University of Exeter and part of the Global Systems Institute, and a Met Office Research Fellow, said: "Our earlier work had showed that model simulations could be used to disentangle the relative contribution of aerosol-cloud-climate impacts and potentially confounding meteorological variability.

"This work is radically different as it does not rely on models; it uses state-of-the-art machine learning techniques applied to satellite observations to simulate what the cloud would look like in the absence of the aerosols.

"Clear differences are observed between the predicted and observed cloud properties which can be used to assess aerosol-cloud-climate impacts."

...

https://www.sciencedaily.com/releases/2022/08/220801111100.htm

[zenith]

Invisible ship tracks show large cloud sensitivity to aerosol
https://www.nature.com/articles/s41586-022-05122-0

"Our results indicate that previous studies of ship tracks were suffering from selection biases by focusing only on visible tracks from satellite imagery. The strong liquid water path response we find translates to a larger aerosol cooling effect on the climate, potentially masking a higher climate sensitivity than observed temperature trends would otherwise suggest."

[jai mitchell]

Thank you zenith for posting that important paper.

[trm1958]

Invisible ship tracks show large cloud sensitivity to aerosol
https://www.nature.com/articles/s41586-022-05122-0

"Our results indicate that previous studies of ship tracks were suffering from selection biases by focusing only on visible tracks from satellite imagery. The strong liquid water path response we find translates to a larger aerosol cooling effect on the climate, potentially masking a higher climate sensitivity than observed temperature trends would otherwise suggest."

Not only is CO2 warming likely actually greater than we thought, but when we reduce the aerosols we will get even more of an uptick from that.

[vox_mundi]

Large Parts of Europe are Warming Twice as Fast as the Planet On Average
https://phys.org/news/2022-11-large-europe-fast-planet-average.html



The warming during the summer months in Europe has been much faster than the global average, according to a new study by researchers at Stockholm University published in the Journal of Geophysical Research: Atmospheres. As a consequence of human emissions of greenhouse gases, the climate across the continent has also become drier, particularly in southern Europe, leading to worse heat waves and an increased risk of fires.

According to the UN's Intergovernmental Panel on Climate Change (IPCC), warming over land areas occurs significantly faster than over oceans, with 1.6 degrees and 0.9 degrees on average, respectively. It means that the global greenhouse gas emissions budget to stay under a 1.5-degree warming on land has already been used up.

Now, the new study shows that the emissions budget to avoid a 2-degree warming over large parts of Europe during the summer half-year (April-September) has also been used up. In fact, measurements reveal that the warming during the summer months in large parts of Europe during the last four decades has already surpassed two degrees.

... In southern Europe, a clear, so-called, positive feedback caused by global warming is evident, i.e. warming is amplified due to drier soil and decreased evaporation.



Moreover, there has been less cloud coverage over large parts of Europe, probably as a result of less water vapor in the air.

"What we see in southern Europe is in line what IPCC has predicted, which is that an increased human impact on the greenhouse effect would lead to dry areas on Earth becoming even drier," says Paul Glantz.

The study also includes a section about the estimated impact of aerosol particles on the temperature increase. According to Paul Glantz, the rapid warming in, for example, Central and Eastern Europe, is first and foremost a consequence of the human emissions of long-lived greenhouse gases, such as carbon dioxide. But since emissions of short-lived aerosol particles from, for example, coal-fired power plants have decreased greatly over the past four decades, the combined effect has led to an extreme temperature increase of over two degrees.

"The airborne aerosol particles, before they began to decrease in the early 1980s in Europe, have masked the warming caused by human greenhouse gases by just over one degree on average for the summer half-year. As the aerosols in the atmosphere decreased, the temperature increased rapidly.

According to Paul Glantz, this effect provides a harbinger of future warming in areas where aerosol emissions are high, such as in India and China.



P. Glantz et al, Unmasking the effects of aerosols on greenhouse warming over Europe, Journal of Geophysical Research: Atmospheres (2022)
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2021JD035889

[vox_mundi]

Increased Atmospheric Dust Is Masking Greenhouse Gases' Warming Effect, Finds Study
https://phys.org/news/2023-01-atmospheric-masking-greenhouse-gases-effect.html


Sources & Sinks

A new study shows that global atmospheric dust—microscopic airborne particles from desert dust storms—has a slight overall cooling effect on the planet that has hidden the full amount of warming caused by greenhouse gases.

The UCLA research, published today in Nature Reviews Earth and Environment, found that the amount of desert dust has grown roughly 55% since the mid-1800s, which increased the dust's cooling effect.

The study is the first to demonstrate the overall cooling effect of atmospheric desert dust. Some effects of atmospheric dust warm the planet, but because other effects of dust actually counteract warming—for example by scattering sunlight back into space and dissipating high clouds that warm the planet—the study calculated that dust's overall effect is a cooling one.

Should dust levels decline—or even simply stop growing—warming could ramp up, said UCLA atmospheric physicist Jasper Kok, the study's lead author.

While atmospheric desert dust levels have increased overall since pre-industrial times, the trend has not been steady—there have been upticks and declines along the way. Because there are so many natural and human-influenced variables that can cause dust levels to increase or decrease, scientists cannot accurately project how the amounts of atmospheric dust will change in the coming decades.

Human actions have warmed the planet by 1.2° Celsius, or 2.2° Fahrenheit, since about 1850. Without the increase in dust, climate change would likely have warmed the planet by about 0.1° Fahrenheit more already, Kok said. With the planet nearing the 2.7° Fahrenheit of warming that scientists consider especially dangerous, every tenth of a degree matters, Kok said.

"We want climate projections to be as accurate as possible, and this dust increase could have masked up to 8% of the greenhouse warming," Kok said.



Jasper F. Kok et al, Mineral dust aerosol impacts on global climate and climate change, Nature Reviews Earth & Environment (2023)
https://www.nature.com/articles/s43017-022-00379-5

[Bruce Steele]

Vox, How mineral dust interacts with phytoplankton in areas of the ocean otherwise lacking in iron, or manganese has large implications for the amount of primary productivity possible in vast swaths of the South Pacific. More dust and an increased carbon sink.
https://news.climate.columbia.edu/2022/11/22/iron-rich-dust-from-south-america-played-role-in-last-two-glacial-periods-says-study/
“ Using a sediment core from the southern seafloor collected in 2009, the researchers were able to reconstruct the contributions from various dust sources located on the surrounding continents. According to the authors, the jet stream, a set of powerful air currents flowing from west to east several kilometers up, picked up fine mineral particles on the east side of the Andes and transported them almost all the way around Antarctica to the southeast Pacific.

Atmospheric dust is thought to be a key component of the climate system. Dust particles influence the Earth’s energy budget, because they reflect incoming sunlight at high altitudes, which has a cooling effect. Mineral particles can also carry nutrients such as iron and manganese to remote ocean areas, where they stimulate the growth of algae. When the algae die and sink to the deep ocean, they remove carbon dioxide from the atmosphere, which also has a cooling effect. These mechanisms can be particularly effective in the remote and iron-deficient southern reaches of the Pacific, Indian and Atlantic oceans, so changes in the Southern Hemisphere dust cycle may have played significant roles in past natural swings between cold glacial and warm interglacial periods. For this reason, the sources and transport pathways of dust have been the subject of intensive research in recent years.”

Seems a good place to start geoengineering . If the right dust can both mask heating and sink carbon and the high Andes are the natural source dust . Well seems kinda obvious . Try to measure what weather is the best high Andes dust producers and maybe augment it somehow.

[Human Habitat Index]

Large Parts of Europe are Warming Twice as Fast as the Planet On Average
https://phys.org/news/2022-11-large-europe-fast-planet-average.html



The warming during the summer months in Europe has been much faster than the global average, according to a new study by researchers at Stockholm University published in the Journal of Geophysical Research: Atmospheres. As a consequence of human emissions of greenhouse gases, the climate across the continent has also become drier, particularly in southern Europe, leading to worse heat waves and an increased risk of fires.

According to the UN's Intergovernmental Panel on Climate Change (IPCC), warming over land areas occurs significantly faster than over oceans, with 1.6 degrees and 0.9 degrees on average, respectively. It means that the global greenhouse gas emissions budget to stay under a 1.5-degree warming on land has already been used up.

Now, the new study shows that the emissions budget to avoid a 2-degree warming over large parts of Europe during the summer half-year (April-September) has also been used up. In fact, measurements reveal that the warming during the summer months in large parts of Europe during the last four decades has already surpassed two degrees.

... In southern Europe, a clear, so-called, positive feedback caused by global warming is evident, i.e. warming is amplified due to drier soil and decreased evaporation.



Moreover, there has been less cloud coverage over large parts of Europe, probably as a result of less water vapor in the air.

"What we see in southern Europe is in line what IPCC has predicted, which is that an increased human impact on the greenhouse effect would lead to dry areas on Earth becoming even drier," says Paul Glantz.

The study also includes a section about the estimated impact of aerosol particles on the temperature increase. According to Paul Glantz, the rapid warming in, for example, Central and Eastern Europe, is first and foremost a consequence of the human emissions of long-lived greenhouse gases, such as carbon dioxide. But since emissions of short-lived aerosol particles from, for example, coal-fired power plants have decreased greatly over the past four decades, the combined effect has led to an extreme temperature increase of over two degrees.

"The airborne aerosol particles, before they began to decrease in the early 1980s in Europe, have masked the warming caused by human greenhouse gases by just over one degree on average for the summer half-year. As the aerosols in the atmosphere decreased, the temperature increased rapidly.

According to Paul Glantz, this effect provides a harbinger of future warming in areas where aerosol emissions are high, such as in India and China.



P. Glantz et al, Unmasking the effects of aerosols on greenhouse warming over Europe, Journal of Geophysical Research: Atmospheres (2022)
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2021JD035889

https://www.bloomberg.com/news/articles/2022-07-01/china-lockdowns-reduced-carbon-emissions-by-7-9-estimates-show?leadSource=uverify%20wall

Assuming aerosols dropped significantly (Mar-May) along with carbon emissions, can we link this to the June - August 2022 Chinese heatwave ?

https://en.wikipedia.org/wiki/2022_China_heat_wave

[gerontocrat]

A cat has been put amongst the pigeons of aerosol science.

The current climate models may have been grossly overestimating the cooling effect sulfur pollutants from industry have had on temperature, perhaps by as much as half.

https://www.sciencealert.com/even-while-dormant-volcanoes-leak-climate-changing-gasses-into-the-atmosphere
Even While Dormant, Volcanoes Leak Climate-Changing Gasses Into The Atmosphere

We know volcanoes can cause dramatic shifts in the atmosphere when they erupt, but what about those long stretches of time when they appear to have fallen silent?

A new study suggests that dormant volcanoes could be leaking out much more sulfur than we thought.

In fact, we might have underestimated sulfur output from sleeping volcanoes by a factor of three. That could mean a recalibration of climate and air quality models, as sulfur is one of the most important elements in terms of providing a climate cooling effect.

These findings are based on tiny particles trapped in layers of an ice core extracted from central Greenland, showing the make-up of the atmosphere circulating above the Arctic between the years 1200 and 1850. Sulfur emissions from dormant volcanoes were much higher than expected.

"We found that on longer timescales the amount of sulfate aerosols released during passive degassing is much higher than during eruptions," says  atmospheric scientist Ursula Jongebloed, from the University of Washington.

"Passive degassing releases at least 10 times more sulfur into the atmosphere, on decadal timescales, than eruptions, and it could be as much as 30 times more."

The original aim of the research was to look at the amount of sulfur marine phytoplankton adds to the atmosphere through compounds they release as they grow. Phytoplankton were thought to be the main source of sulfur emission before humans came along. But the contributions from volcanoes – indicated through isotope measurements – stopped the scientists in their tracks.

Volcanoes might be twice as important as marine phytoplankton when it comes to producing sulfur, the researchers suggest, even when they're not actively erupting. The plumes of gas leaking out of dormant volcanoes aren't picked up on satellite imagery, which may be why their contribution has been underestimated so far.

At the same time, if natural sulfur sources are higher, then we may have been overestimating the cooling effect sulfur pollutants from industry have had on temperature, perhaps by as much as half. This could explain why the Arctic is warming faster than expected – the starting aerosol level is higher than we thought.

"We don't know what the natural, pristine atmosphere looks like, in terms of aerosols," says atmospheric scientist Becky Alexander, from the University of Washington. "Knowing that is a first step to better understanding how humans have influenced our atmosphere."

Aerosols don't travel far and don't last all that long either, further complicating calculations about how this effect might be seen elsewhere – although the researchers are confident their findings, based on measures in the Arctic, will apply to emissions from volcanoes across the world.

Understanding fluctuations in sulfur suspended over our heads is critical in being able to model the balance of heat trapped by our atmosphere and energy reflected back out into space. Aerosol particles can block solar radiation, which is where the cooling effect comes from, but it's a very complex picture. For instance, scientists only just realized this year how dust plumes have been masking the full extent of global heating.

Further research should tell us more about aerosols' influence on global climate. The team behind the new study suspects that the 'missing' emissions that have previously gone undetected are could include compounds other than sulfur dioxide, such as hydrogen sulfide (H2S), but additional work will be required to know for sure.

"It's not good news or bad news for climate," says Jongebloed. "But if we want to understand how much the climate will warm in the future, it helps to have better estimates for aerosols."

The research has been published in Geophysical Research Letters.

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022GL102061
Underestimated Passive Volcanic Sulfur Degassing Implies Overestimated Anthropogenic Aerosol Forcing

Abstract
The Arctic is warming at almost four times the global rate. An estimated sixty percent of greenhouse-gas-induced Arctic warming has been offset by anthropogenic aerosols, but the contribution of aerosols to radiative forcing (RF) represents the largest uncertainty in estimating total RF, largely due to unknown preindustrial aerosol abundance. Here, sulfur isotope measurements in a Greenland ice core show that passive volcanic degassing contributes up to 66 ± 10% of preindustrial ice core sulfate in years without major eruptions. A state-of-the-art model indicates passive volcanic sulfur emissions influencing the Arctic are underestimated by up to a factor of three, possibly because many volcanic inventories do not include hydrogen sulfide emissions. Higher preindustrial volcanic sulfur emissions reduce modeled anthropogenic Arctic aerosol cooling by up to a factor of two (+0.11 to +0.29 W m−2), suggesting that underestimating passive volcanic sulfur emissions has significant implications for anthropogenic-induced Arctic climate change.

Key Points
Sulfur isotopes in a Greenland ice core show that passive volcanic degassing contributes 66% of preindustrial Arctic sulfate

The volcanic inventory used by most climate models underestimates passive degassing, possibly due to missing hydrogen sulfide emissions

Elevated preindustrial passive volcanic degassing reduces the estimated cooling effect of anthropogenic sulfate in the Arctic

Plain Language Summary
Sulfate aerosols are particles in the atmosphere that have a net cooling effect on the climate. One of the most uncertain aspects of climate modeling is the abundance of sulfate aerosols during the preindustrial era. Without knowing the amount of sulfate aerosols during the preindustrial, it is difficult to estimate how much anthropogenic sulfate aerosols have offset warming from anthropogenic greenhouse gases.

In this study, we examine preindustrial sulfate aerosols in a Greenland ice core. We find that sulfate aerosols from passive (i.e., non-eruptive) volcanic degassing contribute almost two thirds of preindustrial Arctic sulfate aerosols in years without major volcanic eruptions. We compare this result to a state-of-the-art global model and find that most climate models use a volcanic emissions inventory that underestimates preindustrial passive volcanic sulfur emissions. That volcanic inventory only includes one type of sulfur emission (sulfur dioxide), but studies have shown that volcanoes emit hydrogen sulfide, which can also form sulfate aerosols. We show that higher emissions of volcanic sulfur during the preindustrial era decrease the estimated cooling effect of anthropogenic aerosols during the industrial era. Thus, the underestimate of preindustrial volcanic emissions in current climate models has significant implications for anthropogenic climate change in the Arctic.

[gerontocrat]

A paper on the varying geographic impact of Aerosols on climate and the effect of sea ice melt.

Key messsages from the paper below (italics here & there by me).

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022JD037716
Distributions and Trends of the Aerosol Direct Radiative Effect in the 21st Century: Aerosol and Environmental Contributions

Abstract
The aerosol direct radiative effect (ADRE) is controlled by both aerosol distributions and environmental factors, making it interesting and important to quantitatively assess their effects on the ADRE inhomogeneity and climate trends. By analyzing the ADRE in the 21st century from a global reanalysis data set, we find that the spatial variability of the ADRE and its trends can be well explained by a linear regression model. In this model, scattering and absorbing aerosol optical depths (AODs) are used, along with critical environmental variables such as surface albedo and cloud radiative effect, as predictors. Based on this model, we find that approximately 70% of the ADRE inhomogeneity is due to the AOD distributions and the remainder is attributable to environmental factors. This study also shows that a stronger cooling effect of the scattering aerosols in the Northern Hemisphere drives northward cross-equator meridional energy transport, although this transport exhibits a declining trend over the last two decades. The changes in surface albedo and cloud radiative effect strongly influence the trends in the regional ADRE and the meridional energy transport driven by them. In particular, the reduction of surface albedo (sea ice) is primarily responsible for the enhancement of the cooling ADRE, as well as an associated trend in meridional energy transport, in the Arctic.

Key Points
Nonaerosol factors contribute significantly to the spatial inhomogeneity of the aerosol direct radiative effect (ADRE) and its trends in recent decades

- The hemispheric difference in scattering aerosols drives northward cross-equator energy transport, which shows a declining trend

- Changes in the surface albedo due to sea ice melt strongly influence the ADRE trends in, and the energy transport to, the Arctic

Plain Language Summary
Aerosols are particles produced by natural events such as volcanic eruptions and anthropogenic emissions such as fossil fuel combustion. They can scatter and absorb incoming solar radiation, leading to a strong local cooling or warming effect on the Earth’s climate. The impact of aerosols on the Earth’s radiative balance is known as the aerosol direct radiative effect (ADRE). Factors that can affect ADRE include the types and amounts of aerosols and the environmental conditions such as surface albedo and clouds. This study proposed a regression model to predict the distributions and trends of global ADRE. According to the results, 70% of the ADRE variability is contributed by aerosols, while the rest is influenced by surface albedo and clouds. The high aerosol concentrations in the Northern Hemisphere require energy to be transported from the South Hemisphere to the North. However, this demand has decreased over the past two decades. Changes in surface albedo and clouds have a significant impact on the ADRE trend. In particular, the retreating sea ice plays a major role in the ADRE trend in the Arctic.

1 Introduction
The aerosol direct radiative effect (ADRE) affects the planet’s energy balance and hence the average temperature of Earth’s climate. The effect is caused by aerosols, which are microscopic particles suspended in the atmosphere that are chemically highly variable. These particles are emitted both by natural events such as sea spray, volcanic eruptions, wildfires, and dust storms and by anthropogenic sources such as fossil fuel combustion and agricultural activities. Aerosols can scatter and absorb solar (shortwave) radiation, leading to a strong cooling or warming effect on the radiation energy budget (Q.-R. Yu et al., 2019). This effect is known as the ADRE, as it does not involve atmospheric adjustments. To determine the ADRE, radiative transfer models require aerosol optical properties obtained from ground-based measurements, satellite observations, or model simulations (Bellouin et al., 2020; Loeb et al., 2021; Thorsen et al., 2020; Wu et al., 2021). The quantification of the ADRE has improved significantly over the past decades

This study aims to develop an analytical model that can explain the global distributions and variations of the ADRE under both clear- and all-sky conditions and to elucidate how aerosols and environmental state variables are tied together to influence the ADRE.

[Human Habitat Index]

A paper on the varying geographic impact of Aerosols on climate and the effect of sea ice melt.

Key messsages from the paper below (italics here & there by me).

https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2022JD037716
Distributions and Trends of the Aerosol Direct Radiative Effect in the 21st Century: Aerosol and Environmental Contributions

If Australia used more coal would it cool the continent in the short and long term ?