The Dimming Dilemma

History | References

“We must not believe those, who today, with philosophical bearing and deliberative tone, prophesy the fall of culture and accept the ignorabimus. For us there is no ignorabimus, and in my opinion none whatever in natural science. In opposition to the foolish ignorabimus our slogan shall be: We must know — we will know!” —David Hilbert

What is Global Dimming?
The topic of global dimming, known in scientific terms as the aerosol masking effect (video), is often misunderstood. Global dimming produces forces that act opposite to global warming for which it has become known as a devil’s bargain. It has been implicated in both climate change denialism and doomism[1]. It is a well-known scientific phenomenon, like its counter part global brightening (video). The global warming puzzle would not be complete without understanding global dimming; the dark side of the debate. This topic is introduced by Dave Borlace of Just Have a Think in the following video.

Global dimming happens when tiny particles, known as aerosols, the by-product of fossil fuels or other pollutants, absorb solar energy and reflect it back into space. The result is a reduction in the amount of global direct irradiance at the Earth’s surface. This creates cooling and warming effects as it decreases the amounts of direct and diffuse solar radiation reaching the surface of the Earth. In addition, global dimming interferes with the hydrological cycles in the biosphere and reduces evaporation rate. It also impacts cloud formation which is an indirect effect that has further implications. Cloud physics and particle physics are fascinating and challenging subjects that we will take a closer look at here. Clouds are climate wild cards (video).

Natural Versus Anthropogenic Aerosol Sources
Anthropogenic aerosol sources include sulphate from burning fossil fuels like coal, soot from factories or wood-burning, and dust from roads and land degradation. It is known that anthropogenic aerosols, like those from factories, tailpipes, and fires negatively impact the environment and can cause everything from warming to cooling, to deadly air pollution, to the acceleration of glacial melt around the globe by impacting albedo.

Typically global dimming discussions focus overly on manmade sources, while forgetting natural ones. Naturally occurring aerosols include plankton, deserts, trees, sea salt, dust, and volcanoes. Volcanoes have long been known to produce a cooling effect in the atmosphere.

Volcanoes emit sulfur dioxide (SO2) into the upper atmosphere, known as the stratosphere. This is above the troposphere where weather actually happens. This impact can last several years unlike industrial aerosol sources which go into the troposphere and are rained out typically in less than a week. Natural aerosols can offset greenhouse gas warming and have the potential to cool the Earth. Natural aerosol sources can have much more powerful impacts than anthropogenic sources and should not be forgotten or underestimated in this discussion. In fact, they are responsible for creating the conditions for a Snowball Earth discussed in the following PBS Eons video.

Real-Time Particulate Maps
NASA has created a map showing global aerosol distribution for further modelling. This will allow scientists and the public to visualize the movement and impacts of these dangerous particles. Scientists must continually investigate the extent and knock-on effects of these large scale phenomena. Other maps that provide data on aerosol pollution include the Aerosol Pollution Map from Windy and the AirVisual Real-time Pollution Map, Zoom Earth, Climate Reanalyzer, NASA Worldview, Earth Nullschool and CAMS Copernicus also provide temperature maps as well as greenhouse gas and particulate matter tracking.

The Hidden Dangers of Aerosol Dimming
The aerosol effect is well-established in scientific research, including the well-known pan evaporation data. There is no question that pollution-based aerosol dimming has an important role to play in climate forcing. This dangerous effect is masking some human-caused global warming, but how much is in question. There is still much scientific debate about the extent and impact of both global warming and global dimming. The purpose[2] of this discussion is to uncover and investigate the sometimes conflicting research on this matter.

Aerosol dimming, caused by introducing industrial pollutants to the natural environment, is a serious threat to the health of human, animal and plant life. People all over the globe are increasingly facing serious health complications related to air pollution, smog, and acid rain. New reports are now linking high risk of respiratory infections like COVID-19 to air pollution. Recent studies report that “the climate effects of anthropogenic aerosols have masked some of the warming induced by greenhouse gases (GHGs) along with some impacts of that warming. These temperature effects may be beneficial but are almost certainly overwhelmed by aerosols’ negative health impacts.”

We will take a closer look at the dimming dilemmas facing us here and update some of the outdated and polarized framing of it that has dominated the discussion for more than a decade.

“Global dimming has devastating effects on the earth’s environment and living beings. The pollutants causing global dimming also lead to acid rain, smog and respiratory diseases in humans. [It also destroys and acidifies natural habitats for animal and plant life].”⁠ —Conserve Energy Future

A Brief History of The Particle Puzzle
Eminent climate scientist James Hansen, former director of NASA’s Goddard Institute for Space Studies, is among the first to publicly debate this problem which has been recognized since 1950. In 1985, an English Scientist, Geraid Stanhill, who coined the term Global Dimming, had noticed a 22 percent drop in sunlight compared to the 1950 findings.

In an epic program on this topic that first aired on PBS in 2006 titled Dimming the Sun, James Hansen introduced global dimming to the public. Additionally Veerabhadran Ramanathan, one of the world’s leading climate scientists, is also credited as being among the first to unravel the mystery of global dimming and to inspire the pan evaporation studies. These studies were further discussed in the BBC Horizon Documentary. This documentary has been archived as outdated by the BBC.

Hansen initially raised the concern that if we cut back on aerosol pollution, global warming would be compounded by this effect, especially if we don’t handle this situation very carefully (by which he meant drawing down gradually). Hansen first referred to this as a Faustian Bargain more than a decade ago stating that “aerosols have a cooling effect (by reducing solar heating of the ground) that depends on the rate that we pump aerosols into the air, because they fall out after about five days.”

Hansen presented the dimming dilemma as a deal with the devil, but one with a potentially manageable solution; that being a gradual reduction in aerosol emissions. Yet the non-science public subsequently began to over-dramatize the dilemma, often characterizing it as a catch-22. It quickly became known as an impending disaster with no way out. This is portrayed in the now outdated and archived original BBC Dimming documentary (video).

Those at NASA Langley, furthering Hansen’s work, have also reported on this topic. In the following video, Bruce Doddrige a NASA scientist, introduces uncertainties surrounding the study of our particulate atmosphere and at the end begins a discussion often left out of the public debate on how to reduce both global warming and global dimming at the same time, using natural geoengineering methods such as biochar, iron salt aerosols, and rewilding.

Doing the Math: How Much Warming Is Dimming Masking?
It is understood that reducing emissions will alter solar irradiance and decrease the aerosol masking effect which might mean the loss of some net cooling. How much is still in question. You will soon notice that there are many different estimates given in different studies. Modeling can vary widely from study to study.

Additionally related phenomena are poorly modeled. “Current global climate predictions do not correctly take into account the significant effects of aerosols on clouds on Earth’s overall energy balance.” says an article on this topic. A related issue is the known diversity in precipitation responses in present climate models (Knutti & Sedláček, 2012), which also affects extreme weather index calculations.

According to this Geophysical Research Letters study, “we show how cleaning up aerosols, predominantly sulfate, may add an additional half a degree (0.5°C) of global warming, with impacts that strengthen those from greenhouse gas warming.” Most scientists, journalists and researchers speaking on this say the amount of warming from dimming given in the most widely cited and published estimates is between 0.25 and 0.5°C. Various other estimates discuss that between 0.25-1.1°C of warming MIGHT BE possible. Studies do vary widely. There is no one answer. But the most common answer given is 0.5°C. This is also given in the AR5, the latest IPCC reporting on this, which also gives 0.5°C.

Some studies do indicate a wider range, but there are less models showing this and they also point to more immediate regional and short-lived impacts. “According to this study, “removing aerosols induces a global mean surface heating of 0.5–1.1°C, and precipitation increase of 2.0–4.6%. Extreme weather indices also increase. […] Under near‐term warming, we find that regional climate change will depend strongly on the balance between aerosol and GHG forcing.” They indicate that a problem with this study is that “one clear limitation of the present study is the low number of models, compared to larger multimodel intercomparisons such as CMIP5.”

The Dimming Dilemma
According to the experts, the only means by which humans can avoid climate catastrophe is to make a significant reduction in industrial activity and greenhouse gasses (GHGs) e.g. carbon dioxide (CO2). This would simultaneously reduce scattering aerosols e.g. sulfur dioxide (SO2) that impact cloud nucleation and formation. Quite simply, less cloud cover means less cooling, i.e. less dimming. In a warming world, there is much fear and trepidation around this notion.

Because of this global dimming has become the constant plot of disaster fiction scenarios contending that we have to keep burning fossil fuels in order to avoid a dimming disaster that will cause all life on Earth to go extinct in short order.  The tendency to oversimplify and overstate aspects of the aerosol masking effect in popular media, among the non-science public, has led to problematic reporting, exaggeration[3], and fake news.

It is clear that the current climate crisis and the sixth mass extinction now underway is due to greenhouse gas emissions. In fact, the last time CO2 emissions were this high, modern humans didn’t exist. Those arguing that we must keep emitting pollution and burning fossil fuels exploit uncertainties surrounding the potential impacts of global dimming and brightening (as well as other physics at work here) the effects of which can be direct as well as indirect making the sum total extremely difficult to map, even for highly trained physicists.

There are also inherent difficulties in modeling. At this point, making definitive claims indicates oversimplification and inference-observation confusion, i.e. jumping to conclusions (video). The top researchers in this field are still investigating what the impacts of this effect and combined phenomena might be on average global temperature (AGT), how global or regional these impacts are, how lasting they are, and what mitigating strategies might effectively reduce these impacts.

This is a matter of scientific inquiry still under investigation. This has long been an understudied phenomena with many potential unknowns. For the last decade or more, one study after another has come out noting various dimming effects and then challenging them. Failing to cite a robust set of sometimes contradictory evidence is a failure of scientific objectivity. It is cherry picking the data.

Studying the Studies
For example, some studies point to the potential under-reported impacts of dimming, while other studies show that cutting pollution won’t cause global warming spike. Yet other reports contend that reducing aerosols that cause dimming may intensify heatwaves due to increases in mean warming, unless we can offset this with trees, biochar and other CO2 reducing agents as well as other last minute natural geoengineering techniques and drawdown gradually.

Another study claims that decreases in cloud-water from some forms of pollution balance out the increases in cloud-water from other sources. Their bottom line conclusion is that “we estimate that the observed decrease in cloud water offsets 23% of the global climate-cooling effect caused by aerosol-induced increases in the concentration of cloud droplets. These findings invalidate the hypothesis that increases in cloud water cause a substantial climate cooling effect and translate into reduced uncertainty in projections of future climate.”

Still other studies are noting that the effects of dimming are more regional than global. Additionally, when you look at the whole world at once, rather than region by region, the net economic effect of this cooling is likely to be small due to these effects between latitudes. It is true that aerosols produce the biggest effects in the regions where they’re emitted. For example, scientists speculate that the dimming over the Arctic may be masking some of the already shocking levels of polar amplification we are already seeing.

Another important thing to remember about aerosols is that they tend to have a rather short lifespan in the atmosphere — eventually, the rain brings them back out of the sky in just a few weeks time or even a matter of days. This means effects are not only more regional than global, but short-lived as well, especially when compared to greenhouse gasses (GHGs).

Related effects can also cancel each other out. Experts are noting more recently that reducing some aerosols, like smog, can even serve to reduce a source of warming and cooling at the same time. Emissions from black carbon from fossil fuels can contribute to both warming and cooling (video) in different ways. This is really tricky stuff. Black carbon (BC) is a primary aerosol emitted directly at the source from incomplete combustion processes.

Climatologist Gavin Schmidt, director of NASA’s Goddard Institute for Space Studies, in a Twitter thread commenting on the new aerosol research further says, “you cannot assume that net zero CO2 emissions must also imply zero anthropogenic aerosol emissions. As a result, he added, it’s important to note that anthropogenic aerosols will not suddenly disappear and make global warming much worse.” And even if they do, as in the COVID-19 shut downs, there are still other aerosol sources which will be discussed below.

There’s No Evidence For A Conflict
The jury is still very much out on the global dimming effect as it presents with other complex related and conflicting phenomena. According to Hansen et al “the amount of dimming is [as yet] uncertain because global aerosols and their effect on clouds are not measured accurately” and other mitigating factors have not been considered until more recently.

The complexity of this problem is clearly bad enough without exaggerating or oversimplifying it. Additionally, the contentious framing among non-science public has now become disabling and increasingly inaccurate on this issue. It forces a narrative that is highly polarizing. It further refuses any proposed solutions as “hopium.” This is great for media drama, click bait and getting attention, but it is bad for science.

While it is true that our continued reluctance to reduce carbon emissions fast enough makes the two goals of eliminating air pollution and limiting global warming seem mutually exclusive, the real dilemma is caused by our inertia and failure to act. It is also because of our continued adherence to business as usual (BAU).

But the good news is that in reality, new studies are finding there is no evidence for a conflict between the goals of reducing climate warming and aerosol pollution at the same time. This is not getting reported even though it is clear that he risks posed by continued industrial aerosol pollution far outweigh the benefits. There is no question that global cities must cut emissions in the scientific literature; which has reached a consensus on this matter.

“Oversimplification of the notion that phasing out fossil fuels may have negative consequences in the immediate term may have delayed uptake of policies that would be beneficial to climate on all timescales as well as to air quality and human health. This study helps make it very plain that robust planning of climate policies requires expert interpretation of plausible scenarios to avoid any such confusion….This means that even a “very ambitious but plausible” phaseout of fossil fuels “leads to relatively minimal change in the near-future warming…The study shows that there is “no evidence for a conflict” between the goals of reducing both climate warming and air pollution, the paper concludes.” ⁠— Carbon Brief

Further, according to, “our study provides assurances that polluted air has a limited ability to prevent the atmosphere from heating up, in addition to being bad for people’s health. There is now one less excuse for us not to cut emissions of both air pollution and greenhouse gases, or we will continue to see temperature rises that put people and the natural world in danger. In any case, a small temperature rise resulting from cutting pollution is a price very much worth paying to prevent greater, long-term harm caused by greenhouse gases.”

The notion that we should keep polluting and burning the world is a disturbing absurdity guaranteed to line the pockets of fossil fuel robber barons. Voltaire said “those who can make us believe absurdities, can make us commit atrocities.” In this case, that would be failing to act to stop the climate and global air pollution crisis unfolding undeniably faster than expected everywhere on the planet.

The Denial Campaigns
Despite the many unknowns here, various types of deniers like to assert that global dimming will make solving global warming impossible. These denier groups vociferously claim in no uncertain terms that we have to keep burning the fossil fuels that are killing us in order to keep temperatures down; temperatures they often claim are not rising in the first place, ironically.

In this fake news and science report tilted “Shocker: Global warming may simply be an artifact of clean air laws,” presented by Watts Up With That, this kind of claim is presented. According to Wikipedia and others, Watts Up With That? (or WUWT) is a fairly well-known blog promoting climate change denial.

Another pseudoscience myth going around on the Internet is that “the aerosol masking effect will cook us with only a 35% reduction in aerosols, so we have to keep burning coal to save ourselves from global dimming” is based on just one study. In this plot, removing the aerosol mask would produce a devastating paradox (video) and an instantaneous temperature rise on the order of as much as 1.2-5°C in global temperatures. However, we know that the entire climate system takes much longer to respond.

The fictional massive rise of 1.2-5°C in temperature as the result of reduced aerosol pollution is a “completely absurd number” (video) says Paul Beckwith, Climate System Scientist. This exaggerated reporting continues to be responsible for repeated fake news warnings from both deniers and doomists who suggest that doing anything about it, like for example actually cutting emissions, is futile because humans are as they like to say “damned if we do, and damned if we don’t.”

Global dimming has become the subject of climate change denial campaigns everywhere, even in the White House. The current POTUS has repeatedly called climate change a hoax. Dimming uncertainties get used by unscrupulous entities as yet another reason to condone defeatism on climate issues in these circles. The goal of these groups is to foment inaction at the worst possible time. Let’s be clear, it’s not too late.

“The Trump administration put out an environmental impact report a couple weeks ago and the content is, well, unexpected. While this particular White House is full of climate change deniers, the report boldly declares that global warming will be immensely devastating – so much so that it’s futile to try to do anything about it…In a move that should be shocking to absolutely no one, the administration used this prediction to justify loosening fuel efficiency standards. The logic seems to be that our fate has already been sealed, so why not make car companies some profits while we drown in the rising ocean levels? ” ⁠— Justin Kamp

Global warming and global dimming are both problems we must solve as a global species; and luckily we know the solution. Sadly, this doesn’t mean we are using what we know. Prevention and mitigation measures have been repeatedly thwarted by fossil fuels and other corporate-controlled interests that have resulted in the current religiously anti-science and science illiterate government that has taken no action on these issues.

This is a constant reminder that we are living in a time when science and scientists are routinely marginalized and undermined by prevalent thinking errors, confusion, confirmation bias, (video) fake news, political agendas, fictionalizing, and denial campaigns.

Fact Check: Is Dimming Shielding Us from Catastrophe?
According to Dr. David A. McKay, currently a Postdoctoral Researcher at Stockholm Resilience Centre (Stockholm University) “while the total removal of human-made aerosols would lead to a short-term warming of ~0.4oC (and ~0.6oC by 2100), an abrupt end to all aerosol emissions at once is very unlikely. Decarbonisation will take decades, and aerosols come from a wide variety of sources beyond just the heaviest emitting power stations. Even a challenging target of halving aerosol emissions in the next couple of decades would only lead to ~0.2oC of warming – the equivalent of around a decade more of the current warming trend – which is preferable to carrying on emitting carbon indefinitely instead and is less likely to trigger any tipping points.”

Fun Stuff: CERN’s CLOUD Project and Galactic Cosmic Rays
CERN’s CLOUD Project is very exciting but not many people know much about it. In fact, Jasper Kirkby at CERN says ‘it is simply too soon to be so polarized over this issue, because it is still being studied.’ Scientists are collecting and analyzing the data. They are working hard to share these models and their data online for the public so we can all stay informed.

According to Skeptical Science, “the CLOUD project at CERN is essentially just getting started. Its preliminary findings will help aerosol modelers, and hopefully it will continue to provide useful results…But there’s no such thing as too debunked when it comes to myths about climate change, and there’s little chance this will be the last time [that this] will be trotted out to claim that we don’t need to reduce greenhouse gas emissions.”

This project is also exploring the connection between climate change and galactic cosmic rays. Yes, that’s right, galactic cosmic rays! In the following video with Dave Borlace of Just Have A Think this is discussed.

According to Skeptical Science, “Henrik Svensmark has proposed that galactic cosmic rays (GCRs) could exert significant influence over global temperatures (Svensmark 1998). The theory goes that the solar magnetic field deflects GCRs, which are capable of seeding cloud formation on Earth. So if the solar magnetic field were to increase, fewer GCRs would reach Earth, seeding fewer low-level clouds, which are strongly reflective. Thus an increased solar magnetic field can indirectly decrease the Earth’s albedo (reflectivity), causing the planet to warm.”

The science here is challenging to say the least. Yet it is necessary for us to study these topics if we are to be members of an informed society. We also have to understand that science never stops questioning or contradicting itself and we must be able to contend with large uncertainties without jumping to conclusions. According to Jasper Kirkby, Particle Physicist at CERN, ‘the area of aerosols is very poorly understood, yet this does not mean we don’t understand the big picture phenomena involved’ implying again, that we must cut GHG emissions.

Global Brightening in the Northern Hemisphere
According to the EPA global dimming has already been reversed in North America and Europe. Sulfate aerosols declined with the Clean Air Act (1970) in the United States and similar policies in Europe. The EPA reports that from 1970 to 2005, total emissions of the six principal air pollutants dropped by 53% in the US. Skeptical Science also says “the global dimming trend reversed around 1990 – 15 years after the global warming trend began in the mid 1970’s.”

In this article from Forbes titled How Can We Stop Global Dimming?, this is summed up as follows: “since the 1980s, pollution controls have substantially reduced air pollution which was one of the major contributors to dimming. Airplane contrails are still around providing some dimming. Places like Poland and Texas are still burning coal by the freight train load and doing their bit to keep the skies dim. But mostly the developed world has either ditched coal or substantially restricted the crap that it puts into the air.”

This means we have already undergone some the worst effects mentioned by deniers. Now we are actually on a brightening (video) trend. According to Wikipedia “this switch from a global dimming trend to a brightening trend happened just as global aerosol levels started to decline (roughly 1990). Analysis of recent data reveals that the surface of the planet has brightened by about 4% in the past decade. The brightening trend is corroborated by other data, including satellite analyses.”

How to Reduce Both Global Warming and Aerosol Pollution
Even though the current trend is toward brightening, we still have to contend with aerosol pollution and the some 2-3% of dimming we are still experiencing. The rate of dimming varies around the world, but is estimated at around 2–3% on average per decade. This may also be increasing due to the increase in wildfires globally.

Let’s finally talk about the many proposed mitigations for the global dimming phenomena. The first thing we need to do is get our emissions down. Some are strongly suggesting that we halt fossil fuel expansion and subsidies by the 2020’s, like the Club of Rome. We need this kind of aggressive approach to make change happen in the time required. Next, because, as many have duly noted we just aren’t doing that, we likely have to consider some other options.

Because we have already unbalanced the system, we must now consider options like geoengineering. Geoengineering is often a feared concept. But it doesn’t have to be. In fact, Paul Hawken’s drawdown techniques would help us cut emissions right away. If we did this while applying the natural geoengineering techniques being discussed now, such as trees, biochar and other CO2 non-toxic and non-invasive reducing agents, we could potentially begin to mitigate the dimming effect. James Hansen has alluded to this all along. It is certain that we must clean up our act and now.

“It is going to be important that emission of both greenhouse gases and particulate matter should be reduced simultaneously [while rewilding, and adding exudates from foliage, etc.]. This will balance out both the phenomena [as we begin to gradually drawdown].⁠— Conserve Energy Future

We Don’t Have to Fear Clean Air
It turns out that trees are known to produce natural aerosol particles that make up what is known to be the largest river on earth in the sky (video) by seeding clouds, creating cloud cover and ultimately producing rain. Tall prairie grass is also now being discussed as it is likely just effective as trees. Vegetation and rewilding are solutions that often get ignored and overlooked amidst all the drama surrounding this issue.

“Whatever way you look at it, we live on a dying planet. But dying does not actually mean dead. Despite all the damage that people have done to planet Earth in the last 100 or so years, the Earth can repair itself if we do the right things.”—John Kennedy

Reforestation (afforestation) is always a good idea. It is also a form of natural, non-toxic and safe geoengineering we don’t have to fear. Not all geoengineering involves techno-fantasy and high stakes risks with toxic components. In this case, we have the technology and it’s called a tree. Tragically, we are cutting them down for profit and industry faster than they can grow. In short, we must end limitless growth economy before it ends us.

“Nature produces abundant particles without any pollution…the trees can do it with zero pollution.” — Jasper Kirkby, CERN

Recent studies reveal that the findings from the several experiments show that trees release molecules that contribute to cloud seeding. According to these studies, it was thought that the pollutant Sulfuric acid is required for a particular cloud formation. Sulphur dioxide (SO2) dissolves in the water vapour in clouds to form form dilute sulphurous acid (H2SO3). But these studies are showing that aerosols can form and grow to the size needed to seed a cloud from the molecules naturally emitted by trees, without requiring Sulfuric acid.

In the following video from ScientistsWarning.TV, Dr. William Moomaw, discusses how carbon emissions can be offset with afforestation and other natural geoengineering techniques.

“What it means is, we don’t have to fear clean air.” —  Bjorn Stevens, Max Plank Institute

Bjorn Stevens, atmospheric scientist, said that “the findings of the experiments have another important implication regarding the public’s perception of global warming and clean air. Some scientists believe that measures such as ridding the atmosphere of Sulfur dioxide by limiting coal plant processes could remove some of the beneficial cooling effect of clouds, and therefore boost global warming. However, upon knowing that trees can do the cloud seeding job themselves, this will be less of a concern today. ” New studies continue to emerge to date recommending planting trees to mitigate climate change.

Fact Check: 9/11 & Coronavirus Aerosol Impacts
Exhaust from an airplane engine contains aerosols and water vapor. Therefore, after 9/11 people contended that the shut down of air traffic following the event would result in warming temperatures as the aerosol mask was suddenly removed. Now people are asking the same question again as air traffic and emissions have been curtailed by the impact of the coronavirus (COVID-19) starting in February 2020. An analysis shows that coronavirus has cut China’s carbon emissions by 100 million metric tons. Also, satellites show Italy’s coronavirus response has dramatically and suddenly reduced air pollution emissions.

Again, we see studies both arguing for and against this. In 2002, a study that came out soon after the 9/11 incident cited by Paul Beckwith in the following video discusses this further.

Here, Professor Paul Beckwith contends that “since global dimming from aerosols is thought to be between 0.25 to 1.1°C, if we take the 1.0°C number as an upper limit, then the coronavirus closures could result in a long-term global surface temperature warming of about 0.06°C; with short-term regional warming over China of about 0.25°C.” The global surface temperature warming or average global temperature warming indicated here (0.06°C) is about the same as continuing the industrial activities known to cause climate warming for another 10-15 years, but we’d get it all at once. This is something we really cannot afford.

Note that the 0.06°C is based on IF the global dimming number is 1.0°C. However the more widely cited estimate is that the global dimming number is actually less than 0.5°C. Paul Beckwith is discussing the worst case or upper limit scenario here. The most widely cited and published estimates for the global dimming number are between 0.25 and 0.5°C, which would mean that the results of coronavirus warming might be more like 0.03°C. There is also some question as to how long the regional impacts might take to show up in the average global temperature (AGT) data. The entire climate system takes much longer to react.

Other studies that came out after the initial 9/11 study challenged it further. They contended that this has become an urban legend as the non-science public often confuses regional temperature fluctuations with AGT changes. “A US study by Dr Gang Hong of Texas A&M University has found that daily temperature range (DTR) variations of 1.0°C during September aren’t all that unusual and that the change in 2001 was probably attributable to low cloud cover. Elsewhere, a team at Leeds University, working with the Met Office Hadley Centre, ran contrails through its climate models and found that you’d need about 200 times the quantity of flights over America to produce a significant effect on DTR.” This will continue to be a matter of debate and likely much controversy.

“Ralph Keeling estimates that global fossil fuel use would have to decline by 10% for a full year to clearly impact CO2 concentrations in the atmosphere … It’s too early to say, if it is related to coronavirus, Keeling said, adding there were big variations from year to year and that the March trend was similar to some previous years.” ― Climate Change News

However, again dimming need not present a dilemma if we drawdown gradually and use natural geoengineering techniques. According to the most recent study on this matter, “this is very much a case of short-term climate pain for long-term gain. It might seem counterproductive to prompt temperature rises by reducing pollution, but this research also shows that this effect will disappear in a few decades. ‘If we carry on emitting greenhouse gases into the atmosphere at the current rate, we will see bigger temperature rises that are far longer lasting. This would be incredibly difficult for society to adapt to, and would cause devastating environmental damage.”

According to the EPA we are already largely in global brightening in the Northern Hemisphere. Asia too should enjoy these same benefits of clean air. After all, it is our demand to their supply chain that is keeping half the globe breathing dangerously polluted air. And what goes around comes around, quite literally, carried by wind currents and jet streams.


Did You Know The Plankton Make The Clouds?
Did you know that Plankton have a large role in cloud production? Environmental Scientist and Climate Writer, Guy Lane says “the Plankton Meditation (video) is a guided meditation that helps you come to terms with fundamental ecological truths that are often overlooked.”

Learn More:


“The evidence that climate change is a serious problem that we must contend with now, is overwhelming on its own. There is no need to overstate the evidence, particularly when it feeds a paralyzing narrative of doom and hopelessness.” – Michael Mann

Dr. Michael Mann and others have published a paper looking at summertime extreme weather patterns in future scenarios of global warming. Mann says that “while climate change will initially exacerbate extreme weather, it is possible that reduction of aerosols from atmospheric pollution could counteract this effect.”

Michael Mann also recently said, “by mid-century, once the aerosols are no longer produced, greenhouse warming will once more dominate climate. The future is still very much in our hands when it comes to dangerous and damaging weather extremes. It’s simply a matter of our willpower to transition quickly from fossil fuels to renewable energy.” Read more on weather extremes still within our grasp.

David Suzuki (video) recently said, to paraphrase, ‘it doesn’t look like we have a chance of staying under 2˚C. But those saying it’s already too late need to go away, and right now.’ We know we are facing extinction, and that is scary enough without over-dramatization.

“It’s frightening but true: Our planet is now in the midst of its sixth mass extinction of plants and animals — the sixth wave of extinctions in the past half-billion years. We’re currently experiencing the worst spate of species die-offs since the loss of the dinosaurs 65 million years ago. Although extinction is a natural phenomenon, it occurs at a natural “background” rate of about one to five species per year. Scientists estimate we’re now losing species at 1,000 to 10,000 times the background rate, with literally dozens going extinct every day. It could be a scary future indeed, with as many as 30 to 50 percent of all species possibly heading toward extinction by mid-century.” — The Extinction Crisis

Scientists do recognize that the situation is dire and an emergency. Paul Beckwith, Climate Systems Scientist of the University of Ottawa has said we need to declare a global climate emergency and now. According, to eminent climate scientist, Michael Mann “‘we can still prevent many of the worst impacts of climate change from playing out”. There’s a lot each individual can do. Get started today.

“Even if there is no hope, we have to do something. Not having hope is not an excuse for not doing anything. But the thing we need more than hope is action, because once there is action there is hope.” —  Greta Thunberg


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  • 10:30 pm Mar. 31, 2020 – S. Cairns – (Updated resources, edited and abbreviated the entire page content, and updated all topic areas).
  • 9:15 am Mar. 2, 2020 – Charles Gregoire – (Updated on behalf of Shani Cairns via phpMyAdmin).
  • 7:30 pm Feb. 14, 2020 – S. Cairns – (Updated resources and added latest study links including the cloud studies).
  • 1:25 pm Aug. 5, 2019 – S. Cairns – (Updated intro paragraphs with even more new study findings and clarified opening remarks, added links to several new studies).
  • 3:35 pm Aug. 4, 2019 – S. Cairns – (Updated intro paragraphs with new study findings and clarified opening remarks. Re-wrote and updated several sections with the latest information).
  • 5:45 pm Jan. 21, 2019 – S. Cairns – (Added new footnotes section and anchors).
  • 2:30 pm Jan. 20, 2019 – S. Cairns – (Added new history/references short-codes and sections. Updated content. Linked to new article regarding aerosol releases double what previously thought).
  • 11:30 am Jan. 1, 2019 – Charles Gregoire – (Fixed a few more offsite links to open in new tabs. Put it up on the Home page new content slider in the number two spot. Updated the title).
  • 6:00 pm Dec. 31, 2018 – Charles Gregoire – (Completed another of several editorial reviews).
  • 1:15 pm Dec. 26, 2018 – S. Cairns – (Updated content and added NASA atmospheric aerosols explanatory lecture video and NASA aerosol distribution map links. Clarified some terminology and introductory matters).
  • 3:15 pm Dec. 23, 2018 – S. Cairns – (Wrote and published working article post of “Debunked: Global Dimming” content).
  • 3:00 pm Dec. 23, 2018 – S. Cairns – (Added “Debunked: Global Dimming” and associated “History” page. This is to address the dilemma of global dimming that has recently been called a paradox and impossible to solve. It is being used by deniers and doomers alike to say that climate change can’t be solved and thus we should continue our path of inaction).

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[1] Usage of the Term Gloom-and-Doomers

Doomers, sometimes called gloom-and-doomers, catastrophists, and doomists are trending terms in climate science communities. They are used here in a descriptive and not a pejorative sense, to refer to those who see no way out of the current predicament and have begun to argue that any action to remediate the situation is futile or ‘hopium’ as we are headed for INEVITABLE catastrophe. This is a dangerous thinking error that generates a self-fulfilling prophecy.

Many in the climate community have been suffering with increased depression and climate anxiety (video) due to the sheer mass of negative, extremely dire data they are confronted with on a daily basis. Those who are experiencing hopeless, otherwise known as clinical depression or PTSD, or have become overwhelmed should seek help and guidance.

Having no hope is a pathological and dangerous condition. According to a Psychiatrist at Psychology Today, “clinically speaking, despair and a lack of hope is a symptom of Complex Post Traumatic Stress Disorder. (Yes, that’s the worst kind of PTSD). At this time we should all be especially aware of Doom Despair (also known as Survival Despair). Individuals with this form of despair presume that their life is over, that their death is imminent. The ones most vulnerable to sinking into this particular [depression] are those diagnosed with a serious, life-threatening illness as well as those who see themselves worn out by age or infirmity. Such individuals feel doomed, trapped in a fog of irreversible decline.”

In popular culture some are now distinguishing between a near-term human extinction doomer and a gloomer as well. It is worth noting that scientists commonly refer to immediate, unpredictable changes as abrupt, non-linear change. Near-term human extinction is not academically preferred terminology and has begun to signal fake news and pseudoscience.

[2] Extended Purpose of This Wiki

The purpose of this wiki page is to educate on the topic of the global dimming theory, while distinguishing between science fact versus science fiction.  Further, it intends to discuss the complexities and much misinterpreted unknowns in order to highlight the potential solutions never addressed by deniers. The primary counter points can be summarized as follows:

1) It is obvious to all in the scientific community and beyond that we cannot cannot afford anymore warming, thus the 0.5-1.1°C of warming anticipated from the global dimming effect must be offset by gradual drawdown solutions which produce natural aerosol effects such as afforestation, plankton cloud generation, and many more listed on the Scientists’ Warning Geoengineering Wiki. These solutions are never discussed by deniers or doomers.

2) Many of the effects of global dimming are as yet unknowns. The impacts of global dimming are not actually always “global” and scientists are just starting to uncover this noting their regional effects differ widely. This is a field in its infancy.

3) We are actually experiencing global brightening since the 1990’s.

4) We don’t have to fear clean air. It’s simple, plant a tree. And;

5) Claiming that we must keep burning fossil fuels because otherwise we will lose our cool, is not cool.

[3] How Deniers Exaggerate

Deniers exaggerate the unknowns related to the effects of aerosols and claim that if we were to stop polluting suddenly, which is unlikely in any case, global average temperatures or surface mean temperatures would shoot up 1-3°C in a few weeks time. Catastrophists, also known as doomists, have made the claim that this is an unsolvable paradox and further, that if we were to stop polluting today by just 35% we would experience an immediate and deadly 1.2-5°C temperature citing this study by Levy et al.

They claim in no uncertain terms that this fictional temperature rise will terminate all life on the planet and drive us extinct overnight. They weave fact and fiction together so seamlessly that some have now begun to identify this as a new science fiction genre now being dubbed “extinction fantasy.” Although in a post-truth era of rabid fake news, this distinction is not clearly made for the non-science public and many begin to take these scenarios very seriously.

Upon closer inspection, this study by Levy et al actually says that these effects are still relatively uncertain, and that they would likely take until at least the end of the 21st century. Additionally, this study is careful to state there are enormous unknowns “regarding the role of aerosols in climate [and] the actual magnitude of the aerosol effect.” This means that the effects are also known to be regional in nature and that they don’t act all at once globally as these doomists erroneously imply.

According to climate scientist Professor James Renwick, from Victoria University, some doomers have claimed that “cutting aerosol pollution to zero (as would happen when and if industrial society falls over) will unmask another 2.5°C of warming. This is a factor of ten too large, as the actual amount would be around 0.25°C by current best estimates (see figure 10.5).” This shows a clear exaggeration of the data.

Doomsday media content creators overstate the unknowns to make the claim that a reduction in global dimming portends an immediate loss of habitat for human animals with human extinction immediately to follow. Based on these biased interpretations they warn copiously that we have to keep polluting or we will go extinct.

Deniers and doomists exploit speculative areas of the research for their own ends. They deliberately oversimplify and exaggerate this issue to make it fit their arguments so that they can conclude that if we keep emitting industrial pollution we are creating the conditions for extinction, and, at the same time, if we stop emitting we are creating the conditions for extinction. They refer to this as a paradox, but this is only a paradox of black and white thinking. By definition, it is not a paradox (video).

It is true that our continued reluctance to reduce carbon emissions fast enough makes the two goals of eliminating air pollution and limiting global warming seem mutually exclusive. This means the real dilemma is, in effect, caused by our inertia and failure to act. It is also because of the continued refusal to discuss what’s really going on or the actual solutions in favor of keeping business as usual (BAU) going at all costs.

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Note: This page, as with many wiki pages, is a work in progress. It aims to debunk erroneous notions related to the notion of global dimming as a paradox that has been circulating in fake news online. It does not debunk the global dimming effect itself.

3 Replies to “Dimming Dilemma”

  1. Good job on a tough topic. You really walked the line here and it’s a hard edge.

    To me it seems that to do NOTHING, as advised by these doomers and deniers, while something wrong is occurring, is symptomatic of the current age. Maybe we need more data, or more iPhone pictures of suffering? To do nothing is neither human, nor civilized.

    It seems like the slew of nutters, doomers, and deniers just keeps coming. I am so glad David Suzuki told them to shut up this week. It’s about time all scientists did. That guy reeks of a Frère Jacques mentality, while begging some “material goods” donations. If he and his flock want to be a monks, they should shut up and be monks.

    Deniers and doomers are going after the gullible to science. We must make ourselves impervious to science by knowing it better and knowing it’s limitations – we must avoid making broad sweeping arguments of certainty from unknowns, which seems to be a thing for doomers.

    Meanwhile, lets make an effort to change the toxic paradigm.


  2. Wow, this really impressed me and made me think. We really need to remember that we are experiencing global brightening as pointed out in this educational page. Why is no one talking about this? Yet, so many are saying we can’t stop burning fossil fuels because of this global dimming dilemma. They are also saying it’s too late to plant trees tragically.

    There’s still plenty of pollution coming at us from many sources, even if we stop burning coal. There are also more particles from increased wildfires and volcanic activity. Also, there will be multi-million tons of more pollution from deregulation of auto emissions under Trump. To advocate increased pollution and GHG which will increase the rate of meltdown of the Arctic methane deposits, permafrost melt and heating oceans is pure madness if you ask me.

    Too many people are talking about global dimming doom theories and not studying the phenomena carefully. Everyone it seems has suddenly become a scientist. Meanwhile the scientists studying the issue note it’s an unknown in how it will play out. Furthermore, there are spatial and geographic characteristics to global dimming you pointed out here very nicely. It will have different manifestations throughout the globe. And to single out one pollutant when there is thousands of them makes no sense either.

    So many have been hoodwinked by the hidden neoliberal agenda of the most prevalent global death cult in the world (Trump et al) and are saying we can’t stop burning fossil fuels because then we’ll have an immediate 1°C temperature rise resulting in what pseudoscience is now referring to as near term human extinction – a concept which seems to ironically feed the largest fossil fuel oligarchs on the planet while claiming to care for the environment. It’s definitely time to debunk this. Good job!

  3. Yes, good debunk of the dimming dilemma or paradox … Here’s even more math the proves it too.

    The Absurd Claim That We Must Keep Burning Fossil Fuels
    Let’s explain the pseudoscience of the so-called “McPherson paradox” (which isn’t any paradox at all). The paradox claims that if we stop burning coal, (especially) and “dirty” diesel and other fossil fuels to a lesser extent, we will remove enough air pollution, if industry also cleans up in general, to cause global average temperatures to spike and warming to increase so quickly that is will bring collapse of civilization in short order.  So, let’s look at two optional approaches based on the 2018 burning rates to keep this example simple.

    Option 1: Business As Usual (BAU)
    (This means we keep burning coal/oil/gas at the 2018 rate of +0.81 w/m**2). +0.80 w/m**2 is the extra warming over the next 20 years if 2018 coal/oil/gas is burned each year, so:

    1.61 w/m2 is the total warming over the next 20 years with continued burning.
    2.41 w/m2 is the total warming over the next 40 years with continued burning.
    3.21 w/m**2 is the total warming over the next 60 years with continued burning.

    Option 2: An As Yet Undetermined Alternative Approach
    (This would be if we cut all coal/oil/gas is burning to zero over 20 years, currently +0.81 w/m2).

    +0.40 w/m2 is the extra warming over the next 20 years if coal/oil/gas burning is reduced to zero over 20 years.
    +0.86 w/m**2 is the extra warming over the next 20 years because the air is getting cleaner due to less coal/oil/gas burning so more “sunlight” gets through. (Note: his one-shot one-time-only large extra warming lump of +0.86 w/m**2 is the amount of the so-called, stupidly-named “McPherson paradox”)

    2.07 w/m2 is the total warming over the next 20 years with coal/oil/gas burning reduced to zero. 2.07 w/m2 is the total warming over the next 40 years with coal/oil/gas burning reduced to zero.. 2.07 w/m**2 is the total warming over the next 60 years with coal/oil/gas burning reduced to zero. This would need to consider the climate lag.

    Note: From this experiment above, it shows there would be 30% MORE warming over the next 20 years if coal/oil/gas burning is reduced to zero over 20 years than if 2018 coal/oil/gas is burned each year (as an example). So, it will +0.52 degrees over the next 20 years instead of +0.40 degrees, an extra +0.12 degrees due to reducing coal/oil/gas burning over 20 years.

    So, there’s NO paradox because at 32 years from now the cleaner air has finished most of its warming and there’s no coal/oil/gas burning so the warming is tapering rapidly down to zero if the sensible choice is made but continues relentlessly upward if the poor choice of continuing the burning of coal/oil/gas is made. The same sort of ratios apply with the actual likely emissions rates except, obviously, the faster the rate of burning turns out to be then the more benefit is accrued by disregarding the  “McPherson paradox” and cutting the burning rate immediately because that faster reduction reduces both sets of numbers above but reduces the 1st set far more than the 2nd set.

    To summarize this paradox implies that if we keep burning coal the radiative forcing of the Earth (in accumulated w/m**2 of heating power flux) is 1.61 2.07 over the next 20 years 2.41 2.07 over the next 40 years 3.21 2.07 over the next 60 years. It’s not a paradox because anyone can clearly see that the continuation of BAU and carbon burning rapidly leads to catastrophic warming as the decades go by, but stopping all carbon pollution over the next 20 years does not.

    It would be absurd not to stop BAU and end Fossil Fuel + dirty energy + dirty money ASAP.

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