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Hotspots of sulfate aerosol pollution in 2005–2007 are highlighted in orange. Such sulfates rarely occur naturally outside of volcanic activity, and their increased levels are the main cause of global dimming[1]
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Global dimming is a decline in the amount of sunlight reaching the Earth's surface.[2][3] It is caused by atmospheric particulate matter, predominantly sulfate aerosols, which are components of air pollution.[4] Global dimming was observed soon after the first systematic measurements of solar irradiance began in the 1950s. This weakening of visible sunlight proceeded at the rate of 4–5% per decade until the 1980s.[1] During these years, air pollution increased due to post-war industrialization. Solar activity did not vary more than the usual during this period.[5][2]

As aerosols have a cooling effect, global dimming has masked the extent of global warming experienced to date, with the most-polluted regions even experiencing cooling in the 1970s.[1][6] Global dimming has interfered with the water cycle by lowering evaporation, and thus has probably reduced rainfall in certain areas.[1] It may have weakened the Monsoon of South Asia and caused the entire tropical rain belt to shift southwards between 1950 and 1985, with a limited recovery afterwards.[7][8][9] Record levels of particulate pollution in the Northern Hemisphere caused or at least exacerbated the monsoon failure behind the 1984 Ethiopian famine.[10][11][12][13]

Since the 1980s, a decrease in air pollution has led to a partial reversal of the dimming trend, sometimes referred to as global brightening.[1] This global brightening had contributed to the acceleration of global warming which began in the 1990s.[1][6] According to climate models, the dimming effect of aerosols most likely offsets around 0.5 °C (0.9 °F) of warming as of 2021.[14] As nations act to reduce the toll of air pollution on the health of their citizens, the masking effect on global warming is expected to decline further.[15] The scenarios for climate action required to meet 1.5 °C (2.7 °F) and 2 °C (3.6 °F) targets incorporate the predicted decrease in aerosol levels.[14] However, model simulations of the effects of aerosols on weather systems remain uncertain.[16][17]

The processes behind global dimming are similar to stratospheric aerosol injection. This is a proposed solar geoengineering intervention which aims to counteract global warming through intentional releases of reflective aerosols.[18] Stratospheric aerosol injection could be very effective at stopping or reversing warming but it would also have substantial effects on the global water cycle, regional weather, and ecosystems. Furthermore, it would have to be carried out over centuries to prevent a rapid and violent return of the warming.[19]

History

Further information: Irradiance and Insolation
The observed trends of global dimming and brightening in four major geographic regions. The dimming was greater on the average cloud-free days (red line) than on the average of all days (purple line), strongly suggesting that sulfate aerosols were the cause.[16]

In the 1970s, numerous studies showed that atmospheric aerosols could affect the propagation of sunlight through the atmosphere, a measure also known as direct solar irradiance.[20][21] One study showed that less sunlight was filtering through at the height of 1.7 km (1.1 mi) above Los Angeles, even on those days when there was no visible smog.[22] Another suggested that sulfate pollution or a volcano eruption could provoke the onset of an ice age.[23][24] In the 1980s, research in Israel and the Netherlands revealed an apparent reduction in the amount of sunlight,[25] and Atsumu Ohmura, a geography researcher at the Swiss Federal Institute of Technology, found that solar radiation striking the Earth's surface had declined by more than 10% over the three previous decades, even as the global temperature had been generally rising since the 1970s.[26] In the 1990s, this was followed by the papers describing multi-decade declines in Estonia,[27] Germany,[28] Israel[29] and across the former Soviet Union.[30]

Subsequent research estimated an average reduction in sunlight striking the terrestrial surface of around 4–5% per decade over the late 1950s–1980s, and 2–3% per decade when 1990s were included.[29][31][32][33] Notably, solar radiation at the top of the atmosphere did not vary by more than 0.1-0.3% in all that time, strongly suggesting that the reasons for the dimming were on Earth.[5][2] Additionally, only visible light and infrared radiation were dimmed, rather than the ultraviolet part of the spectrum.[34] Further, the dimming had occurred even when the skies were clear, and it was in fact stronger than during the cloudy days, proving that it was not caused by changes in cloud cover alone.[35][2][16]

Causes

Further information: Albedo and Atmospheric particulate matter

Anthropogenic sulfates

Satellite snapshot of atmospheric sulfur dioxide on April 15, 2017. Sulfur dioxide forms highly reflective sulfates, which are considered the main cause of global dimming[4]

Global dimming is primarily caused by the presence of sulfate particles which hang in the Earth's atmosphere as aerosols.[36] These aerosols have both a direct contribution to dimming, as they reflect sunlight like tiny mirrors.[37] They also have an indirect effect as nuclei, meaning that water droplets in clouds coalesce around the particles. Increased pollution causes more particulates and thereby creates clouds consisting of a greater number of smaller droplets (that is, the same amount of water is spread over more droplets). The smaller droplets make clouds more reflective, so that more incoming sunlight is reflected back into space and less reaches the Earth's surface.[4] In models, these smaller droplets also decrease rainfall.[38]

Before the Industrial Revolution, the main source of sulfate aerosols was dimethyl sulfide produced by some types of oceanic plankton. Emissions from volcano activity were the second largest source, although large volcanic eruptions, such as the 1991 eruption of Mount Pinatubo, dominate in the years when they occur. In 1990, the IPCC First Assessment Report estimated dimethyl sulfide emissions at 40 million tons per year, while volcano emissions were estimated at 10 million tons.[39] These annual levels have been largely stable for a long time. On the other hand, global human-caused emissions of sulfur into the atmosphere increased from less than 3 million tons per year in 1860 to 15 million tonnes in 1900, 40 million tonnes in 1940 and about 80 million tonnes in 1980. This meant that by 1980, the human-caused emissions from the burning of sulfur-containing fuels (mostly coal and bunker fuel) became at least as large as all natural emissions of sulfur-containing compounds.[39] The report also concluded that "in the industrialized regions of Europe and North America, anthropogenic emissions dominate over natural emissions by about a factor of ten or even more".[39]

Black carbon

Further information: Anthropogenic cloud
If smoke from wildfires mixes into clouds, it darkens them, decreasing their albedo. If there are no clouds, then smoke can increase albedo, particularly over oceans.[40]

Another important type of aerosol is black carbon, colloquially known as soot. It is formed due to incomplete combustion of fossil fuels, as well as of wood and other plant matter.[41] Globally, the single largest source of black carbon is from grassland and forest fires, including both wildfires and intentional burning. However, coal use is responsible for the majority (60 to 80%) of black carbon emissions in Asia and Africa, while diesel combustion produces 70% of black carbon in Europe and The Americas.[42]

Black carbon in the lower atmosphere is a major contributor to 7 million premature deaths caused by air pollution every year.[43] Its presence is particularly visible, as the so-called "brown clouds" appear in heavily polluted areas. In fact, it was 1970s research into the Denver brown cloud which had first found that black carbon particles absorb solar energy and so can affect the amount of visible sunlight.[42] Later research found that black carbon is 190 times more effective at absorbing sunlight within clouds than the regular dust from soil particles.[44] At worst, all clouds within an atmospheric layer 3–5 km (1.9–3.1 mi) thick are visibly darkened, and the plume can reach transcontinental scale[45] (i.e. the Asian brown cloud.) Even so, the overall dimming from black carbon is much lower than that from the sulfate particles.[14]

Reversal

Further information: Clean Air Act (United States)
Sun-blocking aerosols around the world steadily declined (red line) since the 1991 eruption of Mount Pinatubo, according to satellite estimates.

After 1990, the global dimming trend had clearly switched to global brightening.[25][46][47][48][49] This followed measures taken to combat air pollution by the developed nations, typically through flue-gas desulfurization installations at thermal power plants, such as wet scrubbers or fluidized bed combustion.[50][51] In the United States, sulfate aerosols have declined significantly since 1970 with the passage of the Clean Air Act, which was strengthened in 1977 and 1990. According to the EPA, from 1970 to 2005, total emissions of the six principal air pollutants, including sulfates, dropped by 53% in the US.[52] By 2010, this reduction in sulfate pollution led to estimated healthcare cost savings valued at $50 billion annually.[53] Similar measures were taken in Europe,[52] such as the 1985 Helsinki Protocol on the Reduction of Sulfur Emissions under the Convention on Long-Range Transboundary Air Pollution, and with similar improvements.[54]

Satellite photo showing a thick pall of smoke and haze from forest fires in Eastern China. Such smoke is full of black carbon, which contributes to dimming trends but has an overall warming effect.

On the other hand, a 2009 review found that dimming continued to increase in China after stabilizing in the 1990s and intensified in India, consistent with their continued industrialization, while the US, Europe, and South Korea continued to brighten. Evidence from Zimbabwe, Chile and Venezuela also pointed to increased dimming during that period, albeit at a lower confidence level due to the lower number of observations.[55][56] Later research found that over China, the dimming trend continued at a slower rate after 1990,[57] and did not begin to reverse until around 2005.[58] Due to these contrasting trends, no statistically significant change had occurred on a global scale from 2001 to 2012.[1] Post-2010 observations indicate that the global decline in aerosol concentrations and global dimming continued, with pollution controls on the global shipping industry playing a substantial role in the recent years.[59] Since nearly 90% of the human population lives in the Northern Hemisphere, clouds there are far more affected by aerosols than in the Southern Hemisphere, but these differences have halved in the two decades since 2000, providing further evidence for the ongoing global brightening.[60]

Relationship to climate change

Cooling from sulfate aerosols

Air pollution, including from large-scale land clearing, has substantially increased the presence of aerosols in the atmosphere when compared to the preindustrial background levels. Different types of particles have different effects, and there is a variety of interactions in different atmospheric layers. Overall, they provide cooling, but complexity makes the exact strength of cooling very difficult to estimate.[40]

Aerosols have a cooling effect, which has masked the total extent of global warming experienced to date.[40]

It has been understood for a long time that any effect on solar irradiance from aerosols would necessarily impact Earth's radiation balance. Reductions in atmospheric temperatures have already been observed after large volcanic eruptions such as the 1963 eruption of Mount Agung in Bali, 1982 El Chichón eruption in Mexico, 1985 Nevado del Ruiz eruption in Colombia and 1991 eruption of Mount Pinatubo in the Philippines. However, even the major eruptions only result in temporary jumps of sulfur particles, unlike the more sustained increases caused by anthropogenic pollution.[49]

In 1990, the IPCC First Assessment Report acknowledged that "Human-made aerosols, from sulphur emitted largely in fossil fuel combustion can modify clouds and this may act to lower temperatures", while "a decrease in emissions of sulphur might be expected to increase global temperatures". However, lack of observational data and difficulties in calculating indirect effects on clouds left the report unable to estimate whether the total impact of all anthropogenic aerosols on the global temperature amounted to cooling or warming.[39] By 1995, the IPCC Second Assessment Report had confidently assessed the overall impact of aerosols as negative (cooling);[61] however, aerosols were recognized as the largest source of uncertainty in future projections in that report and the subsequent ones.[1]

Warming from black carbon

Unlike sulfate pollution, black carbon contributes to both global dimming and global warming, since its particles absorb sunlight and heat up instead of reflecting it away.[42] These particles also develop thick coatings over time, which can increase the initial absorption by up to 40%. Because the rate at which these coatings are formed varies depending on the season, the warming from black carbon varies seasonally as well.[62]

Though this warming is weaker than the CO2-induced warming or the cooling from sulfates,[14] it can be regionally significant when black carbon is deposited over ice masses like mountain glaciers and the Greenland ice sheet. There, it reduces their albedo and increases their absorption of solar radiation, which accelerates their melting.[45] Black carbon also has an outsized contribution to local warming inside polluted cities.[63] Even the indirect effect of soot particles acting as cloud nuclei is not strong enough to provide cooling: the "brown clouds" formed around soot particles were known to have a net warming effect since the 2000s.[64] Black carbon pollution is particularly strong over India: thus, it is considered to be one of the few regions where cleaning up air pollution would reduce, rather than increase, warming.[65]

Minor role of aircraft contrails

Main article: Contrail § Impacts on climate
Aircraft contrails (white lines) and natural clouds.

Aircraft leave behind visible contrails (also known as vapor trails) as they travel. These contrails both reflect incoming solar radiation and trap outgoing longwave radiation that is emitted by the Earth. Because contrails reflect sunlight only during the day, but trap heat day and night, they are normally considered to cause net warming, albeit very small. A 1992 estimate was between 3.5 mW/m2 and 17 mW/m2 - hundreds of times smaller than the radiative forcing from major greenhouse gases.[66]

However, some scientists argued that the daytime cooling effect from contrails was much stronger than usually estimated, and this argument attracted attention following the September 11 attacks.[3] Because no commercial aircraft flew across the US in the immediate aftermath of the attacks, this period was considered a real-world demonstration of contrail-free weather.[67] Across 4,000 weather stations in the continental United States, the diurnal temperature variation (the difference in the day's highs and lows at a fixed station) was widened by 1.1 °C (2.0 °F) - the largest recorded increase in 30 years.[68] In the southern US, the difference was diminished by about 3.3 °C (6 °F), and by 2.8 °C (5 °F) in the US midwest.[69] This was interpreted by some scientists as a proof of a strong cooling influence of aircraft contrails.[70]

Ultimately, follow-up studies found that a natural change in cloud cover which occurred at the time was sufficient to explain these findings.[71][72] When the global response to the 2020 coronavirus pandemic led to a reduction in global air traffic of nearly 70% relative to 2019, multiple studies found "no significant response of diurnal surface air temperature range" as the result of contrail changes, and either "no net significant global ERF" (effective radiative forcing) or a very small warming effect.[73][74][75]

Historical cooling

This chart shows how much various physical factors affect climate change. For example, sulfur dioxide causes cooling because it reacts to form a variety of sunlight-reflecting sulfates. Its large error bar shows that there is a lot of uncertainty regarding the strength of cooling caused by sulphur dioxide in the atmosphere.

At the peak of global dimming, it was able to counteract the warming trend completely. By 1975, the continually increasing concentrations of greenhouse gases have overcome the masking effect and dominated ever since.[52] Even then, regions with high concentrations of sulfate aerosols due to air pollution had initially experienced cooling, in contradiction to the overall warming trend.[76] The eastern United States was a prominent example: the temperatures there declined by 0.7 °C (1.3 °F) between 1970 and 1980, and by up to 1 °C (1.8 °F) in the Arkansas and Missouri.[77]

Brightening and accelerated warming

Starting in the 1980s, the reduction in global dimming has contributed to higher global temperatures. Hot extremes accelerated as global dimming abated. It has been estimated that since the mid-1990s, peak daily temperatures in northeast Asia and hottest days of the year in Western Europe would have been substantially less hot if aerosol concentrations had stayed the same as before.[1] Some of the acceleration of sea level rise, as well as Arctic amplification and the associated Arctic sea ice decline, was also attributed to the reduction in aerosol masking.[6][78][79][80]

In Europe, the declines in aerosol concentrations since the 1980s had also reduced the associated fog, mist and haze: altogether, it was responsible for about 10–20% of daytime warming across Europe, and about 50% of the warming over the more polluted Eastern Europe.[81] Because aerosol cooling depends on reflecting sunlight, air quality improvements had a negligible impact on wintertime temperatures,[82] but had increased temperatures from April to September by around 1 °C (1.8 °F) in Central and Eastern Europe.[83] The central and eastern United States experienced warming of 0.3 °C (0.54 °F) between 1980 and 2010 as sulfate pollution was reduced,[77] even as sulfate particles still accounted for around 25% of all particulates.[53] By 2021, the northeastern coast of the United States was one of the fastest-warming regions of North America, as the slowdown of the Atlantic Meridional Overturning Circulation increased temperatures in that part of the North Atlantic Ocean.[84][85]

Rapid decline in air pollution caused by the COVID-19 lockdowns in China was responsible for up to 40% of the regional temperature changes in January–March 2020, relative to January–March 2019[86]

In 2020, COVID-19 lockdowns provided a notable "natural experiment", as there had been a marked decline in sulfate and black carbon emissions caused by the curtailed road traffic and industrial output. That decline did have a detectable warming impact: it was estimated to have increased global temperatures by 0.01–0.02 °C (0.018–0.036 °F) initially and up to 0.03 °C (0.054 °F) by 2023, before disappearing. Regionally, the lockdowns were estimated to increase temperatures by 0.05–0.15 °C (0.090–0.270 °F) in eastern China over January–March, and then by 0.04–0.07 °C (0.072–0.126 °F) over Europe, eastern United States, and South Asia in March–May, with the peak impact of 0.3 °C (0.54 °F) in some regions of the United States and Russia.[87][86] In the city of Wuhan, the urban heat island effect was found to have decreased by 0.24 °C (0.43 °F) at night and by 0.12 °C (0.22 °F) overall during the strictest lockdowns.[88]

Future

Since changes in aerosol concentrations already have an impact on the global climate, they would necessarily influence future projections as well. In fact, it is impossible to fully estimate the warming impact of all greenhouse gases without accounting for the counteracting cooling from aerosols.[15][40]

Early 2010s estimates of past and future anthropogenic global sulfur dioxide emissions, including the Representative Concentration Pathways. While no climate change scenario may reach Maximum Feasible Reductions (MFRs), all assume steep declines from today's levels. By 2019, sulfate emission reductions were confirmed to proceed at a very fast rate.[15]

Climate models started to account for the effects of sulfate aerosols around the IPCC Second Assessment Report; when the IPCC Fourth Assessment Report was published in 2007, every climate model had integrated sulfates, but only 5 were able to account for less impactful particulates like black carbon.[37] By 2021, CMIP6 models estimated total aerosol cooling in the range from 0.1 °C (0.18 °F) to 0.7 °C (1.3 °F);[89] The IPCC Sixth Assessment Report selected the best estimate of a 0.5 °C (0.90 °F) cooling provided by sulfate aerosols, while black carbon amounts to about 0.1 °C (0.18 °F) of warming.[14] While these values are based on combining model estimates with observational constraints, including those on ocean heat content,[59] the matter is not yet fully settled. The difference between model estimates mainly stems from disagreements over the indirect effects of aerosols on clouds.[90][91]

Regardless of the current strength of aerosol cooling, all future climate change scenarios project decreases in particulates and this includes the scenarios where 1.5 °C (2.7 °F) and 2 °C (3.6 °F) targets are met: their specific emission reduction targets assume the need to make up for lower dimming.[14] Since models estimate that the cooling caused by sulfates is largely equivalent to the warming caused by atmospheric methane (and since methane is a relatively short-lived greenhouse gas), it is believed that simultaneous reductions in both would effectively cancel each other out.[92][93] Yet, in the recent years, methane concentrations had been increasing at rates exceeding their previous period of peak growth in the 1980s,[94][95] with wetland methane emissions driving much of the recent growth,[96][97] while air pollution is getting cleaned up aggressively.[59] These trends are some of the main reasons why 1.5 °C (2.7 °F) warming is now expected around 2030, as opposed to the mid-2010s estimates where it would not occur until 2040.[15]

Addressing air pollution in Europe line with the current policies (blue line) is likely to increase the frequency of hot days and reduce the frequency of cold ones. Those increases will be even faster with maximum possible reductions (red line), unless the GHG emissions are addressed at the same rate. Similar trends will be seen in China[98]

It has also been suggested that aerosols are not given sufficient attention in regional risk assessments, in spite of being more influential on a regional scale than globally.[17] For instance, a climate change scenario with high greenhouse gas emissions but strong reductions in air pollution would see 0.2 °C (0.36 °F) more global warming by 2050 than the same scenario with little improvement in air quality, but regionally, the difference would add 5 more tropical nights per year in northern China and substantially increase precipitation in northern China and northern India.[99] Likewise, a paper comparing current level of clean air policies with a hypothetical maximum technically feasible action under otherwise the same climate change scenario found that the latter would increase the risk of temperature extremes by 30–50% in China and in Europe.[98] Unfortunately, because historical records of aerosols are sparser in some regions than in others, accurate regional projections of aerosol impacts are difficult. Even the latest CMIP6 climate models can only accurately represent aerosol trends over Europe,[16] but struggle with representing North America and Asia, meaning that their near-future projections of regional impacts are likely to contain errors as well.[100][16][101]

Relationship with water cycle

Further information: Water cycle
Sulfate aerosols have decreased precipitation over most of Asia (red), but increased it over some parts of Central Asia (blue).[102]

On regional and global scale, air pollution can affect the water cycle, in a manner similar to some natural processes. One example is the impact of Sahara dust on hurricane formation: air laden with sand and mineral particles moves over the Atlantic Ocean, where they block some of the sunlight from reaching the water surface, slightly cooling it and dampening the development of hurricanes.[103] Likewise, it has been suggested since the early 2000s that since aerosols decrease solar radiation over the ocean and hence reduce evaporation from it, they would be "spinning down the hydrological cycle of the planet."[104][105]

In 2011, it was found that anthropogenic aerosols had been the predominant factor behind 20th century changes in rainfall over the Atlantic Ocean sector,[106] when the entire tropical rain belt shifted southwards between 1950 and 1985, with a limited northwards shift afterwards.[9] Future reductions in aerosol emissions are expected to result in a more rapid northwards shift, with limited impact in the Atlantic but a substantially greater impact in the Pacific.[107]

Most notably, multiple studies connect aerosols from the Northern Hemisphere to the failed monsoon in sub-Saharan Africa during the 1970s and 1980s, which then led to the Sahel drought and the associated famine.[10][12][11] However, model simulations of Sahel climate are very inconsistent,[108] so it's difficult to prove that the drought would not have occurred without aerosol pollution, although it would have clearly been less severe.[109][13] Some research indicates that those models which demonstrate warming alone driving strong precipitation increases in the Sahel are the most accurate, making it more likely that sulfate pollution was to blame for overpowering this response and sending the region into drought.[110]

In the United States, aerosols generally reduce both mean and extreme precipitation across all four seasons, which has cancelled out the increases caused by greenhouse gas warming[111]

Another dramatic finding had connected the impact of aerosols with the weakening of the Monsoon of South Asia. It was first advanced in 2006,[7] yet it also remained difficult to prove.[112] In particular, some research suggested that warming itself increases the risk of monsoon failure, potentially pushing it past a tipping point.[113][114] By 2021, however, it was concluded that global warming consistently strengthened the monsoon,[115] and some strengthening was already observed in the aftermath of lockdown-caused aerosol reductions.[8]

In 2009, an analysis of 50 years of data found that light rains had decreased over eastern China, even though there was no significant change in the amount of water held by the atmosphere. This was attributed to aerosols reducing droplet size within clouds, which led to those clouds retaining water for a longer time without raining.[38] The phenomenon of aerosols suppressing rainfall through reducing cloud droplet size has been confirmed by subsequent studies.[116] Later research found that aerosol pollution over South and East Asia didn't just suppress rainfall there, but also resulted in more moisture transferred to Central Asia, where summer rainfall had increased as the result.[102] In the United States, effects of climate change on the water cycle would typically increase both mean and extreme precipitation across the country, but these effects have so far been "masked" by the drying due to historically strong aerosol concentrations.[111] The IPCC Sixth Assessment Report had also linked changes in aerosol concentrations to altered precipitation in the Mediterranean region.[1]

Relevance for solar geoengineering

Main article: Stratospheric aerosol injection
This graph shows that if stratospheric aerosol injection were to be deployed starting from 2034, then it could be finely scaled to either halve the speed of warming by 2100, to halt it, or to reverse it entirely. The same degree of control is available under the scenarios of low, medium and high greenhouse gas emissions [117]

Global dimming is also a relevant phenomenon for certain proposals about slowing, halting or reversing global warming.[118] An increase in planetary albedo of 1% would eliminate most of radiative forcing from anthropogenic greenhouse gas emissions and thereby global warming, while a 2% albedo increase would negate the warming effect of doubling the atmospheric carbon dioxide concentration.[119] This is the theory behind solar geoengineering, and the high reflective potential of sulfate aerosols means that they were considered in this capacity for a long time. In 1974, Mikhail Budyko suggested that if global warming became a problem, the planet could be cooled by burning sulfur in the stratosphere, which would create a haze.[120] This approach would simply send the sulfates to the troposphere – the lowest part of the atmosphere. Using it today would be equivalent to more than reversing the decades of air quality improvements, and the world would face the same issues which prompted the introduction of those regulations in the first place, such as acid rain.[121] The suggestion of relying on tropospheric global dimming to curb warming has been described as a "Faustian bargain" and is not seriously considered by modern research.[109]

Instead, starting with the seminal 2006 paper by Paul Crutzen, the solution advocated is known as stratospheric aerosol injection, or SAI. It would transport sulfates into the next higher layer of the atmosphere – stratosphere, where they would last for years instead of weeks, so far less sulfur would have to be emitted.[122][123] It has been estimated that the amount of sulfur needed to offset a warming of around 4 °C (7.2 °F) relative to now (and 5 °C (9.0 °F) relative to the preindustrial), under the highest-emission scenario RCP 8.5 would be less than what is already emitted through air pollution today, and that reductions in sulfur pollution from future air quality improvements already expected under that scenario would offset the sulfur used for geoengineering.[18] The trade-off is increased cost. Although there's a popular narrative that stratospheric aerosol injection can be carried out by individuals, small states, or other non-state rogue actors, scientific estimates suggest that cooling the atmosphere by 1 °C (1.8 °F) through stratospheric aerosol injection would cost at least $18 billion annually (at 2020 USD value), meaning that only the largest economies or economic blocs could afford this intervention.[117][124] Even so, these approaches would still be "orders of magnitude" cheaper than greenhouse gas mitigation,[125] let alone the costs of unmitigated effects of climate change.[119]

Even if SAI were to stop or outright reverse global warming, weather patterns in many areas would still change substantially. The habitat of mosquitoes and other disease vectors would shift, though it's unclear how it would compare to the shifts that are otherwise likely to occur from climate change.[19] Lower sunlight would affect crop yields and carbon sinks due to reduced photosynthesis,[118] but this would likely be offset by lack of thermal stress from warming and the CO2 fertilization effect.[19] Most importantly, the warming from CO2 emissions lasts for hundreds to thousands of years, while the cooling from SAI stops 1–3 years after the last aerosol injection. This means that neither stratospheric aerosol injection nor other forms of solar geoengineering can be used as a substitute for reducing greenhouse gas emissions, because if solar geoengineering were to cease while greenhouse gas levels remained high, it would lead to "large and extremely rapid" warming and similarly abrupt changes to the water cycle. Many thousands of species would likely go extinct as the result. Instead, any solar geoengineering would act as a temporary measure to limit warming while emissions of greenhouse gases are reduced and carbon dioxide is removed, which may well take hundreds of years.[19]

See also

References

  1. ^ a b c d e f g h i j Seneviratne, S.I.; Zhang, X.; Adnan, M.; Badi, W.; Dereczynski, C.; Di Luca, A.; Ghosh, S.; Iskandar, I.; Kossin, J.; Lewis, S.; Otto, F.; Pinto, I.; Satoh, M.; Vicente-Serrano, S. M.; Wehner, M.; Zhou, B. (2021). Masson-Delmotte, V.; Zhai, P.; Piran, A.; Connors, S.L.; Péan, C.; Berger, S.; Caud, N.; Chen, Y.; Goldfarb, L. (eds.). "Weather and Climate Extreme Events in a Changing Climate" (PDF). Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change. 2021: 1513–1766. Bibcode:2021AGUFM.U13B..05K. doi:10.1017/9781009157896.007.
  2. ^ a b c d "Aerosol pollution has caused decades of global dimming". American Geophysical Union. 18 February 2021. Archived from the original on 27 March 2023. Retrieved 18 December 2023.
  3. ^ a b Sington, David (2004). "Global dimming". BBC News Online.
  4. ^ a b c Myhre, Gunnar; Lund Myhre, Cathrine E.; Samset, Bjorn H.; Storelvmo, Trude (2013). "Aerosols and their Relation to Global Climate and Climate Sensitivity". The Nature Education Knowledge Project. Retrieved 6 January 2024.
  5. ^ a b Eddy, John A.; Gilliland, Ronald L.; Hoyt, Douglas V. (23 December 1982). "Changes in the solar constant and climatic effects". Nature. 300 (5894): 689–693. Bibcode:1982Natur.300..689E. doi:10.1038/300689a0. S2CID 4320853. Spacecraft measurements have established that the total radiative output of the Sun varies at the 0.1−0.3% level
  6. ^ a b c Wild, M.; Ohmura, A.; Makowski, K. (2007). "Impact of global dimming and brightening on global warming". Geophysical Research Letters. 34 (4): L04702. Bibcode:2007GeoRL..34.4702W. doi:10.1029/2006GL028031.
  7. ^ a b Lau, K. M.; Kim, K. M. (8 November 2006). "Observational relationships between aerosol and Asian monsoon rainfall, and circulation". Geophysical Research Letters. 33 (21). Bibcode:2006GeoRL..3321810L. doi:10.1029/2006GL027546. S2CID 129282371.
  8. ^ a b Fadnavis, Suvarna; Sabin, T. P.; Rap, Alexandru; Müller, Rolf; Kubin, Anne; Heinold, Bernd (16 July 2021). "The impact of COVID-19 lockdown measures on the Indian summer monsoon". Environmental Research Letters. 16 (7): 4054. Bibcode:2021ERL....16g4054F. doi:10.1088/1748-9326/ac109c. S2CID 235967722.
  9. ^ a b Peace, Amy H.; Booth, Ben B. B.; Regayre, Leighton A.; Carslaw, Ken S.; Sexton, David M. H.; Bonfils, Céline J. W.; Rostron, John W. (26 August 2022). "Evaluating uncertainty in aerosol forcing of tropical precipitation shifts". Earth System Dynamics. 13 (3): 1215–1232. Bibcode:2022ESD....13.1215P. doi:10.5194/esd-13-1215-2022.
  10. ^ a b Rotstayn and Lohmann; Lohmann, Ulrike (2002). "Tropical Rainfall Trends and the Indirect Aerosol Effect". Journal of Climate. 15 (15): 2103–2116. Bibcode:2002JCli...15.2103R. doi:10.1175/1520-0442(2002)015<2103:TRTATI>2.0.CO;2. S2CID 55802370.
  11. ^ a b Hirasawa, Haruki; Kushner, Paul J.; Sigmond, Michael; Fyfe, John; Deser, Clara (2 May 2022). "Evolving Sahel Rainfall Response to Anthropogenic Aerosols Driven by Shifting Regional Oceanic and Emission Influences". Journal of Climate. 35 (11): 3181–3193. Bibcode:2022JCli...35.3181H. doi:10.1175/JCLI-D-21-0795.1.
  12. ^ a b "Global Dimming". bbc.co.uk. BBC. Retrieved 5 January 2020.
  13. ^ a b Herman, Rebecca Jean; Giannini, Alessandra; Biasutti, Michela; Kushnir, Yochanan (22 July 2020). "The effects of anthropogenic and volcanic aerosols and greenhouse gases on twentieth century Sahel precipitation". Scientific Reports. 10 (1): 12203. Bibcode:2020NatSR..1012203H. doi:10.1038/s41598-020-68356-w. PMC 7376254. PMID 32699339.
  14. ^ a b c d e f IPCC, 2021: Summary for Policymakers. In: Climate Change 2021: The Physical Science Basis. Contribution of Working Group I to the Sixth Assessment Report of the Intergovernmental Panel on Climate Change [Masson-Delmotte, V., P. Zhai, A. Pirani, S.L. Connors, C. Péan, S. Berger, N. Caud, Y. Chen, L. Goldfarb, M.I. Gomis, M. Huang, K. Leitzell, E. Lonnoy, J.B.R. Matthews, T.K. Maycock, T. Waterfield, O. Yelekçi, R. Yu, and B. Zhou (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 3–32, doi:10.1017/9781009157896.001.
  15. ^ a b c d Xu, Yangyang; Ramanathan, Veerabhadran; Victor, David G. (5 December 2018). "Global warming will happen faster than we think". Nature. 564 (7734): 30–32. Bibcode:2018Natur.564...30X. doi:10.1038/d41586-018-07586-5. PMID 30518902.
  16. ^ a b c d e Julsrud, I. R.; Storelvmo, T.; Schulz, M.; Moseid, K. O.; Wild, M. (20 October 2022). "Disentangling Aerosol and Cloud Effects on Dimming and Brightening in Observations and CMIP6". Journal of Geophysical Research: Atmospheres. 127 (21): e2021JD035476. Bibcode:2022JGRD..12735476J. doi:10.1029/2021JD035476.
  17. ^ a b Persad, Geeta G.; Samset, Bjørn H.; Wilcox, Laura J. (21 November 2022). "Aerosols must be included in climate risk assessments". Nature. 611 (7937): 662–664. Bibcode:2022Natur.611..662P. doi:10.1038/d41586-022-03763-9. PMID 36411334.
  18. ^ a b Visioni, Daniele; Slessarev, Eric; MacMartin, Douglas G; Mahowald, Natalie M; Goodale, Christine L; Xia, Lili (1 September 2020). "What goes up must come down: impacts of deposition in a sulfate geoengineering scenario". Environmental Research Letters. 15 (9): 094063. Bibcode:2020ERL....15i4063V. doi:10.1088/1748-9326/ab94eb. ISSN 1748-9326.
  19. ^ a b c d Trisos, Christopher H.; Geden, Oliver; Seneviratne, Sonia I.; Sugiyama, Masahiro; van Aalst, Maarten; Bala, Govindasamy; Mach, Katharine J.; Ginzburg, Veronika; de Coninck, Heleen; Patt, Anthony (2022). "Cross-Working Group Box SRM: Solar Radiation Modification" (PDF). Climate Change 2022: Impacts, Adaptation and Vulnerability. 2021: 2473–2478. Bibcode:2021AGUFM.U13B..05K. doi:10.1017/9781009157896.007.
  20. ^ Barnhardt, E. A.; Streete, J. L. (1970). "A Method for Predicting Atmospheric Aerosol Scattering Coefficients in the Infrared". Applied Optics. 9 (6): 1337–1344. Bibcode:1970ApOpt...9.1337B. doi:10.1364/AO.9.001337. PMID 20076382.
  21. ^ Herman, Benjamin M.; Browning, Samuel R.; Curran, Robert J. (1 April 1971). "The Effect of Atmospheric Aerosols on Scattered Sunlight". Journal of the Atmospheric Sciences. 28 (3): 419–428. Bibcode:1971JAtS...28..419H. doi:10.1175/1520-0469(1971)028<0419:TEOAAO>2.0.CO;2.
  22. ^ Hodge, Paul W. (19 February 1971). "Large Decrease in the Clear Air Transmission of the Atmosphere 1.7 km above Los Angeles". Nature. 229 (5894): 549. Bibcode:1971Natur.229..549H. doi:10.1038/229549a0. PMID 16059347.
  23. ^ Rasool, Ichtiaque, S; Schneider, Stephen H. (July 1971). "Atmospheric Carbon Dioxide and Aerosols: Effects of Large Increases on Global Climate". Science. 1 (3992): 138–141. Bibcode:1971Sci...173..138R. doi:10.1126/science.173.3992.138. PMID 17739641. S2CID 43228353.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  24. ^ Lockwood, John G. (1979). Causes of Climate. Lecture Notes in mathematics 1358. New York: John Wiley & Sons. p. 162. ISBN 978-0-470-26657-1.
  25. ^ a b "Earth lightens up". Pacific Northwest National Laboratory. Archived from the original on 16 September 2012. Retrieved 8 May 2005.
  26. ^ Ohmura, A.; Lang, H. (June 1989). Lenoble, J.; Geleyn, J.-F. (eds.). Secular variation of global radiation in Europe. In IRS '88: Current Problems in Atmospheric Radiation, A. Deepak Publ., Hampton, VA. Hampton, VA: Deepak Publ. pp. (635) pp. 298–301. ISBN 978-0-937194-16-4.
  27. ^ Russak, V. (1990). "Trends of solar radiation, cloudiness and atmospheric transparency during recent decades in Estonia". Tellus B. 42 (2): 206–210. Bibcode:1990TellB..42..206R. doi:10.1034/j.1600-0889.1990.t01-1-00006.x. 1990TellB..42..206R.
  28. ^ Liepert, B. G.; Fabian, P.; Grassi, H. (1994). "Solar radiation in Germany – Observed trends and an assessment of their causes. Part 1. Regional approach". Contributions to Atmospheric Physics. 67: 15–29.
  29. ^ a b Stanhill, G.; Moreshet, S. (6 November 2004). "Global radiation climate changes in Israel". Climatic Change. 22 (2): 121–138. Bibcode:1992ClCh...22..121S. doi:10.1007/BF00142962. S2CID 154006620.
  30. ^ Abakumova, G.M. (1996). "Evaluation of long-term changes in radiation, cloudiness and surface temperature on the territory of the former Soviet Union" (PDF). Journal of Climate. 9 (6): 1319–1327. Bibcode:1996JCli....9.1319A. doi:10.1175/1520-0442(1996)009<1319:EOLTCI>2.0.CO;2.
  31. ^ Gilgen, H.; Wild, M.; Ohmura, A. (1998). "Means and trends of shortwave irradiance at the surface estimated from global energy balance archive data" (PDF). Journal of Climate. 11 (8): 2042–2061. Bibcode:1998JCli...11.2042G. doi:10.1175/1520-0442-11.8.2042.
  32. ^ Stanhill, G.; Cohen, S. (2001). "Global dimming: a review of the evidence for a widespread and significant reduction in global radiation with discussion of its probable causes and possible agricultural consequences". Agricultural and Forest Meteorology. 107 (4): 255–278. Bibcode:2001AgFM..107..255S. doi:10.1016/S0168-1923(00)00241-0.
  33. ^ Liepert, B. G. (2 May 2002). "Observed Reductions in Surface Solar Radiation in the United States and Worldwide from 1961 to 1990" (PDF). Geophysical Research Letters. 29 (12): 61–1–61–4. Bibcode:2002GeoRL..29.1421L. doi:10.1029/2002GL014910.
  34. ^ Adam, David (18 December 2003). "Goodbye sunshine". The Guardian. Retrieved 26 August 2009.
  35. ^ Wild, Martin; Wacker, Stephan; Yang, Su; Sanchez-Lorenzo, Arturo (1 February 2021). "Evidence for Clear-Sky Dimming and Brightening in Central Europe". Geophysical Research Letters. 48 (6). Bibcode:2021GeoRL..4892216W. doi:10.1029/2020GL092216. hdl:20.500.11850/477374. S2CID 233645438.
  36. ^ Cohen, Shabtai; Stanhill, Gerald (1 January 2021). "Chapter 32 – Changes in the Sun's radiation: the role of widespread surface solar radiation trends in climate change: dimming and brightening". In Letcher, Trevor M. (ed.). Climate Change (Third Edition). Elsevier. pp. 687–709. doi:10.1016/b978-0-12-821575-3.00032-3. ISBN 978-0-12-821575-3. S2CID 234180702. Retrieved 26 April 2023.
  37. ^ a b "Aerosols and Incoming Sunlight (Direct Effects)". NASA. 2 November 2010.
  38. ^ a b Yun Qian; Daoyi Gong (2009). "The Sky Is Not Falling: Pollution in eastern China cuts light, useful rainfall". Pacific Northwest National Laboratory. Retrieved 16 August 2009.
  39. ^ a b c d IPCC, 1990: Chapter 1: Greenhouse Gases and Aerosols [R.T. Watson, H. Rodhe, H. Oeschger and U. Siegenthaler]. In: Climate Change: The IPCC Scientific Assessment [J.T.Houghton, G.J.Jenkins and J.J.Ephraums (eds.)]. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA, pp. 31–34,
  40. ^ a b c d Bellouin, N.; Quaas, J.; Gryspeerdt, E.; Kinne, S.; Stier, P.; Watson-Parris, D.; Boucher, O.; Carslaw, K. S.; Christensen, M.; Daniau, A.-L.; Dufresne, J.-L.; Feingold, G.; Fiedler, S.; Forster, P.; Gettelman, A.; Haywood, J. M.; Lohmann, U.; Malavelle, F.; Mauritsen, T.; McCoy, D. T.; Myhre, G.; Mülmenstädt, J.; Neubauer, D.; Possner, A.; Rugenstein, M.; Sato, Y.; Schulz, M.; Schwartz, S. E.; Sourdeval, O.; Storelvmo, T.; Toll, V.; Winker, D.; Stevens, B. (1 November 2019). "Bounding Global Aerosol Radiative Forcing of Climate Change". Reviews of Geophysics. 58 (1): e2019RG000660. doi:10.1029/2019RG000660. PMC 7384191. PMID 32734279.
  41. ^ Zeng, Linghan; Tan, Tianyi; Zhao, Gang; Du, Zhuofei; Hu, Shuya; Shang, Dongjie; Hu, Ming (2 January 2024). "Overestimation of black carbon light absorption due to mixing state heterogeneity". npj Climate and Atmospheric Science. 7. doi:10.1038/s41612-023-00535-8.
  42. ^ a b c Bond, T. C.; Doherty, S. J.; Fahey, D. W.; Forster, P. M.; Berntsen, T.; DeAngelo, B. J.; Flanner, M. G.; Ghan, S.; Kärcher, B.; Koch, D.; Kinne, S.; Kondo, Y.; Quinn, P. K.; Sarofim, M. C.; Schultz, M. G.; Schulz, M.; Venkataraman, C.; Zhang, H.; Zhang, S.; Bellouin, N.; Guttikunda, S. K.; Hopke, P. K.; Jacobson, M. Z.; Kaiser, J. W.; Klimont, Z.; Lohmann, U.; Schwarz, J. P.; Shindell, D.; Storelvmo, T.; Warren, S. G.; Zender, C. S. (15 January 2013). "Bounding the role of black carbon in the climate system: A scientific assessment". JGR Atmosheres. 118 (11pages=5380–5552). Bibcode:2013JGRD..118.5380B. doi:10.1002/jgrd.50171.
  43. ^ Gustafsson, Örjan; Ramanathan, Veerabhadran (1 April 2016). "Convergence on climate warming by black carbon aerosols". PNAS. 113 (16): 4243–4245. doi:10.1073/pnas.1603570113.
  44. ^ Jacobson, Mark Z. (21 March 2012). "Investigating cloud absorption effects: Global absorption properties of black carbon, tar balls, and soil dust in clouds and aerosols". JGR Atmosheres. 117 (D6). doi:10.1029/2011JD017218.
  45. ^ a b Ramanathan, V.; Carmichael, G. (23 March 2008). "Global and regional climate changes due to black carbon". Nature Geoscience. 1 (16): 221–227. doi:10.1038/ngeo156.
  46. ^ Wild, M (2005). "From Dimming to Brightening: Decadal Changes in Solar Radiation at Earth's Surface". Science. 308 (2005–05–06): 847–850. Bibcode:2005Sci...308..847W. doi:10.1126/science.1103215. PMID 15879214. S2CID 13124021.
  47. ^ Pinker; Zhang, B; Dutton, EG (2005). "Do Satellites Detect Trends in Surface Solar Radiation?". Science. 308 (6 May 2005): 850–854. Bibcode:2005Sci...308..850P. doi:10.1126/science.1103159. PMID 15879215. S2CID 10644227.
  48. ^ "Global Dimming may have a brighter future". RealClimate. 15 May 2005. Retrieved 12 June 2006.
  49. ^ a b "Global 'Sunscreen' Has Likely Thinned, Report NASA Scientists". NASA. 15 March 2007.
  50. ^ Lin, Cheng-Kuan; Lin, Ro-Ting; Chen, Pi-Cheng; Wang, Pu; De Marcellis-Warin, Nathalie; Zigler, Corwin; Christiani, David C. (8 February 2018). "A Global Perspective on Sulfur Oxide Controls in Coal-Fired Power Plants and Cardiovascular Disease". Scientific Reports. 8 (1): 2611. Bibcode:2018NatSR...8.2611L. doi:10.1038/s41598-018-20404-2. ISSN 2045-2322. PMC 5805744. PMID 29422539.
  51. ^ Lindeburg, Michael R. (2006). Mechanical Engineering Reference Manual for the PE Exam. Belmont, C.A.: Professional Publications, Inc. pp. 27–3. ISBN 978-1-59126-049-3.
  52. ^ a b c "Air Emissions Trends – Continued Progress Through 2005". U.S. Environmental Protection Agency. 8 July 2014. Archived from the original on 17 March 2007. Retrieved 17 March 2007.
  53. ^ a b "Effects of Acid Rain – Human Health". EPA. 2 June 2006. Archived from the original on 18 January 2008. Retrieved 2 September 2013.
  54. ^ Moses, Elizabeth; Cardenas, Beatriz; Seddon, Jessica (25 February 2020). "The Most Successful Air Pollution Treaty You've Never Heard Of".
  55. ^ Wild, Martin; Trüssel, Barbara; Ohmura, Atsumu; Long, Charles N.; König-Langlo, Gert; Dutton, Ellsworth G.; Tsvetkov, Anatoly (16 May 2009). "Global dimming and brightening: An update beyond 2000". Journal of Geophysical Research: Atmospheres. 114 (D10): D00D13. Bibcode:2009JGRD..114.0D13W. doi:10.1029/2008JD011382.
  56. ^ Carnell, R. E.; Senior, C. A. (April 1998). "Changes in mid-latitude variability due to increasing greenhouse gases and sulphate aerosols". Climate Dynamics. 14 (5): 369–383. Bibcode:1998ClDy...14..369C. doi:10.1007/s003820050229. S2CID 129699440.
  57. ^ He, Yanyi; Wang, Kaicun; Zhou, Chunlüe; Wild, Martin (19 April 2018). "A Revisit of Global Dimming and Brightening Based on the Sunshine Duration". Geophysical Research Letters. 6 (9): 6346. Bibcode:2018GeoRL..45.4281H. doi:10.1029/2018GL077424. hdl:20.500.11850/268470. S2CID 134001797.
  58. ^ He, Yanyi; Wang, Kaicun; Zhou, Chunlüe; Wild, Martin (15 April 2022). "Evaluation of surface solar radiation trends over China since the 1960s in the CMIP6 models and potential impact of aerosol emissions". Atmospheric Research. 268: 105991. Bibcode:2022AtmRe.26805991W. doi:10.1016/j.atmosres.2021.105991. S2CID 245483347.
  59. ^ a b c Quaas, Johannes; Jia, Hailing; Smith, Chris; Albright, Anna Lea; Aas, Wenche; Bellouin, Nicolas; Boucher, Olivier; Doutriaux-Boucher, Marie; Forster, Piers M.; Grosvenor, Daniel; Jenkins, Stuart; Klimont, Zbigniew; Loeb, Norman G.; Ma, Xiaoyan; Naik, Vaishali; Paulot, Fabien; Stier, Philip; Wild, Martin; Myhre, Gunnar; Schulz, Michael (21 September 2022). "Robust evidence for reversal of the trend in aerosol effective climate forcing". Atmospheric Chemistry and Physics. 22 (18): 12221–12239. Bibcode:2022ACP....2212221Q. doi:10.5194/acp-22-12221-2022. hdl:20.500.11850/572791. S2CID 252446168.
  60. ^ Cao, Yang; Zhu, Yannian; Wang, Minghuai; Rosenfeld, Daniel; Liang, Yuan; Liu, Jihu; Liu, Zhoukun; Bai, Heming (7 January 2023). "Emission Reductions Significantly Reduce the Hemispheric Contrast in Cloud Droplet Number Concentration in Recent Two Decades". Journal of Geophysical Research: Atmospheres. 128 (2): e2022JD037417. Bibcode:2023JGRD..12837417C. doi:10.1029/2022JD037417.
  61. ^ Zeke Hausfather (5 October 2017). "Analysis: How well have climate models projected global warming?". Carbon Brief. Retrieved 21 March 2023.
  62. ^ Mbengue, Saliou; Zikova, Nadezda; Schwarz, Jaroslav; Vodička, Petr; Šmejkalová, Adéla Holubová; Holoubek, Ivan (28 June 2021). "Mass absorption cross-section and absorption enhancement from long term black and elemental carbon measurements: A rural background station in Central Europe". Science of the Total Environment. 794 (1): 148365. doi:10.1016/j.scitotenv.2021.148365.
  63. ^ Peng, Jianfei; Hu, Min; Guo, Song; Zhang, Renyi (28 March 2016). "Markedly enhanced absorption and direct radiative forcing of black carbon under polluted urban environments". PNAS. 113 (16): 4266–4271. doi:10.1073/pnas.1602310113.
  64. ^ National Science Foundation (1 August 2007). ""Brown Cloud" Particulate Pollution Amplifies Global Warming". Retrieved 3 April 2008.
  65. ^ Miinalainen, Tuuli; Kokkola, Harri; Lipponen, Antti; Hyvärinen, Antti-Pekka; Kumar Soni, Vijay; Lehtinen, Kari E. J.; Kühn, Thomas (20 March 2023). "Assessing the climate and air quality effects of future aerosol mitigation in India using a global climate model combined with statistical downscaling". Atmospheric Chemistry and Physics. 23 (6): 3471–3491. Bibcode:2023ACP....23.3471M. doi:10.5194/acp-23-3471-2023. S2CID 253222600.
  66. ^ Ponater, M. (2005). "On contrail climate sensitivity". Geophysical Research Letters. 32 (10): L10706. Bibcode:2005GeoRL..3210706P. doi:10.1029/2005GL022580.
  67. ^ Perkins, Sid (11 May 2002). "September's Science: Shutdown of airlines aided contrail studies". Science News. Science News Online. Retrieved 13 October 2021.
  68. ^ Travis, David J.; Carleton, Andrew M.; Lauritsen, Ryan G. (2002). "Contrails reduce daily temperature range" (PDF). Nature. 418 (6898): 601. Bibcode:2002Natur.418..601T. doi:10.1038/418601a. PMID 12167846. S2CID 4425866. Archived from the original (PDF) on 3 May 2006.
  69. ^ "Jet contrails affect surface temperatures", Science Daily, 18 June 2015, retrieved 13 October 2021
  70. ^ Travis, D.J.; A.M. Carleton; R.G. Lauritsen (March 2004). "Regional Variations in U.S. Diurnal Temperature Range for the 11–14 September 2001 Aircraft Groundings: Evidence of Jet Contrail Influence on Climate". J. Clim. 17 (5): 1123. Bibcode:2004JCli...17.1123T. doi:10.1175/1520-0442(2004)017<1123:RVIUDT>2.0.CO;2.
  71. ^ Kalkstein; Balling Jr. (2004). "Impact of unusually clear weather on United States daily temperature range following 9/11/2001". Climate Research. 26: 1. Bibcode:2004ClRes..26....1K. doi:10.3354/cr026001.
  72. ^ Hong, Gang; Yang, Ping; Minnis, Patrick; Hu, Yong X.; North, Gerald (2008). "Do contrails significantly reduce daily temperature range?" (PDF). Geophysical Research Letters. 35 (23): L23815. Bibcode:2008GeoRL..3523815H. doi:10.1029/2008GL036108.
  73. ^ Digby, Ruth A. R.; Gillett, Nathan P.; Monahan, Adam H.; Cole, Jason N. S. (29 September 2021). "An Observational Constraint on Aviation-Induced Cirrus From the COVID-19-Induced Flight Disruption". Geophysical Research Letters. 48 (20): e2021GL095882. Bibcode:2021GeoRL..4895882D. doi:10.1029/2021GL095882. PMC 8667656. PMID 34924638.
  74. ^ Gettelman, Andrew; Chen, Chieh-Chieh; Bardeen, Charles G. (18 June 2021). "The climate impact of COVID-19-induced contrail changes". Atmospheric Chemistry and Physics. 21 (12): 9405–9416. Bibcode:2021ACP....21.9405G. doi:10.5194/acp-21-9405-2021.
  75. ^ Zhu, Jialei; Penner, Joyce E.; Garnier, Anne; Boucher, Olivier; Gao, Meng; Song, Lei; Deng, Junjun; Liu, Cong-qiang; Fu, Pingqing (18 March 2022). "Decreased Aviation Leads to Increased Ice Crystal Number and a Positive Radiative Effect in Cirrus Clouds". AGU Advances. 3 (2): ee2020GL089788. Bibcode:2022AGUA....300546Z. doi:10.1029/2021AV000546.
  76. ^ "Crichton's Thriller State of Fear: Separating Fact from Fiction". Archived from the original on 14 June 2006. Retrieved 12 June 2006.
  77. ^ a b ""Warming Hole" Over the Eastern U.S. Due to Air Pollution". NASA. 18 May 2012.
  78. ^ Kerr, Richard A. (16 March 2007). "Climate change: Is a Thinning Haze Unveiling the Real Global Warming?". Science. 315 (5818): 1480. doi:10.1126/science.315.5818.1480. PMID 17363636. S2CID 40829354.
  79. ^ Krishnan, Srinath; Ekman, Annica M. L.; Hansson, Hans-Christen; Riipinen, Ilona; Lewinschal, Anna; Wilcox, Laura J.; Dallafior, Tanja (28 March 2020). "The Roles of the Atmosphere and Ocean in Driving Arctic Warming Due to European Aerosol Reductions". Geophysical Research Letters. 47 (11): e2019GL086681. Bibcode:2020GeoRL..4786681K. doi:10.1029/2019GL086681. S2CID 216171731.
  80. ^ "The Arctic is warming four times faster than the rest of the world". 14 December 2021. Retrieved 6 October 2022.
  81. ^ Vautard, Robert; Yiou, Pascal; Oldenborgh, Geert Jan van (3 December 2021). "Decline of fog, mist and haze in Europe over the past 30 years". Nature Geoscience. 2 (2): 115–119. doi:10.1038/ngeo414.
  82. ^ Markowicz, Krzysztof M.; Zawadzka-Manko, Olga; Posyniak, Michal (3 December 2021). "A large reduction of direct aerosol cooling over Poland in the last decades". International Journal of Climatology. 42 (7): 4129–4146. doi:10.1002/joc.7488. S2CID 244881291.
  83. ^ Glantz, P.; Fawole, O. G.; Ström, J.; Wild, M.; Noone, K. J. (27 November 2022). "Unmasking the Effects of Aerosols on Greenhouse Warming Over Europe". Journal of Geophysical Research: Atmospheres. 127 (22): e2021JD035889. Bibcode:2022JGRD..12735889G. doi:10.1029/2021JD035889. hdl:20.500.11850/584879. S2CID 253357109.
  84. ^ Karmalkar, Ambarish V.; Horton, Radley M. (23 September 2021). "Drivers of exceptional coastal warming in the northeastern United States". Nature Climate Change. 11 (10): 854–860. Bibcode:2021NatCC..11..854K. doi:10.1038/s41558-021-01159-7. S2CID 237611075.
  85. ^ Krajick, Kevin (23 September 2021). "Why the U.S. Northeast Coast Is a Global Warming Hot Spot". Columbia Climate School. Retrieved 23 March 2023.
  86. ^ a b Yang, Yang; Ren, Lili; Li, Huimin; Wang, Hailong; Wang, Pinya; Chen, Lei; Yue, Xu; Liao, Hong (17 September 2020). "Fast Climate Responses to Aerosol Emission Reductions During the COVID-19 Pandemic". Geophysical Research Letters. 47 (19): ee2020GL089788. Bibcode:2020GeoRL..4789788Y. doi:10.1029/2020GL089788.
  87. ^ Gettelman, A.; Lamboll, R.; Bardeen, C. G.; Forster, P. M.; Watson-Parris, D. (29 December 2020). "Climate Impacts of COVID-19 Induced Emission Changes". Geophysical Research Letters. 48 (3): e2020GL091805. doi:10.1029/2020GL091805.
  88. ^ Sun, Shanlei; Zhou, Decheng; Chen, Haishan; Li, Jinjian; Ren, Yongjian; Liao, Hong; Liu, Yibo (25 June 2022). "Decreases in the urban heat island effect during the Coronavirus Disease 2019 (COVID-19) lockdown in Wuhan, China: Observational evidence". International Journal of Climatology. 42 (16): 8792–8803. Bibcode:2022IJCli..42.8792S. doi:10.1002/joc.7771.
  89. ^ Gillett, Nathan P.; Kirchmeier-Young, Megan; Ribes, Aurélien; Shiogama, Hideo; Hegerl, Gabriele C.; Knutti, Reto; Gastineau, Guillaume; John, Jasmin G.; Li, Lijuan; Nazarenko, Larissa; Rosenbloom, Nan; Seland, Øyvind; Wu, Tongwen; Yukimoto, Seiji; Ziehn, Tilo (18 January 2021). "Constraining human contributions to observed warming since the pre-industrial period" (PDF). Nature Climate Change. 11 (3): 207–212. Bibcode:2021NatCC..11..207G. doi:10.1038/s41558-020-00965-9. S2CID 231670652.
  90. ^ Andrew, Tawana (27 September 2019). "Behind the Forecast: How clouds affect temperatures". Science Behind the Forecast. LOUISVILLE, Ky. (WAVE). Retrieved 4 January 2023.
  91. ^ Zhang, Jie; Furtado, Kalli; Turnock, Steven T.; Mulcahy, Jane P.; Wilcox, Laura J.; Booth, Ben B.; Sexton, David; Wu, Tongwen; Zhang, Fang; Liu, Qianxia (22 December 2021). "The role of anthropogenic aerosols in the anomalous cooling from 1960 to 1990 in the CMIP6 Earth system models". Atmospheric Chemistry and Physics. 21 (4): 18609–18627. Bibcode:2021ACP....2118609Z. doi:10.5194/acp-21-18609-2021.
  92. ^ Hausfather, Zeke (29 April 2021). "Explainer: Will global warming 'stop' as soon as net-zero emissions are reached?". Carbon Brief. Retrieved 3 March 2023.
  93. ^ Hassan, Taufiq; Allen, Robert J.; et al. (27 June 2022). "Air quality improvements are projected to weaken the Atlantic meridional overturning circulation through radiative forcing effects". Communications Earth & Environment. 3 (3): 149. Bibcode:2022ComEE...3..149H. doi:10.1038/s43247-022-00476-9. S2CID 250077615.
  94. ^ "Trends in Atmospheric Methane". NOAA. Retrieved 14 October 2022.
  95. ^ Tollefson J (8 February 2022). "Scientists raise alarm over 'dangerously fast' growth in atmospheric methane". Nature. Retrieved 14 October 2022.
  96. ^ Lan X, Basu S, Schwietzke S, Bruhwiler LM, Dlugokencky EJ, Michel SE, Sherwood OA, Tans PP, Thoning K, Etiope G, Zhuang Q, Liu L, Oh Y, Miller JB, Pétron G, Vaughn BH, Crippa M (8 May 2021). "Improved Constraints on Global Methane Emissions and Sinks Using δ13C-CH4". Global Biogeochemical Cycles. 35 (6): e2021GB007000. Bibcode:2021GBioC..3507000L. doi:10.1029/2021GB007000. PMC 8244052. PMID 34219915.
  97. ^ Feng, Liang; Palmer, Paul I.; Zhu, Sihong; Parker, Robert J.; Liu, Yi (16 March 2022). "Tropical methane emissions explain large fraction of recent changes in global atmospheric methane growth rate". Nature Communications. 13 (1): 1378. Bibcode:2022NatCo..13.1378F. doi:10.1038/s41467-022-28989-z. PMC 8927109. PMID 35297408.
  98. ^ a b Luo, Feifei; Wilcox, Laura; Dong, Buwen; Su, Qin; Chen, Wei; Dunstone, Nick; Li, Shuanglin; Gao, Yongqi (19 February 2020). "Projected near-term changes of temperature extremes in Europe and China under different aerosol emissions". Environmental Research Letters. 15 (3): 4013. Bibcode:2020ERL....15c4013L. doi:10.1088/1748-9326/ab6b34.
  99. ^ Li, Yingfang; Wang, Zhili; Lei, Yadong; Che, Huizheng; Zhang, Xiaoye (23 February 2023). "Impacts of reductions in non-methane short-lived climate forcers on future climate extremes and the resulting population exposure risks in eastern and southern Asia". Atmospheric Chemistry and Physics. 23 (4): 2499–2523. Bibcode:2023ACP....23.2499L. doi:10.5194/acp-23-2499-2023. S2CID 257180147.
  100. ^ Wang, Zhili; Lin, Lei; Xu, Yangyang; Che, Huizheng; Zhang, Xiaoye; Zhang, Hua; Dong, Wenjie; Wang, Chense; Gui, Ke; Xie, Bing (12 January 2021). "Incorrect Asian aerosols affecting the attribution and projection of regional climate change in CMIP6 models". npj Climate and Atmospheric Science. 4 (21). Bibcode:2022JGRD..12735476J. doi:10.1029/2021JD035476.
  101. ^ Ramachandran, S.; Rupakheti, Maheswar; Cherian, R. (10 February 2022). "Insights into recent aerosol trends over Asia from observations and CMIP6 simulations". Science of the Total Environment. 807 (1): 150756. Bibcode:2022ScTEn.807o0756R. doi:10.1016/j.scitotenv.2021.150756. PMID 34619211. S2CID 238474883.
  102. ^ a b Xie, Xiaoning; Myhre, Gunnar; Shindell, Drew; Faluvegi, Gregory; Takemura, Toshihiko; Voulgarakis, Apostolos; Shi, Zhengguo; Li, Xinzhou; Xie, Xiaoxun; Liu, Heng; Liu, Xiaodong; Liu, Yangang (27 December 2022). "Anthropogenic sulfate aerosol pollution in South and East Asia induces increased summer precipitation over arid Central Asia". Communications Earth & Environment. 3 (1): 328. Bibcode:2022ComEE...3..328X. doi:10.1038/s43247-022-00660-x. PMC 9792934. PMID 36588543.
  103. ^ Pan, Bowen; Wang, Yuan; Hu, Jiaxi; Lin, Yun; Hsieh, Jen-Shan; Logan, Timothy; Feng, Xidan; Jiang, Jonathan H.; Yung, Yuk L.; Zhang, Renyi (2018). "Sahara dust may make you cough, but it's a storm killer". Journal of Climate. 31 (18): 7621–7644. doi:10.1175/JCLI-D-16-0776.1.
  104. ^ Cat Lazaroff (7 December 2001). "Aerosol Pollution Could Drain Earth's Water Cycle". Environment News Service. Archived from the original on 3 June 2016. Retrieved 24 March 2007.
  105. ^ Kostel, Ken; Oh, Clare (14 April 2006). "Could Reducing Global Dimming Mean a Hotter, Dryer World?". Lamont–Doherty Earth Observatory News. Archived from the original on 3 March 2016. Retrieved 12 June 2006.
  106. ^ Chang, C.-Y.; Chiang, J. C. H.; Wehner, M. F.; Friedman, A. R.; Ruedy, R. (15 May 2011). "Sulfate Aerosol Control of Tropical Atlantic Climate over the Twentieth Century". Journal of Climate. 24 (10): 2540–2555. Bibcode:2011JCli...24.2540C. doi:10.1175/2010JCLI4065.1.
  107. ^ Allen, Robert J. (20 August 2015). "A 21st century northward tropical precipitation shift caused by future anthropogenic aerosol reductions". Journal of Geophysical Research: Atmospheres. 120 (18): 9087–9102. Bibcode:2015JGRD..120.9087A. doi:10.1002/2015JD023623.
  108. ^ Monerie, Paul-Arthur; Dittus, Andrea J.; Wilcox, Laura J.; Turner, Andrew G. (22 January 2023). "Uncertainty in Simulating Twentieth Century West African Precipitation Trends: The Role of Anthropogenic Aerosol Emissions". Earth's Future. 11 (2): e2022EF002995. Bibcode:2023EaFut..1102995M. doi:10.1029/2022EF002995.
  109. ^ a b Schmidt, Gavin (18 January 2005). "Global Dimming?". RealClimate. Retrieved 5 April 2007.
  110. ^ Schewe, Jacob; Levermann, Anders (15 September 2022). "Sahel Rainfall Projections Constrained by Past Sensitivity to Global Warming". Earth's Future. 11 (2): e2022GL098286. Bibcode:2022GeoRL..4998286S. doi:10.1029/2022GL098286.
  111. ^ a b Risser, Mark D.; Collins, William D.; Wehner, Michael F.; O'Brien, Travis A.; Huang, Huanping; Ullrich, Paul A. (22 February 2024). "Anthropogenic aerosols mask increases in US rainfall by greenhouse gases". Nature Communications. 15. doi:10.1038/s41467-024-45504-8.
  112. ^ Tao, Wei-Kuo; Chen, Jen-Ping; Li, Zhanqing; Wang, Chien; Zhang, Chidong (17 April 2012). "Impact of aerosols on convective clouds and precipitation". Reviews of Geophysics. 50 (2). Bibcode:2012RvGeo..50.2001T. doi:10.1029/2011RG000369. S2CID 15554383.
  113. ^ Schewe, Jacob; Levermann, Anders (5 November 2012). "A statistically predictive model for future monsoon failure in India". Environmental Research Letters. 7 (4): 4023. Bibcode:2012ERL.....7d4023S. doi:10.1088/1748-9326/7/4/044023. S2CID 5754559.
  114. ^ "Monsoon might fail more often due to climate change". Potsdam Institute for Climate Impact Research. 6 November 2012. Retrieved 25 March 2023.
  115. ^ Katzenberger, Anja; Schewe, Jacob; Pongratz, Julia; Levermann, Anders (2021). "Robust increase of Indian monsoon rainfall and its variability under future warming in CMIP-6 models". Earth System Dynamics. 12 (2): 367–386. Bibcode:2021ESD....12..367K. doi:10.5194/esd-12-367-2021. S2CID 235080216.
  116. ^ Fan, Chongxing; Wang, Minghuai; Rosenfeld, Daniel; Zhu, Yannian; Liu, Jihu; Chen, Baojun (18 March 2020). "Strong Precipitation Suppression by Aerosols in Marine Low Clouds". Geophysical Research Letters. 47 (7): e2019GL086207. Bibcode:2020GeoRL..4786207F. doi:10.1029/2019GL086207.
  117. ^ a b Smith, Wake (October 2020). "The cost of stratospheric aerosol injection through 2100". Environmental Research Letters. 15 (11): 114004. Bibcode:2020ERL....15k4004S. doi:10.1088/1748-9326/aba7e7. ISSN 1748-9326. S2CID 225534263.
  118. ^ a b Gramling, Carolyn (8 August 2018). "Global dimming may mitigate warming, but could hurt crop yields". Science News Online. Retrieved 6 January 2024.
  119. ^ a b "The Royal Society" (PDF). royalsociety.org. p. 23. Archived (PDF) from the original on 21 July 2015. Retrieved 20 October 2015.
  120. ^ Spencer Weart (July 2006). "Aerosols: Effects of Haze and Cloud". The Discovery of Global Warming. American Institute of Physics. Archived from the original on 29 June 2016. Retrieved 6 April 2009.
  121. ^ Ramanathan, V. (2006). "Atmospheric Brown Clouds: Health, Climate and Agriculture Impacts" (PDF). Pontifical Academy of Sciences Scripta Varia (Pontifica Academia Scientiarvm). 106 (Interactions Between Global Change and Human Health): 47–60. Archived from the original (PDF) on 30 July 2007.
  122. ^ Crutzen, P. (August 2006). "Albedo enhancement by stratospheric sulfur injections: a contribution to resolve a policy dilemma?" (PDF). Climatic Change. 77 (3–4): 211–220. Bibcode:2006ClCh...77..211C. doi:10.1007/s10584-006-9101-y. S2CID 154081541.
  123. ^ William J. Broad (27 June 2006). "How to Cool a Planet (Maybe)". The New York Times. Retrieved 6 April 2009.
  124. ^ Robock, Alan; Marquardt, Allison; Kravitz, Ben; Stenchikov, Georgiy (2009). "Benefits, risks, and costs of stratospheric geoengineering" (PDF). Geophysical Research Letters. 36 (19): L19703. Bibcode:2009GeoRL..3619703R. doi:10.1029/2009GL039209. hdl:10754/552099.
  125. ^ Grieger, Khara D.; Felgenhauer, Tyler; Renn, Ortwin; Wiener, Jonathan; Borsuk, Mark (30 April 2019). "Emerging risk governance for stratospheric aerosol injection as a climate management technology". Environment Systems and Decisions. 39 (4): 371–382. Bibcode:2019EnvSD..39..371G. doi:10.1007/s10669-019-09730-6.

External links

source: http://en.wikipedia.org/wiki/Global_dimming