Global dimming is a decline in the amount of sunlight reaching the Earth's surface, a measure also known as global direct solar irradiance.[2][3] It was observed soon after the first systematic measurements of solar irradiance began in the 1950s, and continued until 1980s, with an observed reduction of 4–5% per decade,[1] even though solar activity did not vary more than the usual at the time.[4][2] Instead, global dimming had been attributed to an increase in atmospheric particulate matter, predominantly sulfate aerosols, as the result of rapidly growing air pollution due to post-war industrialization. After 1980s, reductions in particulate emissions have also caused a "partial" reversal of the dimming trend, which has sometimes been described as a global brightening.[1] This reversal is not yet complete, and it has also been globally uneven, as some of the brightening over the developed countries in the 1980s and 1990s had been counteracted by the increased dimming from the industrialization of the developing countries and the expansion of the global shipping industry,[5] although they have also been making rapid progress in cleaning up air pollution in the recent years.[6][7]

Global dimming has interfered with the hydrological cycle by lowering evaporation, which is likely to have reduced rainfall in certain areas,[1] and may have caused the observed southwards shift of the entire tropical rain belt between 1950 and 1985, with a limited recovery afterwards.[8] Since high evaporation at the tropics is needed to drive the wet season, cooling caused by particulate pollution appears to weaken Monsoon of South Asia, while reductions in pollution strengthen it.[9][10] Multiple studies have also connected record levels of particulate pollution in the Northern Hemisphere to the monsoon failure behind the 1984 Ethiopian famine,[11][12][13] although the full extent of anthropogenic vs. natural influences on that event is still disputed.[14][15] On the other hand, global dimming has also counteracted some of the greenhouse gas emissions, effectively "masking" the total extent of global warming experienced to date, with the most-polluted regions even experiencing cooling in the 1970s. Conversely, global brightening contributed to the acceleration of global warming which began in the 1990s.[1][16]

In the near future, global brightening is expected to continue, as nations act to reduce the toll of air pollution on the health of their citizens. This also means that less of global warming would be masked in the future. Climate models are broadly capable of simulating the impact of aerosols like sulfates, and in the IPCC Sixth Assessment Report, they are believed to offset around 0.5 °C (0.9 °F) of warming. Likewise, climate change scenarios incorporate reductions in particulates and the cooling they offered into their projections, and this includes the scenarios for climate action required to meet 1.5 °C (2.7 °F) and 2 °C (3.6 °F) targets.[17] It is generally believed that the cooling provided by global dimming is similar to the warming derived from atmospheric methane, meaning that simultaneous reductions in both would effectively cancel each other out.[18] However, uncertainties remain about the models' representation of aerosol impacts on weather systems, especially over the regions with a poorer historical record of atmospheric observations.[19][20][21][22]

The processes behind global dimming are similar to those which drive reductions in direct sunlight after volcanic eruptions. In fact, the eruption of Mount Pinatubo in 1991 had temporarily reversed the brightening trend.[23] Both are considered an analogue for stratospheric aerosol injection, a solar geoengineering intervention which aims to counteract global warming through intentional releases of reflective aerosols, albeit at much higher altitudes, where lower quantities would be needed and the polluting effects would be minimized.[24] That intervention may be very effective at stopping or reversing warming and its main consequences, yet it would also have substantial effects on the global hydrological cycle, as well as regional weather and ecosystems. Further, it would have to be carried out over centuries until the greenhouse gas concentrations are normalized to avoid aerosols leaving the atmosphere too early. Otherwise, a rapid and violent return of the warming, sometimes known as termination shock, would occur.[25]

History

Further information: Climate model and pyranometer

The observed trends of global dimming and brightening in four major geopolitical 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.[20]

In the 1970s, numerous studies have shown that the atmospheric aerosols could affect the propagation of sunlight through the atmosphere.[26][27] One of them had shown 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. [28] Another suggested that sulfate pollution or a volcano eruption could provoke the onset of an ice age.[29][30] In the 1980s, research in Israel and the Netherlands revealed an apparent reduction in the amount of sunlight,[31] 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.[32] In the 1990s, this was followed by the papers describing multi-decade declines in Estonia,[33] Germany,[34] Israel[35] and across the former Soviet Union.[36]

In the 1990s, experiments comparing the atmosphere over the northern and southern islands of the Maldives, showed that the effect of macroscopic pollutants in the atmosphere at that time (blown south from India) caused about a 10% reduction in sunlight reaching the surface in the area under the Asian brown cloud – a much greater reduction than expected from the presence of the particles themselves.[37]

Subsequent research estimated an average reduction in sunlight striking the terrestrial surface of around 4–5% per decade over late 1950s–1980s, and 2–3% per decade when 1990s were included.[35][38][39][40] 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.[4][2] Additionally, only visible light and infrared radiation were dimmed, rather than the ultraviolet part of the spectrum.[41] 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.[42][2][20]

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.[31][43][44][45][46] 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.[47][48] 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.[49] By 2010, this reduction in sulfate pollution led to estimated healthcare cost savings valued at $50 billion annually.[50] Similar measures were taken in Europe,[49] 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.[51]

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 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 continued dimming during that period, albeit at a lower confidence level due to the lower number of observations.[5][52] Later research found that over China, the dimming trend continued at a slower rate after 1990,[53] and did not begin to reverse until around 2005.[54] 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.[7] 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.[55]

Causes

Further information: Albedo, irradiance, insolation, and Anthropogenic cloud

Snapshot of atmospheric sulfur dioxide on April 15, 2017. As it moves through the atmosphere with prevailing winds, weather patterns and seasonality alter these distributions from day-to-day. Sulfur dioxide forms highly reflective sulfates, which are considered the main cause of global dimming.[56]

Global dimming had been widely attributed to the increased presence of aerosol particles in Earth's atmosphere, predominantly those of sulfates.[57] While natural dust is also an aerosol with some impacts on climate, and volcanic eruptions considerably increase sulfate concentrations in the short term, these effects have been dwarfed by increases in sulfate emissions since the start of the Industrial Revolution.[46] According to the IPCC First Assessment Report, the global human-caused emissions of sulfur into the atmosphere were less than 3 million tons per year in 1860, yet they increased to 15 million tons in 1900, 40 million tons in 1940 and about 80 millions in 1980. This meant that the human-caused emissions became "at least as large" as all natural emissions of sulfur-containing compounds: the largest natural source, emissions of dimethyl sulfide from the ocean, was estimated at 40 million tons per year, while volcano emissions were estimated at 10 million tons. Moreover, that was the average figure: according to the report, "in the industrialized regions of Europe and North America, anthropogenic emissions dominate over natural emissions by about a factor of ten or even more".[58]

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.[59]

Aerosols and other atmospheric particulates have direct and indirect effects on the amount of sunlight received at the surface. Directly, particles of sulfur dioxide reflect almost all sunlight, like tiny mirrors.[60] On the other hand, incomplete combustion of fossil fuels (such as diesel) and wood releases particles of black carbon (predominantly soot), which absorb solar energy and heat up, reducing the overall amount of sunlight received on the surface while also contributing to warming.[61] Indirectly, the pollutants affect the climate by acting as nuclei, meaning that water droplets in clouds coalesce around the particles.[56] 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. This same effect also reflects radiation from below, trapping it in the lower atmosphere. In models, these smaller droplets also decrease rainfall.[62]

Relationship to climate change

Past and present

The extent to which physical factors in the atmosphere or on land affect climate change, including the cooling provided by sulfate aerosols and the dimming they cause. The large error bar shows that there are still substantial unresolved uncertainties.

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.[46] 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.[58] By 1995, the IPCC Second Assessment Report had confidently assessed the overall impact of aerosols as negative (cooling);[63] however, aerosols were recognized as the largest source of uncertainty in future projections in that report and the subsequent ones.[1]

At the peak of global dimming, it was able to counteract the warming trend completely, but by 1975, the continually increasing concentrations of greenhouse gases have overcome the masking effect and dominated ever since.[49] Even then, regions with high concentrations of sulfate aerosols due to air pollution had initially experienced cooling, in contradiction to the overall warming trend.[64] 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. As the sulfate pollution was reduced, the central and eastern United States had experienced warming of 0.3 °C (0.54 °F) between 1980 and 2010,[65] even as sulfate particles still accounted for around 25% of all particulates.[50] By 2021, the northeastern coast of the United States was instead 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.[66][67]

Between 1980s and 2010s, the reduction in aerosol density over Europe had lowered the difference between thermal energy entering the atmosphere from the sun and between thermal energy radiating off the ground (top left, blue), which increased the net amount of heating and contributed to increase in extreme temperatures (other images, red).[68]

Globally, the emergence of extreme heat beyond the preindustrial records was delayed by aerosol cooling, and 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] 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.[69] Because aerosol cooling depends on reflecting sunlight, air quality improvements had a negligible impact on wintertime temperatures,[70] but had increased temperatures from April to September by around 1 °C (1.8 °F) in Central and Eastern Europe.[68] 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.[71][72][73]

Pollution from black carbon, mostly represented by soot, also contributes to global dimming. However, because it absorbs heat instead of reflecting it, it warms the planet instead of cooling it like sulfates. This warming is much weaker than that of greenhouse gases, but it can be regionally significant when black carbon is deposited over ice masses like mountain glaciers and the Greenland ice sheet, where it reduces their albedo and increases their absorption of solar radiation.[74] 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.[75] Black carbon pollution is particularly strong over India, and as the result, it is considered to be one of the few regions where cleaning up air pollution would reduce, rather than increase, warming.[76]

Future

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.[59]

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. 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.[60] 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);[77] 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.[17] While these values are based on combining model estimates with observational constraints, including those on ocean heat content,[7] the matter is not yet fully settled. The difference between model estimates mainly stems from disagreements over the indirect effects of aerosols on clouds.[78][79]

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.[6]

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.[17] 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.[18] Yet, in the recent years, methane concentrations had been increasing at rates exceeding their previous period of peak growth in the 1980s,[80][81] with wetland methane emissions driving much of the recent growth,[82][83] while air pollution is getting cleaned up aggressively.[7] 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.[6]

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.[22] 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.[84] 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.[85] 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,[20] but struggle with representing North America and Asia, meaning that their near-future projections of regional impacts are likely to contain errors as well.[19][20][21]

Aircraft contrails and lockdowns

Main article: Contrail § Impacts on climate

Aircraft contrails both reflect incoming solar radiation and trap outgoing longwave radiation that is emitted by the Earth. Their heat-trapping effect is larger than their dimming effect, which results in a net increase in radiative forcing. In 1992, the overall warming effect of contrails was estimated to be between 3.5 mW/m2 and 17 mW/m2.[86]

Aircraft contrails (white lines) and natural clouds.

Certain real-world events have been studied for their potential to provide short-term demonstrations of global dimming and the associated effects.[3] For instance, aircraft leave behind visible contrails (also known as vapor trails) as they travel. In the 1990s, it was suggested that these trails have a strong cooling effect,[87] and when no commercial aircraft flew across the USA following the September 11 attacks, 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).[88] Measured across 4,000 weather stations in the continental United States, this increase was the largest recorded in 30 years.[88] Without contrails, the local diurnal temperature range was 1 °C (1.8 °F) higher than immediately before.[89] 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.[90][91] However, follow-up studies found that a natural change in cloud cover can more than explain these findings.[92][93] 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.[94][95][96]

In addition to revealing the limited effect of contrails, COVID-19 lockdowns provided another "natural experiment", as there had been a marked decline in sulfate 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.[97][98] 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.[99]

Relationship to hydrological cycle

Further information: Hydrological cycle

Sulfate aerosols have decreased precipitation over most of Asia (red), but increased it over some parts of Central Asia (blue).[100]

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.[101] 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."[102][103] In 2011, it was found that anthropogenic aerosols had been the predominant factor behind 20th century changes in rainfall over the Atlantic Ocean sector,[104] when the entire tropical rain belt shifted southwards between 1950 and 1985, with a limited northwards shift afterwards.[8] 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.[105]

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.[11][13][12] However, model simulations of Sahel climate are very inconsistent,[106] so it's difficult to prove that the drought would not have occurred without aerosol pollution, although it would have clearly been less severe.[14][15] 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.[107]

Another dramatic finding had connected the impact of aerosols with the weakening of the Monsoon of South Asia. It was first advanced in 2006,[9] yet it also remained difficult to prove.[108] In particular, some research suggested that warming itself increases the risk of monsoon failure, potentially pushing it past a tipping point.[109][110] By 2021, however, it was concluded that global warming consistently strengthened the monsoon,[111] and some strengthening was already observed in the aftermath of lockdown-caused aerosol reductions.[10]

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.[62] The phenomenon of aerosols suppressing rainfall through reducing cloud droplet size has been confirmed by subsequent studies.[112] 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.[100] IPCC Sixth Assessment Report had also linked changes in aerosol concentrations to altered precipitation in the Mediterranean region.[1]

Solar geoengineering

Main article: Stratospheric aerosol injection

This graph shows baseline radiative forcing under three different Representative Concentration Pathway scenarios, and how it would be affected by the deployment of SAI, starting from 2034, to either halve the speed of warming by 2100, to halt the warming, or to reverse it entirely.[113]

Global dimming is also a relevant phenomenon for certain proposals about slowing, halting or reversing global warming.[114] 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.[115] 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.[116] 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.[117] 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.[14]

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.[118][119] 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.[24] 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.[113][120] Even so, these approaches would still be "orders of magnitude" cheaper than greenhouse gas mitigation,[121] let alone the costs of unmitigated effects of climate change.[115]

The main downside to SAI is that any such cooling would still cease 1–3 years after the last aerosol injection, while the warming from CO2 emissions lasts for hundreds to thousands of years. 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.[25]

While stratospheric aerosol injection may temporarily halt or outright reverse the warming, there would still be significant changes in weather patterns in many areas, affecting the ecosystems. Climate change can affect the distribution of infectious diseases, and these changes would also shift the habitat of mosquitoes and other disease vectors, with currently unclear impacts. There have also been early concerns about the impacts on crop yields and carbon sinks,[114] but most recent science suggests that globally, they would be largely unaffected or may even increase slightly relative to the early 21st century. This is because reduced photosynthesis due to lower sunlight would be offset by CO2 fertilization effect and the reduction in thermal stress.[25]

See also

References

  1. ^ a b c d e f g h i Seneviratne S, 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 SM, Wehner M, Zhou B (2021). Masson-Delmotte V, Zhai P, Piran A, Connors S, 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 D (2004). "Global dimming". BBC News Online.
  4. ^ a b Eddy JA, Gilliland RL, Hoyt DV (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
  5. ^ a b Wild M, Trüssel B, Ohmura A, Long CN, König-Langlo G, Dutton EG, Tsvetkov A (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.
  6. ^ a b c Xu Y, Ramanathan V, Victor DG (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.
  7. ^ a b c d Quaas J, Jia H, Smith C, Albright AL, Aas W, Bellouin N, Boucher O, Doutriaux-Boucher M, Forster PM, Grosvenor D, Jenkins S, Klimont Z, Loeb NG, Ma X, Naik V, Paulot F, Stier P, Wild M, Myhre G, Schulz M (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.
  8. ^ a b Peace AH, Booth BB, Regayre LA, Carslaw KS, Sexton DM, Bonfils CJ, Rostron JW (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.
  9. ^ a b Lau KM, Kim KM (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.
  10. ^ a b Fadnavis S, Sabin TP, Rap A, Müller R, Kubin A, Heinold B (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.
  11. ^ a b Rotstayn and Lohmann, Lohmann U (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.
  12. ^ a b Hirasawa H, Kushner PJ, Sigmond M, Fyfe J, Deser C (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.
  13. ^ a b "Global Dimming". bbc.co.uk. BBC. Retrieved 5 January 2020.
  14. ^ a b c Schmidt G (18 January 2005). "Global Dimming?". RealClimate. Retrieved 5 April 2007.
  15. ^ a b Herman RJ, Giannini A, Biasutti M, Kushnir Y (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.
  16. ^ 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.
  17. ^ a b c 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.
  18. ^ a b Hausfather Z (29 April 2021). "Explainer: Will global warming 'stop' as soon as net-zero emissions are reached?". Carbon Brief. Retrieved 3 March 2023.
  19. ^ a b Wang Z, Lin L, Xu Y, Che H, Zhang X, Zhang H, Dong W, Wang C, Gui K, Xie B (12 January 2021). "Incorrect Asian aerosols affecting the attribution and projection of regional climate change in CMIP6 models". npj Climate and Atmospheric Science. 4. doi:10.1029/2021JD035476.
  20. ^ a b c d e Julsrud IR, Storelvmo T, Schulz M, Moseid KO, 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.
  21. ^ a b Ramachandran S, Rupakheti M, 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.
  22. ^ a b Persad GG, Samset BH, Wilcox LJ (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.
  23. ^ Hegerl GC, Zwiers FW, Braconnot P, Gillett N, Luo Y, Marengo Orsini J, Nicholls N, Penner J, Stott P (2007). "Chapter 9, Understanding and Attributing Climate Change – Section 9.2.2 Spatial and Temporal Patterns of the Response to Different Forcings and their Uncertainties" (PDF). In Solomon S, Qin D, Manning M, Chen Z, Marquis M, Averyt K, Tignor M, Miller H (eds.). Climate Change 2007: The Physical Science Basis. Contribution of Working Group I to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change. Intergovernmental Panel on Climate Change. Cambridge, United Kingdom and New York City, USA: Cambridge University Press.
  24. ^ a b Visioni D, Slessarev E, MacMartin DG, Mahowald NM, Goodale CL, Xia L (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.
  25. ^ a b c Trisos CH, Geden O, Seneviratne SI, Sugiyama M, van Aalst M, Bala G, Mach KJ, Ginzburg V, de Coninck H, Patt A (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.
  26. ^ Barnhardt EA, Streete JL (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.
  27. ^ Herman BM, Browning SR, Curran RJ (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.
  28. ^ Hodge PW (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.
  29. ^ Rasool IS, Schneider SH (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)
  30. ^ Lockwood JG (1979). Causes of Climate. Lecture Notes in mathematics 1358. New York: John Wiley & Sons. p. 162. ISBN 978-0-470-26657-1.
  31. ^ a b "Earth lightens up". Pacific Northwest National Laboratory. Retrieved 8 May 2005.
  32. ^ 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.
  33. ^ 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.
  34. ^ Liepert BG, 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.
  35. ^ 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.
  36. ^ Abakumova G (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.
  37. ^ J. Srinivasan (2002). "Asian Brown Cloud – fact and fantasy" (PDF). Current Science. 83 (5): 586–592.
  38. ^ 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 (inactive 8 February 2024).((cite journal)): CS1 maint: DOI inactive as of February 2024 (link)
  39. ^ 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.
  40. ^ Liepert BG (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.
  41. ^ Adam D (18 December 2003). "Goodbye sunshine". The Guardian. Retrieved 26 August 2009.
  42. ^ Wild M, Wacker S, Yang S, Sanchez-Lorenzo A (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.
  43. ^ 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.
  44. ^ 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.
  45. ^ "Global Dimming may have a brighter future". RealClimate. 15 May 2005. Retrieved 12 June 2006.
  46. ^ a b c "Global 'Sunscreen' Has Likely Thinned, Report NASA Scientists". NASA. 15 March 2007.
  47. ^ Lin C, Lin R, Chen P, Wang P, De Marcellis-Warin N, Zigler C, Christiani DC (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.
  48. ^ Lindeburg MR (2006). Mechanical Engineering Reference Manual for the PE Exam. Belmont, C.A.: Professional Publications, Inc. pp. 27–3. ISBN 978-1-59126-049-3.
  49. ^ 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.
  50. ^ a b "Effects of Acid Rain – Human Health". EPA. 2 June 2006. Archived from the original on 18 January 2008. Retrieved 2 September 2013.
  51. ^ Moses E, Cardenas B, Seddon J (25 February 2020). "The Most Successful Air Pollution Treaty You've Never Heard Of".
  52. ^ Carnell RE, Senior CA (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.
  53. ^ He Y, Wang K, Zhou C, Wild M (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.
  54. ^ He Y, Wang K, Zhou C, Wild M (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.
  55. ^ Cao Y, Zhu Y, Wang M, Rosenfeld D, Liang Y, Liu J, Liu Z, Bai H (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.
  56. ^ a b Myhre G, Lund Myhre CE, Samset BH, Storelvmo T (2013). "Aerosols and their Relation to Global Climate and Climate Sensitivity". The Nature Education Knowledge Project. Retrieved 6 January 2024.
  57. ^ Cohen S, Stanhill G (1 January 2021), Letcher TM (ed.), "Chapter 32 – Changes in the Sun's radiation: the role of widespread surface solar radiation trends in climate change: dimming and brightening", 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
  58. ^ a b 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,
  59. ^ a b Bellouin N, Quaas J, Gryspeerdt E, Kinne S, Stier P, Watson-Parris D, Boucher O, Carslaw KS, Christensen M, Daniau A, Dufresne J, Feingold G, Fiedler S, Forster P, Gettelman A, Haywood JM, Lohmann U, Malavelle F, Mauritsen T, McCoy DT, Myhre G, Mülmenstädt J, Neubauer D, Possner A, Rugenstein M, Sato Y, Schulz M, Schwartz SE, 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.
  60. ^ a b "Aerosols and Incoming Sunlight (Direct Effects)". NASA. 2 November 2010.
  61. ^ "Transported Black Carbon A Significant Player In Pacific Ocean Climate". Science Daily. 15 March 2007.
  62. ^ 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.
  63. ^ Zeke Hausfather (5 October 2017). "Analysis: How well have climate models projected global warming?". Carbon Brief. Retrieved 21 March 2023.
  64. ^ "Crichton's Thriller State of Fear: Separating Fact from Fiction". Archived from the original on 14 June 2006. Retrieved 12 June 2006.
  65. ^ ""Warming Hole" Over the Eastern U.S. Due to Air Pollution". NASA. 18 May 2012.
  66. ^ Karmalkar AV, Horton RM (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.
  67. ^ Krajick K (23 September 2021). "Why the U.S. Northeast Coast Is a Global Warming Hot Spot". Columbia Climate School. Retrieved 23 March 2023.
  68. ^ a b Glantz P, Fawole OG, Ström J, Wild M, Noone KJ (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.
  69. ^ Vautard R, Yiou P, Oldenborgh GJ (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.
  70. ^ Markowicz KM, Zawadzka-Manko O, Posyniak M (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.
  71. ^ Kerr RA (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.
  72. ^ Krishnan S, Ekman AM, Hansson H, Riipinen I, Lewinschal A, Wilcox LJ, Dallafior T (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.
  73. ^ "The Arctic is warming four times faster than the rest of the world". 14 December 2021. Retrieved 6 October 2022.
  74. ^ Ramanathan V, Carmichael G (2008). "Nature Geoscience: Global and regional climate changes due to black carbon". Nature Geoscience. 1 (4): 221–227. Bibcode:2008NatGe...1..221R. doi:10.1038/ngeo156. S2CID 12455550.
  75. ^ National Science Foundation (1 August 2007). ""Brown Cloud" Particulate Pollution Amplifies Global Warming". Retrieved 3 April 2008.
  76. ^ Miinalainen T, Kokkola H, Lipponen A, Hyvärinen A, Kumar Soni V, Lehtinen KE, Kühn T (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.
  77. ^ Gillett NP, Kirchmeier-Young M, Ribes A, Shiogama H, Hegerl GC, Knutti R, Gastineau G, John JG, Li L, Nazarenko L, Rosenbloom N, Seland Ø, Wu T, Yukimoto S, Ziehn T (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.
  78. ^ Andrew T (27 September 2019). "Behind the Forecast: How clouds affect temperatures". Science Behind the Forecast. LOUISVILLE, Ky. (WAVE). Retrieved 4 January 2023.
  79. ^ Zhang J, Furtado K, Turnock ST, Mulcahy JP, Wilcox LJ, Booth BB, Sexton D, Wu T, Zhang F, Liu Q (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.
  80. ^ "Trends in Atmospheric Methane". NOAA. Retrieved 14 October 2022.
  81. ^ Tollefson J (8 February 2022). "Scientists raise alarm over 'dangerously fast' growth in atmospheric methane". Nature. Retrieved 14 October 2022.
  82. ^ 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.
  83. ^ Feng L, Palmer PI, Zhu S, Parker RJ, Liu Y (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.
  84. ^ Li Y, Wang Z, Lei Y, Che H, Zhang X (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.
  85. ^ Luo F, Wilcox L, Dong B, Su Q, Chen W, Dunstone N, Li S, Gao Y (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.
  86. ^ Ponater M (2005). "On contrail climate sensitivity". Geophysical Research Letters. 32 (10): L10706. Bibcode:2005GeoRL..3210706P. doi:10.1029/2005GL022580.
  87. ^ Perkins S (11 May 2002). "September's Science: Shutdown of airlines aided contrail studies". Science News. Science News Online. Retrieved 13 October 2021.
  88. ^ a b Travis, D.J., A. Carleton, R.G. Lauritsen (August 2002). "Contrails reduce daily temperature range". Nature. 418 (6898): 601. Bibcode:2002Natur.418..601T. doi:10.1038/418601a. PMID 12167846. S2CID 4425866.
  89. ^ Travis D, 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.
  90. ^ "Jet contrails affect surface temperatures", Science Daily, 18 June 2015, retrieved 13 October 2021
  91. ^ Travis DJ, Carleton AM, Lauritsen RG (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.
  92. ^ 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.
  93. ^ Hong G, Yang P, Minnis P, Hu YX, North G (2008). "Do contrails significantly reduce daily temperature range?" (PDF). Geophysical Research Letters. 35 (23): L23815. Bibcode:2008GeoRL..3523815H. doi:10.1029/2008GL036108.
  94. ^ Digby RA, Gillett NP, Monahan AH, Cole JN (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.
  95. ^ Gettelman A, Chen C, Bardeen CG (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.
  96. ^ Zhu J, Penner JE, Garnier A, Boucher O, Gao M, Song L, Deng J, Liu C, Fu P (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.
  97. ^ Gettelman A, Lamboll R, Bardeen CG, Forster PM, Watson-Parris D (29 December 2020). "Climate Impacts of COVID-19 Induced Emission Changes". Geophysical Research Letters. 48 (3): e2020GL091805. doi:10.1029/2020GL091805.
  98. ^ Yang Y, Ren L, Li H, Wang H, Wang P, Chen L, Yue X, Liao H (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.
  99. ^ Sun S, Zhou D, Chen H, Li J, Ren Y, Liao H, Liu Y (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.
  100. ^ a b Xie X, Myhre G, Shindell D, Faluvegi G, Takemura T, Voulgarakis A, Shi Z, Li X, Xie X, Liu H, Liu X, Liu Y (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.
  101. ^ Pan B, Wang Y, Hu J, Lin Y, Hsieh J, Logan T, Feng X, Jiang JH, Yung YL, Zhang R (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.
  102. ^ 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.
  103. ^ 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.
  104. ^ Chang C, Chiang JC, Wehner MF, Friedman AR, 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.
  105. ^ Allen RJ (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.
  106. ^ Monerie P, Dittus AJ, Wilcox LJ, Turner AG (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.
  107. ^ Schewe J, Levermann A (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.
  108. ^ Tao W, Chen J, Li Z, Wang C, Zhang C (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.
  109. ^ Schewe J, Levermann A (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.
  110. ^ "Monsoon might fail more often due to climate change". Potsdam Institute for Climate Impact Research. 6 November 2012. Retrieved 25 March 2023.
  111. ^ Katzenberger A, Schewe J, Pongratz J, Levermann A (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.
  112. ^ Fan C, Wang M, Rosenfeld D, Zhu Y, Liu J, Chen B (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.
  113. ^ a b Smith W (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.
  114. ^ a b Gramling C (8 August 2018). "Global dimming may mitigate warming, but could hurt crop yields". Science News Online. Retrieved 6 January 2024.
  115. ^ a b "The Royal Society" (PDF). royalsociety.org. p. 23. Archived (PDF) from the original on 21 July 2015. Retrieved 20 October 2015.
  116. ^ 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.
  117. ^ 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.
  118. ^ 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.
  119. ^ William J. Broad (27 June 2006). "How to Cool a Planet (Maybe)". The New York Times. Retrieved 6 April 2009.
  120. ^ Robock A, Marquardt A, Kravitz B, Stenchikov G (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.
  121. ^ Grieger KD, Felgenhauer T, Renn O, Wiener J, Borsuk M (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.