These two satellite images show how aerosols can obscure the land and sea beneath, blocking incoming sunlight. On the top, aerosols over northeastern India and Bangladesh partially obscure the Ganges River and then are swept out over the Bay of Bengal. Notice how the high-altitude air over the Himalayas, near the top of the image, is clearer. On the bottom, smoke from dozens of fires (left side of image) in China swirls down along valleys and then out over Bo Hai Bay (upper right) on its way towards Korea and the Pacific Ocean.
Credits: Images courtesy of Jacques Descloitres, MODIS Land Rapid Response Team, NASA GSFC. Text from UCAR’s page on aerosols here.
From Ascribe Newswire
COLLEGE PARK, Md, March 12 — A University of Maryland-led team has compiled the first decades-long database of aerosol measurements over land, making possible new research into how air pollution changes affect climate change.
Using this new database, the researchers show that clear sky visibility over land has decreased globally over the past 30 years, indicative of increases in aerosols, or airborne pollution. Their findings are published in the March 13 issue of Science.
“Creation of this database is a big step forward for researching long-term changes in air pollution and correlating these with climate change,” said Kaicun Wang, assistant research scientist in the University of Maryland’s department of geography and lead author of the paper. “And it is the first time we have gotten global long-term aerosol information over land to go with information already available on aerosol measurements over the world’s oceans.”
Wang, together with Shunlin Liang, a University of Maryland professor of geography, and Robert Dickinson, a professor of geological science at the University of Texas, Austin, created a database that includes visibility measurements taken from 1973 – 2007 at 3,250 meteorological stations all over the world and released by the National Climatic Data Center (NCDC). Visibility was the distance a meteorological observer could see clearly from the measurement source. The more aerosols present in the air, the shorter the visibility distance.
According to the researchers, the visibility data were compared to available satellite data (2000-2007), and found to be comparable as an indicator of aerosol concentration in the air. Thus, they conclude, the visibility data provide a valid source from which scientists can study correlations between air pollution and climate change.
Aerosols, Greenhouse Gases and Climate Change
Aerosols are solid particles or liquid droplets suspended in air. They include soot, dust and sulfur dioxide particles, and are what we commonly think of when we talk about air pollution. Aerosols come, for example, from the combustion of fossil fuels, industrial processes, and biomass burning of tropical rainforests. They can be hazardous to both human health and the environment.
Aerosol particles affect the Earth’s surface temperature by either reflecting light back into space, thus reducing solar radiation at Earth’s surface, or absorbing solar radiation, thus heating the atmosphere. The variable cooling and heating effects of aerosols also modify properties of cloud cover and rainfall.
Unlike aerosol particles, carbon dioxide and other greenhouse gases are transparent and have no effect on visibility. Sunlight passes right through them, just as it does through the oxygen and nitrogen that are the main constituents of our atmosphere. Though present in the atmosphere in relatively small amounts, greenhouse gases cause global warming because these “trace” gases trap solar energy absorbed at the earth’s surface and prevent it from being radiated as heat back into space.
While the climate warming impacts of increased greenhouse gases are clear, the effects of increased aerosols are not. Studies of the long-term effects of aerosols on climate change have been largely inconclusive up to now due to limited over-land aerosol measurements, according to Wang and his team. However, with this database researchers now can compare temperature, rainfall and cloud cover data from the past 35 years with the aerosol measurements in the new database.
Global Dimming
According to the authors, a preliminary analysis of the database measurements shows a steady increase in aerosols over the period from 1973 to 2007. Increased aerosols in the atmosphere block solar radiation from the earth’s surface, and have thus caused a net “global dimming.” The only region that does not show an increase in aerosols is Europe, which has actually experienced a “global brightening,” the authors say.
The largest known source of increased aerosols is increased burning of fossil fuels. And a major product of fossil fuel combustion is sulfur dioxide. Thus, the team notes, that their finding of a steady increase in aerosols in recent decades, also suggests an increase in sulfate aerosols. This differs from studies recently cited by the Intergovernmental Panel Climate Change showing global emissions of sulfate aerosol decreased between 1980 and 2000.
I am concerned that the warmists will use the aerosols as part of their arsenal, saying: “See, if it weren’t for the aerosols, the planet would be warming up faster!”
Or do they have a point? I have been to-ing and fro-ing with a warmist friend who has contacts in the climatology business, and he has continually thrown out this concept of “The Plume”, a.k.a. the “brown cloud”. I wonder if he has fact on his side or if the brown cloud is only a side show, a distraction.
I look for further knowledgeable comment on the subject of whether this brown cloud is having an effect on “global temperature”.
From UCAR’s page — These images show three of the most important sources of atmospheric aerosols that can influence Earth’s climate: dust blown aloft by winds, soot from fires, and ash from volcanic eruptions.
India is one of the major countries that still uses open cooking fires for food preparation. Even in rural areas, the burning of wood, charcoal, and dung for fuel, coupled with dust from wind erosion during the dry season, creates an air pollution problem.
Here is an interesting research mashup — http://firefly.geog.umd.edu/firemap/ — It uses MODIS data. It shows in a near real time basis the fires that are burning around the globe. Most are agricultural fires, purpose set in third world countries for land clearing and old crop clearing operations. Sometimes it’s easy to spot the problems.
I contacted the group doing this and suggested a volcano mashup would be nice providing information about volcanic eruptions and the gases they spew worldwide. I noted some recent graphics of Kilauea and how large the plume of toxic fumes was. They took the suggestion into advisement.
Why do we always target the hard stuff first? Because that’s where the taxes are, and research needs tax money. Who is going to pay in Africa, India or the wilds of the Amazon.
Ian M (05:23:03) :
Current studies speculate that brown cloud could be a cause for global warming:
Deadly ‘brown cloud’ over South Asia caused by wood and dung burning
Jeremy Hance
mongabay.com
January 23, 2009
Lucy Skywalker (00:13:26) :”Silly naive question. (aha!) Why does the sky look blue when you look up, lightening the black night sky; but it doesn’t blue out the blackness of the oceans, even though it’s the same thickness?”
It is my understanding that the blueness of the water depends on the depth, the color of the bottom and the clarity of the water. The light is relfected off the bottom back up through the water. Clean, shallow water with a white sand bottom will give a very nice blue but if there is seaweed or grass on the bottom or if the water is dirty you only see “darkness”. In very deep water the light doesn’t get all the way to the bottom so there is nothing to reflect back. Light passing through water comes out blue. I do not know technically if it is refracted, reflected, or aborbed and re-emitted. But I do know that with everything else being equal, the more water light passes through the more blue color you see.
I read that, when pollution over LA was at its worst, it changed the weather patterns over the American west by wafting downwind, and weakening the summertime “Heat Low” which exists over Arizona. Then, when they cleaned up their act, the “Heat Low” regained its strength.
Anyone know if this is true?
It would be interesting to see if weather patterns show any change as various places on the planet go from clean to dirty, and then back to clean.
tarpon,
“From UCAR’s page — These images show three of the most important sources of atmospheric aerosols that can influence Earth’s climate: dust blown aloft by winds, soot from fires, and ash from volcanic eruptions.”
Hey, this can’t be right – where are the sulphate aerosols from fossil fuel burning that the article was going on about? 🙂
I think before this blue sky research gets too far along, I would pause and ask what conditions were like in terms of aerosols in the past. Oregon State University is a repository for research on natural fire cycles, catastrophic fires, Indian practices in fire management, fire suppression, and current controlled burn practices. The general consensus is that prior to 1900, the air was filled, regularly, with lots and lots of aerosols. The tree ring pattern suggests, around evidence of fire scars, that pre-fire conditions were wet and conducive to rapid growth. Just prior to , during fire, and just after scar evidence, drought conditions predominated. But then, rather rapidly, post-fire temperatures were once again wet and conducive to growth.
So did aerosols cause temperature changes in the past? The evidence is not clear just prior to and just after fire scars. What is clear is that tree ring growth, on average, between fire scars indicate wet conditions up to the year prior to fire scar, and then drought conditions occurred just before, during, and shortly after fire scar. Conditions then returned to wet growing years. The cycles in and around the western part of the US shows catastrophic fire cycles occurring in a mulitdecadal pattern (30 to 40 years) punctuated with major fires here and there inbetween in irregular patterns (accidental human caused fires? freak storm?). My bet is that temperature changed first, setting up dry fuel load from abundant growth during wet years. The fires then filled the air with aerosols. Therefore temperature change precedes aerosol load. Knowing what we do about cold versus warm temperatures, I would say that dry years were likely colder. Wet years were likely warmer. Wet and warm causes rapid growth of trees and underbrush alike. Cold and dry leads to freeze kill, drought kill, and fuel load.
Here is just one sample of many scholarly works on this topic.
http://www.nwmapsco.com/ZybachB/DRAFT/PhD_Thesis/Contents.htm
“Visibility was the distance a meteorological observer could see clearly from the measurement source. The more aerosols present in the air, the shorter the visibility distance.”
How do they differentiate between polution and clouds? Or are both consedered aerosols (even though water vapor was not listed in the description of aerosols in the next paragraph)?
From what i can gather sulphur compounds are involve in water droplet nucleation reactions. Therefor an increase would cause clouds to rain out quicker, reduce humidity and reduce albedo, potentially creating warming.
Cheers
This study is fatally flawed. You can’t calibrate aerosol proxies for 1973 through 2007 using data from 2000-2007 because the geographic distribution of aerosol generation during 1973-1993 was wildly different than during the calibration period.
Specifically, massive economic development in China and India have skewed the results.
RE: schnurrp (04:12:34)13/03 concerning: 1940-1975 warming “pause” as perhaps being caused by air pollution.
The matter could be a fine test on consistency of arguments, by checking the sulphate aerosols relation towards the mid-century global cooling concerning three facts, namely
A. the cooling started with extreme winters in Northern Europe in winter 1939/40; and
B. the temperatures were low during the winter season, when the effect of sulphate aerosols on sun ray was at the lowest, and thirdly
C. the pre WWII industrial activities presumably had been much higher than immediately after the end of WWII in 1945.
See: http://www.oceanclimate.de/Archiv/apr_08.html
Already back in 1981 the James Hansen’s team published their finding that, overall, Earth’s average temperature rose by about 0.4°C for the period from 1880 to 1978, but there was a global cooling from 1940-1970 that he considered subsequently as follows: “I think the cooling that Earth experienced through the middle of the twentieth century was due in part to natural variability,” he said. “But there’s another factor made by humans which probably contributed, and could even be the dominant cause: aerosols.” Meanwhile it is widely claimed that a high concentration of sulphate aerosols in the atmosphere may have had a cooling effect on the climate because they scatter light from the Sun, reflecting its energy back out into space, by industrial activities at the end of the second world war.
The way Hansen and his supporting colleagues handle the matter is hardly convincing. Anyhow one day the 1940-1975 warming “pause” needs to be explained much more convincingly.
Next thing you know, we will be told *pollution is ‘masking global’ warming*!
One study in Europe indicated much of the warming there in the ’80s and 90s was due to less aerosols blocking sunlight. As pollution controls kicked in, so did the effects of increased sunlight striking the earth.
I think you will find that in large areas of India and Bangladesh the main domestic fuel is still dried cow dung. I guess that would give off plenty of smoke.
I liked this part:
Unlike aerosol particles, carbon dioxide and other greenhouse gases are transparent and have no effect on visibility. Sunlight passes right through them, just as it does through the oxygen and nitrogen that are the main constituents of our atmosphere.
Apparently these “researchers” have either determined that water is not a GHG, or that clouds are transparent. Or maybe excluding cloud effect is settled science.
The focus shouldn’t be on that silly preoccupation with CO2, but rather on the particulate matter that’s spewn into the atmosphere from the inefficient use of fuels, whether biomass or coal. The more efficient the process under which coal is burned, the less particulate matter results and greater energy yield is realized. Today China is at the low end of the energy curve in their rush to power their growing economy. As a result, they emit large quantities of particulate matter. In the future they will appreciate that it’s not just particulate matter, but money that’s spewing from their smokestacks.
Tim Clark (11:37:41) :
Remember that sunlight is largely visible/UV wavelengths and these excite electronic transitions in appropriate molecules (chromophores). The greenhouse gases don’t particularly absorb EM radiation of these energies. The greenhouse gases absorb EM radiation in the infra red (especially long wave IR) which is emitted from the earth’s surface (LWIR excites vibrational transitions, not electronic transitions). That’s how the greenhouse gases work. They allow the solar irradiation through the atmosphere (ozone traps quite a lot of the UV) and partially “trap” the LWIR as it is emitted from the earth’s surface on its way back to space….
Of course if there are lots of atmospheric aerosols this can directly intercept/reflect some of the solar radiation, such that less reaches the Earth’s surface (“global dimming”), and thus these aerosols generally counter the effects of greenhouse gases (they have a nett cooling contribution), and it seems that their effect is currently to mitigate a significant part of the warming that would accrue from the enhanced greenhouse gas concentration in a “clean” (aerosol-free) atmosphere….
schnurrp (06:16:57) :
That’s not quite right I think. It is specifically the black carbon (BC) component of atmospheric brown clouds (ABC) that has an atmospheric warming effect. However overall the estimates of forcings from ABC are nett negative, and brown clouds have a cooling effect. If one were able specificially to remove the BC component from the ABC one would expect to get a bit of a cooling. However it’s not easy to see how one could do this.
Ramanathan and Carmichael wrote a detailed review of this subject last year:
V. Ramanathan & G. Carmichael (2008) Global and regional climate changes due to black carbon; Nature Geoscience 1, 221-227.
For a slightly less scholarly account, but with much of the salient detail see Ramanathan’s prepared testimony for the 2007 Wegman climate subcommittee hearing:
http://oversight.house.gov/documents/20071018110734.pdf
Evidently, these “clerics” know that when the Sun is at a long minimum, areosols increase due to a more active vulcanism, like the biggest known volcanic eruption of the Huaynaputina (See:
http://en.wikipedia.org/wiki/Huaynaputina )
And they are already prepared to explain the next Jose’ s Minimum by blaming anthropogenic contamination (CO2, aerosols, etc.)
Tom in Florida (07:07:59) :
Lucy Skywalker (00:13:26) :”Silly naive question. (aha!) Why does the sky look blue when you look up, lightening the black night sky; but it doesn’t blue out the blackness of the oceans, even though it’s the same thickness?”
It is my understanding that the blueness of the water depends on the depth, the color of the bottom and the clarity of the water. The light is relfected off the bottom back up through the water. Clean, shallow water with a white sand bottom will give a very nice blue but if there is seaweed or grass on the bottom or if the water is dirty you only see “darkness”. In very deep water the light doesn’t get all the way to the bottom so there is nothing to reflect back. Light passing through water comes out blue. I do not know technically if it is refracted, reflected, or aborbed and re-emitted. But I do know that with everything else being equal, the more water light passes through the more blue color you see.
having read up a little on this during the day, it seems that there are a few things happening.
In Daylight, scattering of molecules in the atmosphere creates a blue sky, this is turn is reflected of the surface of the water. On top of this, the ocean waters absorb red light from the refraction of waves/currents etc, which shows out the blue/green colour.
In darkness, the ocean reflects the black sky and there is very little light to refract in the water. The reason that lighting doesn’t show a blue ocean is mainly due to the ocean reflecting the usually white light of the lightning. Due to light refraction of the ocean, the reflection isn’t very well defined and can look very dark against a brightly lite sky from the lightning strike.
Hope this helps!
Please see Douglas Hoyt’s post below. He is the same D.V. Hoyt who authored/co-authored the four papers referenced below.
Please note there is historic data available that could be of considerable use.
BUT: “There is no funding to do complete checks.”
Anyone want to take on this challenge?
Suggest tapping into the millions that Obama has allocated for climate modelling to get these modelers some real data on aerolsols.
I understand they’ve been inventing aerosol data to get their models to history-match the cooling period from ~1945-1975. Hoyt says so such evidence exists in his data.
Regards, Allan
http://www.climateaudit.org/?p=755
Douglas Hoyt:
July 22nd, 2006 at 5:37 am
Measurements of aerosols did not begin in the 1970s. There were measurements before then, but not so well organized. However, there were a number of pyrheliometric measurements made and it is possible to extract aerosol information from them by the method described in:
Hoyt, D. V., 1979. The apparent atmospheric transmission using the pyrheliometric ratioing techniques. Appl. Optics, 18, 2530-2531.
The pyrheliometric ratioing technique is very insensitive to any changes in calibration of the instruments and very sensitive to aerosol changes.
Here are three papers using the technique:
Hoyt, D. V. and C. Frohlich, 1983. Atmospheric transmission at Davos, Switzerland, 1909-1979. Climatic Change, 5, 61-72.
Hoyt, D. V., C. P. Turner, and R. D. Evans, 1980. Trends in atmospheric transmission at three locations in the United States from 1940 to 1977. Mon. Wea. Rev., 108, 1430-1439.
Hoyt, D. V., 1979. Pyrheliometric and circumsolar sky radiation measurements by the Smithsonian Astrophysical Observatory from 1923 to 1954. Tellus, 31, 217-229.
In none of these studies were any long-term trends found in aerosols, although volcanic events show up quite clearly. There are other studies from Belgium, Ireland, and Hawaii that reach the same conclusions. It is significant that Davos shows no trend whereas the IPCC models show it in the area where the greatest changes in aerosols were occurring.
There are earlier aerosol studies by Hand and in other in Monthly Weather Review going back to the 1880s and these studies also show no trends.
So when MacRae (#321) says: “I suspect that both the climate computer models and the input assumptions are not only inadequate, but in some cases key data is completely fabricated – for example, the alleged aerosol data that forces models to show cooling from ~1940 to ~1975. Isn’t it true that there was little or no quality aerosol data collected during 1940-1975, and the modelers simply invented data to force their models to history-match; then they claimed that their models actually reproduced past climate change quite well; and then they claimed they could therefore understand climate systems well enough to confidently predict future catastrophic warming?”, he close to the truth.
_____________________________________________________________________
Douglas Hoyt:
July 22nd, 2006 at 10:37 am
Re #328
“Are you the same D.V. Hoyt who wrote the three referenced papers?” Yes.
“Can you please briefly describe the pyrheliometric technique, and how the historic data samples are obtained?”
The technique uses pyrheliometers to look at the sun on clear days. Measurements are made at air mass 5, 4, 3, and 2. The ratios 4/5, 3/4, and 2/3 are found and averaged. The number gives a relative measure of atmospheric transmission and is insensitive to water vapor amount, ozone, solar extraterrestrial irradiance changes, etc. It is also insensitive to any changes in the calibration of the instruments. The ratioing minimizes the spurious responses leaving only the responses to aerosols.
I have data for about 30 locations worldwide going back to the turn of the century.
Preliminary analysis shows no trend anywhere, except maybe Japan.
There is no funding to do complete checks.
These brown clouds certainly reduce the amount of solar radiation reaching the surface but no actual impact has been demonstrated from them.
A few salient points.
The models cannot properly model naturally-produced white clouds let alone human-produced brown clouds.
The impact of natural white clouds are orders of magnitude greater than any human-produced brown clouds.
Aerosols have been concentrated in the northern hemisphere mid-latitudes and NH lower latitudes recently but there is no cooling at these latitudes or in the immediate region nearby or in the regions affected by the prevailing winds.
The NH has been increasing at a faster rate than the SH which does not have anywhere near the Aerosols impact.
So, the conclusion has to be that human-produced Aerosols SHOULD reduce temperatures in isolation of other changes but they DON’T in actual fact.
“The numbers should always tell the story.” …
… “The story should not tell us what the numbers should be / must be changed to.”
Another way of saying it is, “facts are facts.”
Svante Arrhenius ( http://en.wikipedia.org/wiki/Svante_Arrhenius ) based his mathematical equations(model) on seeing big dirty smoke stacks chocking out a city( his bias) back in the 1800’s for his idea of CO2 poisoning. But he had good reason, because there was a lot of particulate seen(visible) in the air from coal burning in the homes and factories in those days, this is also the reason for his theory of trapped CO2 gas as in a “greenhouse gas strapping heat ” in a CLOSED ISULATED SYSTEM.
His idea doesn’t fly in the real world and has been proven WRONG in the OPEN SYSTEM of earth. And all the modern modeling programs or quantum computers on earth couldn’t figure that out.
And here we are in the future, chasing natural life giving CO2 as a poison/pollution?!
We’ve already cleaned with our fossil fuel burning, plus the particulate/off gases that could actually harm you. I hope that places like this get better advancements in fuel efficiency and emissions control. Not for the AGW flat earth sciences, but for the health of the people around and in close proximity to the REAL pollution.
“These brown clouds certainly reduce the amount of solar radiation reaching the surface but no actual impact has been demonstrated from them.”
You mean other than the decrease in pan evaporation that was one of the key results that led to the discovery of global dimming. But do carry on otherwise 😉
“Adolfo Giurfa (13:47:18) :
Evidently, these “clerics” know that when the Sun is at a long minimum, areosols increase due to a more active vulcanism, like the biggest known volcanic eruption of the Huaynaputina”
I am going to regret asking this but how does a solar minimum affect the earths vulcanism? And are you suggesting that industrial activity does not produce sulphate polution?
Dorlomin (05:27:58) :
“And are you suggesting that industrial activity does not produce sulphate pollution?”
As one who suffered an accident in a zinc refinery with SO2 gas I wouldn´t say that, BUT ANY AMOUNT THAT THE WHOLE HUMANITY (WHICH YOU OVERESTIMATE) could produce is but ridiculous compared to a single hour of a volcanic eruption.
All the GWRs. affirmations are also preposterous, as the CARBON CAPTURE issue for example capturing CO2 involves washing towers where this gas is washed with milk of lime (calcium oxide), which in turn it is obtained by calcining calcium carbonate (this means producing CO2)….so it is a matter of “biting its own tail”. The tale of CO2 as a greenhouse gas…(laughs in the background)
Come on!…so you go, when your feet are cold, to your bed with a bottle filled with AIR?, the air (once and for all) has a volumetric heat capacity 3,227 times LESS than water, so…my advice, take a bottle filled with hot water instead.
And that story which tells that CO2 (by the way 0.038% of the atmosphere) when heated doesn´t goes up to free its heat to stratosphere, and instead radiates down its heat, is like saying that a Balloon can not fly way up when filled with hot air heated with a propane burner (which produces CO2 and H2O- Water-).
The real issue is political and I have nothing to say about that except that all this telltale was invented by the Nazi party before the second world war.
See:
http://www.spunk.org/texts/places/germany/sp001630/peter.html