From the abstract of the lead paper by Martin Wild: Recent evidence suggests that solar radiation reaching the Earth’s surface has not been constant over time but has undergone substantial variations on decadal timescales. The available observations suggest a widespread decrease in surface solar radiation between the 1950s and 1980s (popularly referred to as “global dimming”), with some more recent evidence for a partial recovery (“brightening”).
From ETH Zurich News
“Global dimming and brightening” – The role of solar radiation in climate change
A special volume of the “Journal of Geophysical Research” reviews the growing research field of “global dimming” and “global brightening” in over 20 articles. These phenomena, supposedly human-induced, control solar radiation incident at the Earth’s surface and thus influence climate.
Special instruments have been recording the solar radiation that reaches the Earth’s surface since 1923. However, it wasn’t until the International Geophysical Year in 1957/58 that a global measurement network began to take shape. The data thus obtained reveal that the energy provided by the sun at the Earth’s surface has undergone considerable variations over the past decades, with associated impacts on climate.
Research focus at ETH Zurich
Investigating which factors reduce or intensify solar radiation and thus cause “global dimming” or “global brightening” is still very much a nascent field of research in which especially scientists from ETH Zurich became renowned. The American Geophysical Union (AGU) has now published a special volume on the subject which presents the current state of knowledge in detail and makes a considerable contribution to climate science. “Only now, especially with the help of this volume, is research in this field really taking off”, stresses Martin Wild, senior scientist at the Institute for Atmospheric and Climate Science of ETH Zurich, who is a specialist on the subject.
Decrease in solar radiation discovered
The initial findings, which revealed that solar radiation at the Earth’s surface is not constant over time but rather varies considerably over decades, were published in the late 1980s and early 1990s for specific regions of the Earth. Atsumu Ohmura, emeritus professor at ETH Zurich, for example, discovered at the time that the amount of solar radiation over Europe decreased considerably between the 1950s and the 1980s. It wasn’t until 1998 that the first global study was conducted for larger areas, like the continents Africa, Asia, North America and Europe for instance. The results showed that on average the surface solar radiation decreased by two percent per decade between the 1950s and 1990.
In analyzing more recently compiled data, however, Wild and his team discovered that solar radiation has gradually been increasing again since 1985. In a paper published in “Science” in 2005, they coined the phrase “global brightening” to describe this new trend and to oppose to the term “global dimming” used since 2001 for the previously established decrease in solar radiation.
Only recently, an article in the journal “Nature”, which Wild was also involved in, brought additional attention to the topic of global dimming/brightening.
Air pollution favors photosynthesis
In this study, for the first time, the scientists examined the connection between global dimming/brightening and the carbon cycle. They demonstrated that more scattered light is present during periods of global dimming due to the increased aerosol- and cloud-amounts, enabling plants to absorb CO2 more efficiently than when the air is cleaner and thus clearer. According to the scientists, this is because scattered light penetrates deeper into the vegetation canopy than direct sunlight, which means the plants can use the light more effectively for photosynthesis. Consequently, there was around 10 percent more carbon stored in the terrestrial biosphere between 1960 and 1999.
The special volume, which appears in the AGU’s renowned “Journal of Geophysical Research”, provides an overview of the current state of knowledge. Almost half of the publications in the volume were either completely or partially written by ETH Zurich scientists. Wild is the guest editor, and author or co-author of ten of these articles.
The articles provide the first indication of the magnitude of these effects, how they vary in terms of time and space and what the possible consequences might be for climate change. They also discuss in detail the underlying causes and mechanisms, which are still under debate.
Many questions left open
It is particularly unclear as to whether it is the clouds or the aerosols that trigger global dimming/brightening, or even interactions between clouds and aerosols, as aerosols can influence the “brightness” and lifetime of the clouds. The investigation of these relations is complicated by the fact that insufficient – if any – observational data are available on how clouds and aerosol loadings have been changing over the past decades. The recently launched satellite measurement programs should help to close this gap for the future from space, however.
“There is still an enormous amount of research to be done as many questions are still open”, explains Wild. This includes the magnitude of the dimming and brightening effects on a global level and how greatly the effects differ between urban and rural areas, where fewer aerosols are released into the atmosphere. Another unresolved question is what happens over the oceans, as barely any measurement data are available from these areas.
A further challenge for the researchers is to incorporate the effects of global dimming/brightening more effectively in climate models, to understand their impact on climate change better. After all, studies indicate that global dimming masked the actual temperature rise – and therefore climate change – until well into the 1980s. Moreover, the studies published also show that the models used in the Intergovernmental Panel on Climate Change’s (IPCC) fourth Assessment Report do not reproduce global dimming/brightening adequately: neither the dimming nor the subsequent brightening is simulated realistically by the models. According to the scientists, this is probably due to the fact that the processes causing global dimming/brightening were not taken into account adequately and that the historical anthropogenic emissions used as model input are afflicted with considerable uncertainties.
“This is why at ETH Zurich we are working with a research version of a global climate model, which contains much more detailed aerosol and cloud microphysics and can reproduce global dimming/brightening more effectively”, says Wild. For him, the studies so far constitute “initial” estimates that need to be followed up with further research.
Link to these papers in JGR here
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…studies indicate that global dimming masked</b< the actual temperature rise…
Can everyone stop using the word mask. Please ?
It suggests errors in observation and/or method:
the car’s true speed was masked by the over-sized tires
If we really mean that effect X was reduced or countered by some opposite effect Y then why not just say so…
the car’s speed was reduced by a strong headwind
the effect of the heater was reduced when Sally opened the window
Or was the global dimming so bad that no-one could even see the thermometers and weather stations ? This would “mask the actual temperature rise…”
My poor lil brain is getting confudled by this dimming brightening stuff… Ok so dimming at the surface would make sense to me as causing cooling, but dimming by viewing from the outter atmosphere would suggest to me more short wave is being absorbed (and long wave radiated), and brightening would mean more is being reflected. Maybe the dimming is caused by the atmospheric depth scattering the short wave and… nope still makes no sense too me! Does increased GHG’s effect atmospheric depth?(im thinking humidity)
The musings o an ignorant farmer im afraid.
ON topic:
I need a little help from my friends. My question is as follows:
If the range of attractive force between nuclei in the core of the Sun (ro) are < 1.4 x 10^-13 cm and the kinetic energy is 10^-3 the required energy to overcome the Coulomb barrier (repulsive force between charged nuclei, protons in this case); how nuclear reactions (fusion) could take place? I mean, by means of what mechanism the nuclear reactions can take place if there is not a single nucleus in the Sun with the load of energy enough as to overcome the repulsive force?
It is not a question to resolve homework neither a loaded question; I am thinking on a possible mechanism by which the nuclear reactions in the Sun would continue happening still when the Sun switches off in this precise moment (we would not perceive any change for at least 40000 years). Perhaps, from your response I could answer MikeE’s questions.
I would be very grateful if anyone can answer my question or, at least, gives me a clue. Thanks!
Another paper highlighting short comings in the IPCC models!
Interesting to know whether GCR are involved in these changes or whether or not it is a response to ocean temperature.
Nasif Nahle (17:36:34) :
What if the conventional idea of how the sun works it is another urban myth?
Look: http://www.thesurfaceofthesun.com/
Nasif Nahle 08:44 thanks for the link and invitation to visit AGU. I looked at their site and much is very general, and I would not expect geophysicists to be seduced by the AGW siren song — unless finances are involved. I must defer to the scientists to assess that one.
“Brightening” and “Dimming” simply raise my grumpy meter. I like concepts like aerosols, atmospheric gases like water vapor, “real” pollution, dust, smoke (like lots of black carbon in Los Angeles, a real health hazard), etc. The “globalness” of it all gives me the creeps, like all the AGW scams.
Pamela Gray, I guess I must be glad that I don’t live in northeast Oregon, even with your magnificently clear skies. However, at least in late spring, your country is one of the wonders of the world; the beauty is unsurpassed — the Blues, Wallowas. And looking down from a mile high at the Snake River in Hells Canyon is spectacular. Probably farming the area would be a challenge. Perhaps “she” is a white witch even though offering a cold you-know-what?
Nasif Nahle (17:36:34) :
ON topic:
I need a little help from my friends. My question is as follows:
If the range of attractive force between nuclei in the core of the Sun (ro) are < 1.4 x 10^-13 cm and the kinetic energy is 10^-3 the required energy to overcome the Coulomb barrier (repulsive force between charged nuclei, protons in this case); how nuclear reactions (fusion) could take place? I mean, by means of what mechanism the nuclear reactions can take place if there is not a single nucleus in the Sun with the load of energy enough as to overcome the repulsive force? .
Quantum mechanics.
Once the distances between nuclei become of the same range as strong interactions, due to the gravitational pressure, quantum mechanics takes over. Coulomb repulsion at that distance level is orders of magnitude smaller than the strength of strong interactions ( hence the term).
Nasif Nahle (17:36:34) :
continuing:
add the “tunneling effect” of quantum mechanics for the borderline cases.
In a sense there is no barrier for the strong force to overcome, except to come into range, and the gravitational pressure takes care of that.
The whole AGW debate has, in my view, been sidetracked into a debate about what to do as a result of the predictions of a generation of models.
That’s all it ever was in the first place.
I can’t find a copy of the first IPCC report, but from memory it concludes – The science is too uncertain as to what will happen to the climate in the future therefore we have to rely on the climate models.
Head’s up for those interested in North-South asymmetry:
Research the works of Russian scientist Yu.V. Barkin.
“If the range of attractive force between nuclei in the core of the Sun (ro) are < 1.4 x 10^-13 cm and the kinetic energy is 10^-3 the required energy to overcome the Coulomb barrier (repulsive force between charged nuclei, protons in this case); how nuclear reactions (fusion) could take place?"
In the core of the sun the pressure and temperature are high enough that it can overcome Coulomb forces in order for nuclei to get within range of the strong force and fuse. Quantum tunnelling is associated with the wave-length of a particle which gets longer (hence can tunnel further) as you get colder, so you won't find tunnelling effects in the sun.
In Quantum Mechanics (the physics of small things) there is no certainty, only probability. So even if a particle does nor have enough energy to cross a barrier, there is a probability it will do so anyhow. Like going through a tunnel.
(The square of the absolute value of Schrödinger’s wavefunktion that describes the particle is the probability-density to find it in that spot).
Weather predictions of 85 to 90 degrees today for eastern slope of Rockies (Denver area). It was cooler than normal this morning, and very hazy from (I assume) the California wildfires. I “assume” because every time there are wildfires in California, it’s hazy – and often cooler – “downwind”.
Anyhow… it’ll be interesting to see how the predictions for mid-80’s pan out.
Thanks for your answers, Sandy, Anna, Nogw and Alexej Buergin.
Nogw (18:02:07) :
Nasif Nahle (17:36:34) :
What if the conventional idea of how the sun works it is another urban myth?
Look: http://www.thesurfaceofthesun.com/
Very intersting. I wonder how that theory would solve the problem, although according to the theory it would be restricted to the photosphere, in any case.
Sandy (00:34:24) :
In the core of the sun the pressure and temperature are high enough that it can overcome Coulomb forces in order for nuclei to get within range of the strong force and fuse. Quantum tunnelling is associated with the wave-length of a particle which gets longer (hence can tunnel further) as you get colder, so you won’t find tunnelling effects in the sun.
I had priory thought in this solution; I mean, high pressure and temperature in the core of the Sun as possible solution. However, this solution generates more unsolvable events, like geometrical dilution and premature exhausting of protons, for example. Besides, the kinetic energy of protons in the core at high temperature and pressure lessens the nuclear cross section for nuclear reactions, so the dependence of nuclear fusion on quantum tunneling escalates, probabilistically talking.
anna v (22:34:56): and anna v (22:46:21):
Quantum mechanics.
Once the distances between nuclei become of the same range as strong interactions, due to the gravitational pressure, quantum mechanics takes over. Coulomb repulsion at that distance level is orders of magnitude smaller than the strength of strong interactions ( hence the term).
add the “tunneling effect” of quantum mechanics for the borderline cases.
In a sense there is no barrier for the strong force to overcome, except to come into range, and the gravitational pressure takes care of that.
The problem is that the kinetic energy of the protons in the core is not high enough as for protons overcome the Coulomb barrier. When one proton comes into range of another proton the repulsive force is stronger than the gravitational influence and protons’ kinetic energy doesn’t rise above the Coulomb barrier.
I think your explanation of quantum tunneling is the most feasible solution. The classical solution complicates more the problem and ends for radiating inconsistencies.
By the way, I’d like to know the total amount of protons playing in the Sun; I do remember from my school a ghostly cipher with many zeroes, but don’t remember it.
Alexej Buergin (06:15:06):
In Quantum Mechanics (the physics of small things) there is no certainty, only probability. So even if a particle does nor have enough energy to cross a barrier, there is a probability it will do so anyhow. Like going through a tunnel.
(The square of the absolute value of Schrödinger’s wavefunktion that describes the particle is the probability-density to find it in that spot).
Definitely, this is the solution; Anna and you coincide on this. Do you know what the total amount of protons in the Sun is? I don’t remember the cipher.
If my calculi run Ok, I’ll give an answer to MikeE’s question in one or two hours. Thank you friends!
“”” Alexander Feht (01:26:32) :
I have an ability to see a little more into the UV part of the spectrum than most people (I call the shade that I see “bluish white” or “ultramarine white”), and I routinely noticed that the sunlight in the end of 1990s was much harsher, and much more suffused with the UV radiation than the sunlight of my childhood years (1960s). Especially harsh “bluish white” Sun even made me worry about my eyesight in Arizona in 1998.
But who would pay attention to the observations of an obscure Russian poet? “Experts” know it all, don’t they. “””
Optics Handbooks dealing with the sun, as an example of “natural light sources” comment on the fact that the effective color temperature of the sun (as seen from the earth’s surface) is known to vary seasonally, and also erratiucally at other intervals. Such studies date back to the 1940s and 50s when the Air Force was doing studies related to high altitude flight.
Such color temperature changes were attributed to changes (seasonal and otherwise) in the UV end of the solar spectrum; which is an area where the solar spectrum is known to deviate from a simple black body radiation curve.
They don’t mention it, but such observations can arguably be attributed to the appearance and disappearance of Ozone holes, which have a seasonal component.
In other words; ozone holes existed, long before CFCs, and caused variations in the ground level solar spectrum; long before somebody wondered about ozone holes and looked for them; which I think was somewhere around the IGY in 1957/8
So solar UV variations are nothing new.
George E. Smith (13:14:55) and Alexander Feht (01:26:32):
No holes in the ozone layer. Really, there are not holes in the ozone layer.
The term “ozone hole” was invented by environmentalists for shaking the public up, but there are not ozone holes in the ozone layer. Perhaps slight depletions that seasonally grow and diminish in association with geomagnetic fluctuations, but no, nothing like holes in the ozone layer.
Nasif Nahle (09:43:42) Here you’ll find the papers of the author of this theory
http://www.omatumr.com/
I shall elaborate a little on the effect i was kinda referring too… i dont know what the term for it is, but one easy way for short term weather prediction is how distant objects appear.. for instance, i live in the shadow of a volcano(mt taranaki) when it appears distant, its going to be fine, when it appears magnified, its going to rain. Id imagine people have used this method for thousand of years for weather prediction.(obviously in conjunction with cloud formation/wind direction/type o light at setting/rising o sun, way sound travels etc)
I hadnt given it any thought at all until i read this thread, and really have no idea on the mechanism of this phenomenon.(a quick google didnt help.. probably because im unsure on the labeling) But the atmosphere defiantly displays variable optical properties, seemingly influenced by atmospheric pressure/ or possibly humidity/ or possibly thermal disruption?(but independent of aerosols… well as far as i can tell) It indicates to me that light is scattered more, during atmospheric highs… and if it does it laterally, it seems possible that this would also be true vertically? although not necessarily.
If anyone could enlighten me, id appreciate it. 🙂
“”” Nasif Nahle (13:29:33) :
George E. Smith (13:14:55) and Alexander Feht (01:26:32):
No holes in the ozone layer. Really, there are not holes in the ozone layer.
The term “ozone hole” was invented by environmentalists for shaking the public up, but there are not ozone holes in the ozone layer. Perhaps slight depletions that seasonally grow and diminish in association with geomagnetic fluctuations, but no, nothing like holes in the ozone layer. “””
I didn’t coin the term Nasif; but “ozone holes” is the name under which this phenomenon is understood by the lay public.
I merely pointed out that there is ample evidence for the existence of whatever it is that they call “ozone holes” long before someone decided to make them headline news; and long before any possible man made cause (that’s anthropogenic in four letter words (mean word length of course)).
Well after a few days of thought, and watching my mountain as we’ve just come out of a depression into a high… ive come to the conclusion that its an air pressure caused phenomenon, basically during a high pressure, the light is traveling through more air, and getting scattered more than during a low pressure. Although humidity also seems to play a role… I know that the seasonal effect is quite noticeable, with the mountain being close to seeming half the size during a hot summer high, than during a winter low. And the variations between highs and lows being most noticeable during the summer months(thus the reason im speculating that humidity plays a role.)
But i have become quite curious about this, and would truly be thankful if one of the more enlightened posters would be able to explain what does cause this effect.
And if its a stupid question i apologize, but just say so;-)
Oh and obviously the reason why this thread got me thinking about this effect, is that it seems that the dimming/brightening seems to be in counter phase to climate trends… roughly. And if higher humidity(not relative humidity) on average is expected through warming periods, and less humidity through cooling, and it effects atmospheric depth, It dosnt seem entirely impossible that this could cause a counter feed back to the current trends, irrespective if its a positive or negative trend.
just the rambling thoughts of a curious farmer.
MikeE
As regards your mountain and weather/visibility changes I think you are commenting on a different phenomenon to the global dimming/brightening aspect.
There are old weather sayings that clearer air is less stable air (generally but not always). That is because rainfall washes particulates out whereas stable air tends to accumulate airborne particulates over time.
However I do agree that it is logical to suppose that a generally warming atmosphere might have different optical qualities to a generally cooling atmosphere. I suggested that in my earlier post on this thread.
Stephen Wilde (23:24:30) :
Thanks Stephen for the response, this could certainly explain this effect. I do understand the traditional theory of global dimming with sulphates/particulates basically reflecting away more light. ( through creating a nucleus for cloud formation)
in my mind at least, it seems possible that if the atmosphere causes more scattering of the light at certain stages that it could effect the amount of light reaching the ground, but more dependent on angle of light(time o year/latitude) more so than high reflective cloud as such.
Pamela Gray wrote:
“…Under clear sky conditions, we “look” brighter if we were standing on the moon. Under dusty, cloudy, murky conditions, we “look” dimmer if we were standing on the moon. …”
At the next moon landing, instrumentation that measures the earth’s albedo should be put in place. This would eliminate all the missing ocean data.
George E. Smith (15:20:44) :
“”” Nasif Nahle (13:29:33) :
The term “ozone hole” was invented by environmentalists for shaking the public up, but there are not ozone holes in the ozone layer. Perhaps slight depletions that seasonally grow and diminish in association with geomagnetic fluctuations, but no, nothing like holes in the ozone layer. “””
I didn’t coin the term Nasif; but “ozone holes” is the name under which this phenomenon is understood by the lay public.
I merely pointed out that there is ample evidence for the existence of whatever it is that they call “ozone holes” long before someone decided to make them headline news; and long before any possible man made cause (that’s anthropogenic in four letter words (mean word length of course)).
I apologize and agree with your last statement. 🙂