fr en es pt
        rss astronoo

Global dimming

Global dimming

 Automatic translationAutomatic translation Category: ecology and environment
Updated June 01, 2013

The global dimming, changes the climate of our planet since the 1950s.
The darkening, revealed for the first time by Gerald Stanhill, Israeli biologist, is the reduction of light intensity that reaches the Earth day.
The dimming creates a cooling effect is counteracting greenhouse warming our climate.
It is likely that this effect is partly masked the magnitude of global warming.
From 1950 to 1985, the solar radiation on the surface of the land has decreased from 8 to 30% taking into account regional and seasonal fluctuations. While the African and American continents, the researchers measured a decrease of 15% sunlight, darkening the lowest were measured in northern Europe and Australia and strongest darkening (30%), Russia . The main cause of this "global dimming" is the activity of the rich countries that emit continuous microparticles in the air.
These microparticles from our factories and the burning of oil in our vehicles, load water droplets of clouds, turning them into real mirrors.


Sunlight reflected from the cloud layer is then more important and less light reaches us.
Less light means lower temperatures in some areas of the planet and less evaporation in the oceans. The drama of the 1980s drought in Ethiopia would be one consequence.
The slightly cooler temperatures have prevented masses of humid tropical Africa to go back to the Sahel.
This decrease in brightness which mitigates global warming, shows that we may have underestimated the magnitude of global warming.
The situation is so complicated for humanity, since we must not only respond promptly against global warming but also against the global dimming.

 cloud of pollution

Image: June 20, 2008 Temperature 39 ° C, a thick cloud of pollution hangs over the city of Athens. It was during a heat wave that industrial pollution is seen most.

Rapid climate change


The rapid climate change is not limited to a simple rising temperatures. The reasons are many and complex.
The most surprising is that independent studies are part of a phenomenon which joins that of global warming, global dimming.
This effect, found everywhere in the world, is the result of increased average rate of aerosols in the atmosphere after emission of various particles related to forest fires, motorized transport, the activity of our factories and the burning of fossil fuels.
Gerald Stanhill, in its action of sunlight in Israel for an irrigation project, "I was amazed to see a very substantial reduction of sunlight in Israel. When we compare these measurements in the fifties with the current measures, we see that there was a decrease of 22% astronomical, and it is incredible. "
We see all this dark mist suspended in the atmosphere of our cities.
Beate Liepert, German graduate researcher in climatology, conducted an independent study on the subject and found similar results. "I also tank as any climatologist. But once I found the same results in Germany, so I thought, "says she.


50 years later, global dimming is no longer doubt, also confirmed by two Australian biologists, Graham Farquhar and Michael Roderick, both of the Australian National University. They found a global decline in the rate of evaporation, and think about the question "It appears that the key factors for evaporation are the sunlight, humidity and wind. But the sunlight is really the dominant factor. If the evaporation rate decreases, it may be because the sun declines, "they say.
The impact of this global dimming can significantly alter the rate of precipitation and decrease in other monsoon regions such as Asia, which may eventually lead to famine in Africa first, then Asia. Dr. Leon Rotstayn, climatologist working in atmospheric research, said that "these droughts in the seventies, eighties, may have been caused by pollution from Europe and North America, affecting properties clouds and cooling the oceans of the Northern Hemisphere.
Pollution from the industrialized North is indirectly related to food tragedies countries developing. "There is no choice here, we need to reduce air pollution, or elimination," he concluded.

 tiny drops of water

Image:  Clouds are formed by tiny drops of water. When the water vapor that is in the air begins to condense, it captures what is in the air like pollen, dust and any particles of ash, soot and sulfur dioxide that it meets.
Thus, the pollution clouds contain more water droplets, but much smaller than those formed in the absence of particle.

The sky dramatically clean September 12, 2001


Aerosols and other micro particles emitted into the atmosphere apparently limited impact of global warming. David Travis, a climatologist, has studied the impact of aircraft contrails on climate. For this he took the ban on overflying U.S. following the attacks of September 11, 2001. There was an increase of more than one degree in three days.
"To a layman it is not very impressive, but the climate plan is enormous," he explains. The world-renowned climatologist, Veerabhadran Ramanathan of the University of California, laying a new stone to the edifice: "Almost everything we do to create energy pollutes.
According to our models, human impact was 1%, in fact, multiply it by 10. Since 1985, we see a return of sunlight in areas where emissions of these particles decreased significantly.


Climatologist David Travis concluded: "We thought we lived in a warming world, but it is actually not true. We live in a world of global warming over a weakening global world, and now we remove the overall weakening. We thus find a world of global warming, which will be much worse than we thought, much warmer.

Image: David Travis: from 11 to 13 September 2001, data collected from more than 5000 weather stations in 48 states across the country have shown that the temperature can vary considerably from one day to another. Then it usually changes very slowly, the temperature variation between day and night was higher, higher day and lower at night during those three days of observation.

 temperature variation between day and night

Strangely evaporation reduction


For decades, nobody has paid attention to measures of evaporation, but in 1990, scientists noticed something strange, the evaporation rate is declining.
Professor Graham Farquhar "There was a paradox between the fact that the evaporation rate of the tank was down, while global warming was increasing.
Moreover the increase in global temperature should increase the rate of evaporation of water, but Farquahr after some calculations, concluded that the temperature is not the only important factor in the evaporation of water. Dr. Michael Roderick: Although the reasons for the evaporation in the tank, are the rate of sunlight, humidity and wind, the determining factor here is the evaporation rate of radiation from the sun and therefore the light.
They found that through the energy of photons that reach the Earth as sunlight, the evaporation of water molecules occurs in the atmosphere. If the level of evaporation reduction is that perhaps the intensity of the sun was lower. The decrease in evaporation is clear evidence of global dimming. In the middle of the Indian Ocean, the Maldives chain of islands, has enabled Veerabhadran Ramanathan, meteorologist, to unravel the mystery of what is causing the blackout.


Prof. VR: the decline of the sun on Earth, is obvious. Virtually everything we produce as energy produces pollution.
By burning fuel we increase the greenhouse effect and thus global warming but also small particles of soot and other pollutants floating in the air, which are the cause of the haze that covers our cities . Then wondered Ramanathan pollution could be the cause of global dimming. The Maldives seems a place without pollution, but done in the northern islands of dirty dust, from India, reached the islands. Only the southernmost islands of the archipelago, enjoy the clean air of Antarctica. When comparing the air from the north with the south, Ramanathan and his colleagues establish a link with pollution of the atmosphere and the effect it causes.

 Veerabhadran Ramanathan

Image:  Veerabhadran Ramanathan "The most impressive experience was the size of the layer of pollution, which amounted to 3 km. Thick, preventing the passage of sunlight, estimated at 10%. Our models have shown that the human impact on global dimming of the planet is multiplied by 10 compared to our forecasts. "

Solar activity


Since the 1950s, the sun has a phase of extraordinary activity.
This is the conclusion reached that researchers at the Max Planck Institute for Research on the Solar System, in collaboration with Finnish scientists in an article published in the journal Physics Letters Revew.
The temporal development of solar activity seems to follow very closely that of the mean temperature at Earth's surface, which reflects the sun's influence on the Earth's climate.
However, researchers have shown that the warming of the last 30 years can only partially be attributed to solar activity.
It follows that if the solar activity affects the climate, it played only a minor role in the recent warming.
The sun, great source of heat, has allowed life to flourish on our planet and guides its major climatic changes. Seen from Earth, the moon seems very peaceful yet it is the seat of storms and explosions of extreme violence.
The European Space Observatory Soho allows specialists to have a full and uninterrupted view of the Sun.


They can analyze it from several angles: oscillations, electromagnetic radiation, plasma and solar wind.
The satellite collects each day thousands of images and data that allow scientists to better understand weather on a planetary scale.

Image:  Prominences seen by the SOHO satellite from January 2000 to May 2001. Credits: SOHO / EIT (ESA & NASA)

 activite Solaire Soho

World energy demand


World oil demand will probably continue to rise in the next thirty years.
According to the International Atomic Energy Agency (IEA), this growth could be 60%, a forecast that remains uncertain, as it is difficult to assess population trends, economies, ways of Life, technology or geopolitical developments.
All forecasters agree on the fact that consumption growth will be largely driven by emerging countries like China or India, which have experienced buoyant economic growth.
The application of these countries will increase three times faster than the OECD area to almost half the total oil demand in 2030 (against 13% in 1970).

Image: tep (ton oil equivalent)

 demande pétrolière mondiale



It seems that scientists have great difficulty in unanimously affirming that global warming is anthropogenic. Some figures denounced the part of humankind in this warming, others show that the temperature of the planet is undergoing upheaval in time and this is natural.
Cycles in Earth's climate, we are in the hottest period of the interglacial curve which means that we are heading towards an ice age but it is difficult to see, our time is not superimposed in time geology of our planet. Yet the return of ice on the planet should arrive within several tens of thousands of years.
Since the end of the last glacial period there are 18 000 years, the climate is mild and relatively stable.


We are therefore in this period where it averaged 15° Celsius on the planet. Nevertheless there is a dangerously rapid rise in temperature, corroborated by the summary of the IPCC 2007, which describes a temperature rise of 0.74 ° C per 100 years, over 25% more than the increase of 0 6 ° C cited in its 3rd report 2001. What is certain is that we reject more and more CO2 and other wastes, stinking and this may continue, because the energy needs of the global population increases with population.
We note that both the nature rages more violently and at the same time that the living world is struggling to adapt to these climatic fluctuations, leaving the weakest.


It is as if our macro body "the Earth is currently experiencing a little" fever ".
Just as in warm-blooded animals, his fever is a defense against internal aggression which forced him to turn certain immune mechanisms to regain his balance.
Just hope that these mechanisms do not fight the man as if it were a foreign infectious agent. Humanity must now prove wise it is a clean, non-grantor foreign planet Earth.

Toumai our ancestor,
old 7 million years...
The bipedalism
in hominids...
1997 © − Astronomy, Astrophysics, Evolution and Earth science.
Contact    Mentions légales
Hurricane Catarina
Effects of
the global warming...
Cloud cover above the earth
Cloud cover
above the earth...
tornado, scale Fujita
of tornadoes...
tree Of Life
Border between
inanimate and living...
volcan gris
at the origin of life...
galaxy NGC1672
Are we alone
in the universe?
Aquarius satellite observation of ocean salinity
New picture of ocean salinity...
ice cores tell us about the past...
Ice cores tell us about the past...
la vie de la Terre
The life of the Earth
seen by man...
solar Storms
The perfect storm
would be devastating...
DNA carrier of genetic information
Story of the evolution
towards the living...
développement durable
Sustainable development,
the living observe us...
The positions of the space probes in 2011
Where are our space probes?