Global Dimming Causes and Effects
“It is thought that global dimming is probably due to the increased presence of aerosol particles in the atmosphere caused by human action. Aerosols and other particulates absorb solar energy and reflect sunlight back into space. The pollutants can also become nuclei for cloud droplets. Water droplets in clouds coalesce around the particles Increased pollution causes more particulates and thereby creates clouds consisting of a greater number of smaller droplets (that is, the same amount of water is spread over more droplets). The smaller droplets make clouds more reflective, so that more incoming sunlight is reflected back into space and less reaches the Earth’s surface. This same effect also reflects radiation from below, trapping it in the lower atmosphere. In models, these smaller droplets also decrease rainfall.
Clouds intercept both heat from the sun and heat radiated from the Earth. Their effects are complex and vary in time, location, and altitude. Usually during the daytime the interception of sunlight predominates, giving a cooling effect; however, at night the re-radiation of heat to the Earth slows the Earth’s heat loss, this causes storms and subsequent flood rains and flooding.” (WIKIPEDIA)
In 1999, Dr. Joyce Penner’s research concluded that aircraft contrails warm the climate. This IPCC study was published two years before aircraft were grounded following the 9/11 event. IPCC Special Report on Aviation and the Global Atmosphere”, 1999 (PDF)
The post 9/11 observation that reported a diurnal temperature range increase didn’t change Penner’s conclusion that contrails drive global warming.
For example, the temperature “range” (hot to cold) can increase while the average temperatures would become cooler.
According to Dr. Penner’s study the absence of “thin high clouds” will cause average temperatures to drop when long-wave radiation is free to radiate back into space and not trapped by man-made cirrus clouds from aircraft contrail emissions. This fact is usually ignored or presented in such a way as to be intentionally confusing. The post 9/11 diurnal measurement is a statement about temperature “range” (highs and lows) rather than how the increased fluctuations would lower surface temperatures.
This Science Daily article discusses the increase in diurnal temperature range but fails to mention how the expected result would be lower surface temperatures.
[ IPCC Special Report on Aviation and the Global Atmosphere”, 1999 ] (PDF)
(Pg.7) “Contrails tend to warm the Earth’s surface, similar to thin high clouds”
(Pg.8) “Increases in soot tend to warm while increases in sulfate tend to cool the Earth’s surface.”
Example of Extreme Aircraft SOOT “Contrail” Emissions:
Mike Decker Published Mar 27, 2018
A study by J. Marvin Herman, PhD names Coal Fly Ash (soot) as aerosol cloud seeding agent – “Obtaining Evidence of-Coal Fly Ash” (PDF)
Herndon also points to the more generic issue of pollution as a cause for atmospheric warming – “Air Pollution, Not Greenhouse Gases: The Principal Cause of Global Warming” (PDF)
(VIDEO) Years of persistent drought over California can be credited to heavy aerosol cloud seeding over the eastern Pacific ocean.
(VIDEO) Time-lapse video by Patrick Roddie demonstrates aerosol cloud seeding drifting inland from eastern Pacific ocean.
Climate scientist, Jasper Kirkby confirms aircraft are seeding clouds with aerosols in the troposphere. Kirkby makes the point that super-saturation with aerosols causes clouds to rain-out more slowly, thus forcing drought.
GLOBAL DIMMING (IMDb) – Horizon producer David Sington on why predictions about the Earth’s climate will need to be re-examined. Questions and answers about global dimming.
NOTE: The following narrative and assumptions about global dimming before 2005 come under serious question in the light of climate engineering via deliberate aerosol super-saturation by aircraft. Aerosols deployed in the troposphere will inevitable warm the climate by trapping long-wave infrared radiation – especially the carbon black aerosols increasingly documented with powerful telescopic lens cameras.
Horizon producer David Sington on why predictions about the Earth’s climate will need to be re-examined.
Questions and answers about global dimming
We are all seeing rather less of the Sun. Scientists looking at five decades of sunlight measurements have reached the disturbing conclusion that the amount of solar energy reaching the Earth’s surface has been gradually falling. Paradoxically, the decline in sunlight may mean that global warming is a far greater threat to society than previously thought.
The effect was first spotted by Gerry Stanhill, an English scientist working in Israel. Comparing Israeli sunlight records from the 1950s with current ones, Stanhill was astonished to find a large fall in solar radiation. “There was a staggering 22% drop in the sunlight, and that really amazed me,” he says.
Intrigued, he searched out records from all around the world, and found the same story almost everywhere he looked, with sunlight falling by 10% over the USA, nearly 30% in parts of the former Soviet Union, and even by 16% in parts of the British Isles. Although the effect varied greatly from place to place, overall the decline amounted to 1-2% globally per decade between the 1950s and the 1990s.
Gerry called the phenomenon global dimming, but his research, published in 2001, met with a sceptical response from other scientists. It was only recently, when his conclusions were confirmed by Australian scientists using a completely different method to estimate solar radiation, that climate scientists at last woke up to the reality of global dimming.
Dimming appears to be caused by air pollution. Burning coal, oil and wood, whether in cars, power stations or cooking fires, produces not only invisible carbon dioxide (the principal greenhouse gas responsible for global warming) but also tiny airborne particles of soot, ash, sulphur compounds and other pollutants.
This visible air pollution reflects sunlight back into space, preventing it reaching the surface. But the pollution also changes the optical properties of clouds. Because the particles seed the formation of water droplets, polluted clouds contain a larger number of droplets than unpolluted clouds. Recent research shows that this makes them more reflective than they would otherwise be, again reflecting the Sun’s rays back into space.
Scientists are now worried that dimming, by shielding the oceans from the full power of the Sun, may be disrupting the pattern of the world’s rainfall. There are suggestions that dimming was behind the droughts in sub-Saharan Africa which claimed hundreds of thousands of lives in the 1970s and 1980s. There are disturbing hints the same thing may be happening today in Asia, home to half the world’s population. “My main concern is global dimming is also having a detrimental impact on the Asian monsoon,” says Prof Veerhabhadran Ramanathan, one of the world’s leading climate scientists. “We are talking about billions of people.”
But perhaps the most alarming aspect of global dimming is that it may have led scientists to underestimate the true power of the greenhouse effect. They know how much extra energy is being trapped in the Earth’s atmosphere by the extra carbon dioxide (CO2) we have placed there. What has been surprising is that this extra energy has so far resulted in a temperature rise of just 0.6°C.
This has led many scientists to conclude that the present-day climate is less sensitive to the effects of carbon dioxide than it was, say, during the ice age, when a similar rise in CO2 led to a temperature rise of 6°C. But it now appears the warming from greenhouse gases has been offset by a strong cooling effect from dimming – in effect two of our pollutants have been cancelling each other out. This means that the climate may in fact be more sensitive to the greenhouse effect than thought.
If so, then this is bad news, according to Dr Peter Cox, one of the world’s leading climate modellers. As things stand, CO2 levels are projected to rise strongly over coming decades, whereas there are encouraging signs that particle pollution is at last being brought under control. “We’re going to be in a situation, unless we act, where the cooling pollutant is dropping off while the warming pollutant is going up. That means we’ll get reduced cooling and increased heating at the same time and that’s a problem for us,” says Cox.
Even the most pessimistic forecasts of global warming may now have to be drastically revised upwards. That means a temperature rise of 10°C by 2100 could be on the cards, giving the UK a climate like that of North Africa, and rendering many parts of the world uninhabitable. That is unless we act urgently to curb our emissions of greenhouse gases.