[Films/Docu's/Boeken] Over de elementen op onze aarde

Lolz, @postings ik moet naar de videotheek of zo.

quote:

Op vrijdag 5 januari 2007 10:03 schreef addie het volgende:
Voor een mod heb je soms wel erg vage posts

Dat is mijn handelsmerk. Easy living.

quote:

Op vrijdag 5 januari 2007 09:57 schreef addie het volgende:
Ik zat te twijfelen of ik deze zou toevoegen of niet. De docu is sterk, maar wellicht voer voor een eigen topic, vanwege de discussiewaarde

Daar was ooit een topic van en gevonden (search@FOK). Aanvraag loopt om het deze kant op te krijgen.

Niet echt een speelfilm maar een BBC-docu (Horizon).

Global Dimming


Horizon producer David Sington on why predictions about the Earth's climate will need to be re-examined.

Omschrijving
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.

Eigen Review
De BBC is gewelding als het gaat om docu's. Deze heb ik zeer recentelijk gedownload. En is echt een beetje een 'Shock and Awe' docu. Er komen vele wetenschappers aan het woord. En de uitleg achter dit fenomeel is goed geformuleerd. Ik sta niet echter achter alle gepresenteerde data die in deze docu worden besproken. Maar globaal lijken de conclusies wel juist te zijn. Deze docu is zeker de moeite waard (aanrader zelfs, omdat je met andere ogen naar het zogenaamde broeikaseffect gaat kijken).

quote:

Op vrijdag 5 januari 2007 10:52 schreef addie het volgende:
Maak anders van de TT: Speelfilms/docu's etc

Het lukt net, meer ascii tekens krijg ik niet kwijt in de TT.
Toch maar weer ingekort.