http://www.democraticunderground.com/discuss/duboard.php?az=view_all&address=385x271149">17 minutes into the stand alone torrent version & the last quarter of part 2 of the Youtube version - with some great graphics
NARRATOR: Ramanathan was certain of one thing, the big drop in sunlight reaching the ground had to be something to do with changes in the Earth's atmosphere. There was one obvious suspect.
PROF VEERABHADRAN RAMANATHAN: Almost everything we do to create energy causes pollution.
NARRATOR: Burning fuel doesn't just produce the invisible greenhouse gases which cause global warming. It also produces visible pollution, tiny airborne particles of soot and other pollutants. These produce the haze which shrouds our cities. So Ramanathan wondered: Could this pollution be causing Global Dimming? The Maldives were the perfect place to find out. The Maldives seem unpolluted, but in fact the northern islands sit in a stream of dirty air descending from India. Only the southern tip of the long island chain enjoys clean air coming all the way from Antarctica. So by comparing the northern islands with the southern ones, Ramanathan and his colleagues would be able to see exactly what difference the pollution made to the atmosphere and the sunlight. Project INDOEX, as it was called, was a huge multinational effort. For four years every possible technique was used to sample and monitor the atmosphere over the Maldives. INDOEX cost twenty-five million dollars, but it produced results - and they surprised everyone.
PROF VEERABHADRAN RAMANATHAN: The stunning part of the experiment was this pollutant layer which was three kilometre thick, cut down the sunlight reaching the ocean by more than 10%.
NARRATOR: A 10% fall in sunlight meant that particle pollution was having a far bigger effect than anyone had thought possible.
PROF VEERABHADRAN RAMANATHAN: Our models led us to believe the human impact on the dimming was close to half to one per cent. So what we discovered was tenfold.
NARRATOR: INDOEX showed that the pollution particles were blocking some sunlight themselves; but far more significant was what they were doing to the clouds. They were turning them into giant mirrors. Clouds are made of droplets of water. These only form when water vapour in the atmosphere starts to condense on the surface of naturally occurring airborne particles, typically pollen or sea salt. As they grow, the water droplets eventually become so heavy they fall as rain. But Ramanathan found that polluted air contained far more particles than the unpolluted air, particles of ash, soot and sulphur dioxide.
PROF VEERABHADRAN RAMANATHAN: We saw ten times more particles in the polluted air mass north of the Maldives compared with what we saw south of the Maldives which was a pristine air mass.
NARRATOR: In the polluted air billions of man-made particles provided ten times as many sites around which water droplets could form. So polluted clouds contained many more water droplets, each one far smaller than it would be naturally. Many small droplets reflect more light than fewer big ones. So the polluted clouds were reflecting more light back into space, preventing the heat of the sun getting through. This was the cause of Global Dimming.
PROF VEERABHADRAN RAMANATHAN: Basically the Global Dimming we saw in the North Indian Ocean, it was contributed on the one hand by the particles themselves shielding the ocean from the sunlight, on the other hand making the clouds brighter. So this insidious soup, consisting of soot, sulphates, nitrates, ash and what have you, was having a double whammy on the Global Dimming.
"This is the real sting in the tail" 36 minutes 30 seconds into
http://www.mininova.org/tor/635157">the torrent version
Or, 2nd half of part 4:
http://www.youtube.com/watch?v=37SAFkvz6uY and all of part 5:
http://www.youtube.com/watch?v=CyVOvRm45-I DR DAVID TRAVIS: The nine eleven study showed that if you remove a contributor to Global Dimming, jet contrails, just for a three day period, we see an immediate response of the surface of temperature. Do the same thing globally we might see a large scale increase in global warming.
NARRATOR: This is the real sting in the tail. Solve the problem of Global Dimming and the world could get considerably hotter. And this is not just theory, it may already be happening. In Western Europe the steps we have taken to cut air pollution have started to bear fruit in a noticeable improvement in air quality and even a slight reduction in Global Dimming over the last few years. Yet at the same time, after decades in which they held steady, European temperatures have started rapidly to rise culminating in the savage summer of 2003.
Forest fires devastated Portugal. Glaciers melted in the Alps. And in France people died by the thousand. Could this be the penalty of reducing Global Dimming without tackling the root cause of global warming?
DR BEATE LIEPERT: We thought we live in a global warming world, um but this is actually er not right. We lived in a global warming plus a Global Dimming world, and now we are taking out Global Dimming. So we end up with the global warming world, which will be much worse than we thought it will be, much hotter.
NARRATOR: This is the crux of the problem. While the greenhouse effect has been warming the planet, it now seems Global Dimming has been cooling it down. So the warming caused by carbon dioxide has been hidden from us by the cooling from air pollution. But that situation is now starting to change.
DR PETER COX (Hadley Centre, Met Office): We're gonna be in a situation unless we act where the cooling pollutant is dropping off while the warming pollutant is going up, CO2 will be going up and particles will be dropping off and that means we'll get an accelerated warming. We'll get a double whammy, we'll get, we'll get reducing cooling and increased heating at the same time and that's, that's a problem for us.
NARRATOR: And that's not all. Climatologists like Peter Cox have begun to worry that Global Dimming has led them to underestimate the true power of global warming. They fear that the Earth could be far more vulnerable to greenhouse gases than they had previously thought.
DR PETER COX: We've got two competing effects really, that we've got the greenhouse effect, which has tended to warm up the climate. But then we've got this other effect that's much stronger than we thought, which is a cooling effect that comes from particles in the atmosphere. And they're competing with one another. And we know the climate's moved to a warmer state by about point six of a degree over the last hundred years. So the whole thing's moved this way. If it turns out that the cooling is stronger than we thought then the warming also is a lot stronger than we thought, and that means the climate's more sensitive to carbon dioxide than we originally thought, and it means our models may be under sensitive to carbon dioxide.
NARRATOR: The models that everyone has been using to forecast climate change predict a maximum warming of 5 degrees by the end of the century. But Cox and his colleagues now fear those models may be wrong. Temperatures could rise twice as fast as they previously thought with irreversible damage just twenty-five years away.
Transcript continues:
http://www.bbc.co.uk/sn/tvradio/programmes/horizon/dimming_trans.shtmlIf new generation biofuels that are being looked at seriously by Boeing and the airline companies (as can be seen here:
http://www.democraticunderground.com/discuss/duboard.php?az=view_all&address=385x267281:URL|Air New Zealand - Jatropha Biofuel Test Flight (is this the "Holy Grail" of biofuel?)>) do not emit the same kind of particles when they are burnt, they need to step up the production immediately, instead of thinking about pumping more particles into the atmosphere.
There's simply no time to waste...
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