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BBC on Global Dimming
linoleo writes "The BBC reports that the amount of solar energy reaching the Earth's surface has declined significantly between the 1950s and the 1990s, apparently due to particulate air pollution. Scientists are worried that this global dimming may be disrupting the pattern of the world's rainfall. Most alarmingly, it may have led us to greatly underestimate the greenhouse effect: with particulate pollution being brought under control, a global temperature rise of 10 degrees Celsius by 2100 could be on the cards, rendering many parts of the world uninhabitable." The lengthy transcript of the show is available.
And at the same time the amount of energy put out by the Sun is increasing.y /sun_output_0 30320.html
http://www.space.com/scienceastronom
http://www.hypography.com/article.cfm?id=32945
Yes, essentially the program says that we are getting less sunlight and the world is getting hotter.
They say we are getting less sunlight thanks the visible pollution in the atmosphere which encourages cloud formation in a fashion which reflects more sunlight than clouds formed around natural pollutants such as pollen.
We are making big steps to clean up the visible pollution and therefore bringing the amount of sunlight back to normal levels.
However given that the world is still warming up despite the cooling effect of this reduction of sunlight they are supposing this must mean that global warming is in fact a lot more powerful than they first thought since we can still detect noticable warming despite a reduction in sunlight.
As we clean up more and more of our visible pollution without cleaning up our CO2 pollution we may face a much bigger temperature increase than we were expecting.
The program was fairly sensastionalist and towards the end went through some highly speculative "we are all going to die" scenarios. I would have liked them to concetrate more on the evidence they have for global dimming and maybe some contrary evidence or any doubts the scientific community may have about the results of the scientists they did show.
"Waking up" to something simply means to take notice of it. Rejecting the obvious truth has nothing to do with it. It's impossible for scientists to keep track of all the minutiae that comprise the universe.
Secondly, I don't think the journalist came up with that conclusion. Scientists did, and the journalist is just reporting it, which incidentally is his job.
The media can be irresponsible at times, and does make mistakes. But reporting the findings of scientists, like this, is not one of them, even if the conclusions they have reached do not agree with yours. After all, if they didn't report it, and thus did not feed the "pop-sci crap" to the public, others would feel they're not doing their job. So relax.
I saw the actual programme, and it was far from Pop Science. In paticular the 9/11 data was fairly stark in underlining the impact of removal of aeroplanes from the skys for just two days over the US.
But of course, we could all just bury our heads in the sand and claim it is pop science.
The programme went into a "light" amount of detail, but mainly said this was something that required more research but was on the scary side of its implications. They certainly didn't say it was cancelling out the greenhouse effect, they claimed it was MASKING its impact, a very different claim.
The real trouble is that anything that claims there is a global warming problem caused by pollution comes up against one basic problem:
The US Energy Policy.
To my mind these elements equate to the old "the odds of this thing going critical if I drop it are pretty low" school of porting nuclear materials. The odds may be low, but the cost is huge, hence the reason you don't just lob the stuff about.
So it was a lightweight programme, well yes it wasn't the Open University, but "Pop Science", not really. It definately played for some dramatic effect, but there was evidence for those who were watching.
An Eye for an Eye will make the whole world blind - Gandhi
As a student of global climate change (the warming part has long since been dropped), a few scientific facts need to be added.
#1 - Global climate change means exactly that - it will get warmer in some places, colder in others. And while idyllic thoughts of long summers around Great Bear Lake might spark a real estate boom, there will be a few downsides to the change. Disease vectors love warm weather, which means that pesky malaria (so, caused by bad air after all!) will become a feature of northern summers.
#2 - The problem of increased warming due to pollution reduction is well known. These are relatively large particles being talked about, the ones that reflect sunlight back out (like after a volcano) - this does not include the smaller particles that have a much larger "green house" effect. Thus as we reduce large particulate pollution, the speed of warming will indeed increase.
#3 - The "wait and study it so we know what is happending" arguement. This arguement has many supporters, including those who love discount rates. The fact is, once a glacier begins to melt (ahem, Greenland), there will be no way to stop it. Mind you, it might take a few hundred to a few thousand years... so maybe 2k'ers get the last laugh?
sig? what sig? i didn't see any sig...
Fortunately, the models & supercomputers are just slightly more complex than your fallacious argument. Merits of the BBC presention nonwithstanding, the theory that is advanced is not inconsisent with the observations at all. (Any of those could might be wrong, but that's a different story.)
... errr... well, greenhouses and shading/clouds. They may may have opposite effect on temperature, but they are not matter & antimatter. The theory of global shading has two major implications:
Replace the common useage of' 'Global warming' as 'greenhouse effect', and then park GW for the time being. If you don't understand this, consider that a car with windows rolled up acts a like a greenhouse. Sit in the shade and you might get a little uncomfortable, but not seriously so. Move out of the shade and... toast. In both cases there was complete Car Warming, but you can easily see the two major and independent factors. The make of the car does *not* matter...
So, greenhouse effects and shading are as different as
1 - Our models are wrong. Shading deducts X amount of energy which means that our estimate for the strength of greenhouse-effect is probably off by X.
2 - Ironically, shading helps, in the sense that we get less total increase in temperature - but it isn't all good, and it isn't that simple. Most importantly, reducing shading by without reducing the greenhouse effect would is tantamount to raising the temperature - which is a big no-no.
Incidentally, the particles are doing exactly what you suggest, but the implication is not what you understand it to be. One of many observations was that during flight-less days post 9/11, it didn't just get "warmer", energy flow & flux (both ways!) increased. Warmer days, cooler nights.