Slashdot Mirror
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.
Actually, what they're saying is that since we are finally getting pollution under control, the increased amount of sunlight will compound with the current greenhouse effect. At least that's how I read it
Don't you hate pants?
Really, this article jumps to far too many conclusions with far too little data.
And with exactly the same certainty as this statement expresses, if I dance around in a circle every Thursday night, an average rainfall increase of 17 inches could be in the cards!
Finally, of course there's more to the story than just particles in the air, but do you really expect a thorough background in geothermal science which touches on all pertinent topics such as ocean currents when you're talking about this? That would be grounds for accusations of poor journalism.
"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
There are many factors that go into creating the temperature of the planet. Reflectivity of the atmosphere, distance to the sun, atmospheric composition, etc. The greenhouse effect from CO2 is predictable and provable. Just because we have had global temperatures fluxuating does not disprove that CO2 is an atmospheric insulator and traps solar energy. Unless this CO2 is being drawn back out of the atmosphere (by plantlife, by carbon deposition, water absorption, or whatever else it can do), continually ramping up CO2 production into the atmsophere may cause the density to increase to the point where it becomes a problem. Thing is, once it's a problem, how long will it take to fix it, and depending on how hot it gets (10 degrees C hotter? more?) will we have time to do so before we get cooked?
While admittedly, just because we exist, we are going to change the environment around us. I fail to see the benefit in assuming that nothing that we do can or will affect the global perspective, especially when we have countries around the globe working their industrial magic. We should seek to stave off problems before they occur. In the global scale, if it takes 100 years to stabilize the temperature again, and that's a short time, it may be insufficient for us to adapt to if the temperature increases too fast.
By the way, since you're quoting data, where exactally did that come from. Care to quote the source, too?
IMHO even over 50 years, we should be able to spot trends of that order of magnitude in our food crops.
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.