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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
The sunlight is hitting the earth, just not reaching the surface. This has the effect of heating the upper atmosphere, and reducing the power at the earth's surface.
You may now run some atmospheric modelling code to work out what the hell this will do to the climate.
An immediate conclusion made in the article is that this effect is masking the current rate of climate change due to CO2, so that as we clean up the atmosphere due to reduced particulate emissions, the greenhouse effect will get worse, even if there isn't an increase in CO2 in the atmosphere.
This would certainly explain something that has bothered me for some time. I am cursed with a memory that remembors images with clarity I wish I didn't have. I have noticed that images from my childhood, (admittedly decades old now), seem to be 'brighter' than those I have of recent times. It's not a 'hazy' difference as you would expect. It is that the images seem 'brighter' to me. If I revisit the same location, it's not the same, even on a bright sunny day.
I know it probably seems ludicrous to most people. I don't talk about things like that normally, because people just dismiss you as nuts, but it's real to me. I am curious, are there any others out there with long term photo memories that exhibit the same thing as I see?
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...
If everybody started driving electric/hybrid vehicles today, in 5 years there would be less pollutants/carbon dioxide in the atmosphere. Scientists now believe that these ingredients are keeping sunlight out. So if the amount of carbon dioxide etc. decreased so would global warming. Right????? Come on people. Don't let the extremests make you feel guilty for driving your "environmentally unfriendly" vehicle. Our vehicles are maintaining the "delicate balance" of the cooling and warming cycles.
I am myself (as most Slashdotters) often dubious of the spin put on science for main-stream TV, and while the Horizon program did indeed have lots of the usual London flooded/dust-storm enveloping the BT tower/etc. scenes, plus lots of "but then, things get even worse..." sort of narrative - there was still some good science and a genuine warning to be heeded.
Consider the solid data accumulated from such straight-forward measurements as solar energy and pan evaporation, and the reasoning behind cloud reflectance (particulates building more/smaller raindrops). Together with the observations on the effects of contrails taken during the only time aircraft were grounded in the US (after 9/11). Also, the fact that while industrialised nations have cleaned up air quality - their summers have also been getting warming...
OK, so maybe global warming is/isn't held in check by global dimming. But does anyone here really believe that 6 billion people spewing out CO^2 shouldn't have had more effect by now...
This is why I support wind farms (& nuclear) and don't believe in low cost airlines!
I believe you have a point, but here`s the other side of the story:
To state things the way the media state them is indeed quite pulling the umbrella because they themselves did not cover this news when it was presented to the world for the first time in 2001, 4 years ago. Media themselves did not do the effort to go far on this topic, or to understand the scope of the research. (I actually wanted to post this story 3 days ago, when I discovered the topic had allready been covered in 2001, 2003 and may 2004, so here you`re right about that brick wall.)
But! As for the topic itself, Global Dimming, I have no problem accepting the theory of more reflection of sunlight by denser clouds (particles) in the atmosphere. And I also have no problem accepting that this evolution is even worse to nature than global warming would be. If both effects go hand in hand, and the atmosphere is covering up, it could get dark and cold quite fast here. China hasn`t even begun fully transforming into a capitalistic low-cost no-eco-concerned mass producing country. Half of the world lives there. And Kyoto is constantly being bashed by them smart yankees driving their roaring SUVs. I`m really concerned, and if you think that`s because the media paint it wrong, I leave that judgement up to you.
When I look at factories with their chimney`s, I can`t wonder but think where all that black stuff goes.. isn`t it time we invent something better to get rid of waste, even if it`s just carbon oxides.
With great power comes great electricity bills.
According to the articles, the particulates are not absorbing solar radiation, they are reflecting it. Thus they don't get hotter, the just reflect the energy back out into space and it doesn't stay in the earth's thermodynamic system. Thus it causes cooling.
Did you buy a Neuros today?
The programme claimed that the worst case scenario - melting of the methane clathrates - would be an uncontrollable massive acceleration in the greenhouse effect, leading to temperatures not seen on Earth for billions of years. That is geological time changes, compressed into 100 years or less.
That's not certain to happen, but I think we should be very concerned about that possibility, if it is a possibility, however small the probability.
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