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BBC Horizon: Global Dimming
Climate scientists have discovered a phenomenon that threatens to disrupt our world. It may already have contributed to the deaths of hundreds of thousands through drought and famine. But by trying to cure it we may unleash a climate catastrophe on the planet.
Jul 25, 2007 4:03 AM
Re: BBC Horizon: Global Dimming
Winner of the 2006 Earth Sciences Award, another 50 minute bit of gripping science.
By: spam_vigilante
Re: BBC Horizon: Global Dimming
Absolutely astounding.
The best way to put it would have to be: "Wow, we fucked up bad."
The best way to put it would have to be: "Wow, we fucked up bad."
By: kanemk2
Re: BBC Horizon: Global Dimming
Its seems we need to invest more in nuclear power and find alternative ways to reflect photons (e.g. satellites with reflection panels). I know it sounds crazy but it is feasible.
By: EnderWiggin
Pointing the finger?
Nuclear power only reduces CO2 emissions by a half. This is because of the methods needed to extract the ore (which is powered by petrol). Its not as ‘wonderful’ as politicians keep making out. Few scientists approve of using nuclear power. It just seems to be a solution as it is a known 'tried and tested' method of mass producing electricity.
As for the satellite thing? Assume there are 100,000 satellites in space and each has a perfectly reflecting surface area of 10 meters squared. End to end, that’s a million meters squared of perfect reflection. Earth has a surface area of 510 million meters squared. That’s a trivial reduction of 0.2% of intercepting photons on the earth. I would think the reflective roofs of cars on the street would have more of an impact, but considering the earth is over two thirds water (which reflects), then most man made structures can be ignored.
The atmosphere is by far the biggest contributor. After all, it covers the whole of the earth. I wouldn’t bother pointing the finger anywhere else.
As for the satellite thing? Assume there are 100,000 satellites in space and each has a perfectly reflecting surface area of 10 meters squared. End to end, that’s a million meters squared of perfect reflection. Earth has a surface area of 510 million meters squared. That’s a trivial reduction of 0.2% of intercepting photons on the earth. I would think the reflective roofs of cars on the street would have more of an impact, but considering the earth is over two thirds water (which reflects), then most man made structures can be ignored.
The atmosphere is by far the biggest contributor. After all, it covers the whole of the earth. I wouldn’t bother pointing the finger anywhere else.
By: wackabay
Re: Pointing the finger?
Wackabay you make some very good points in your argument. Just thinking out loud, is there any solution? or perhaps multiple tiny solutions that could make an impact? regarding my previous post I would think that as a reflection panel in space is moved farther from earth and in the direction of the sun its effective surface area becomes exponentially larger. Just 1 % coverage of the surface area of earth (I'm not an expert, but I speculate that in your calculations one should only consider half the Earth's surface area which is exposed to radiation, ? maybe I'm wrong). Anyways I was just hoping that solutions are being funded or pursued. I know the US didn't abide by the last Kyoto Protocol, so I was wondering do we have any hope of fixing this. Besides fusion power it seems nuclear power is the best existing method even if CO2 emmisions exist from mining, you made a good observation there. I enjoy these forums and looking forward to any comments.
By: EnderWiggin
Re: Pointing the finger?
I agree about the lots of little solutions to make a whole thing.
I just realised that using resources such as bio-fuel would still cause global dimming. However, I think that this method of povering cars will win over hydrogen. This is purely because bio-fuels can run in existing cars. Switching fuel methods will take time and money. I doubt commercial companies would be willing to commit to a long term plan.
Personally Im all for wind and solar power. In one country (I cant remember which), they collect bio mass (like any recycling) and process it into bio gas. Its produces methane to burn and a good fertiliser. Why dont most countries do this.
[that half-earth thing...wouldnt matter as the number of sats would halve too (sets for each side). I think you made a good point about the distance thing tho. But the approximations are still eqivalent due to minimal aberration. Also, larger raduis of sat orbit, means less interception between sats and earth if evenly distributed....god im a physics geek :) ]
I just realised that using resources such as bio-fuel would still cause global dimming. However, I think that this method of povering cars will win over hydrogen. This is purely because bio-fuels can run in existing cars. Switching fuel methods will take time and money. I doubt commercial companies would be willing to commit to a long term plan.
Personally Im all for wind and solar power. In one country (I cant remember which), they collect bio mass (like any recycling) and process it into bio gas. Its produces methane to burn and a good fertiliser. Why dont most countries do this.
[that half-earth thing...wouldnt matter as the number of sats would halve too (sets for each side). I think you made a good point about the distance thing tho. But the approximations are still eqivalent due to minimal aberration. Also, larger raduis of sat orbit, means less interception between sats and earth if evenly distributed....god im a physics geek :) ]
By: wackabay
Re: Pointing the finger?
It's uncertain that solar power sats will ever be competitive with ground based solar. I think a better immediate solution would be air scrubbers and a solar shade.
By: Hummm
Re: BBC Horizon: Global Dimming
Link died. Mirror added:
http://video.google.com/videoplay?docid=-2058273530743771382&hl=en
http://video.google.com/videoplay?docid=-2058273530743771382&hl=en
By: spam_vigilante
