Slashdot Mirror
Global Dimming
wiredog writes "The Guardian reports on research which shows that the amount of sunlight reaching the Earth's surface has decreased by 10% in 30 years. This has implications for global warming models and, especially, agricultural output."
of Global Warming, we have to worry about Global Cooling. Is that why it is 45F out in S. Florida? :-)
This makes me wonder about the drive towards a hydrogen-powered economy. All that water vapour coming out of car exhaust pipes, etc. Probably a better form of pollution from a health perspective, but will it also result in limiting sun light or producing clouds that trap heat?
We can thus conclude that we know nothing. Weather patterns haven't been recorded for a long enough time to make any valid long time prediction of such things as global warming or freezing. Once they manage to consistently predict tomorrows weather successfully they may go onwards and claim they have a clue how the weather will be 100 years from now. For those screaming "Kyoto!" etc: yes, reducing pollution is good and should be something to strive for for every somewhat intelligent human being, but I wouldn't draw a conclusion about global warming from what was presented yet.
Quite weird - there was an elderly farmer saying much the same thing this morning on my bus to work.
I'm pretty sure he wasn't a guardian reader, it's just something he'd noticed over the years.
At the time, I thought he was talking crazy talk...
I suspect that some of this global dimming is due to pollution from sulfates (coal), jet contrails, and dust from wind-borne erosion. Sulfate and particulate pollution provides nice nucleation sites for cloud formation. These pollution-created artificial clouds probably reduce global warming (the article mentions this effect and a correlated decrease in cloudiness and increase in temperatures in the 1990s).
The scary part comes if we reduce these forms of pollution, reduce cloudiness, and thus accelerate global warming. Whether we like it or not, humanity is changing the climate -- as attractive as it seems, preservation is impossible. At this point, it might be better to think about climate engineering -- deciding how we want to change the climate rather than holding on to the false hope that we can avoid changing the climate.
Two wrongs don't make a right, but three lefts do.
I wonder if this is similar to a greenhouse. This would explain both the dimming AND the global warming. The glass from a greenhouse (comparable to the atmospheric gasses) undoubtably blocks some of the sunlight getting to the plants/surface. Yet we all know it's a bit warmer in the greenhouse than in the surrounding area outside.
If this analogy is correct, we really do have a lot to fear. Not only will we continue to have global warming but it seems as if the humidity level of the planet may rise too. Of course, at some point (if we're losing 10% a decade) you would think there is a break-even point and we'll start experiencing global cooling because it'll be like putting the shades down on the windows.
"He uses statistics as a drunken man uses lampposts...for support rather than illumination." - Andrew Lang
That said, there has been an increase in the solar output. The number of sun spots at solar peak is increasing steadily. And the Mars polar cap is melting, which is consistent with the solar output increase observation.
Note that currently, the sun is close to its radiation peak. Which means that since the high atmosphere is acting like a bubble chamber, we will see more ice crystals and water droplets at high altitude (and more precipitations). Which raises the Earth's albedo (reflectivity) and could decrease the amount of solar light reaching the ground. So at least, the findings don't contradict atmospheric physics.
But I still want to see these measurements done over an 11-year solar cycle, otherwise it's gimme-a-grant voodoo, not science.
--
Mad science! Robots! Underwear! Cute girls! Full comic online! http://www.girlgeniusonline.com/
Every day, we get enough sunlight to power 27 years worth of the world's energy needs. Now, I thought about the implications of that. Obviously, we couldn't absorb/store the entire amount, but if we could put a dent in it, we'd have some global cooling. That is what this article is about.
On a similar note, the US could obtain all energy from the sun if it were to install a 200 mile square solar installation (assuming 15 percent efficiency... easily doable today). I say, put a dime of tax on each gallon of gas and use this money to subsidize solar generation - one of the only energy producers out there with net positive energy (more energy produced in the cell's lifetime than it takes to produce the cell itself). Hydro, wind and solar... I can't wait for the day.
On yet another related note, I'm in the process of building a solar/NiMH PC. I'm simply going to use store-bought NiMH rechargables to store excess daytime solar input. It certainly won't be cost effective but it'll be pretty high on the geek factor.
Life is the leading cause of death in America.
Dimming != Cooling
The article is about less sunlight reaching the earth's surface. Nothing about the earth cooling down....
Lets have an experiment:
1 Take a black (or very dark) plastic bag.
2 Go stand in the sun.
3 Pull the bag over your head (not to tight you are not going for a Darwin Award)
4 Stand for a while
You will notice the following:
1 You don't see much since the sunlight does not reach your eyes. (Lets call this 'dimming')
2 It gets hot in the bag. (Lets call this 'warming')
Conclusion:
You can have dimming and warming at the same time.
Jeroen
Secure messaging: http://quickmsg.vreeken.net/
So I blame jet airplane contrails.
- "History shows again and again how nature points out the folly of men" -- Blue Oyster Cult, 'Godzilla'
Some counterpoints:
2) Astronomers tools have been improving and changing alot over the time period in question, and as a result their measurements may not be consistant enough going back for them to compare and notice the trend, especially if they aren't looking for it.
3) It's not necessarily just absorbed by the atmosphere, it could be reflected back into space by increased cloud cover.
4) In the long run it could be consistant with either warming or cooling, depending on the mechanism that is reducing the light levels (absorbtion vs reflection). There are other factors that could have a bigger impact on short term warming/cooling that could easily overpower the temp change from dimming in the 80s.
Also, it seems that the assumption has been made that the sun produces constant output. I don't think we can make this assumption. The sun, as a system, is way bigger than our atmosphere. Until we have thousands of years worth of data, observed from outside the atmosphere, we can't prove that solar radiation is a constant. In fact, since solar flares temporarily increase solar output, you could postulate that thousand year trends in flare frequency and magnitude could affect the overall output of the sun.
So, while global dimming may or may not affect us in the short term (on the scale of centuries) and pollution is still bad (again very long term effects are unrecorded, but it's obviously very bad in the short term (again measured in centuries) and it is ugly), I'm still not all that concerned that the world is going to ice over or boil away any time soon.
i don't like my old sig.
Good: We'll all have great skin for starts.
Actually, the article mentioned that it was visable and infrared light that was being blocked by an excess of clouds, not ultraviolet. Add to this the fact that our magnetic feild is becoming less polarized, in the process of flipping. As it does so there will be a bunch of little poles (places where the magnetic feild points into the earth not parrallel to it), guiding in additional radiation (and aroras, yay!). So if anything we will have more problems with bad skin not less.
Also, as the earth has warmed we have seen an the wet places getting more precipitation and the dry places getting less. And the article said the dimming was not constant, just that we have had more clouds and the clouds obviously block light, but the deserts, with no precipitation will have fewer clouds and thus less dimming.
My prediction: the world will be divided into radsuit wearing deserts desert dwellers, and mutant frog men, who live in swamps.
Although you probably meant this as a joke, it might be. The amount of light people recieve affects lots of physical things. Chronically light deprived people (such as those who work night shifts) are heavier on average than those who don't. Lack of sufficient light also affects alertness and mood, and not only in those who have seasonal affective disorder.
That being said, I don't think a 10% reduction in light would cause a significant increase in obesity, but it might be an interesting experiment.
I like my beverages with warning labels!
initial planning, design, materials and implementation, maintenance and repair...good idea but I doubt it would come close to paying for itself.
Is the juice worth the sqeeze?
Please note here, much of this 10% is being reflected. There are people in this thread pointing out how untrue the observations must be because if 10% of the sun's energy was being absorbed by the atmosphere, the Earth would be getting a heck of a lot warmer than it is. Instead, the Earth should be getting 10% brigher from the moon or anywhere else in space. Particulates are reflecting and clouds are forming (which look very bright to me when I fly over them).
I've been wondering about this. Would global warming end up creating enough clouds to reflect enough energy from the sun that it balances itself out after a few decades? Or will global warming cause an imbalance in the sun's reflected energy after a few decades that causes a swing on the cold side? How much does the CO2 green house effect compare to the particulate / cloud reflector effect?
Actually you can mine H, it is a waste by product of most natural gas production. It currently gets wasted, but it can be mined
I wonder if this will have any sort of noticeable effect on Seasonal Affective Disorder. It has been shown that people feel more depressed with less exposure to the sun (this disorder is especially common in winter).
It's funny, everyone talks about how people seem sadder and grumpier "these days". I wonder if there could be an actual link to this "global dimming".
"Reality is merely an illusion, albeit a very persistent one " -Albert Einstein
Actually, the entire electricity requirements of the United States could be served by wind turbines with a combined land-use footprint of only 14,000 acres, including enough grid redundancy to provide 99.5% uptime through long grid transmission to areas experiencing calm winds. (The remaining 0.5% backup could be hydro or whatever.) That area is only twice the size of the Stanford campus, and as large as the amount of Oak forest that California loses each year.
Some people consider turbines ugly at first glance, but more people want wind turbines in their neighborhood than want mercury-spewing coal smokestacks in their state.
Wind power is the fastest growning renewable industry and is expected to be the dominant form of power production in less than 30 years.
Please see the Windpower FAQ for more information.