The largest extinction the Earth has ever seen, the end-Permian extinction, is generally believed to have been a result of the eruptions which the created the Siberian Traps releasing massive amounts of acids (which free carbon dioxide when they hit the ocean) as well as sending lava into limestone deposits, which released large amounts of carbon dioxide, which caused global warming, which caused massive release of methane from methane hydrates, which caused even more global warming, which caused massive ocean anoxia, which caused devastating massive hydrogen sulfide emissions which destroyed the ozone layer, which caused massive UV radiation. Killed land vegetation would further increase CO2 levels.
There are smaller areas of the ocean which are anoxic and have been since before significant human impacts, such as the bottoms of the Black Sea, the Red Sea, and the Persian Gulf. Under rare weather conditions, these seas on occasion emit hydrogen sulfide from the depths causing massive fish kills and some emission to the atmosphere. There are larger and more common emissions from sediments off Namibia. All of these natural emissions occur at depth and result in a relatively small fraction of the hydrogen sulfide being emitted to the air.
There are intermittent and increasingly more frequent anoxic events in the Baltic Sea (most likely due to global-warming induced increased rainfall), the Gulf of Mexico (most likely due to nutrient runoff from the US), off of the northwestern US (cause unknown), and off of Baja California (cause unknown).
Even if most of the deep north Pacific goes anoxic, we probably don't see anything near as bad as these extinction events, because little of the hydrogen sulfide would make it to the surface until the depth of the chemocline pushed up near the surface, which isn't likely to happen at anything near current carbon dioxide levels. Still, finding how high the carbon dioxide levels need to be to do something like this by experiment as we seem to be determined to do does not seem wise.
I'm a bit rusty on this, and the writeup doesn't seem to clarify -- isn't oxygen in the ocean the responsibility of phytoplankton? The way I remember its supposed to work is that the phytoplankton takes in the CO2 and through photosynthesis captures the carbon and gives off oxygen. There was some discussion about seeding iron in the ocean to promote phytoplankton growth (evidently they eat the stuff) and thereby causing life to flourish.
Now logically -- the amount of oxygen on earth is relatively steady. If its low somewhere like in the oceans, it must be in the atmosphere. Gaia theory and all right? So why not just go dump a bunch iron fillings in the ocean and call it a day?
Memory is a strange bell, jubilee and knell.
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Re: rusty on oxygen cycle
Mon Feb 18, 2008 at 01:16:34 PM EST
5.00 (informative, informative)
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Oxygen in the ocean is controlled primarily by exchange with the surface. The surface is usually approximately in equilibrium with the atmosphere, as is the rest of the top "mixed layer" of the ocean which is well mixed by waves. This layer usually includes all of the ocean with enough light for photosynthesis. Oxygen concentrations are in absolute terms fairly low even at the saturation values called "high".
Below the mixed layer, oxygen continues to be consumed by animals and by chemical and biological decomposition of detritus falling from above, and the only source is slow exchange with the mixed layer. Since full deep ocean circulation takes roughly 3,500 years, the small amount of oxygen initially in the water must last for 3,500 years.
The deep northern Pacific has the oldest water and lowest oxygen content of the world's major open ocean basins, running roughly 1/2 to 1/3 of saturation pressure. Both circulation rates and ocean oxygen content are forecast to fall as as result global warming.
The total amount of oxygen (O2) on Earth is if course falling rather constantly, though with a seasonal variation. Every time a hydrocarbon is burned, this removes some oxygen. Since there is a whole lot of oxygen on Earth, the effect is very small, but this could potentially be a problem far in the future if we find far more hydrocarbons that we know we can extract now, continue burning them, and find some way to dispose of the CO2.
Dumping iron filings will remove some CO2, but will increase the amount of falling detritus and lower ocean oxygen content.
I live in an area with inclement weather. Last year we had a freak of nature storm that put the entire area out of power for ~1 week+. Because of this, many people invested in computer aided natural gas powered generators. Basically how they work is when you have a power outage it is sensed instantaneously and the backup generator powers up to run off your (expensive) natural gas connection. But, you have the ability to run all your appliances and the A/C with all the windows open while the rest of your neighborhood descends into 3rd world conditions! Hooray!
Now, for a similar amount of money (or a little more) you could have put a solar power panel on your roof. Besides being ready to go for freak storms and apocalypses, you will also be able to cut your electric bills in half or more. It can even pay you money, by producing more electricity than you can store or consume... this gets sold to the power company.
The question is, why are all these people going with Natural Gas generators that belch exhaust into the air, when they could be saving tons of cash in the long run with solar power panels? The latter also cuts down on global warming because it requires the Power company to produce less. Why not offer tax cuts (make the entire cost of installation, etc a deduction) to homeowners who add solar power, backup batteries and net metering to an existing home? What about all those apartment buildings with empty roof space? Offer the management a similar ginormous credit to help them cut down on their electricity output. If you're going to piss money away into a deficit, I'd rather do it on something like this that will help everybody in the long run rather than some land war in Asia.
Now for part two. Let's take the above idea and apply it to our foreign policy. Why do India, China et al refuse to sign on to these environmental treaties all the time? Is it because they are contrarian pains in the rear? Maybe. But that's not the point. Why should a 3rd world country that is just beginning its industrial revolution be forced to ignore its coal resources? Why not help China/India out and build some goodwill in the process? What if we manufactured solar paneling here, exported it across the world to 3rd world countries and sent our techs over there for installation in exchange for the appropriate concessions (no nuclear weapons, access to manufactured goods, etc)? Even if you built power plants over in India or China, with their poor infrastructure transmission would remain a daunting task. Solar power banks could run a small remote village or a panel on top of an important building could ensure a single hospital or housing complex gets electricity. To our benefit, unemployed people put out of work by the Chinese get jobs, manufacturing picks back up, and greenhouse gases get cut. The end result?
Good guys win, bad guys lose, and as always, the Ozone layer prevails.
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Re: Things that make you go Hmmm...
Mon Feb 18, 2008 at 12:38:56 PM EST
5.00 (interesting)
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Natural gas power plants are by far the cheapest for equipment (except for gasoline/diesel which are close to the same). If you are intending it only for backup power, the fraction of time that it will run is very small, so fuel consumption is largely irrelevant. In the winter here, we often don't see the sun for more than a week at a time, which means that solar panels would do nothing if your power outage hit at a time like that unless you had a week of battery backup, in which case you don't need the solar panels in the first place.
Despite receiving much less press, concentrated solar energy is still far cheaper than photovoltaic power, but it is not something that can be easily placed on a rooftop. The idea is to go out into the desert, build a tower, make the top a black-painted boiler, surround it with computer-controlled mirrors aiming sunlight at the tower and run a steam generator.
The Pacific Northwest continental shelf is a upwelling region which generates algal blooms and has always had low-oxygen water in summer when upwelling is greatest and surface mixing is lowest. What we have recently seen is an expansion of this hypoxic area and not something entirely new. Since this area is ventilated in winter, only a small fraction of the oxygen demand will reach the large area of the deep northern pacific, which has low oxygen levels which are expected to drop further as a result of global warming.
The press reports about this seem to me to be a bit overexcited.
