Here’s a statement recently made in an argument over Global Warming, CO2 emissions, etc.
"Given the fact that ONE volcano erruption can spit out more CFCs and green house gasses than man ever has, the only logical conclusion is that WE DON’T HAVE A CLUE as to whether man’s activities have had any effect whatsoever on the the earth’s mean temperature. " [sic]
Here’s a statement made by Ace Face on one of the GD Threads re: Global Warming.
“The current best estimate is that all volcanoes combined produce about 110 million tons of carbon dioxide a year, while humans produce about 10 billion tons per year. The other major greenhouse gas contributed by volcanoes is sulfur dioxide, which is converted to sulfuric acid aresols, which have a cooling effect.”
Does anyone have any facts supporting one view or the other?
Volcanos do indeed produce carbon dioxide and sulfur dioxide, both greenhouse gases. A volcanic eruption spews a lot of gases in a relatvely short period of time, while man-made emissions are continuous year after year.
I doubt that volcanos spew out chloroflurocarbons (CFCs), since these wholly man-made. Regardless, CFCs don’t contribute to global warming - they break down ozone and are implicated in the development of the ozone hole over Antarctica. Volcanic impact, if any, on the ozone layer is due to emission of HCl.
According to the CIA, emissions of CO[sub]2[/sub] from many of the major contributors amounted to 4.5 billion metric tons in the year 1994. This can be expressed as 6.2 billion tons of *carbon equivalent * (weighing the CO[sub]2[/sub] by its Global Warming Potential)according to this site (mostly focused on Japanese emissions).
From Volcanologist Don Thomas, volcanoes worldwide produce an average of about 500,000,000,000 kilograms of CO[sub]2[/sub] a year or 0.25 billion metric tons a year. While Dr. Thomas has listed 8.8 billion metric tons as anthropogenic inputs of CO[sub]2[/sub], somewhat different from the numbers I posted above, I think it likely that derives from his using different sources from mine, and perhaps different years, possibly different estimates of net input.
It strikes me as likely that the first statement you quoted hinges on the word can. How extreme would an eruption have to be to exceed the amount of greenhouse gasses man has ever emitted?
It’s also interesting to note that the first person you quoted talks about “greenhouse gasses,” while the second talks about carbon dioxide.
I’m an idiot!! The Japanese site I linked is using different figures than the CIA site. They just happen to be for the same year. Carbon equivalent weights of carbon dioxide are exactly the same as the weight of carbon dioxide. What was I thinking??
In Carl Sagan’s “Pale Blue Dot” (sorry, that’s the best reference I have on-hand at the moment), he says that CFCs are a greenhouse gas, but a very minor one. Of course, as you said, the main concern with CFCs is ozone layer depletion.
Sagan, IMO, was using the term a bit too liberally. Nearly any gas in the atmosphere is a greenhouse gas to some extent. Note that if we did not have any greenhouse effect at all, this would be a far, far colder planet.
And is it too much to ask that Journalists reporting on energy matters get an education and try to at least understand how the World Around Them works? While reading a Time magazine on the flight last night, I noted that they claimed that wind power had already removed the need for “15 coal power plants”.
Just that - 15 coal power plants.
Oh really? What kind of coal power plants? Did they mean 15 of 20 MW stoker boilers, or did they mean 15 of 1350 MW AEP pulverized coal furnaces? And what is a plant? The terms “unit” and “plant” are used interchangably, both inside and outside the industry. Is a “plant” one unit (such as a single 200 MW unit), or is a “plant” a whole plant site of multiple units (like one of ESKOM’s 10x600 MW plants, for 6000 MW total)? Their definition of “15 coal plants” could mean as little as 300 MW, or as much as the entire generating capacity of the Tennessee Valley Authority.