Millions of years is one thing while a few [couple of] hundred years is another. That would be: "The reputed largest historical eruption occurred in 1815 from the volcano Tambora, an explosive caldera located on the island of` Sumbawa, Indonesia. The eruption injected so much ash into the upper atmosphere that, at least in the northern hemisphere, there was a cooling of the atmosphere, which resulted in snow in Boston in July and a faminine across parts of Europe." [http://volcano.und.edu/vwdocs/frequent_questions/grp7/asia/question3381.html] These effects are in the ice core and tree ring data of the last 1,000 years. While it was a "blip", the magnitude doesn't come close to the changes in the past 150 years. Which makes me wonder where the shows are for the "anti-global warming"? My power company is running ads about methane and cows. I don't know how many cows there are today, but wonder if this is such a "new" problem, what about the buffalo herds 200 years ago? I can't think the world has significantly more grazers now than before. If you're using cold water, how much energy are you using? Since it's getting warmer, isn't this a "good thing"? Currently hydrogen comes from fossil fuels. There is some solar hydrogen production, but the current level of technology can't produce enough to make it viable. Until the production of hydrogen can be solved, it's just another dead end. Another dead end. Alcohol has around an eighth the energy per gallon of gasoline, so "per gallon" you'll get less distance. Brazil uses alcohol, but they make it from sugar cane. In the process they burn the used cans to fuel it. The net energy "gain" is significantly greater than using corn. Soybean bio-diesel maybe be an answer but we all need to buy diesels to use it.