Richard94611 wrote:
Homestead, volcanoes are NOT a major cause of changes in the climate like the ones we are seeing. I must find the section in the course that deals with that falsehood. Volcanoes can cause a temporary shift -- TEMPORARY. They were one of the causes of "The Little Ice Age," a period of colder temperatures in Europe. But their effect only amounts to something about equal to the yearly burning of fossil fuels in Turkey, a rather minor effect, I would say.
Here is the material relating to the effects of volcanoes. As you can see, they are NOT a major cause of climate change/global warming:
But, despite all of the evidence, some people persist in claiming that the recent rise in
carbon dioxide is all natural for example, they say that instead of it being caused by humans, it all came out of volcanoes.
Now, it is quite true that volcanoes emit some carbon dioxide and thatover very long periods of geological timethose small amounts can add up to make a really significant change to the atmosphere. However, over a couple of hundred years, the emissions arent large enough to make a difference.
There are two main classes of volcano: there are the ones that erupt under the ocean and the ones that erupt into the air. Both kinds are linked to the goings-on at the boundaries of the tectonic plates and to the upwelling of hot rock from the Earths mantle-- the layer below the crust. The undersea volcanoes are by far the more numerous, making up about 90% of the worlds volcanoes, although few of us have ever seen them. These volcanic chains are where new ocean crust is produced. But undersea volcanoes dont produce very much carbon dioxideonly about 100 million tonnes per yearabout the same amount as an average US state emits. Humans produce about 350 times as much carbon dioxide as the undersea volcanoes do. Carbon dioxide not only gets produced at the ocean ridges; it also gets consumed there. What happens is that the newly formed basaltic rock undergoes chemical changes when it contacts seawater. This reaction absorbs carbon dioxide from the water at a rate of about 150 million tonnes per year. The mid-ocean ridge volcanic processes as a whole, therefore, probably consume more carbon dioxide than they emit. We are much more familiar with the kind of volcanoes that erupt into the air. The biggest chain of these is the famous Pacific Ring of Fire. This is a belt running all the way around the ocean from New Zealand to Japan, then to Alaska and down to the Andes. Old oceanic crust is consumed at these places and they form volcanoes that produce much more carbon dioxide than the ones under the sea. The magma in these volcanoes comes not just from the Earths mantle, but also from the melting of the more carbon- and water-rich rocks in the crust. One reason these types of volcano tend to be more explosive is because of the larger amount of water vapour and carbon
dioxide in their magma. Mount Etna in Sicily is one of the most prolific carbon-dioxide producing volcanoes in the world. It produces about 13 million tonnes per year, but this amount is still only about half as much as what Sicilys five million people emit from burning fossil fuels.
Dormant volcanoes and volcanic lakes together emit as much carbon dioxide as the actively erupting volcanoes do. Altogether, volcanoes that emit carbon dioxide into the air produce much more than undersea
volcanoes: about five times as much.
Volcanic rocks on the surface undergo weathering and this chemical process absorbs carbon dioxide out of the airabout 180 million tonnes per yearthats approximately one-third of the amount put into the air by volcanoes. If we add up all the sources of volcanic carbon dioxide, we get 640 million tonnes per year. Once we subtract the carbon dioxide that the reactions with volcanic rocks consume, we are left with a net 310 million tonnes per year. This last amount is roughly equal to the human emissions from the country of Turkey, thats less than one percent of all human emissions. Human emissions for the planet as a whole in 2012 were 60 to 120 times bigger than volcanic emissions. Carbon dioxide emissions from cement-making alone are 3 to 6 times bigger than those from volcanoes.
Homestead, volcanoes are NOT a major cause of chan... (
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Update on volcanoes....until 20 years ago only a couple volcanoes were blowing their tops each year, today and every day there are not less than 3-5 EACH DAY. Volcanoes are playing a significant roll in global weather.