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What an interesting article, Kenneth!

Thank you very much for the link!

I am afraid that we ignore much more than we know about the effects of volcanism in the current climate.

But I insist on a specific question: how much juvenile water (of magmatic origin) do aerial volcanoes emit each year? Is there any reliable estimate to the repect? Some range of magnitude?

Depends on what scale you are considering (time and distance). From a total water cycle perspective there is no new water on earth. It is all recycled in various forms.

Any typical water cycle picture often only has evaporation off the oceans, falling as rain/snow (precipitation) flows down the rivers and back into the ocean again. Very simplistic. It ignores the precipitation that percolates into the earth to become groundwater that contributes to baseflow in rivers (days to years), deep groundwater cycles (years to millennium) that can get down into large alluvial aquifers or fractured rock aquifers that can get into deep sedimentary basins that can get into rocks that get subducted into the mantle to be extruded as volcanoes, water vapour etc. So once again it is a scale thing. How long have you got?

Some may argue what about meteorites bring new water earth. It can be calculated. I suppose someone has done it.

Hello again!

I suppose that the water content emitted by the volcanoes of subduction zones will contain water from both: the "primordial" magma and the earth's crust fused by the "friction" of the converging plates, that is to say: a water that has never been in the atmosphere (a brand new water that opens in the hydrological cycle) and other water that has belonged to a hydrological cycle before its aquifer entered a subduction phase. To distinguish between both waters seems to me nearly impossible.

But the water vapor emanating from volcanoes located in divergent plates or those located in hot spots, I suppose that this water is totally juvenile, it “premieres” in the atmospheric hydrological cycle.

I am asking about this water, the amount of this water emissions. It is to know to what extent the hydrological cycle is closed (or not).

The problem I see, to be able to answer this question, is that the main submarine volcano is 40,000 miles long and it is under water some miles deep in the ocean. - Not an easy task to solve at all!

The subject seems very interesting to me.

Thank you very much for your helpful answers and information.

Best regards,

As has been pointed out, the concept of "juvenile" water is a fuzzy one. Since the earth remains pretty much the same size, for each bit of new gas, water, or rock that bubbles up from a volcano there is a bit of gas, water, or rock that is being recycled down inside the earth. That said there are likely pulses to both sides of the equation at various time scales. The key point is that whatever they are, they will be cyclic variations about a mean that balance out over time.

When considering the extensive volcanic activity that occurs along the mid-ocean ridges, it is important to remember that the magma associated with mid-ocean ridges is relatively poor in gasses compared to volcanic sources that are associated with subduction zones or the melting of continental crust.

Water vapor is a greenhouse gas, but it is treated very differently in climate modeling because the time scale for its residency in the atmosphere is very short. Water vapor is cycling in and out of the atmosphere at very high rates. There are quick mechanisms for getting water into and out of the atmosphere (evaporation and rainfall). This is different from carbon dioxide. There are analogous processes for carbon dioxide, but the time scales are different. The amount of water vapor in the air we inhale varies by 10s of grams per cubic meter (roughly 0 to 28 grams per cubic meter) while the amount of carbon dioxide in the air we inhale tends to vary more on a scale of 10s of parts per million (The average having increased from around 280 ppm to around 400 ppm in the past couple of hundred years). The point being that the amount of water vapor in the atmosphere is much more dynamic than the amount of carbon dioxide. The mechanisms for removing a pulse of water vapor from the atmosphere can operate much more quickly than do the mechanisms for removing a pulse of carbon dioxide.

According to the USGS, Mount Pinatubo vented 250 megatons of gas in a single day (https://volcanoes.usgs.gov/vhp/gas.html this gas being a combination of water vapor, carbon dioxide, sulfur dioxide and other gases). That is just the amount of water vapor that precipitates in one day's rain storm on the Pacific Coast of the United States (1/2 inch of rainfall over an area 200 miles by 50 miles is over 10E9 cubic feet of water which has a weight of over 300 megatons). Globally, water vapor coming from volcanic sources is probably very close to a literal drop in a bucket compared to the water being evaporated and precipitated globally.

https://eos.org/research-spotlights/does-water-vapor-from-volcanic-eruptions-cause-climate-warming