How do we detect undersea volcanoes? Have we found them all?

They can detect them now by satelite, but since new ones arise constantly there is always a chance they can miss one for a few months.

Seems like you aren't going to get the answer with this question either.

"In 2004, the team discovered the volcano by tracking a large, yellowish plume in the water back to its source. They returned last month, in time to witness a full eruption."

"29 May 09 - Marine scientists have discovered a massive

underwater volcano off Indonesia’s western coast"

There may not be a sensor system in place to identify undersea volcanoes. Since no one has mentioned one in either of the questions you asked I think it's safe to say they find them when there is surface evidence leading them to it or if they happen to be doing research in an area of the ocean floor where they find activity.

These volcanoes may not affect the atmosphere directly but I'd be surprised to learn they have no affect on ocean currents and global climate.

As has been said the Gakkel Ridge volcano's in the Artic ocean were only discovered in the early 90s were discovered mostly by accident because of experiments with deep diving submarines in the area. The articles below describe how the discovery took place and to a certain extent why they were previously unknown. The big question currently unanswered are these volcano's responsible for slow or reduced ice formation in the artic ocean. This is basically unknown as nobody is tracking water temps in the region to determine if the massive string of volcano's is causing noticeable warming of the region or not.

http://news.nationalgeographic.com/news/2008/06/08...

http://www.sullivan-county.com/nf0/ep/la_times.htm

http://www.canada.com/story.html?id=81bb2fd3-63f1-...

http://www.volcanolive.com/gakkel.html

http://www.msnbc.msn.com/id/25419241/

http://strata-sphere.com/blog/index.php/archives/5...

http://www.sciencedaily.com/releases/2008/06/08062...

Undersea volcanoes are continuous all along the Mid Atlantic ridge from near Antarctica to the Arctic, all across the Indian Ocean, all across the Pacific including the Pacific Rim and the Hawaiian Islands, under the Arctic ice cap, etc... all the Hawaiian Islands are volcanoes, and many of the islands of the Philippians are inactive volcanoes. In the middle of the Atlantic the Azores are all volcanic islands.

Think of continental plates like rafts that are floating around and pushing against each other. The reason that the crust floats on the molten core is because the material that the Earth's crust is made of is lighter than the magma and molten metals in the earth's center. Our planet has a radioactive molten metal core. The degrading metals produce tremendous heat much like the sun and this is why the continental plates are constantly moving and volcanoes constantly erupt.

Everywhere there is a crack in the earth's crust under the oceans lava is constantly oozing up onto the ocean floors. The red dots on the maps are volcanoes

http://vulcan.wr.usgs.gov/Glossary/PlateTectonics/...

http://upload.wikimedia.org/wikipedia/commons/b/b4...

http://www.globalchange.umich.edu/globalchange1/cu...

Yes. Volcanic activity definitely has an effect on climate. How much? Go figure...

We probably haven't found them all, but we don't need to have an accurate count to know we are still producing most of the increase in CO2.

Carbon comes in many isotopes, the most common are C12, C13, and C14. The increase in CO2 has less C13 than volcanic carbon, a tell-tale marker of life. It is also almost depleted of C14. This means it is very, very old.

Old and organic. That means fossil fuels.

If a volcano erupts close enough to the surface with enough energy in a place where people will notice and report it, it gets discovered.

http://www.sciencecodex.com/marine_scientists_disc...

It stands to reason that since new ones still get discovered from time to time, and since many are dormant for long periods of time, there are many more to be discovered.

As for the CO2 effect that undersea volcanoes have on our atmosphere, probably most of it is known:

1) The dormant volcanoes do not contribute so much CO2 as the active ones.

2) Volcanoes that emit CO2 deep undersea will have trouble affecting the atmosphere at the surface.

- If giant gobs of CO2 were bubbling to the surface, it is likely someone would notice.

- CO2 in the atmosphere is absorbed by the calcium in the ocean. It is the equilibrium between the atmosphere and the ocean that determines the CO2 concentration of the atmosphere. The ocean has a great deal of ability to absorb more CO2. Adding more CO2 to the atmosphere only temporarily ups the concentration until the ocean can absorb it again. Starting with the CO2 at the bottom of the sea needing to bubble through will greatly speed up the process.

http://www2.canada.com/components/print.aspx?id=43...

- CO2 is goes supercritical at 7.38 MPa (74 atmospheres = 740 meters depth) and denser than H2O.

http://en.wikipedia.org/wiki/File:Carbon_dioxide_p...

It would sink rather than proceed to the surface. The idea of underwater reservoirs of super critical CO2 has been born out by tragic observation.

http://www.neatorama.com/2007/05/21/the-strangest-...

Yes, there could be more CO2 being released by volcanoes than we realize, but that should not impact the atmospheric CO2 levels much, nor alter the debate on where it comes from.

EDIT @Antarctica: You need to be more clear about how your links in any way refute Jim Z's previous answer. I really don't get it.

Let's look at the heat.

The interior of the Earth provides a well known total amount of heat, about .075 watts per square meter, on average.

http://geophysics.ou.edu/geomechanics/notes/heatfl...

In some locations, it's a lot more, but the relevant thing for global warming is the average.

The Sun provides about 350 watts per square meter.

http://stephenschneider.stanford.edu/Climate/Clima...

So the interior heat of the Earth is negligible on a global scale, no matter how many volcanoes there are. More volcanoes would mean the heat is more spread out, but don't increase the TOTAL amount.

They may be spectacular, and have a spectacular effect locally. But go a mile away, and you wouldn't notice one. They don't contribute a significant amount of heat. It's not remotely close.

It's exactly like the urban heat island effect, powerful locally, but not important on a global scale.

Snapping fingers

The 'best answer' in your previous question was chosen by voters and given to someone who claims to be a geologist, you would think a geologist would know about this.

http://earthobservatory.nasa.gov/Features/monvoc/

or the data that is referred to in the story

http://goes.higp.hawaii.edu/newindex.shtml

This is certainly not the first time he has been shown to know little about the field he claims to be qualified in.

Easy answer, we don't, that's why the tsunami came as such a shock.

There must be hundreds still to come.