Scroll To Top

Friday, October 3, 2014

It's (not) volcanoes: WUWT ponders the implications of newly discovered old seamounts

Sou | 5:07 PM Go to the first of 14 comments. Add a comment

Gravity gradient model, Mid-Atlantic Ridge; green dots are earthquakes of at least magnitude 5.5
CreditDavid Sandwell, SIO

There is a new paper in Science this week about the latest ocean topographic mapping effort. A team of researchers led by David T. Sandwell "combined new radar altimeter measurements from satellites CryoSat-2 and Jason-1 with existing data to construct a global marine gravity model that is two times more accurate than previous models." As the editor's summary stated:
Detailed topographic maps are available for only a small fraction of the ocean floor, severely limited by the number of ship crossings. Global maps constructed using satellite-derived gravity data, in contrast, are limited in the size of features they can resolve. Sandwell et al. present a new marine gravity model that greatly improves this resolution (see the Perspective by Hwang and Chang). They identify several previously unknown tectonic features, including extinct spreading ridges in the Gulf of Mexico and numerous uncharted seamounts.  

North Atlantic Ocean gravity gradient model showing plate tectonic history of rifting continents.
Credit: David Sandwell, SIO

The paper indicated that this research will help improve the estimates of sea-floor depth in the 80% of the oceans having no depth soundings, and will greatly help scientists add to knowledge of ocean tectonic processes.

Brittle stars and deep-sea corals cover
a known seamount in the western Pacific Ocean.
Credit: NOAA
If you are interested in the subject, you can learn more about the work at the NSF website and read the paper at Science (subs required).

The press release was also published at

The Hwang and Chang perspective mentioned in the editor's summary can be read here, though you might need a subscription to Science.

It's (not) undersea volcanoes

Whenever the topic of volcanoes under the ocean comes up, you're bound to get deniers claiming global warming is caused by undersea volcanoes. Or something along those lines. (The under-sea volcanoes notion isn't that uncommon, but it is pretty silly. It doesn't make the top 176 denier memes at

A moment's reflection would stop this denier meme in its tracks. Deniers are not good at reflection.

Let's reflect on the question: is global warming or ocean acidification being caused by volcanoes? That's what Anthony Watts wonders today (archived here). He says to his readers:
One wonders how many of these newly found thousands of volcanic seamounts are producing CO2 that bubble into the ocean

Does he really wonder that or not? No-one but him probably knows because that's as far as his public wondering utterances went. He left it up to his readers to ponder and post their various comments.

Think about it. The press release that Anthony copied and pasted mentioned new discoveries of volcanic seamounts. These are mostly remnants of volcanoes.

First of all, a newly discovered seamount is not the same thing as a new seamount. The higher resolution mapping identified topographic features that were previously undetected. That's all. Most would have been there for a very, very long time.

Second of all. There is no suggestion in this work that there has been a very recent heightening of volcanic activity. Whether or not there is CO2 or anything else seeping from under the ocean, there is no reason to believe that it is any different now to what has been happening for the past thousands of years and lots of evidence that on balance, little has changed during the Holocene at least and probably much longer.

Thirdly. Even were there found to be some new volcanic activity under the ocean, or massive new source of sub-oceanic CO2, there would have to be an equally large CO2 sink that has yet to be discovered. People have calculated how much CO2 is going into the oceans, how much into land sinks and how much into the atmosphere. Plus how much has been created by humans burning fossil fuels. The sums balance pretty well. We can't pass the blame for global warming or ocean acidification onto volcanoes - above or below the ocean surface. It's us.

FourthlyGerlach (2011) reports that the total amount of CO2 from all volcanoes in the world averages somewhere between  0.13 to 0.44 billion tonnes a year, with a most likely range from  0.15 to 0.26 billion tonnes a year. We spew more than 35 billion tonnes a year. Volcanoes contribute barely a drop in the bucket compared to what we are adding. From the AGU:
On average, human activities put out in just three to five days the equivalent amount of carbon dioxide that volcanoes produce globally each year.

Further reading

If you're interested in volcanoes in the context of global warming I recommend the Gerlach paper to start with. It has a lot of references for further reading. Terry Gerlach wrote about it at There's also the USGS and AGU.

From the WUWT comments

At WUWT there is, as usual, a lot of nonsense with a few more knowledgeable comments thrown into the mix. Here's a non-representative sample.

Tim Ball confuses the source of CO2 emissions with the fact that once emitted, CO2 disperses through the troposphere and is a well-mixed greenhouse gas. For an ex-professor of any discipline, this level of ignorance is not funny:
October 2, 2014 at 4:19 pm
None of this is new. Some of us have been asking and writing about these issue for decades. The sad part is we were ignored by most, including many of the so-called skeptics.
CO2 escapes in large quantities not just from the crater but for 100s of square kilometres around the volcano. This is also detected on land based volcanoes but is effectively ignored, especially on Mauna Loa. Some of the early studies were done on Mt Etna. The porosity of the lava makes a considerable difference.
CO2 uniformly distributed in the atmosphere; what a joke, except it is not funny.

Gamecock has a bright idea. He should write a paper:
October 2, 2014 at 5:05 pm
Additionally, what impact do the undersea volcanoes have on the size of the ocean basin? Could the 1.9mm/year SLR be due to volcanoes?

Bill Taylor says he's been building straw men for years in an effort to persuade people that scientists don't know nuffin':
October 2, 2014 at 6:59 pm
as a layman i have tried to tell folks for decades that the earth spews forth gases and oil 24/7 has been doing so for eons……to claim that humans release of co2 has upset some delicate balance is utter IDIOCY………there is no delicate balance, there is a chaotic system seeking balance that can never be found……..

TRG is one of the very few who makes a reasonable point:
October 2, 2014 at 9:19 pm
If the increasing CO2 in the atmosphere is due to undersea volcanoes, does anyone have an explanation as to why it has been rising so smoothly and steadily all these years. I didn’t think so.

Sparks scoffs at the notion that atmospheric CO2 has been rising.  And gets jumped on by all the informed WUWT-ers. Oops. No he doesn't.
October 2, 2014 at 9:25 pm
Rising? give some context as in capacity and potential? spill it genius!

Here's the spill for Sparks. Skip to the end to see CO2 over the past 800,000 years:

D. T. Sandwell, R. D. Muller, W. H. F. Smith, E. Garcia, R. Francis. "New global marine gravity model from CryoSat-2 and Jason-1 reveals buried tectonic structure." Science, 2014; 346 (6205): 65 DOI: 10.1126/science.1258213 DOI: 10.1126/science.1258213. (subs req'd)

Gerlach, Terry. "Volcanic versus anthropogenic carbon dioxide." Eos, Transactions American Geophysical Union 92, no. 24 (2011): 201-202. DOI: 10.1029/2011EO240001 (open access)


  1. I guess it is a waste of time pointing out to them that CO2 emissions from volcanos are already included in the carbon budget - they would require science and the understanding of the complete carbon cycle.

    I heard an anecdotal story that when that Icelandic volcano erupted and grounded all those jetliners, it actually caused a measurable FALL in the atmospheric CO2 - a great case study that proves reducing human-made carbon emissions works.

  2. Seeing as how the vast majority of seamounts are long orphaned from midocean rifts and thus are long dead, one wonders how discovering more volcanic corpses could somehow reanimate the "it's volcanoes" claim.

    Assuming he has a grain of intelligence and critical thinking skills, it's hard to conclude other than that Watts is fostering rumors for consumption by the gullible. "One wonders how many of these newly found thousands of volcanic seamounts are producing CO2 that bubble into the ocean..." is really "I want to leave you wondering this aloud in other places, and you being the proven gormless saps that you are, you'll reliably march forth and regurgitate.

    1. "Assuming he has a grain of intelligence and critical thinking skills ..."

      Nice use of irony there :)

      Of course we all know Watts has neither.

  3. One funny typo -- you referred to Gerlach (apparently) and "Gerlich" at one point.

    Gerlach is evidently a highly competent earth scientist.

    Gerlich, on the other hand -- at least the Gerlich of Gerlich and Tsheuschner -- uh, is not.

    And, of course, the whole "undersea volcanoes" thing is, as you point out, moronic for may reasons. About par!

  4. Ach, I meant "Gerlach as Gerlich".

    Friends don't let friends make typos.

  5. It's good to see that, having got the priorities out of the way by mapping Mars and the Moon in great detail, we're getting around to mapping this planet.

  6. "Second of all. There is no suggestion in this work that there has been a very recent heightening of volcanic activity. Whether or not there is CO2 or anything else seeping from under the ocean, there is no reason to believe that it is any different now to what has been happening for the past thousands of years and lots of evidence that on balance, little has changed during the Holocene at least and probably much longer."

    There is no reason to believe it is not changing either. Nobody knows how numerous, how large, or how active the undersea volcanoes are.

    1. Knowing as we fairly well do the complicated fate of C02 emerging from the ocean floor or a submarine volcano, perhaps you can at least make an estimate of what sort of additional submarine volcanic activity would be necessary to produce the additional CO2 signal we now see in the atmosphere? One can set boundaries of plausibility regarding submarine volcanic activity despite not having exact details of where and how much activity there is.

      Meanwhile up here in the gaseous atmosphere where full visibility and grounded reality prevail, we have a very good understanding of the provenance of additional CO2 we see. Imaginary submarine volcanoes need not be invoked, at all.

    2. Volcanic CO2 comes out as complete CO2 molecules, so that doesn’t decrease atmospheric oxygen. But burning carbon uses up oxygen.

      TAR Fig 3.4 (p206) plots atmospheric O2 vs. CO2 from 1990-2000. If the rise in CO2 were due to volcanoes, the line would be horizontal because O2 wouldn’t decrease.

    3. And that's leaving aside the fact that burning known quantities of hydrocarbons produces known amounts of CO2. Similarly clearing known sq km of forest results in known net increase in CO2.

      And ocean acidification is being measured these days, too.

      I think someone somewhere would have noticed if there was a sudden burst of supervolcanic eruptions under the oceans.

      For some weird reason, deniers seem to think that burning hydrocarbon doesn't result in CO2 or reduce oxygen. It also looks as if johnnycrash has summarily dismissed a published paper, probably without even reading it.

    4. "Nobody knows..."

      No Johnny, you don't know.

      But those of us with a clue - just at least some slight connection to reality - can check with the US Geological Survey or with the British Geological Survey. And those guys tell us that CO2 emissions from volcanoes (including submarine ones) are two levels of magnitude below human emissions.

      So unless there has been an extraordinary upsurge of volcanic activity, and this has happened (even more extraordinarily ) without leaving a tremor on seismometers throughout the world, then no.

      Or to put it more succinctly: the climate change deniers are talking out their arses yet again.

    5. Do you believe in elves and pixies Johnny? Why not? Can you prove they don't exist?

    6. Remember telegrams?
      Scientists report finding new unknown dormant undersea volcanoes. Stop
      Denialists seize upon this new information to prove yet again how stupid they are. Stop


Instead of commenting as "Anonymous", please comment using "Name/URL" and your name, initials or pseudonym or whatever. You can leave the "URL" box blank. This isn't mandatory. You can also sign in using your Google ID, Wordpress ID etc as indicated. NOTE: Some Wordpress users are having trouble signing in. If that's you, try signing in using Name/URL or OpenID. Details here.

Click here to read the HotWhopper comment policy.