Are volcanoes a major source of global warming?

[Johnny Skeptic]

I look forward to reading comments from readers.

[Major Billy]

I don't know how great an effect they have these days but greenhouse gases from volcanoes probably freed the planet from the Snowball Earth (http://www.snowballearth.org) effect.

[Aptorian]

Actually they tend to contribute to global cooling as they throw a lot of dust/ash into the air, blocking sunlight. Even though they also release co2, the cooling effect is greater.

However, large underwater eruptions can cause an increase in temperatures, but I'm not sure how common or how large they need to be to play a significant part.

[DNAReplicator]

Er.....yes, volcanoes release CO2 into the atmosphere.

And yes, CO2 is a greenhouse gas.

And yes, the more greenhouse gas in the atmosphere, the hotter the world will get.

So, are you suggesting that we should scrap volcanoes instead of reducing other forms of CO2 emission?

Great idea! I look forward to your detailed implementation plans.

[wonkothesane]

I think we need to nuke a bunch of volcanoes. Make then erupt, and cool the planet.

It always works in the movies...

[ninewands]

Are volcanoes a major source of global warming?
Major? Not anymore ... carbon emissions from human activities far outweigh CO2 emissions from volcanoes. Contributors? Definitely! Significant contributors? I don't know. Maybe the IPCC ought to look into it is they haven't already.

[Craig]

They put out roughly 1% of what human activities do per year, if that's what you're asking.

But they've been doing it for far longer than we have... :)

[David B]

It gets very complicated. But certainly there were short term cooling effects from Pinatubo (spelling?), bigger ones from Tambora, and radical climate effects from Toba.

The non explosive eruptions would tend to be warming, I think.

If a big volcano allowed a lot of snow to settle year round, or nearly so, in high latitudes for a few years, then that would make the albedo greater, and tend to reinforce the effect, even as the greenhouse gasses would do the opposite.

Complicated!

David B

[Loren Pechtel]

They are a very minor source, not a major source.

[modernPrimitive]

I read somwhere that sulfur released by volcanoes into the upper atmosphere creates a global cooling effect. Take your pick acid rain or global warming!

[theyeti]

Are volcanoes a major source of global warming?

No. Not even close. The amount of CO2 they produce is a tiny fraction of human emissions.

Look at a graph (http://en.wikipedia.org/wiki/Image:Mauna_Loa_Carbon_Dioxide.png) of rising CO2 concentrations and you can see that they have been rising in a slow and consistent manner, plus you can readily observe a seasonal cycle. If volcanoes were responsible for a large fraction of CO2 emissions, then CO2 levels would jump after every major eruption and would mask seasonal variation in the short-term.

theyeti

[theyeti]

I read somwhere that sulfur released by volcanoes into the upper atmosphere creates a global cooling effect.

Major volcanic eruptions do noticeably lower global temperatures due to aerosols and ash blocking out sunlight. Human pollution causes a similar problem. However, the effect is short lived because the emissions don't remain long in the atmosphere. Global warming on the other hand is a long-term issue because CO2 and most other greenhouse gases remain in the atmosphere for centuries.

theyeti

[Musing Man]

Major volcanic eruptions do noticeably lower global temperatures due to aerosols and ash blocking out sunlight. Human pollution causes a similar problem. However, the effect is short lived because the emissions don't remain long in the atmosphere. Global warming on the other hand is a long-term issue because CO2 and most other greenhouse gases remain in the atmosphere for centuries.

theyeti

Now, with all due respect, that was a badly worded and inconsistent explanation attempt.
What emissions? Whose emissions?

Volcanoes can have a dramatic effect on climate, usually a (historically) short lived one and generally leaning towards cooling (way more ash and/or other gases than CO2).
Part of the human emissions also contribute to cooling, but the bulk of them contribute to warming, both directly and indirectly (via a multitude of proxy effects).

[theyeti]

Now, with all due respect, that was a badly worded and inconsistent explanation attempt.
What emissions? Whose emissions?

Sorry. I meant aerosol and particulate emissions, regardless of source.

theyeti

[inmeitrust]

Dammit peoples, links please. I debate with a Michael Savage ditto head and need good links. Preferably from NASA, JPL, or similar sources.

[Musing Man]

If that's what you want, something like this (http://earthobservatory.nasa.gov/Study/Volcano/), then you might as well UTFG (http://www.urbandictionary.com/define.php?term=utfg)... :Cheeky:

[unrealist42]

After Krakatoa erupted Europe had the "Year with no Summer". It was so cold crops failed and snow fell in June. It has been estimated that global average temperature fell by about 3 degrees that year.

Pinutabo and Mt St Helens had a similar but much less drastic effect.

It may be that short term cooling due to particulate discharge is offset by the long term effects of CO2 and other gas emission which stays in the atmosphere longer.

Geologic records point to long term massive volcanic activity as contributing to warmer periods on earth but we dont have that now.

[Hooboy !!]

The Little Ice Age (http://en.wikipedia.org/wiki/Little_Ice_Age#Volcanic_activity) was a likely a consequence of volcanic activity.

I think the answer to the question is... it depends on the type of the eruption, the scale of the eruption, and the chemical composition of the eruption.

I think too that the steady average of volcanic activity on the planet is inconsequential, and it is only the extraordinary eruptions, either in quantity or severity, that have any kind of real effect on the global climate.

[Berthold]

After Krakatoa erupted Europe had the "Year with no Summer". It was so cold crops failed and snow fell in June. It has been estimated that global average temperature fell by about 3 degrees that year.
That was Tambora (http://en.wikipedia.org/wiki/Year_Without_a_Summer).

[judge]

They put out roughly 1% of what human activities do per year, if that's what you're asking.

But they've been doing it for far longer than we have... :)

How do we know this?

[Boro Nut]

I think we need to nuke a bunch of volcanoes. Make then erupt, and cool the planet. It always works in the movies...Don't be so flippant. Unlike bombs, nuclear weapons have loads of scientific stuff in them. How else could you expect to be able to finely control chaotic variables in natural geological processes that you don't understand either unless you use something with loads of scientific stuff in it?

It's how science works. Some bloke in a lab coat understands it all for you and you just have to push the button. TV's work on exactly the same principle, and they blow volcanoes up successfully all the time. As long as they provide a button I can't see what could go wrong. I work in engineering, and although they may spend decades designing and building massive bridges, tunnels, ships etc they still need to employ a highly trained dignitary to press a button before it will work.

Boro Nut

[Boro Nut]

Take your pick acid rain or global warming!Either. Just not global rain again please.

Boro Nut

[blastula]

On comparing volcanic vs. anthropogenic co2 emissions:

From the British Geological Survery (pdf) (http://volcanology.geol.ucsb.edu/gas.htm)

Geological carbon emissions include both volcanic emissions (both passive, from volcanoes in repose, and those related directly to eruptive activity) and non-volcanic — direct emissions from the Earth's crust and lithosphere. The contribution to present day atmospheric CO2 loading from volcanic emissions is relatively insignificant, Morner & Etiope (2002) estimate that subaerial volcanism releases around 300 Mt/yr CO2 representing the equivalent of just ~1 % of anthropogenic emissions. Even during extraordinary times in the geological past, such as the eruption of flood basalts [e.g. the Deccan Traps, 66 Ma], the additional CO2 emission is estimated to be only 0.3-2 Mt/yr. Nevertheless, the eruption of individual flows would have released significant volume of CO2 over very short time periods and such volcanic emissions may have contributed to significant “greenhouse" effects at times in Earth history, and additionally by precipitating of large scale methane hydrate melting (Svenson et al, 2004). Therefore, understanding the impact of such temporary increases on global temperatures may be critical to understanding the impact of present day anthropogenic emissions.

From an abstract (http://adsabs.harvard.edu/abs/1992GeCoA..56.1765W) of a paper published in Geochimica et Cosmochimica Acta.

Global emission of carbon dioxide by subaerial volcanoes is calculated, using CO 2 / SO 2 from volcanic gas analyses and SO 2 flux, to be 34 ± 24 × 10 l 2 g CO 2 / yr from passive degassing and 31 ± 22 × 10 12 g CO 2 / yr from eruptions. Volcanic CO2 presently represents only 0.22% of anthropogenic emissions but may have contributed to significant "greenhouse" effects at times in Earth history. Models of climate response to CO 2 increases may be tested against geological data.