Atmospheric Sciences Research Spotlight

Does Water Vapor from Volcanic Eruptions Cause Climate Warming?

By studying past volcanic eruptions, scientists find that the amount of water vapor reaching the stratosphere during moderately explosive eruptions may not be contributing to the greenhouse effect.

Source: Geophysical Research Letters


When the Earth absorbs solar radiation, the planet heats up. Some of that energy escapes back into space as electromagnetic radiation, but certain gases in the atmosphere can trap the electromagnetic radiation, warming the planet like a blanket.

A longstanding question involves whether gases emitted by volcanoes help trap energy on a global scale. Specifically, water vapor—which traps more radiation in the atmosphere than any other gas, alone accounting for half of the greenhouse gas effect—is of great interest to scientists studying volcanoes and global climate change. In theory, the force of eruptions could inject water vapor into the stratosphere, where the water vapor could reside for months and cause significant warming. Days after Mount St. Helens erupted in 1980, for example, researchers measured increased water vapor in the stratosphere, but little evidence has emerged since then that moderately explosive eruptions significantly increase the amount of water vapor in the stratosphere. Still, numerous studies have attempted to model the impact that water vapor spewed from volcanoes has on the global climate.

Here Sioris et al. took measurements from the 2015 eruption of the Calbuco volcano in Chile to see how much vapor a moderate-sized volcanic eruption would spew into the stratosphere. The researchers used the Aura satellite to take samples of the water vapor in the volcanic plume following the eruption. This is the first time that satellite observations have been used to determine the total amount of water vapor injected into the stratosphere by a volcanic eruption, giving researchers a more representative data reading than in situ observations used in an earlier study.

The satellite data revealed that the ratio of water vapor to dry air reached 14 parts per million by volume in the stratosphere days after the eruption. The researchers found that this significant vapor enhancement from Calbuco, as had been observed following Mount St. Helens, persisted for only a few days in the stratosphere. Using the data in this study and the measurements of other eruptions, the authors confirm that moderate-sized volcanic eruptions do not deliver enough water vapor to the stratosphere on timescales long enough to consistently contribute to the greenhouse effect. (Geophysical Research Letters, doi:10.1002/2016GL069918, 2016)

—Alexandra Branscombe, Freelance Writer

Citation: Branscombe, A. (2016), Does water vapor from volcanic eruptions cause climate warming?, Eos, 97, Published on 11 August 2016.
© 2016. The authors. CC BY-NC-ND 3.0
  • davidlaing

    There is no “greenhouse effect,” as far as we know. We ASSUME there is, but there is absolutely no experimental or even observational evidence that it works as theorized. This is inexcusable in science, taking a concept as true without proof. At the same time, we focus on explosive (andesitic) volcanoes and completely ignore the effects of non-explosive (basaltic) volcanoes in releasing HCl and HBr, which are known to be photodissociated in early spring on polar stratigraphic clouds, thinning the ozone layer and admitting more irradiance by solar UV-B, which is 48 times as effective a warming agent as the low-frequency IR known to be absorbed by CO2. Until we are willing to re-examine our ASSUMPTIONS regarding greenhouse warming, we will continue to get nowhere in solving or understanding the global warming issue.

    • Bin_Madden

      Please do not mislead the public. Of course there is a greenhouse effect. The atmosphere is transparent to visible band (sunlight) radiation and moderately opaque (with exception to the 8-12 micron window) to thermal radiation emitted to space. Water vapor is a principal greenhouse gas in the sense that it strongly absorbs across wide bands of the infrared (this is common knowledge, demonstrable by spectroscopy), re-emitting the warmer upwelling emissions from the lower atmosphere/surface to space at cooler temperatures and also emitting some of the energy back downward. This is the reason that our surface temperature averages 288K while the planetary temperature as observed from space is about 255K. The greenhouse effect accounts for this difference. The analogy to a literal greenhouse only goes so far, but the term was coined because the material of the literal greenhouse follows a similar transparency to visible, opacity to thermal infrared property.

      Back to the atmosphere: the question of whether anthropogenic CO2 enhances this effect, either through direct absorption/emission or indirectly through its influence to the principal greenhouse gas (GHG), water vapor, is what is relevant to the question of human-induced global warming. When we introduce misnomers like “climate denier” (of course we have a climate!), “climate change denier” (climate is always changing due to natural variability of the non-linear feedback system, even without humans around), and comments such as “There is no greenhouse effect” the public IQ lowers.

      • davidlaing

        You do a very good job of spitting out the officially sanctioned dogma, but you do not think for yourself. Can you point to the actual experimental data that proves that CO2 causes global warming? No, of course you can’t, because it doesn’t exist. Until someone actually performs the experiment, preferably more than once, and the results actually prove that CO2 causes warming, we have no proof, period, only supposition, and that is unacceptable in science. The climate science community has latched onto a convenient, but facile explanation for global warming that is loaded with all sort of problems, requiring all sorts of elaborate explanations of why it doesn’t work the way it’s supposed to, and that is just not right. Meanwhile, climate scientists aggressively ignore other reasonable explanations to which numerous observations of real phenomena lend ample support, such as ozone depletion from anthropogenic CFCs and non-explosive volcanoes, like the 2014-15 eruption of Iceland’s Bardarbunga, causing increased UV-B irradiation, which is 48 times more powerful than the weak IR radiated by Earth and absorbed by CO2. Scientists have a real obligation to do real science, and not just fall back on theory and elaborate mathematics to prove a-priori reasoning.

        • Bin_Madden

          On two points you are mistaken. First, I am not in the camp of blind acceptance that anthropogenic CO2 leads unequivocally to global warming; I am of the camp that we need to understand the complex, non-linear feedbacks of the earth’s climate system prior to understanding the role of anthropogenically introduced CO2 to the system. The reason for “elaborate explanations of why it doesn’t work the way it’s supposed to” is tied directly to this limited understanding of the full system response.

          As for the fact that the molecule CO2 does absorbs thermal emission, just like the most abundant greenhouse gas (water vapor) does, this has been demonstrated in spectroscopy. My background is in remote sensing, and we use the aforementioned property of atmospheric CO2 absorption to conduct temperature soundings of the atmosphere. There is no mystery, debate, nor conspiracy theory behind it whatsoever.

          Your strong polarization on this issue has clouded your ability to even comprehend my original point. The moment you read my message it is clear that you made an immediate assumption that I was a disciple the climate science community’s assertions that you are railing against, and went off on a tirade of counterarguments to a position I never took.

          So, back to my original point: your assertion that “There is no ‘greenhouse effect.'” This ridiculously incorrect statement is tantamount to saying that the sun does not heat the earth, or meteorological clouds are not composed of water. It sounds like Donald Trump proclaiming that there is drought in the western US, because he does not have fundamental knowledge about what drought is. Again, the greenhouse effect is an intrinsic property of Earth’s atmosphere, with or without humans present to muck with it, and with or without CO2 for that matter! Missing this simple point reveals that your foundational knowledge of atmospheric science must be very poor, even if your appeal for more scientific evidence for the exact roles of anthropogenic CO2 in the climate response are correct. It puts into question what might have otherwise been reasonable statements from you, because although you appear to sound open minded to other possibilities, you use very close-minded language. Worse, it suggests that you would likely not be receptive to proof of anthropogenic CO2’s role in global warming, derived from pure scientific method.

          The agenda to disprove something is just as bad as the agenda to prove something. There should be no agenda other than to put forward hypotheses and evaluate them.

          We cannot, as a society, have a discussion on this topic if we continue to polarize the problem to the extent that we cannot even agree on the basics.

          • davidlaing

            The fact that you resort to ad-hominem remarks about me shows that you are insecure in your argument. You are annoyed, you are irritated, that I do not blindly accept your, or anyone’s, facile pronouncements about the way the Earth system works. I look to Earth itself for information regarding Earth subsystems, not to self-styled experts, who pretend to understand how things work, but really don’t.

            No, greenhouse warming is not a fact. It is a supposition, and it is not backed up by hard data. We know that CO2 absorbs Earth IR, We do not know that CO2 causes warming, because it has never been proven that it does beyond any reasonable doubt. The experiments showing warming simply haven’t been done. This is inexcusable in scientific circles, and it is an unfortunate commentary on the way science is done in the world today, that is, by “consensus,” which is not the stuff of science, but the stuff of politics. Pundits can agree that the world is flat all they want, but the fact is that it’s round. Where earth is concerned, there is only one truth, and it is our job to find out what that is. I do my part. Why do you refuse to do yours?

            • Bin_Madden

              You have forgotten your original comment, “There is no greenhouse effect.” This original comment, which is simply wrong, is what I was responding to. You do not seem to understand that the greenhouse effect happens with or without anthropogenic CO2. There is no use in trying to argue with you about a simple point so I will stop now. Go ahead and finish this thread up with the last word about how your opinion trumps Physics 101 if you like.

              • davidlaing

                Simple. THERE IS NO EVIDENCE. In science, theory MUST be backed up by hard evidence, either from experiment or from observation, and for greenhouse warming, this hasn’t been done (ignoring Angstrom, 1900). The theory is internally consistent, and it is sophisticated and convincing, but there is nothing behind it. If you can prove me wrong on this, please do.

    • Jesse4

      The greenhouse effect has been observed and understood for generations.

      • davidlaing

        Can you cite at least one study involving real (i.e., observed or experimental) data that supports greenhouse warming theory? if you can’t, then my point stands. The theory was developed by Svante Arrhenius in 1896 and it was disproven by Angstrom in 1900. To my knowledge, no actual experimental data or even real observations have come forth since. Flat Earthers used the same argument that you just used, that “Everybody knows that! Only a fool would argue otherwise, etc.” My point is that we are using theory alone to justify a highly important conclusion about atmospheric behavior, and we can’t point to real evidence that it is true. Bottom line: Earth is always right. What we say about it may or may not be, depending on the real evidence.