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Podcast: Volcanic Eruptions Stymie Global Warming

This week's physics central podcast is about hot and cold. Volcanoes—which spew material that reaches thousands of degrees Fahrenheit—can actually cool the planet. Volcanoes eject aerosols that reflect sunlight, and climate scientists have observed the cooling effects of major volcanic events in 1991 and 1982. Those effects can sometimes take years to reverse. New research in the journal Nature Geophysics has shown that the combination of minor volcanic events between 1998 and 2010 had a measurable cooling effect on the Earth.

This is a big deal because it partly explains the so-called global warming slow-down: a decrease in the acceleration of rising global temperatures. For the most part, climate models have not been able to replicate the slow-down. But most of those models do not include recent volcanic activity as a cooling factor.

In 2011, Susan Solomon and colleagues at MIT wrote a paper showing that the volcanic contribution from 1998 to 2010 was likely large enough to have a significant cooling effect on the earth. The new work by Ben Santer and colleagues at Lawrence Livermore National Laboratory provides the quantitative evidence to back up Solomon's conjecture.

Using satellite data going back to 1998, Santer and his team measured the extent to which volcanic aerosols blocked sunlight and moonlight coming through the atmosphere. They estimate that volcanic activity may be responsible for 15 to 20% of the global warming slow-down.

The results counter the notion that climate models do not predict the slow-down because they are "oversensitive" to greenhouse gasses. Santer emphasized that this logic is flawed for multiple reasons, but the new results offer more clear evidence against it.

This new information will help scientists make better predictions about future climate conditions (it is already being incorporated into climate models), but it don't be mislead by the title of this post: these cooling effects do not reverse the effects of climate change. If volcanic activity and other cooling effects are reduced in the future, temperatures will once again start to soar.


  1. I find it odd that scientists and climatologists continue to perpetuate the myth that global warming and climate change are the result of CO2 and other greenhouse gas emissions. The ice core samples from Antarctica and Greenland conclusively demonstrate that atmospheric CO2 levels lag behind temperature change by 400-1200 years. How did this 2004 conclusion not change the global warming/climate change theory? The recent (1980-2000-ish) temperature increase on the earth corresponded with an increase on other planets within our solar system. The only logical conclusion is that the increase (and recent decrease, by the way) is a result of variations in solar activity.

    Add to it the corrupted data (Temperature readings in urban areas that once were rural; CO2 readings in close proximity to an active volcano, spewing out CO2), and this further erodes the overall theory and even calls into question every conclusion that was ever derived from this data. Where is the science in all this?

    No algorithm will ever be able to predict climate changes until two things happen: First, ensure all variables are included in the algorithm, even the inconvenient ones that don’t support the theory you want to propagate; and second, ensure only data that is verified accurate is used in calculations. This verification needs to be conducted by an independent third party.

  2. No one and no model has proven that volcanic aerosols have thwarted "Global Warming". Scientists who have bet their reputations on models are now madly scrambling to find anything else to blame, since the global temperatures have stopped rising for over seventeen and a half years.

    All models are wrong. Some models are useful.

    Volcanic CO2 contributions have been seriously underestimated. The accounting for CO2 from volcanoes was limited to obvious (active) volcanoes, but then it was discovered that inactive volcanoes release CO2, as do mid-oceanic ridges and vents. Scientists don't have a count of how many volcanoes are under the ocean, or the quantity of submarine ridges or ocean floor vents, or how much CO2 they release. Scientists don’t even have a handle on geologic CO2 sources on the earth’s land surfaces, let alone what is hidden under the oceans.

    The Gakkel ridge, under the Arctic Ocean, is far more active, in a volcanic way, than scientists thought, just a few years ago.

    The western Antarctic ice shelf sits over an active volcano. Do you think that might have an effect on the "collapse" of the glacier? It has grown so large as to extend out into the ocean; there is a point where the glacier's ice floats up, and detaches from the land it scoured. As such, it is naturally unstable, and certainly will break off someday. Maybe an active volcano, near to that transition point (where the ice begins to float) makes a difference.

    Isotopic analysis of CO2 in the atmosphere has been claimed as 'proof' that the CO2 added to the atmosphere is from mankind's burning of fossil fuels. This is a sham. The whole basis is that measured shifts of unstable isotopes, relative to stable ones, "proves" that the CO2 is ancient carbon. Fine. However, ancient carbon is released by volcanoes, which get it from decomposition of rocks, as well as oxidation of hydrocarbons (ancient hydrocarbons, like fossil fuel deposits that mix in with magma). Oil seeps release fossil fuels, too. Half of all the oil that fouls the earth's waters comes not from mankind, but from natural seeps. This oil and other hydrocarbons is oxidized, and eventually becomes CO2 in the atmosphere, with no blame on mankind.


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