Climate Controversy Solved By Chemistry? Which Volcanic Eruptions Caused Global Cooling
    By News Staff | February 11th 2013 03:39 PM | 6 comments | Print | E-mail | Track Comments

    In the ongoing culture war among climate scientists, climate scientologists and climate deniers, few things stands out like the effect of volcanoes. 

    Volcanoes are well-known for cooling the climate but how much has been unclear, leading to radically differing claims and interpretations. Atmospheric chemists from the Tokyo Institute of Technology and the University of Copenhagen say that patterns of isotopes found in ancient volcanic sulfur trapped in ice cores, and patterns due to stratospheric photochemistry, are a way to say for sure which historic episodes of global cooling were caused by volcanic eruptions. 

     Powerful volcanoes can shoot gases through the atmosphere and high into the stratosphere where it can affect climate globally for a year or more. Less powerful eruptions can also have powerful impacts, but only locally, and for shorter times. And that's the trick. High plumes spend longer in the harsh sunlight of the stratosphere, and that changes the chemical signature of the sulfur in the plume. The balance of various isotopes is changed according to very precise rules, they say. 

    Matthew Johnson, associate professor in chemistry at  the University of Copenhagen, studies chemical mechanisms in the atmosphere, and wanted to provide a more precise tool to historians studying cold spells. "Historical records are not always so accurate. Some may have been written down long after the fact, or when a different calendar was in use by a different culture. But the chemistry does not lie.

    "Using our method we can determine whether a given eruption was powerful enough for the plume to enter the stratosphere affecting global climate. If we can find material from ancient eruptions it can now be used to give an accurate record of global volcanic events extending many hundreds of thousands of years back in time."

    Clue to fires found in ice

    The best place to look for traces of the fiery events is in ice. Tracking climate history is performed on cores drilled from the ice shields of Greenland and Antarctica. Much like tree rings, the snows of each year is compacted into a layer representing that year. As you go further down in the borehole, you descend deeper into history.

    If volcanic material shows up in a layer, you know there was an eruption in that year. Using the method developed by Johnson and his colleagues it is now possible to analyze exactly how powerful a given eruption was.

    "With the sulfur isotope method, we now have a way to prove whether a given eruption was so explosive that it entered the stratosphere, affecting global climate and civilizations, or, whether a given eruption was confined to the troposphere and local in its effects" says Johnson. "There are many controversial eruptions. The Mediterranean island of Santorini blew apart and caused the end of the Minoan culture. But there is a huge debate about when exactly this occurred. 1601 was the 'year without a summer' - but nobody knows where the volcano was that erupted. There's debate over whether there was an eruption on Iceland in 527, or 535, or 541. The sulfur isotope trick is a definite method to solve debates like this and get the most information out of the ice core records."

    Denmark has no volcanoes so collaborating with Japan made sense. "The Tokyo Institute of Technology specializes in analysis of the patterns of sulfur isotopes found in samples in nature, and was able to synthesize the isotopically labeled samples. The University of Copenhagen has a strong group in atmospheric chemistry and spectroscopy; the laboratory measurements were carried out in Copenhagen. Together we were able to do the experiments and build the atmospheric chemical model that demonstrated the stratospheric photo-excitation mechanism."

    Published in PNAS


    As I read this article, I really was left curious about the view of climatologists on global cooling patterns as a whole. There is so often talk in the media about climate change and its repercussions for all life on earth; however, this is typically demonstrated by climate data from a relatively short period of time. And often ignored are the cooling periods that the earth goes through as well. Mathematically, we know these peaks lead to troughs. And data, such as the volcanic sulfur in ice cores, show that the earth goes through cooling periods as well as warming. Very rarely does one see a climate catastrophe graph that includes these periods. The "deniers" this blog references are so often portrayed as flat-earthers, while in reality, they do not deny the idea of human influence on global temperature. Contrarily, it is often a case of lacking information about temperature change for the entire timeline of Earth's existence. Hopefully, as better information becomes available, examing the climate will become more scientific endeavor than political melee.

    Climate change is real. Just ask 97% of the top climate scientists or any national science academy in the world.
    Who loves Al ? I do

    This article was very interesting coming from an environmentalist. This new method seems like it will be very useful, especially in areas like Japan and coastal areas along the Ring Of Fire, where there are 75% of the world's active volcanoes. It also is described in a way that will be easy to teach. Having experience with using the tree-ring method before, the sulfur isotope method will be easy to educate the public and students how to use in the future.
    As mentioned in the comment above, the world does have history of going through cooling and heating periods, mathematically this will always happen with the peaks and troughs. And while it does occur in a short period of time in comparison to the length of Earth's history, a catastrophic volcanic eruption could lead to a cooling period that effected human's agricultural needs. Having a blocked sky leads to less sun, which leads to less crops, as in basic photosynthesis. It is more difficult to grow a crop in an environment where it's constantly cloudy.
    But, using this method to get more precise dates on previous eruptions, could that lead to better predictions to future eruptions? Obviously it could not be exact, but instead of guessing the last time a volcano erupted and estimating when it might again; could it help get a closer approximation? For example, Yellowstone. If this method could dig deep enough, they might be able to get a closer decade of that impending eruption than 'in our life time'.

    Activists gather to Protest Keystone XL

    Activists arrested at White House protesting Keystone pipeline

    Shortly after noon, D.C. police began arresting the protesters, who included actress Daryl Hannah as well as prominent climate scientist James E. Hansen, Sierra Club Executive Director Michael Brune and civil rights veteran Julian Bond. Some of the activists tied themselves to the gates with plastic handcuffs; others sat and refused to budge despite officers’ multiple requests. Bill McKibben, co-founder of, which has helped galvanize significant grass-roots opposition to the plan, said Obama cannot ignore that the carbon-intensive process of extracting crude from Alberta’s oil sands will destabilize the planet. “Whether it’s convenient or not for our politicians, this is the test,” McKibben said in an interview before being arrested, adding that Wednesday’s protest and a climate rally slated to take place Sunday in Washington were designed “just to keep this in front of people’s minds. . . . This is the first environmental issue that’s brought Americans into the streets in many, many years.”

    Activists arrested at White House protesting Keystone pipeline – The Washington Post

    Pompous ass wipes.
    Never is a long time.
    Keystone isn't an an environmental issue - on the Ogallala acquifer, it's 400 miles of very safe pipe in addition to the 20,000 already there. The problem is this; Dr. Hansen asks that the public accept science when he says it, but not when any other government scientist says it. That mentality is corrosive to acceptance of science.
    As you so often write about, it's what Activists do, not scientists.
    Never is a long time.