A 2014 image of the crater lake of the Póas volcano, Costa Rica, where DCO scientists used permanent gas-monitoring devices. Photo: Katie Pratt, University of Rhode island
A 2014 image of the crater lake of the Póas volcano, Costa Rica, where DCO scientists used permanent gas-monitoring devices. Photo: Katie Pratt, University of Rhode island

Dear Earth, we have a carbon situation

  • Latest findings on Deep Earth carbon suggest man-made emissions are 40-100 times greater than those from volcanoes
  • The monitoring of gas composition (changes in the CO2 to SO2 ratio before large eruptions) has proven to be a better forecasting tool for volcanoes

When the Deep Carbon Observatory (DCO) project was started 10 years ago, not much was known about the different forms of carbon in Earth and the sources from where it originated. That most of our carbon is sequestered in the rocks and soil is known, but just two-tenths of 1% of Earth’s total carbon is above the surface.

Now, findings from the project show that anthropogenic (man-made) carbon emissions are 40-100 times greater than those from all volcanic emissions. The findings have also revealed key figures about the total amount of carbon stored on Earth. According to current estimates, Earth’s total carbon content is around 1.85 billion gigatonnes. These findings are due to be discussed further at a conference in Washington, DC from 24-26 October.

DCO, an international collaboration of more than 1,200 scientists from 55 countries, is working on understanding the quantities, forms and origins of the carbon on Earth. Research included studies by scientists on 100 field sites around the world—from setting up volcano monitoring systems to collecting rock samples from the seafloor.

In an interview with Mint earlier this year, Marie Edmonds, a reader in earth sciences at the University of Cambridge, had said that “we have a much greater understanding of how carbon is transferred into the Deep Earth by a process called subduction." Edmonds is responsible for the overall scientific and intellectual oversight of DCO’s synthesis and integration activities.

According to an official release on the findings, Edmonds says that in order for us to “secure a sustainable future", it is “of utmost importance" to understand Earth’s entire carbon cycle. “Key to unravelling the planet’s natural carbon cycle is quantifying how much carbon there is and where, how much moves—the flux—and how quickly, from Deep Earth reservoirs to the surface and back again," she adds.

One of the key findings published in a series of papers in the journal Elements earlier this month is that the CO2 released into the atmosphere and oceans today from volcanoes and other “magmatically active" or volcanic regions is estimated at 280-360 million tonnes. The findings say volcanoes, both “young and very old", may be emitting some C02 into the atmosphere. DCO experts estimate that while 400 of the 1,500 volcanoes active since the last Ice Age, 11,700 years ago, are venting CO2, another 670 could be producing diffused emissions—102 such volcanoes have been already documented.

Gas sampling at the Lastarria volcano, on the border of Chile and Argentina.
Gas sampling at the Lastarria volcano, on the border of Chile and Argentina.
A snapshot of the total carbon on Earth.
A snapshot of the total carbon on Earth.

Scientists from DCO’s DECADE (Deep Earth Carbon DEgassing) subgroup used gas instrument monitoring stations to gather real-time data from volcanoes. According to the release, there are about 30 collaboratively operated gas monitoring stations on volcanoes across five continents—these monitor, among other things, readings on CO2, sulphur dioxide and hydrogen sulphide.

In the interview, Edmonds had explained how volcanic eruptions are preceded by rapid increases in CO2 flux, making it possible for scientists to forecast them. Now, using data from the monitoring devices and drones at volcanoes, scientists have gained new insights. They were able to deduce that the “level of carbon dioxide relative to sulphur dioxide in volcanic gases systematically changes in the hours to months before an eruption."

This deduction was possible after year-round monitoring of volcanoes in Costa Rica, Italy, Chile and Nicaragua. The monitoring of gas composition (changes in the CO2 to SO2 ratio before large eruptions) has proven to be a better forecasting tool for volcanoes, and, according to the release, it precedes ground deformation or seismic activity in some cases.

Perhaps the most startling finding was that human activities like burning fossil fuels and forests were emitting more carbon into the atmosphere than volcanic and tectonic sources combined. In their paper titled Earth Catastrophes And Their Impact On The Carbon Cycle, Edmonds, Celina Suarez from the department of geosciences, University of Arkansas, US, and Adrian Jones from the department of earth sciences, University College London, explain that “the flux of anthropogenically generated carbon, primarily from burning of fossil fuels that formed over millions of years, is contributing to a major perturbation to the carbon cycle".

Any major shift in Earth’s carbon cycle spells bad news for living organisms. The paper adds that while Earth’s carbon cycle returned to a “steady state" after perturbations caused by short, rapid events in the past, some “major shifts perturbed the system so rapidly that organisms could not adapt quickly enough to the associated environmental change, causing mass extinction." One such major shift event was the Chicxulub asteroid impact 66 million years ago, which rapidly warmed the planet and wiped out all plants and animals, including dinosaurs.

The findings indicate that humans currently release approximately 10 gigatonnes of CO2 into the atmosphere every year—which is higher than that from the Chicxulub impact and “voluminous outpourings of lava" on to Earth’s surface.

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