Though volcanoes are known for their destructive, life-altering power, a study released Monday finds that human-caused climate change dwarfs what ancient volcanic activity did to the planet.
(CN) — Compared to volcanoes, people seem powerless.
Collectively, however, the power of humans in the modern age dwarfs the destructive potential of volcanoes, according to a study on ancient ocean conditions published Monday in the journal Proceedings of the National Academy of Sciences.
By comparing current carbon emissions to ocean data from 55.6 million years ago, researchers at Columbia University’s Lamont-Doherty Earth Observatory discovered that the rate of human-caused climate change dwarfs the ability of ancient volcanic activity to alter the climate, releasing carbon as much as eight times faster than prehistoric volcanoes.
The research is relevant to today, said lead author Laura Haynes, an assistant professor at Vassar College.
“We want to understand how the earth system is going to respond to rapid CO2 emissions now,” Haynes stated. “The PETM is not the perfect analog, but it’s the closest thing we have. Today, things are moving much faster.”
The period researchers studied is known as the Paleocene-Eocene Thermal Maximum, an ancient time considered for decades to be the closest natural analog to current climate upheaval conditions.
The planet was already considerably warmer than modern times when volcanoes at the beginning of the PETM began spewing carbon into the atmosphere, boosting global temperatures by as much as 14 degrees Fahrenheit.
The rapid temperature change coincided with mass extinction of certain marine species and the proliferation of others such as plankton, as well as the appearance of primates and other modern mammals in Europe and North America.
Aside from volcanic eruptions, scientists in recent years have theorized that the global temperature spike during the period was driven by the sudden release of methane previously frozen in mud on the ocean floor, or perhaps even by Earth colliding with a comet. But how much carbon dioxide was present in the air remained uncertain.
While previous studies of the PETM used computer modeling that relied on minimal chemical data coupled with assumptions, Haynes and her colleagues took a more direct approach.
They cultured tiny shelled marine organisms called foraminifera in seawater formulated to resemble the highly acidic conditions of the period, then they recorded how the organisms took up the element boron into their shells as they grew.
Comparing their findings with analyses of boron from fossilized foraminifera in Pacific and Atlantic ocean-floor cores that span the PETM, researchers identified carbon-isotope signatures associated with specific carbon sources, indicating that volcanoes were the main source — probably from massive eruptions in Iceland, Greenland and North America.
Haynes and her colleagues found that the carbon pulses added as much as 14.9 quadrillion metric tons of carbon to the oceans, increasing carbon dioxide levels by more than 60%. Nearly all of that carbon came directly from volcanic eruptions, as well as combustion from surrounding sedimentary rocks and the subsequent release of methane from the ocean floor.
Waters became highly acidic as the oceans absorbed carbon from the atmosphere, a condition that likely lasted for thousands of years and killed most of the creatures in the depths of the oceans.
The tragedy is that history often repeats itself, although this time human activity is the toxic culprit, introducing within decades the level of C02 it took volcanoes millennia to achieve.
“If you add carbon slowly, living things can adapt,” concluded study co-author Bärbel Hönisch, a geochemist at Lamont-Doherty. “If you do it very fast, that’s a really big problem. We’re outpacing the past, and the consequences are probably going to be very serious.”