While the idea that human-generated carbon emissions are nothing new, and the impact of greenhouse gasses on global warming have been evident for quite some time, there has been a great deal of debate over exactly how much humans have been contributing to the issue, as opposed to the natural portion of the warming cycle that the planet has been undergoing since the start of the Holocene era. But now a new study seems to have quantified our contribution — and it isn’t insignificant.
Using chemical and biological signatures obtained from deep sea sediments, a research team from the University of Hawai’i at Manoa School of Ocean and Earth Science and Technology (SOEST) has mapped carbon emissions going back 66 million years, when the dinosaurs went extinct. They found that the peak of carbon emissions over that time period occurred in 2014, when about 37 billion metric tons of CO2 was released. The only other time since the end of the Cretaceous period that could even come close to modern levels was an event that occurred 56 million years ago, called the Paleocene-Eocene Thermal Maximum (PETM), where 4 billion metric tons of CO2 per year was dumped into the atmosphere — a mere one-tenth of current levels.
This produced a quandary for the researchers, as they effectively had no other event to compare modern CO2 levels to: “Because our carbon release rate is unprecedented over such a long time period in Earth’s history, it also means that we have effectively entered a ‘no-analogue’ state. This represents a big challenge for projecting future climate changes because we have no good comparison from the past,” explains University of Hawai’i professor and study author Richard Zeebe.
In addition to our finding ourselves in uncharted territory, Zeebe also warns that such a sudden change in the atmosphere’s makeup might make predicting what will happen nearly impossible: “If you kick a system very fast, it usually responds differently than if you nudge it slowly but steadily. Also, it is rather likely that future disruptions of ecosystems will exceed the relatively limited extinctions observed at the PETM.”
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