According to the authors, this is especially worrisome from an adaptation perspective, as plants and animals require extended time periods to effectively adapt to new and unfamiliar conditions.
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Scientists are uncertain as to what caused the PETM spike in atmospheric Carbon dioxide and how quickly that increase occurred. Some think there was a huge release of subsea methane that somehow made its way to the atmosphere – and that the series of events might have been kickstarted by major volcanic eruptions.
Today, scientists often look to the PETM as an analog for current rising temperatures.
The study connected the dots, and the scientists’ findings paint a bad picture for the future of marine life.
A news release from the University of Hawaii describing the details of the study can be found here.
They were stunned to know that modern carbon emissions have surpassed every limit that earth has seen over the entire Cenozoic, a period that started after the K-T extinction.
To look further back in time, scientists investigate air bubbles trapped in ice cores, expanding the scope of climate records to almost a million years. In other words, earth has apparently never seen a situation like today’s for at least 66 million years, if ever.
A new study has found that carbon emissions are now so high, the last time they hit similar levels was 66 million years ago, when many species of dinosaur were wiped off the face of the planet.
A lot of carbon indeed injected themselves into the atmosphere during the PETM, and the warming event that followed it lasted more than 100,000 years.
Lead researcher Richard Zeebe, an oceanographer from the University of Hawaii, Manoa, said ecosystems need time to adjust.
Zeebe and co-authors Andy Ridgwell (University of Bristol/ University of California) and James Zachos (University of California) combined analyses of chemical properties of PETM sediment cores with numerical simulations of Earth’s climate and carbon cycle. Using the new approach, they were able to study the rates of change from the sediment record. However, humans are now releasing approximately 10 billion tons of carbon each year, leading to a much more rapid pace of climate change. A large interval between the two indicates high levels of carbon were released while a small interval or none means less carbon was emitted over a longer time period. “We suggest that such a “no-analogue” state represents a fundamental challenge in constraining future climate projections”. The climate system is non-linear, which means that its response to inputs, such as Carbon dioxide emissions, is a complex process involving multiple components.
“If you kick a system very fast, it usually responds differently than if you nudge it slowly but steadily”.
“Future ecosystem disruptions are likely to exceed the relatively limited extinctions observed at the PETM”, he continued. The rate continues to go up, despite taking up resolutions to end fossil fuel consumption this century. But that’s only two generations from today. Climate scientists and world policy makers agree that 2 degrees more is all humans can probably take-or maybe 1.5, as more cautious voices are warning. However, too much heat can change weather and climate patterns, impacting where flora and fauna can survive.
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“Our results suggest that future ocean acidification and possible effects on marine calcifying organisms will be more severe than during the PETM”, Zeebe said.
