For decades, scientists have studied shells that look for clues about the temperature of the Earth’s ancient ocean, its carbon budget, and the composition of minerals circulating through the air and the sea. Now, in a new study published today (10 September) in the journal ScienceResearchers have analyzed the chemical elements in thousands of forum samples to create the Earth’s most detailed climate record – and find out how serious our current climate situation is.
The new paper, which includes decades of deep sea drilling missions in a single record, details the swings of the Earth’s climate. Cenozoic era – A period of 66 million years that began with the death of Dinosaurs And extends to the present era of human-inspired Climate change. The results show how Earth transitioned through four different climate states – dubbed warmhouse, hothouse, coolhouse, and icehouse states – in response to changes in the planet’s orbit, green house gas Level and extent of polar ice sheet.
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The zig-zagging chart (shown above) ends with a daring peak. According to researchers, the current speed of anthropogenic Global temperature The natural climate is greater than the fluctuations seen at any other point in the distant Cenozoic era, and has the ability to hyper-drive our planet from a prolonged ice phase to a flowing hull state.
“Now that we have succeeded in capturing natural climate variability, we can see that the predicted anthropological warming will be much higher than that,” studies co-author James Zachos, professor of earth and planetary science at the University of California, Santa Cruz. , Said in a statement. “Intergovernmental Panel on Climate Change (IPCC) Estimate for 2300 The ‘business-as-usual’ scenario has not seen global temperatures potentially in 50 million years. “(IPCC is a United Nations group that assesses the science, risks and impacts of climate change. Planets.)
In the hothouse
To compile their new era-long climate map, the study authors examined fossil-like shells in deep-sea sediment cores – long tubes of rock, sediment and germs drilled from the world’s oceans over the past several decades . Vanams (short for Foraminifera) are microscopic plankton whose oldest relatives appeared in the ocean a billion years ago; Deep scientists dig into the seabed, the old famed specimens they uncover.
Ratio of Carbon And Oxygen Isotopes (versions of elements) in forest shells contain important climatic information. The ratio between oxygen isotopes oxygen-18 and oxygen-16, for example, may reveal how hot the surrounding water was when the Asar formed its shell; High ratio, cold water. The ratio between carbon-13 and carbon-12 shows how much organic carbon was available to feed microbes; Here, a higher proportion correlates with more greenhouse gases (such as carbon dioxide) in the atmosphere.
Because the team’s climate record covers such an incredibly long period of time, the researchers also had to consider the astronomical effects on the planet’s climate – that is, the Earth’s slowly changing orbit and tilt toward the sun, sunlight. It affects the zodiac when it reaches different parts of the planet. At different times, also known as Milankovic Cycle. When the team overlaid the orbital data with their isotopic climate data, they observed that the orbital variations caused different but relatively small-scale changes in the global climate. Critically, there was a large-scale shift in each big jump between climate states. green house gas Level, the researchers said.
For example, about 10 million years after the extinction of the dinosaurs, Earth Jumped from a hothouse state to a hothouse state. The phenomenon, known as the Paleocene-Eocene thermal maximum, saw temperatures up to 29 degrees Fahrenheit (16 degrees Celsius) above modern levels, Zakos said, and a massive release of carbon in the atmosphere Was thought to be the result of a huge volcanic eruption in the North Atlantic. As carbon dioxide disappeared from the atmosphere over the next 20 million years, ice sheets began to form Antarctica And the planet entered a coolhouse phase, with a surface temperature of 7 F (4 C) above modern levels.
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About 3 million years ago, Earth entered an ice phase, driven by waxing and waning ice sheets in the Northern Hemisphere. Now, human greenhouse gas emissions are increasing temperatures that cannot be seen in tens of millions of years. This increase goes beyond the natural variations triggered by the Earth’s changing orbit, the researchers concluded. And if current greenhouse emissions remain constant, the climate cannot be traced to the later levels of the Paleocene – Eocene thermal maximum. The transition from icehouse to hothouse would not take millions of years, Zachos said – it would take hundreds.
“We now know more precisely when it was hot or cold on the planet and have a better understanding of the underlying dynamics and processes driving them,” lead study author Thomas Westerold, director of the University of Bremen Center for Marine Environmental Sciences Germany said in the statement. “Time since 66 [million] 34 million years ago, when the planet was much warmer than it is today, is particularly interested, as it represents a parallel in the past to what anthropogenic changes may occur in the future. ”
Editor’s note: This story was updated on September 11 to fix two Celsius and Fahrenheit conversions.
Originally published on Live Science.