65 million years of Climate Change

Nobody explains it as well as Dr. Jeremy Rugenstein of ETH Zurich.

This is a cut-n-paste from ETH Zurich on his work:

Fossil soils hold climate data

Instead of focusing on the future, Rugenstein is travelling millions of years into the past, analysing fossil soils in order to uncover information about the prehistoric climate. “By looking into the past – a time when the atmosphere contained much more carbon dioxide – we can understand how the climate behaves with different CO₂ concentrations, allowing us to predict our future climate,” he explains.
This research field is known as palaeoclimatology. For his doctoral thesis, the young American researched the prehistoric climate in Central Asia. He demonstrated how we can deduce the amount of precipitation and abundance of vegetation in the past by using mass spectrometric analyses on sedimentary rock. “Plants are a key climate factor, because their water absorption and release determines how much water is available on the earth,” he says.
The geochemist uncovered information about the state of prehistoric vegetation by analysing the fossil soils in which these plants once grew. During root respiration, these plants left behind CO₂, which still remains in the soil today in the form of calcium carbonate. This mineral, particularly the carbon and oxygen isotopes it contains, enables Rugenstein to draw conclusions about the past: the carbon reveals how much vegetation grew, and the oxygen reveals the amount and even the origin of rain.

Climate change over the past 65 million years

The 30-​year-old researcher is primarily interested in fossil soils from the most recent geological time period, the Cenozoic era, which encompasses the last 65 million years – in other words, from the dinosaurs’ extinction through to the present day. His teaching experience becomes obvious when he begins describing the geological era during which mammals and flowering plants began spreading across wide landmasses.

“It was warmest around 50 million years ago.

 It’s very likely that there were no

 landmasses on earth permanently covered in ice.

 We had palm trees in Antarctica and

 crocodiles frolicking around Greenland,”...

       

...why since then, average temperatures have fallen

 by ten to fifteen degrees Celsius

 and the carbon dioxide content

 in the atmosphere has fallen

 from around 2,000 parts per million to under 400.

 
Rugenstein

 

“It was warmest around 50 million years ago. It’s very likely that there were no landmasses on earth permanently covered in ice. We had palm trees in Antarctica and crocodiles frolicking around Greenland,” says Rugenstein, describing the scenery of that time period. He is particularly interested in why “It was warmest around 50 million years ago. It’s very likely that there were no landmasses on earth permanently covered in ice. We had palm trees in Antarctica and crocodiles frolicking around Greenland,” says Rugenstein, describing the scenery of that time period. He is particularly interested in why since then, average temperatures have fallen by ten to fifteen degrees Celsius and the carbon dioxide content in the atmosphere has fallen from around 2,000 parts per million to under 400.

Volcanoes and marine organisms

The young scientist, who is clearly pursuing an academic career, is currently focusing on the weathering of rock and understanding how this process is linked to the atmosphere’s CO₂ content.
He explains: “In a world without modern, industrialized society, most of the carbon dioxide in the atmosphere comes from volcanoes. However, the majority of it is then removed again by the weathering of rock.” In short, it works as follows: CO₂ dissolved in rainwater creates acid and reacts with silicate rock. This produces bicarbonate, which is washed into the ocean in the course of the water cycle. Marine organisms, such as corals, absorb the bicarbonate and use it to build reefs. As a result, the CO₂ is taken out of the global carbon cycle for a long time.

New perspectives at ETH

To better understand the role of silicate rock weathering in the carbon cycle, Rugenstein has been carrying out research since January 2017 as an ETH Fellow in the Earth Surface Dynamics group. His work includes puzzling over computer models used to simulate weathering processes.
As a geochemist, Rugenstein has found it enriching to be surrounded by geophysicists in his research group at ETH. He enjoys considering his research questions from different perspectives and bringing his own expertise to other research fields. For this reason, he attaches great importance to connecting with other researchers. With that in mind, he considers the relatively large size of the ETH research group with which he works to be more of a disadvantage: “I’m rarely able to discuss my work with scientists outside of the group.”

Volcanoes and marine organisms

The young scientist, who is clearly pursuing an academic career, is currently focusing on the weathering of rock and understanding how this process is linked to the atmosphere’s CO₂ content.
He explains: “In a world without modern, industrialized society, most of the carbon dioxide in the atmosphere comes from volcanoes. However, the majority of it is then removed again by the weathering of rock.” In short, it works as follows: CO₂ dissolved in rainwater creates acid and reacts with silicate rock. This produces bicarbonate, which is washed into the ocean in the course of the water cycle. Marine organisms, such as corals, absorb the bicarbonate and use it to build reefs. As a result, the CO₂ is taken out of the global carbon cycle for a long time.


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