LONDON — Researchers have found geological evidence that some of the same natural forces as today were at play 1.4 billion years ago and triggered climate change.
Fluctuating climate is a hallmark of the Earth and the present greenhouse effect is by far the only force affecting today's climate.
On a larger scale, the Earth's climate is also strongly affected by how the Earth orbits around the Sun.
This is called orbital forcing of climate change.
These changes happen over thousands of years and they bring ice ages and warming periods.
The team from the University of Southern Denmark, China National Petroleum Corporation and others looked deep into the Earth's history and revealed that orbital forcing of climate change contributed to shaping the Earth's climate 1.4 billion years ago.
"This study helps us understand how past climate changes have affected the Earth geologically and biologically," said Donald Canfield, principal investigator and professor at Nordic Centre for Earth evolution at the University of Southern Denmark.
The evidence comes from analyses of sedimentary records from the approximately 1.4 billion-year-old and well preserved "Xiamaling Formation" in China.
Today the Earth is affected by fluctuations called the Milankovich cycles.
There are three different Milankovich cycles and these occur each 20,000, 40,000 and 100,000 years.
Over the last one million years, these cycles have caused ice ages every 100,000 years, and right now, we are in the middle of a warming period that has so far lasted 11,000 years.
"Earth's climate history is complex. With this research, we can show that cycles like the Milankovich cycles were at play 1.4 billion years ago - a period we know only very little about", Canfield informed.
The research will help scientists understand how Milankovitch cyclicity ultimately controls climate change on the Earth.
The paper appeared in the journal PNAS.