A new study has found geological evidence that some of the very same forces today caused climate change 1.4 billion years ago.
A new study has found geological evidence that some of the very same forces today caused climate change 1.4 billion years ago.
Fluctuating climate is a hallmark of 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.
Now researchers from University of Southern Denmark, China National Petroleum Corporation and others have looked deep into Earth's history and can reveal that orbital forcing of climate change contributed to shaping the Earth's climate 1.4 billion years ago. Researcher Donald Canfield said that this study helps them understand how past climate changes have affected Earth geologically and biologically.
The evidence comes from analyses of sedimentary records from the approximately 1.4 billion-year-old and exceptionally well preserved Xiamaling Formation in China. The sediments in the Xiamaling Formation have preserved evidence of repeated climate fluctuations, reflecting apparent changes in wind patterns and ocean circulation that indicates orbital forcing of climate change.
Today Earth is affected by fluctuations called the Milankovich cycles. There are three different Milankovich cycles, and they 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.
Canfield added that earth's climate history is complex. With this research they can show that cycles like the Milankovich cycles were at play 1.4 billion years ago, a period, they know only very little about, adding this research will also help them understand how Milankovitch cyclicity ultimately controls climate change on Earth.
The study appears in the journal PNAS.
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