Carbon dioxide levels are higher today than they have been for the past 23 million years, according to a study led by Dr. Brian Schubert at the University of Louisiana at Lafayette.
The findings, published in the scientific journal Geology, are significant. A frequently accepted theory by many scientists puts the time frame at about 1 million years ago. That assumption is based on CO2 measurements from Antarctica that date back 800,000 years.
The new determination was made by Schubert, an associate professor in the University’s School of Geosciences, and co-authors Dr. Ying Cui, of Montclair State University, and Dr. A. Hope Jahren, of the University of Oslo, Norway.
The scientists used an innovative method to reach their conclusion.
They measured the relative amounts of two stable carbon isotopes using fossilized plants. The research enabled them to calculate CO2 concentrations during the period the plants grew. As a result, the team produced a new record of atmospheric CO2 that spans 23 million years of uninterrupted Earth history.
The scientists also concluded that current CO2 levels can be traced to human activity, and are increasing at a rate never before seen in geologic history.
“There have been past time periods in Earth’s history where CO2 levels are both higher than today and lower than today. The difference, though, is that past changes in CO2 and climate usually happen over very long time scales – thousands or millions of years. The rise in CO2 that we’re seeing today is much, much faster,” Schubert explained.
Carbon dioxide is a gas that plays a vital role in processes essential to life, such as photosynthesis in plants and respiration in animals. While necessary for survival, rising levels of CO2 in the atmosphere may be responsible for long-term changes in Earth's climate.
“When it happens slowly, the Earth’s ecosystems can respond. When it happens quickly, it’s a lot harder,” he added.
Geology is published by the Geological Society of America.
Photo caption: UL Lafayette researcher Dr. Brian Schubert led a study published in the scientific journal Geology that shows CO2 levels are higher today than they have been for the past 23 million years. The study was conducted with innovative research that used fossilized plants to calculate CO2 concentrations. Shubert is shown above during a research trip to Siberia. Photo credit: University of Louisiana at Lafayette