Scientists have found that parts of the southern polar region may have been as hot as modern day California and Florida over 50 million years ago. The new findings were the product of a new way of measuring temperatures in the past
The study was conducted by a team of researchers led by scientists from Yale. Based on their findings, CO2 levels in the atmosphere were high enough in the past to bring about greenhouse climate conditions in Antarctica. This period of polar warming happened around 40 million to 50 million years ago during a period of time known as the Eocene epoch. The researchers published their findings in the online journal the Proceedings of the National Academy of Sciences (PNAS).
"Quantifying past temperatures helps us understand the sensitivity of the climate system to greenhouse gases, and especially the amplification of global warming in polar regions," said Yale associate professor of geology and geophysics Hagit Affek.
In contemporary times, Antarctica is considered as one of the coldest places on the planet. However, the new research shows that even the polar regions are susceptible to drastic changes in temperature. The new method of measuring temperatures in the past can also be used to improve current climate modeling systems in order to increase the accuracy of climate forecasts in the future.
"By measuring past temperatures in different parts of Antarctica, this study gives us a clearer perspective of just how warm Antarctica was when the Earth's atmosphere contained much more CO2 than it does today," said Yale graduate student and researcher Peter M.J. Douglas. "We now know that it was warm across the continent, but also that some parts were considerably warmer than others. This provides strong evidence that global warming is especially pronounced close to the Earth's poles. Warming in these regions has significant consequences for climate well beyond the high latitudes due to ocean circulation and melting of polar ice that leads to sea level rise." Douglas is also the lead author of the study.
The team was able to measure temperatures in the past by analyzing concentrations of certain rate isotopes found in fossil shells that were millions of years old. The team's analysis showed that 50 million years ago, temperatures in some parts of Antarctica could reach around 63 degrees Fahrenheit or 17 degrees Celsius. The researchers were also able to calculate that temperatures in certain parts of the continent were around 57F (14C).
"We managed to combine data from a variety of geochemical techniques on past environmental conditions with climate model simulations to learn something new about how the Earth's climate system works under conditions different from its current state," Affek said. "This combined result provides a fuller picture than either approach could on its own."