Tropical regions could be facing more intense warming than previously thought, according to a recent study conducted by researchers at CU Boulder. By examining Earth’s ancient climate, the study provides new insights into how these areas might respond to ongoing climate change.
Insights from Ancient Sediments
Researchers analyzed lake sediments from the Colombian Andes to uncover how the planet’s climate behaved millions of years ago. These sediments indicated that during periods when carbon dioxide levels were akin to today’s, tropical land areas experienced nearly twice the temperature increase compared to the oceans. The findings were published in the Proceedings of the National Academy of Sciences.
Lina Pérez-Angel, the lead author, emphasized the significance of understanding regional climate changes. “The tropics are home to about 40% of the world’s population, yet we’ve had very little direct evidence of how tropical land temperatures respond to climate change,” Pérez-Angel noted. “If we want to study climate change to help people, we need to pay more attention to the regional changes so those living there know what to expect.”
Exploring the Pliocene Epoch
During the Pliocene, about 2.5 to 5 million years ago, Earth was on average warmer by 2.5 to 4 °C (4.5 to 7.2°F) than today. This period serves as a valuable reference for current climate trends due to its similar carbon dioxide concentrations. Sediment cores, which accumulate chemical signals and fossils over time, allow scientists to reconstruct past climates. These cores are especially useful because they provide a continuous record of Earth’s climatic history.
In 1988, a team of scientists extracted a 580-meter sediment core from Colombia’s Bogotá basin. This region has preserved its sediments largely undisturbed since the late Pliocene. Lina Pérez-Angel and her team analyzed bacterial fats preserved within these cores to trace temperature changes from the Pliocene to the Ice Age. Their findings revealed that the tropical Andes were approximately 3.7 °C (6.6°F) warmer than today, while the tropical sea surface was only 1.9 °C (3.4°F) warmer, indicating more pronounced warming on land.
The Role of Feedback Loops
Pérez-Angel’s research points to the presence of a nearly permanent El Niño condition during the late Pliocene, which contributed to the increased warmth in the tropical Andes. This phenomenon, already causing warming and drought in modern times, could intensify with more frequent El Niño events due to climate change. According to Julio Sepúlveda, senior author and associate professor, “If you compare the temperature records for the past couple of decades with what climate models predicted a few decades ago, you see that all the real-world data is at the uppermost end of those predictions.”
Focus on the Tropics
Despite the significant implications for tropical regions, they often receive less attention in climate studies compared to higher latitude areas like Greenland or Antarctica. Pérez-Angel highlights that the lower level of attention is partly due to most climate research institutions being located outside the tropics. However, in these already warm regions, even small temperature increases could exceed tolerable limits for humans and wildlife.
Pérez-Angel stresses the importance of regional climate understanding, especially given the limited resources available for adaptation in many tropical communities. “When we model climate change, we tend to focus on how temperatures are going to change globally. But people experience climate change at the regional level.” Expanding knowledge of regional climate impacts is crucial for fostering resilience and adaptation strategies.
Original Story at www.colorado.edu