Ancient Antarctic ice cores reveal ocean heat, not greenhouse gases, caused significant climate shifts over the past three million years
Ancient climate insights
One study reconstructed global ocean heat content using noble gas ratios trapped in ancient ice.
Results showed CO2 only decreased by about 25 parts per million between 2.9 and 1.2 million years ago, indicating greenhouse gases alone cannot explain temperature variability during this period.
Shifts in ocean circulation and heat distribution are highlighted as influential factors in climate change.
Researchers affiliated with the National Science Foundation-funded Center for Oldest Ice Exploration collected the ice cores used in these studies.
Dr. Sarah Shackleton from the Woods Hole Oceanographic Institution emphasised the value of ice cores in understanding past climate conditions.
The findings coincide with another study from the British Antarctic Survey, which demonstrates the ocean’s role in influencing Antarctic ice dynamics.
Researchers investigated 18,000 years of bottom-water temperatures on the Amundsen Sea continental shelf.
Warm ocean water was identified as a key factor in the retreat of the West Antarctic Ice Sheet after the last ice age.
Future climate research
The studies stress the need for deeper ice core records to enhance comprehension of Earth’s climatic history.
Projects like the European-led Beyond EPICA and Australia’s Million Year Ice Core aim to extend climate archives significantly.
Scientific efforts will focus on understanding Earth’s glacial cycle changes over the last million years.
These recent insights challenge previous notions that greenhouse gases alone dictated climate shifts.
They underscore the complex interactions between ocean temperatures and atmospheric conditions in shaping Earth’s climate history.
