
This diatom species, Fragilariopsis kerguelensis, is a floating algae that is abundant in the Antarctic Ocean and was the major species in the samples collected for the study by Princeton University and the Max Planck Institute for Chemistry. These microscopic organisms live near the sea surface, then die and sink to the sea floor. The nitrogen isotopes in their shells vary with the amount of unused nitrogen in the surface water. The researchers used that to trace nitrogen concentrations in Antarctic surface waters over the past 150,000 years, covering two ice ages and two warm interglacial periods.
"The cause of the ice ages is one of the great unsolved problems in the geosciences," said Daniel Sigman, the Dusenbury Professor of Geological and Geophysical Sciences. "Explaining this dominant climate phenomenon will improve our ability to predict future climate change."
In the 1970s, scientists discovered that the concentration of the atmospheric greenhouse gas carbon dioxide (CO2) was about 30% lower during the ice ages. That prompted theories that the decrease in atmospheric CO2 levels is a key ingredient in the glacial cycles, but the causes of the CO2 change remained unknown. Some data suggested that, during ice ages, CO2 was trapped in the deep ocean, but the reason for this was debated.














Comment: It's possible that the obsession with CO2 has led researchers to confuse correlation with causation, because, while it does appear that the activities in our oceans can provide clues as to the changes that occur on our planet during an ice age, there are much greater drivers behind Earth's climate - and it's not just Earth that is seeing significant changes:
- The Seven Destructive Earth Passes of Comet Venus
- Antarctica's growing algae blooms
- Worldwide ocean anoxia driven by global cooling was possible factor in previous mass extinctions
- Mysterious new invasive algae smothering Hawaii's coral reefs
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