Three Abrupt Pulses of Carbon Dioxide May Have Melted the Last Ice Age

What caused the end of the last ice age more than 10,000 years ago? It turns out that it wasn't a gradual process. Instead, scientists have found that three abrupt pulses of carbon dioxide may have ended the cold snap during that time period.

Previous research has hinted at the possibility that spikes in atmospheric carbon dioxide may have accelerated the last deglaciation. Yet it isn't until now that scientists have confirmed these spikes. They discovered an ice core in West Antarctica that provided them an unprecedented glimpse into the past.

The new core was drilled to a depth of 3,405 meters and spanned the last 68,000 years. What's most interesting about this core is that it has extraordinary detail since the area where the core was taken has high annual snowfall.

"It is a remarkable ice core and it clearly shows distinct pulses of carbon dioxide increase that can be very reliable dated," said Edward Brook, one of the researchers. "These are some of the fastest nautral changes in CO2 we have observed, and were probably big enough on their own to impact Earth's climate. The abrupt events did not end the ice age by themselves. That might be jumping the gun a bit. But it is fair to say that the natural carbon cycle can change a lot faster than previously thought-and we don't know all of the mechanisms that caused that rapid change."

The abrupt spike in CO2 took place over just 10,000 years. Currently, scientists aren't sure what caused the three individual spikes that helped end the last ice age, and they're quick to point out that the CO2 increase wasn't the only process that led to the deglaciation.

"At the same time CO2 was increasing, the rate of methane in the atmosphere was also increasing at the same or a slightly higher rate," said Shaun Marcott, lead author of the new study, in a news release. "We also know that during at least two of these pulses, the Atlantic Meridional Overturning Circulation changed as well. Changes in the ocean circulation would have affected CO2 and indirectly methane by impacting global rainfall patterns."

The findings are published in the journal Nature.