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The Mendenhall Glacier’s recession is unveiling the remains of ancient forests that have remained frozen beneath the ice for up to 2,350 years. UAS Professor of Geology and Environmental Science Program Coordinator Cathy Connor said she and others have been tracking the emergence of the forests’ remains...

As the glacier advanced, it snapped off the tops of the trees in its path, Connor said. The stumps were buried — and protected — in gravel. Now, as the glacier melts, the melt water carves out paths in that gravel, revealing the remains of the trees.

The most recent stumps she’s dated emerging from the Mendenhall are between 1,400 and 1,200 years old. The oldest she’s tested are around 2,350 years old. She’s also dated some at around 1,870 to 2,000 years old.

Ajax: And keep in mind that both warm periods took place without the presence of CO2.

Despite the name of your source Not A Lot Of People Know That, it turns out that quite a few people did know that. It has been well known for years that there has been a gradually cooling over the past few thousand years.

The Marcott et al (2013) temperature reconstruction of the past 11000 years, courtesy of RealClimate, shows this long-term trend well:

That paper also shows the source: a strong decline in orbital forcings, particularly from solar insolation at high latitudes during northern summer:

We don't need changes in CO2 to explain this. As has been said on this board over and over and over again, there are forcings other than CO2 that affect the climate. It's just that the rapid increase in atmospheric CO2 in recent decades completely dominates those changes today.

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