JimBowie1958
Old Fogey
- Sep 25, 2011
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Orbital forcing of tree-ring data : Nature Climate Change : Nature Publishing Group
In other words the overall temperature trend for the last two thousand years is that the planet is cooling, not heating up and recent temp increases are just another blip in that trend.
Here, we present new evidence based on maximum latewood density data from northern Scandinavia, indicating that this cooling trend was stronger (−0.31 °C per 1,000 years, ±0.03 °C) than previously reported, and demonstrate that this signature is missing in published tree-ring proxy records. The long-term trend now revealed in maximum latewood density data is in line with coupled general circulation models7, 8 indicating albedo-driven feedback mechanisms and substantial summer cooling over the past two millennia in northern boreal and Arctic latitudes. These findings, together with the missing orbital signature in published dendrochronological records, suggest that large-scale near-surface air-temperature reconstructions9, 10, 11, 12, 13 relying on tree-ring data may underestimate pre-instrumental temperatures including warmth during Medieval and Roman times.

In other words the overall temperature trend for the last two thousand years is that the planet is cooling, not heating up and recent temp increases are just another blip in that trend.
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