Scientists may intend to report unusual modern warming due to human activity, suggesting that all or nearly all modern warming and treeline advancement at Rocky Mountain ice mass sites occurred between the 1910s and 1940s. [emphasis, links added]
An interesting observation was found in the text of a new study (Pederson et al., 2025): 30% of the world’s forests have not even warmed in modern times (1900s to present)and only 50% of the world's forests have not yet moved uphill.
This appears to challenge the narrative of global warming.
“Changes in local conditions may explain why the recently recorded global warming of about 70% of treelines has resulted in only about 50% of treelines being upslope.”
This study documents millennium-scale treeline and temperature records at high altitude sites (>3,000m) [9,843 feet] elevation) in the American Rockies (Yellowstone region).
Melting ice reveals a pine forest growing at an altitude of about 180 m [591 feet] About 6,500 to 4,200 years ago, above today's treeline limits.
Higher tree lines indicate higher Holocene temperatures.
Volcano-induced cooling around 4,200 yr caused late Holocene treeline elevations to decline to modern levels.
The author points out, Twenty-first century warming in the region is now equivalent to mid-Holocene warm season temperatures.
interestingly, The observed (instrumental) and reconstructed modern warming trends shown in the paper suggest that all or almost all of it was accomplished in the decades from the 1910s to the 1940s.
Advances in modern treeline were also achieved in the 1940s.
This seems to indicate There has been no significant net warming trend or net treeline advancement since the 1940s This is despite the sharp increase in greenhouse gas emissions from fossil fuel combustion after 1945.
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