{"id":362900,"date":"2025-01-21T15:21:05","date_gmt":"2025-01-21T14:21:05","guid":{"rendered":"https:\/\/climatescience.press\/?p=362900"},"modified":"2025-01-21T15:21:07","modified_gmt":"2025-01-21T14:21:07","slug":"new-study-globally-30-of-modern-forests-have-not-warmed50-of-treelines-have-not-advanced","status":"publish","type":"post","link":"https:\/\/climatescience.press\/?p=362900","title":{"rendered":"New Study: Globally, 30% Of Modern Forests Have Not Warmed\u202650% Of Treelines Have Not Advanced"},"content":{"rendered":"\n
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(A) Location of the ice patch (TOL) with the mid-Holocene whitebark pine stand relative to the modern treeline site (TAL). The map inset shows t
approximate location of the study site (purple circle) within the Greater Yellowstone Ecosystem (GYE; green polygon) (Basemaps from Natural Earth and Google
Earth courtesy of Maxar Technologies). (B) Aerial image showing the ice patch and ice-patch margin where the whitebark pine trees were sampled (red polygon)
(photo by Joe McConnell, captured 6 Sep 2021). (C) The sampled subfossil whitebark pine trees along the margin of the TOL ice patch (photo by Daniel Stahle).
(D) Panoramic view of the forefield of the ice patch showing the exposed ice surface from extensive melt during the 2024 ablation season (photo by Gregory
Downloaded from https:\/\/www.pnas.org<\/a> by 198.203.28.123 on January 21, 2025 from IP address 198.203.28.123.
Pederson, captured 8 Sep 2024)<\/figcaption><\/figure>\n\n\n\n

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From NoTrickZone<\/a><\/p>\n\n\n\n

By\u00a0Kenneth Richard<\/a>\u00a0<\/em><\/p>\n\n\n\n

Scientists presumably intending to report unusual modern warming in response to anthropogenic activities actually indicate all or nearly all modern warming and treeline advances at a Rocky Mountain ice patch site occurred from the 1910s to the 1940s.<\/strong><\/h4>\n\n\n\n

An interesting observation found in the body of a new study (Pederson et al., 2025<\/a><\/strong>) is that 30% of the globe\u2019s forests have not even warmed in the modern era (1900s-present), and just 50% of the globe\u2019s forests have not advanced upslope. This would appear to challenge claims of global-scale warming.<\/p>\n\n\n\n

\u201cVariations in local conditions likely explain why recent warming documented at approximately 70% of treelines globally only resulted in ~50% exhibiting upslope advances.\u201d<\/em><\/p>\n\n\n\n

The study documents a millennia-scale tree line and temperature record from a high-elevation site (>3,000 m above sea level) in the USA\u2019s Rocky Mountains (Yellowstone region).<\/p>\n\n\n\n

A melting ice patch reveals a pine forest grew at this elevation, which is ~180 m above today\u2019s tree line limit, approximately 6,500 to 4,200 years ago. Higher tree lines are indicative of warmer Holocene temperatures. Volcanically induced cooling after 4,200 years ago led to the decline in tree line elevation to modern levels in the Late Holocene.<\/p>\n\n\n\n

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The authors point out that the 21st century warming in this region has now equaled the warm-season temperatures of the Mid-Holocene.<\/p>\n\n\n\n

Interestingly, though, the observed (instrumental) and reconstructed modern warming trends shown in the paper indicate all or nearly all accomplished in the decades between the 1910s and 1940s. The modern treeline advance was also achieved by the 1940s.<\/p>\n\n\n\n

This would appear to indicate there has been no obvious net warming trend or net tree line advance since the 1940s\u2026despite the abrupt increase in greenhouse gas emissions from fossil fuel burning after 1945.<\/p>\n\n\n\n

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Image Source:\u00a0Pederson et al., 2025<\/a><\/strong><\/figcaption><\/figure>\n\n\n\n

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