Re: [HPAC] Observed shifts in regional climate linked to Amazon deforestation

[John Nissen]

Hi Tom,

That's interesting.  There seems to be some deadly positive feedback at play: global warming means more stress on trees and "forest loss has contributed to higher land surface temperature".

I listened to a keynote talk at AGU 2022 by Carlos Nobre, a Brazilian scientist.  He warned that the Amazon rainforest is close to a tipping element close to a point of no return, when it will irrevocably turn (or revert) to savannah.  He said it could happen by 2040 if I remember correctly, assuming deforestation continues and the global temperature continues to rise unabated.  He has spoken more recently about this; see for example [1].

He also mentioned that an AMOC collapse would be catastrophic for the Amazon rainforest, but I can't find a reference.  It was an example of cascading tipping elements, with the Arctic sea ice being a potential cascade originator.

Cheers, John

[1] https://www.theguardian.com/environment/ng-interactive/2025/jun/26/tippping-points-amazon-rainforest-climate-scientist-carlos-nobre

On Mon, Nov 24, 2025 at 11:39 AM Tom Goreau <gor...@globalcoral.org> wrote:

• Article
• Open access

• Published: 21 November 2025

Observed shifts in regional climate linked to Amazon deforestation

• Marcus V. F. Silveira, 
• Patrick W. Keys, 
• Anderson Ruhoff, 
• Paulo Artaxo, 
• Marcos H. Costa, 
• Liana O. Anderson, 
• Marcos Adami, 
• Celso von Randow & 
• Luiz E. O. C. Aragão 

Communications Earth & Environment volume 6, Article number: 948 (2025) 

Abstract

Deforestation is an important driver of regional climate change in the Amazon; thus, assessments of climate impacts from deforestation can provide key insights to climate change mitigation and adaptation strategies in the region. Using satellite-based observational data, here we investigated how accumulated deforestation in the Amazon may have contributed to shifting climate away from reference conditions in highly forested regions. We assessed differences in several essential climate variables between 0.5° deforested cells grouped by their extent of remaining forest cover and their highly forested neighboring cells. Our findings show compelling evidence that forest loss has contributed to shift climate toward higher land surface temperatures, lower evapotranspiration, lower dry season rainfall, and fewer rainy days, especially in regions with forest cover <60%. Highly deforested regions share some climatic similarities with transitional regions between the moist forest and savanna biomes, which was generally not observed in highly forested regions. Our findings underscore the importance of deforestation control and forest restoration to improve climate resilience of Amazonian ecosystems and climate-dependent economic activities.

 

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[Tom Goreau]

Carlos Nobre, and Paulo Artaxo (a lead author on this paper) are Brazil’s top atmospheric experts, I knew both of them in Amazonia in the 1980s.

 

This effect was first shown by the head of the Brazilian National Amazon Research Institute (INPA), Eneas Salati, who helped  me start the Amazonia GHG ground flux measurements. All the data since then supports his inferences.

 

But even earlier than that Robert Goodland pointed out that all these effects would become inevitable in the classic Amazon Jungle: Green Hell to Red Desert, 1975:

 

 

AMOC-Amazonia teleconnections probably work through changes in Equator to Pole temperature and pressure gradients.