Assessing the climate benefits of afforestation: processes, methods, and frameworks

TL;DR

This paper reviews the complex effects of afforestation on climate, identifies key knowledge gaps, and proposes a comprehensive assessment framework to better evaluate its climate mitigation potential, especially in northern boreal and arctic regions.

Contribution

It synthesizes current understanding, highlights uncertainties, and introduces a new multi-component assessment framework for evaluating afforestation's climate benefits.

Findings

Identified significant knowledge gaps in forest-climate interactions.

Highlighted regional and historical factors affecting afforestation impacts.

Proposed a comprehensive framework considering multiple forcing components.

Abstract

Afforestation greatly influences several earth system processes, making it essential to understand these effects to accurately assess its potential for climate change mitigation. Although our understanding of forest-climate system interactions has improved, significant knowledge gaps remain, preventing definitive assessments of afforestation's net climate benefits. In this review, focusing on the Canadian northern boreal and southern arctic, we identify these gaps and synthesize existing knowledge. The review highlights regional realities, Earth's climatic history, uncertainties in biogeochemical (BGC) and biogeophysical (BGP) changes following afforestation, and limitations in current assessment methodologies, emphasizing the need to reconcile these uncertainties before drawing firm conclusions about the climate benefits of afforestation. Finally, we propose an assessment framework which considers multiple forcing components, temporal analysis, future climatic contexts, and implementation details. We hope that the research gaps and assessment framework discussed in this review inform afforestation policy in Canada and other circumpolar nations.