Research press release


Nature Communications

Environment: Assessing the impact of forestation on global climate patterns

大規模な植林プロジェクトは地球のエネルギー収支を変化させ、地球全体の大気循環パターンと海洋循環パターンの両方に影響を与える可能性のあることがモデリング研究によって示唆された。この知見は、気候変動の影響の緩和に役立てるための大規模な植林プログラムが、地球全体の気候に思いがけない影響を及ぼす可能性があることを示している。今回の研究について報告する論文が、Nature Communications に掲載される。


今回、Raphael Portmanたちの研究チームは、産業革命前の植被を完全に森林に転換するシナリオと完全に草地に転換するシナリオで、大気中のCO2濃度を産業革命前のレベルに維持して、数世紀にわたる結合気候モデルによるシミュレーションを行った。Portmanたちが作成したモデルは、地球規模の植林と森林減少が地球のエネルギー収支に影響し、それぞれ正反対の影響を及ぼして、大気循環パターン、海流と熱帯収束帯を強めたり、弱めたり、変化させたりすることを示した。このように、植林と森林減少のいずれもが、全世界で、降水量、気温、雲量や地上風の地域的パターンの変化を引き起こす可能性がある。


Large-scale forestation projects may alter the Earth’s energy balance, affecting both global atmospheric and ocean circulation patterns, suggests a modelling study published in Nature Communications. The findings indicate that massive tree planting programs, to help mitigate the effects of climate change, may have potentially unforeseen influences on global climate.

Large-scale forestation (afforestation and reforestation) projects have been proposed to mitigate climate change and its related impacts through carbon storage, and there is popular support for this idea. Both forestation and deforestation are known to affect the carbon cycle and CO2 concentrations, influencing global and local climates. There has been debate about the carbon-storage potential of forests and the local and global thermodynamic impacts of reforestation. However, due to complexity, effects on weather and climate patterns remain unresolved and are not yet considered in planning and policy.

Raphael Portman and colleagues performed multi-century coupled climate model simulations where preindustrial vegetation cover is either completely forested or deforested, and atmospheric CO2 levels are kept at constant preindustrial levels. The authors indicate that their models show that global-scale forestation and deforestation may affect the global energy balance, having opposing effects which strengthen, weaken or shift air circulation patterns, ocean currents and convection cells. In this way, both forestation and deforestation may cause changes in regional precipitation, temperature, cloud cover and surface wind patterns worldwide.

The authors caution that their findings should not be used as a general argument against forestation, as it has benefits including in relation to air quality, biodiversity and nutrition amongst others. They indicate that the design of large-scale forestation projects needs to take into account potential unforeseen influences on climate in regions far away from the forested area.

doi: 10.1038/s41467-022-33279-9


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