A recent study published in the Journal Science suggests that nature-based projects aimed at removing carbon, particularly those focused on forestation, may not be as effective as previously thought.

Tree Planting Effectiveness in Climate Mitigation, Background

• Absorption of Carbon dioxide by Plants and Soils: Plants and soils absorb 30 per cent of carbon dioxide emissions from human activities each year, thereby mitigating climate change and its consequences.
• A New Study highlighted some gaps in our understanding. For example, it is unclear how this storage happens, and its stability is not well understood.

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Key findings of the Study

• Shortcomings in Current Climate Models: The climate models currently used to predict the longevity of carbon stored in trees have shortcomings. 
  • The models may be overestimating the amount of time carbon stays trapped in plants and underestimating the impact of climate change on forests themselves.
• Shorter Carbon Storage Duration in Plants Due to Faster Atmospheric Return: Plants absorb more carbon than expected, but they remain stored for a shorter period of time because it returns to the atmosphere sooner than previously predicted. 
  • Therefore, many nature-based carbon removal projects and strategies of the government are limited.
• Carbon Cycles: Carbon cycles (moves faster) more rapidly between the atmosphere and biosphere than previously thought.

Methodology Used

• Radiocarbon: The researchers utilised Radiocarbon (C-14) to Study Global Carbon Cycling Dynamics.
  • Radiocarbon Increased from Nuclear Testing: Though radiocarbon is produced naturally, nuclear bomb testing in the 1950s and 1960s increased its atmospheric levels. 
  • Global Tracking of C-14 Absorption: This extra C-14 was absorbed by plants all over the world, allowing researchers to track its accumulation in the terrestrial biosphere and assess rates of carbon uptake and turnover. 
  • Assessment of Carbon Uptake and Turnover: This was compared to the accumulation of C-14 in plants between 1963 and 1967 when no major nuclear detonations existed.
  • Modelling Plant Carbon Use: They fed this into the model to simulate how plants use carbon dioxide globally and the interactions between the atmosphere and the biosphere.

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Conclusion

• Need to understand carbon cycle better: There is a need to better understand and account for this more rapid carbon cycling in climate models.
• Urgent need for rapid reduction in fossil fuel emissions:  to lessen the effects of climate change.