Deforestation releases carbon dioxide through disturbance of the residue of carbon in the soil, the decay of leaves and wood, and combustion. Figures published in 2013 by the Intergovernmental Panel on Climate Change showed that deforestation contributes about 10% of global greenhouse gas emissions, most of which relates to tropical forests.

Forest ecosystems will themselves react to the changing climate, creating a potential feedback loop. In very general terms, greater concentration of atmospheric carbon dioxide increases biomass formation whilst higher temperatures reduce it. The net effect is likely to be positive in temperate forest regions (mostly richer countries) and negative in the tropical forests (mostly poorer countries).

Tropical forests face the added uncertainty of regional climate instability brought about by deforestation, independent of the effect of global warming. In trying to make sense of this complex cocktail of environmental change, scientists are particularly concerned that warmer and drier conditions could transform parts of the Amazon rainforest into savannah, with implications for disrupting rainfall patterns in the United States.

The implications of a positive feedback loop between deforestation and climate change casts doubt on the wisdom of regarding a two degree average temperature rise as tolerable, in UN climate negotiations. There can be no certainty that this threshold lies within the boundaries of the precautionary principle for sustainable rainforest ecosystems.

As the scientific understanding of the impact of global warming on tropical forests is far from confident, adaptation strategies remain difficult. One scenario under urgent consideration is the risk of fire – for which rainforests have no natural protection. Fire is known to have been an important factor in recent forest losses, in reaction to the El Nino phenomenon in 2015.

The urgency surrounding climate change has created opportunities to embed measures to protect forests within proposed international agreements on emissions. Such measures are considered to be particularly cost effective options for mitigation. However, the interminable delays in climate negotiations contrast with the rampant global forces that ultimately drive deforestation.

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more Forests briefings (updated March 2018)
Importance of Tropical Forests
Deforestation and Forest Degradation
Causes of Deforestation
Sustainable Development Goal for Deforestation
Consumer Solutions to Deforestation
Rights-based Solutions to Deforestation
Market-based Solutions to Deforestation
Source material and useful links