Periodic Reporting for period 5 - DECAF (Deforestation – Climate –Atmospheric composition – Fire interactions and feedbacks)
Reporting period: 2024-03-01 to 2024-12-31
Tropical deforestation and forest degradation have important environmental impacts. Extensive air pollution from deforestation fires is a serious health issue across the tropics, but large uncertainties remain in its quantification. Deforestation alters rainfall, both through changes to the land surface and through the impacts of smoke from deforestation fires. However, the magnitude and sign of the rainfall response to deforestation is not clear because underlying land-atmosphere interactions are poorly understood and because the net response is a result of multiple, complex interactions that have not been fully assessed. The impacts of deforestation on atmospheric composition and climate causes a complex set of biosphere interactions resulting in potential Earth system feedbacks. These feedbacks have not yet been quantified and so their importance is not known. Despite recent progress, many of these key interactions between deforestation, fire, atmospheric composition and climate remain poorly understood. In particular, previous studies focused on individual interactions; the combined impacts of land surface change and smoke from fires on air quality and climate have not been quantified. Action to mitigate the air quality and climate impacts of deforestation and associated fires is hindered by these substantial gaps in understanding. DECAF addressed this important challenge, delivering improved process-level knowledge of the impacts of deforestation on atmospheric composition and climate and a step change in our understanding of the impact of deforestation on the Earth system.
The primary aim of DECAF was to make a step change in our understanding of the impacts of deforestation on the Earth system through the interactions and feedbacks between tropical deforestation, fires, atmospheric composition and climate. DECAF is the first integrated study of the combined interactions and feedbacks between tropical deforestation, fire, atmospheric composition and climate. DECAF has the following objectives:
To address this important challenge, DECAF exploited new information from laboratory experiments, in-situ and satellite observations in combination with state-of-the-art numerical models.
DECAF provided evidence of the impacts of tropical deforestation on local and regional climate and air quality. We found that tropical deforestation causes local and regional warming and drying (reduced rainfall). Fires associated with deforestation causes regional air pollution with negative health impacts. Overall, the work provides evidence of the local and regional benefits of polices that aim to reduce tropical deforestation.
The primary aim of DECAF was to make a step change in our understanding of the impacts of deforestation on the Earth system through the interactions and feedbacks between tropical deforestation, fires, atmospheric composition and climate. DECAF is the first integrated study of the combined interactions and feedbacks between tropical deforestation, fire, atmospheric composition and climate. DECAF has the following objectives:
To address this important challenge, DECAF exploited new information from laboratory experiments, in-situ and satellite observations in combination with state-of-the-art numerical models.
DECAF provided evidence of the impacts of tropical deforestation on local and regional climate and air quality. We found that tropical deforestation causes local and regional warming and drying (reduced rainfall). Fires associated with deforestation causes regional air pollution with negative health impacts. Overall, the work provides evidence of the local and regional benefits of polices that aim to reduce tropical deforestation.
Through Activity 1 (Deforestation – Fire Interactions) we have worked to understand the drivers of deforestation and fire (Doggart et al., 2020a), the drivers of impacts of selective logging (Ngo et al., 2020) and the drivers of changing biofuel use (Doggart et al., 2020b). Our work demonstrates that agriculture, not charcoal, is the main driver of deforestation in Tanzania. Beyond protected areas, there is no clear policy limiting the conversion of forests to agricultural land. Reducing deforestation in Tanzania requires greater inter-sectoral coordination between the agriculture, livestock, land, energy and forest sectors. To understand the drivers and impacts of logging in Vietnam, we combined information from livelihood surveys, remote sensing and forest inventories around a protected natural forest area in North Central Vietnam. Our analysis suggests activities to reduce forest degradation in protected areas are likely to be financially viable through Vietnam's REDD+ program.
Through Activity 2 Particulate emissions from tropical fires and impacts on air quality we have worked to constrain fire emissions and assess impacts on air quality (Butt et al., 2020) and the impacts of interventions to reduce fire and air quality impacts (Conibear et al., 2020). We estimate that the prevention of vegetation fires would have averted 16 800 (95UI: 16 300–17 400) premature deaths across South America. The health benefits of fire prevention in the Amazon are comparable to those found in Equatorial Asia.
Through Activity 3 We analysed remote sensing and models to assess the impacts of land-use change on rainfall and local and regional climate. We found evidence that tropical deforestation leads to observed reductions in rainfall (Smith et al., 2023) and local and regional warming (Butt et al., 2023).
Through Activity 4 We analysed state-of-the-art climate models and showed that models confirm reduced rainfall and enhanced warming over regions of deforestation.
Through Activity 2 Particulate emissions from tropical fires and impacts on air quality we have worked to constrain fire emissions and assess impacts on air quality (Butt et al., 2020) and the impacts of interventions to reduce fire and air quality impacts (Conibear et al., 2020). We estimate that the prevention of vegetation fires would have averted 16 800 (95UI: 16 300–17 400) premature deaths across South America. The health benefits of fire prevention in the Amazon are comparable to those found in Equatorial Asia.
Through Activity 3 We analysed remote sensing and models to assess the impacts of land-use change on rainfall and local and regional climate. We found evidence that tropical deforestation leads to observed reductions in rainfall (Smith et al., 2023) and local and regional warming (Butt et al., 2023).
Through Activity 4 We analysed state-of-the-art climate models and showed that models confirm reduced rainfall and enhanced warming over regions of deforestation.
Through Activity 1 (Deforestation – Fire Interactions) we have developed new methodologies to assess the drivers of deforestation and fire in tropical countries. In Doggart et al. (2020) we combined satellite remote sensing with field surveys and interviews to better assess the drivers. Through ground surveys and stakeholder interviews we assessed the proximate deforestation drivers at each point.
Through Activity 2 Particulate emissions from tropical fires and impacts on air quality we have combined remote sensing and atmospheric models to constrain fire emissions and assess impacts on air quality (Butt et al., 2020). This work has so far focused on the Amazon. We estimate that the prevention of vegetation fires would have averted 16 800 premature deaths across South America. The health benefits of fire prevention in the Amazon are comparable to those found in Equatorial Asia.
Through Activity 1 (Deforestation – Fire Interactions) we have developed new interdisciplinary approaches to assess the role of the selective logging on forest biomass in tropical forests. Our analysis combines field data, satellite remote sensing and participatory interviews (Ngo et al., 2020). Analysis of Landsat images over the period 1990 to 2014 combined with forest inventory data, demonstrates selective logging was leading to ongoing degradation of natural forests resulting in loss of 3.3 ± 0.8 Mg biomass ha−1 yr−1 across the protected area. We estimate that preventing illegal logging would incur local opportunity costs of USD $4.10 ± 0.90 per Mg CO2, similar to previous estimates for tropical forest protected areas and substantially less than the opportunity costs in timber or agricultural concessions.
Through Activity 3 we reported the first evidence of pan-tropical reductions in rainfall over regions of deforestation in the tropics (smith et al., 2023a). We also reported enhanced warming both over and downwind of tropical deforestation (Butt et al., 2023).
Through Activity 4 we analysed climate models and found they predict reduced rainfall and enhanced warming over tropical deforestation.
Overall, our work shows the negative local and regional impacts of tropical deforestation on climate and human health. Our work provides evidence to support policies that protect and restore tropical forests and demonstrates the local and regional benefits this will provide.
Through Activity 2 Particulate emissions from tropical fires and impacts on air quality we have combined remote sensing and atmospheric models to constrain fire emissions and assess impacts on air quality (Butt et al., 2020). This work has so far focused on the Amazon. We estimate that the prevention of vegetation fires would have averted 16 800 premature deaths across South America. The health benefits of fire prevention in the Amazon are comparable to those found in Equatorial Asia.
Through Activity 1 (Deforestation – Fire Interactions) we have developed new interdisciplinary approaches to assess the role of the selective logging on forest biomass in tropical forests. Our analysis combines field data, satellite remote sensing and participatory interviews (Ngo et al., 2020). Analysis of Landsat images over the period 1990 to 2014 combined with forest inventory data, demonstrates selective logging was leading to ongoing degradation of natural forests resulting in loss of 3.3 ± 0.8 Mg biomass ha−1 yr−1 across the protected area. We estimate that preventing illegal logging would incur local opportunity costs of USD $4.10 ± 0.90 per Mg CO2, similar to previous estimates for tropical forest protected areas and substantially less than the opportunity costs in timber or agricultural concessions.
Through Activity 3 we reported the first evidence of pan-tropical reductions in rainfall over regions of deforestation in the tropics (smith et al., 2023a). We also reported enhanced warming both over and downwind of tropical deforestation (Butt et al., 2023).
Through Activity 4 we analysed climate models and found they predict reduced rainfall and enhanced warming over tropical deforestation.
Overall, our work shows the negative local and regional impacts of tropical deforestation on climate and human health. Our work provides evidence to support policies that protect and restore tropical forests and demonstrates the local and regional benefits this will provide.