Abstract
AbstractUnprecedented fire events in recent years are leading to a demand for improved understanding of how climate change is already affecting fires, and how this could change in the future. Increased fire activity in South America is one of the most concerning of all the recent events, given the potential impacts on local ecosystems and the global climate from the loss of large carbon stores under future socio‐environmental change. However, due to the complexity of interactions and feedbacks, and lack of complete representation of fire biogeochemistry in many climate models, there is currently low agreement on whether climate change will cause fires to become more or less frequent in the future, and what impact this will have on ecosystems. Here we use the latest climate simulations from the UK Earth System Model UKESM1 to understand feedbacks in fire, dynamic vegetation, and terrestrial carbon stores using the JULES land surface model, taking into account future scenarios of change in emissions and land use. Based on evaluation of model performance for the present day, we address the specific policy‐relevant question: how much fire‐induced carbon loss will there be over South America at different global warming levels in the future? We find that burned area and fire emissions are projected to increase in the future due to hotter and drier conditions, which leads to large reductions in carbon storage, especially when combined with increasing land‐use conversion. The model simulates a 30% loss of carbon at 4°C under the highest emission scenario, which could be reduced to 7% if temperature rise is limited to 1.5°C. Our results provide a critical assessment of ecosystem resilience under future climate change, and could inform the way fire and land‐use is managed in the future to reduce the most deleterious impacts of climate change.
Highlights
Record fire events in recent years across the Arctic (Witze, 2020), Europe, western USA (Higuera & Abatzoglou, 2020), Australia (Boer et al, 2020) and Brazil’s rainforest and wetland biomes (Lizundia-Loiola et al, 2020; Mega, 2020) are leading to questions about how climate change is affecting fire regimes, and how this could change in the future
In this paper we have posed a specific policy-relevant question: how much fire-induced carbon loss will there be over South America at different global warming levels in the future? Using our most advanced representation of the Earth system to date, we have shown that burned area is projected to increase in the future with Global Warming Levels (GWLs) in all SSP scenarios, driven by an increase in temperature and decrease in moisture availability
In this paper we have shown that under high warming, high emissions scenarios, additional feedbacks from increased fire over South America in the future could lead to significant loss of tree cover, vegetation carbon and productivity
Summary
Record fire events in recent years across the Arctic (Witze, 2020), Europe, western USA (Higuera & Abatzoglou, 2020), Australia (Boer et al, 2020) and Brazil’s rainforest and wetland biomes (Lizundia-Loiola et al, 2020; Mega, 2020) are leading to questions about how climate change is affecting fire regimes, and how this could change in the future. Fires in South America are mainly focused across Brazil’s Cerrado region, where conditions are hot and dry, over the June-October fire season. Vegetation in this region is heterogeneous fire-adapted paths of woodlands, mixed with more sparse vegetation dominated by small trees, shrubs and grasses (Ratter et al, 1997). The risk of fires may increase over wider areas in the future due to warming and drying over the century as the climate continues to change (Ciais et al, 2013). It is estimated that currently, 58% of the Amazon is too humid to support fires, but climate change may reduce this area to 37% by 2050 (Ciais et al, 2013; Le Page et al, 2010), potentially introducing fires to a region of the Amazon where trees are more vulnerable to burning (Staver et al, 2020)
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