Warming-induced CO₂, CH₄ and N₂O emissions from land ecosystems and wildfire feedbacks simulated by the Dynamic Land Ecosystem Model (DLEM)

Climate warming can trigger additional greenhouse gas (GHG) emissions from terrestrial ecosystems, thereby amplifying climate change through positive biogeochemical feedbacks. Quantifying the magnitude, mechanisms, and spatial heterogeneity of these warming-induced emissions remains a major source of uncertainty in projections of the remaining carbon budget. In this study, we use the Dynamic Land Ecosystem Model (DLEM), a participating model in the Warming-Induced Emissions Model Intercomparison Project (WIE-MIP), to quantify warming-induced emissions of carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O), and to assess the role of climate-driven changes in wildfire activity following the standardized WIE-MIP protocol.

We analyze ensemble simulations driven by two general circulation models under five climate scenarios, including one idealized pathway, three temperature-overshoot scenarios, and one unmitigated high-warming pathway. These simulations allow us to disentangle the responses of terrestrial carbon storage, ecosystem productivity, microbial processes, and wildfire dynamics to varying levels and trajectories of warming.

Our results indicate that climate warming leads to a substantial net loss of terrestrial carbon, dominated by enhanced soil organic matter decomposition and ecosystem respiration, which outweigh gains from increased plant productivity. Warming also strongly intensifies wildfire activity, increasing fire frequency, burned area, and fire intensity across multiple regions. These changes generate large additional pulses of CO₂, CH₄, and N₂O from biomass combustion and post-fire ecosystem recovery. In parallel, higher temperatures stimulate microbial processes that enhance CH₄ emissions from wetlands and N₂O emissions from agricultural and natural soils.

Together, emissions from terrestrial ecosystems, wetlands, soils, and wildfires form a strong positive climate feedback that amplifies with increasing warming. Spatial hotspots emerge in high-latitude regions, fire-prone landscapes, tropical wetlands, and intensively managed agricultural areas. These warming-induced feedbacks substantially tighten the remaining carbon budget and underscore the importance of explicitly representing coupled biogeochemical and disturbance processes in Earth system projections.