This article discusses a new study showing that combinations of climate extremes—such as drought paired with heatwaves, or storms followed by hot, dry periods—can trigger abrupt and substantial carbon releases from ecosystems.
By integrating global observational records, field experiments, and numerical modeling, researchers show that these compound events generate non-linear carbon responses that exceed the sum of their parts, affecting forests, peatlands, grasslands, and agricultural soils.
The result is a stronger, faster push on atmospheric CO2 and a potential acceleration of climate change.
Compound climate extremes and the carbon cycle
These interactions destabilize carbon stores in vegetation and soils through elevated mortality, faster decomposition, and fire, turning once-secured sinks into sources for years to decades.
The study highlights that the impact of compound events is not simply additive; the combined stressors elicit responses that are amplified by feedbacks within the carbon cycle.
These dynamics are visible across major ecosystems—including forests, peatlands, grasslands, and agricultural soils.
Current models tend to miss how compound-event processes unfold in nature.
As warming continues, the risk of large, abrupt carbon releases grows.
Fire, drought, and the carbon balance
In drought and heat, the probability and intensity of fires rise markedly, transforming carbon sinks into sizeable carbon sources for years or even decades.
Fire not only releases stored carbon but also damages vegetation that would otherwise sequester CO2, creating a longer tail of emissions.
Mortality during drought, followed by periods of drying and high temperatures, can accelerate decomposition and respiration, amplifying the atmospheric CO2 signal.
The researchers emphasize that these fire-driven losses are a dominant pathway through which compound extremes reconfigure regional and global carbon budgets.
- Fire risk escalates under combined drought and heat with lasting effects on carbon stocks.
- Mortality and decomposition amplify CO2 release beyond single-stressor expectations.
- Feedbacks between vegetation loss, soil warming, and fire create persistent sources of carbon.
Peatlands, permafrost, and soil carbon under sequential warming
In peatlands and permafrost, sequential warming and drying expose long-stored organic matter to decomposition, releasing ancient carbon that does not belong to the contemporary carbon cycle.
This legacy carbon can be released over extended timescales, complicating efforts to attribute emissions to current land-use or climate conditions.
Agricultural landscapes are similarly stressed—multiple pressures reduce vegetation biomass and soil carbon while heightening erosion and nutrient losses.
This weakens both climate regulation and food security.
Model gaps and the way forward
Researchers note that many Earth system models underestimate carbon losses driven by compound extremes because they typically isolate single stressors and miss nonlinear interactions.
The paper calls for integrating compound-event processes into models, expanding monitoring networks, and conducting experiments that recreate realistic sequences of extremes to improve projections.
Until such advances are incorporated, climate models will continue to under-represent the risk of rapid carbon releases and the associated feedbacks to warming.
Policy implications and actions
The findings carry clear policy implications.
To limit the magnitude of compound-driven carbon losses, rapid emissions reductions are essential to constrain warming.
Targeted land management can reduce risk by protecting vulnerable carbon stores and decreasing fire susceptibility.
Restoring degraded soils can bolster both carbon sequestration and resilience.
Monitoring networks should be expanded to capture the sequence and timing of extreme events.
Land management practices should be adapted to minimize compound stresses on carbon-rich ecosystems.
- Protect and conserve peatlands and other high-carbon ecosystems.
- Implement strategies to reduce fire risk and improve fire management in vulnerable regions.
- Restore degraded soils to boost soil carbon stocks and resilience.
- Expand and harmonize monitoring networks for compound-event dynamics.
- Advance Earth system models to include compound extremes and legacy effects.
- Promote climate-resilient agricultural practices to maintain biomass and soil carbon under stress.
Here is the source article for this story: Combinations of climate extremes may prompt carbon budget rethink