The land sector is affected not only by management decisions of humans but also by natural processes. Extreme events such as windfalls of trees through storms, insect outbreaks or fires in forests can significantly affect the GHG inventories of countries in single years. Under climate change, intensity and frequency of natural disturbances is expected to increase.
To some degree these emissions are beyond the control of the country. Therefore, the LULUCF Regulation allows Member States to exclude or compensate for emissions from extreme events and climate change impacts. For the first period emissions from extreme disturbance events can be partly excluded from accounting. In the second compliance period the Regulation allows to compensate for emissions from climate change impacts on managed land.
What does the LULUCF Regulation say?
The LULUCF Regulation defines natural disturbances as “non-anthropogenic events or circumstances that cause significant emissions”. Their occurrence is assumed to be “beyond the control of the relevant Member State” and cause emissions that the Member State is not able significantly to limit. The inclusion of natural disturbance emissions in the accounting bears the risk of large debits from these events for affected countries but also the EU as a whole. The LULUCF Regulation, therefore, allowed countries to exclude part of the emission peaks caused by natural disturbances from the accounting .
Exclusion of emissions from extreme events in forests
The regulation allows for the exclusion of a limited amount of emissions from natural disturbances on afforested land and managed forest land in the period 2021 to 2025. Art. 10 and Annex VI of the Regulation provide details on how such events can be identified and how the exclusion is done.
The basic rules and calculation steps are the following:
A country needs to identify whether an ‘extreme event’ has occurred. To detect extreme events, a country’s usual level of emissions from natural disturbance events is recorded based on past data - so called ‘background level’. It represents the emissions that have occurred without any extreme events, excluding outliers.
The background level serves then as a benchmark for what are considered ‘normal’ levels of emissions from natural disturbances in a country. An extra amount (called margin) is added to the background level to account for uncertainties. If, according to the GHG inventory of the years 2021 to 2025, emissions from natural disturbances in one year are higher than the background level plus the margin, it is considered an ‘extreme’ event. For such events, the emissions beyond the background level can be left out of the total emissions count.
For a balanced accounting it is important that carbon removals from the regeneration of forests after disturbance are not counted for the remaining compliance period as climate mitigation contribution if emissions from the losses have been excluded earlier.
The areas in which the events took place need to be known to be able to document that removals occurring on the disturbed area are excluded.
Emissions from harvesting, salvage logging or deforestation after the disturbance event and emissions from prescribed burning on the disturbed land areas cannot be excluded.
Areas affected through fire events are relatively easily detectable through remote sensing technologies . Such technologies can help documenting geographical location but also an attribution to disturbance type and driver .
More challenging is the estimation of related emissions and tracking of subsequent regrowth that requires terrestrial information such as National Forest Inventory data (Castagna et al. 2023). However, despite the challenges, the option to exclude emissions from extreme events is an important instrument for countries in which such events can easily exceed normal years of emissions and removals by an order of magnitude.
Compensation for natural disturbances under managed forest land flexibility
Member States that want to make use of the managed forest land flexibility in the period 2021-2025 will need to provide documentation on the impact of natural disturbances. Specific information includes the “identification of all land areas affected by natural disturbances in that particular year, including their geographical location, the period and types of natural disturbances.”
Evidence needs to be provided that natural disturbances are responsible for higher emissions. This can be done using the historic background level of emissions from natural disturbances as described above. A debit resulting from accounting forest sinks that are reduced by extreme events against the forest reference level can be compensated.
Data sources for providing such evidence include remote sensing-based products and statistics that are collected by international data bases such as the European Forest Fire Information System (EFFIS), the Database of European Forest Insect and Disease Disturbances (DEFID2), and FORWIND
Compensation of emissions from climate change impacts
Similarly to the managed forest land flexibility of the period 2021-2025, Member States that provide evidence to the Commission concerning the impact of natural disturbances are eligible for compensation under the land use mechanism. Like the managed forest land flexibility, the land use mechanism requires “evidence concerning the impact of natural disturbances calculated pursuant to Annex VI”.
The sources of information for such documentation are the same as for documenting managed forest land flexibility. The mechanism additionally demands evidence on “the long-term impact of climate change resulting in excess emissions or diminishing sinks that are beyond their control.” This evidence involves a quantitative assessment of climate change effects on net emissions or net removals for the affected area.
As evidence Member States should document changes of climate characteristics relevant for the LULUCF sector, including aridity, mean temperatures, mean precipitation, frost days, and the duration of droughts. Such data need to cover at least the period 2001 to 2025. Scientifically reviewed projections and observations for the period 2026 to 2030 should be included. Such records can at least be used to identify statistical relationships between occurrence of disturbances and observed changes in climate.
Ideally, Member States can make use of models used for GHG reporting that include climate sensitivity and natural disturbances. An example is the CBM-CFS3 (Kurz et al. 2009) model already applied by a number of Member States.
Why are natural disturbances relevant?
GHG inventories reflect natural disturbances in different ways, depending on the size and type of disturbance. Disturbance events may have impacts on both carbon removals and CO2 and non-CO2 GHG emissions. The following types of events typically occur in the EU:
Drought events reduce CO2 removals. This is because they negatively affect tree growth and increase tree mortality. Drought events do not necessarily directly lead to high emissions. However, such emissions might occur through drought-induced disturbances such as insect and pest outbreaks.
Insect outbreaks reduce CO2 removals and can potentially lead to high emissions. Insects can reduce forest growth, kill individual trees or even entire forest stands. Dying and dead trees might be harvested through salvage logging and thus may in part enter the HWP pool.
Forest fires reduce CO2 removals and can potentially lead to high emissions. Emissions occur from burning litter and understory in case of less intensive fires or from burning of tree biomass if the fire is more intense.
Windfalls from storm events reduce CO2 removals and can potentially lead to high emissions. Storms damage trees by breaking the stem or uprooting. Windfalls are often followed by insect outbreaks as storm-damaged trees are less resilient. The damaged trees might still be used for products. However, often timber quality is reduced.
Over the last 20 years, the impact of natural disturbances was estimated to amount to 16% of the annual timber harvest in Europe (Patacca et al. 2023). Wind is the most important disturbance agent (46% of unplanned harvest), followed by fire (24%) and insect outbreaks (17%). Natural disturbances lead to additional unplanned harvest, e.g. as salvage logging, meaning that dying or dead trees are removed. A recent study indicate that forest disturbances in Europe are projected to increase substantially, exceeding 1986–2020 levels under all climate scenarios and more than doubling by the end of the century (+122%) under unabated climate change (Grüning et al 2026).
There is often a relationship between management choices and natural disturbances. Therefore, opportunities exist to reduce natural disturbances through adapted forest management. Changes in forest composition, e.g. mix of tree species, vertical and horizontal structure of stands etc., can reduce the impact of forest fires, windthrows, insect and fungi pest outbreaks. For example, converting forests from single-species coniferous forests to mixed forests, including broad-leaved trees species, will increase forest resilience.
There are important synergies between mitigation and adaptation measures. For example, greater tree-species diversity can increase forest growth and, at the same time, increase the resilience of forests to natural disturbances (Verkerk et al. 2022)
