On April 9, 2025 at approximately 19:30, a wildfire erupted on the island of Sotra, west of Bergen, Norway. The fire spread quickly through dry vegetation, intensified by windy conditions, prompting a substantial response from local emergency services. Firefighters from seven nearby stations, supported by helicopters conducting aerial water drops, worked intensely together with civil defense to contain the blaze despite challenging terrain. The rocky, steep landscape made firefighting efforts difficult, yet crews managed to extinguish the flames later that night. Authorities considered evacuating nearby residents due to concerns that the fire might spread toward inhabited areas, but fortunately, the fire was brought under control before evacuation became necessary. The precise cause of the wildfire remains unclear but an investigation by the police was carried out to clarify the circumstances surrounding the event.

Following the fire, researchers at NILU involved in the Sparks projects utilized satellite imagery to map and assess the impacted area. They employed Sentinel-2 multispectral data to compare conditions before and after the fire, creating false-color images to highlight changes in vegetation health clearly. Unburned vegetation appeared green in images taken prior to the blaze, while burnt areas were distinguishable by their characteristic reddish-brown hues afterward. To quantify the damage, researchers calculated the difference in the Normalized Burn Ratio (dNBR), a standard remote sensing metric used for evaluating wildfire impacts, highlighting the areas of most severe damage. Further analysis included applying a land mask to exclude water bodies and using Otsu’s automated thresholding method to differentiate burned from unburned areas. The resulting binary classification allowed researchers to vectorize the affected region, delineating the extent of damage precisely. According to this satellite-based assessment, the wildfire burned approximately 0.22 square kilometers of terrain.

This detailed mapping demonstrates the critical role satellite imagery plays in assessing damage from wildfires. Rapid assessments provide essential information to emergency responders and environmental agencies, supporting effective recovery measures, ecological impact evaluations, and improved preparedness for future events. Given increasing wildfire risks in Norway associated with climate change and evolving land-use patterns, using Earth observation technologies for swift, accurate damage assessments becomes increasingly important for safeguarding both communities and ecosystems.

See the new SPARKS data viewer at: https://arctic-atmosphere.nilu.no/Fire

A small grass fire burned in the night of 28 April 2024 on the island of Vågsøy, which lies circa 80 km southwest of the town of Ålesund. The fire burned in very steep and inaccessible terrain, which made fighting the fire challenging. Nonetheless, the firefighters were available to extinguish the fire within ca. 6 hours. in the course of the night. Despite the small size of the fire, its impacts were visible from space. The SPARKS burned area algorithm based on data from the Sentinel-2/MSI instrument estimated a total burned area of approximately 12.3 hectares. More information about the fire can be found here (in Norwegian).

Johannes Kaiser from NILU’s SPARKS team is holding a presentation entitled “Arctic peat fire emissions estimated from satellite observations of fire radiative power” at the General Assembly of the European Geophysical Union (EGU). The talk will be on Monday, 15 Apr, 09:25–09:35 (CEST) in Room C as part of the session on “The Role of Fire in the Earth System: Understanding Interactions with the Land, Atmosphere, and Society“.

See here for more details about the conference. The summary of the presentation can be found here.

A series of large Arctic wildfires burned in the remote region of Magadan in Siberia/Russia in the summer of 2023. One example of such a fire is shown here, located at roughly 64.9N and 154.6E. The fire broke out in late June 2023. It burned very quickly and had already consumed over 700 km² in only 3-4 days. For comparison, the entire area of Oslo municipality is only just over 400 km². As part of the SPARKS project we estimated the burnt area of the fire using the MSI instrument onboard of Sentinel-2. We found that by the cut-off date of 19 August 2023, the fire had consumed a total area of 822 km².

Wildfires have become increasingly frequent and intense in recent years, resulting in significant environmental and health implications. Beyond the immediate damage caused by flames, wildfires also release substantial amounts of pollutants into the atmosphere, which can have far-reaching consequences for atmospheric composition, air quality, and climate change. Carbon monoxide (CO), a colorless and odorless gas, is one of the prominent pollutants released during wildfires. CO plays a crucial role in the atmospheric chemistry. It affects the oxidizing capacity of the atmosphere, influences the lifetime of other gases such as methane (CH₄), which is a potent greenhouse gas, and contributes to the formation of harmful air pollutants such as tropospheric ozone (O₃).

TROPOMI, the state-of-the-art satellite instrument aboard the European Space Agency’s Sentinel-5 Precursor satellite, plays a critical role in monitoring atmospheric composition, including emissions from wildfires. TROPOMI measures the solar radiation reflected by the Earth’s surface and atmosphere in various spectral ranges. Its high spatial resolution and sensitivity allow it to detect carbon monoxide and other atmospheric gases as well as aerosols, thereby providing valuable data on the distribution and transport of pollutants released during wildfire events. By analyzing TROPOMI data, we can study the distribution of carbon monoxide, its transport patterns, and its interaction with other atmospheric constituents. The satellite observations provide essential input for atmospheric models that simulate the atmospheric chemistry and help assess the influence of wildfire emissions on air quality and climate change. The data can aid in the development of mitigation strategies, early warning systems, and policies for managing wildfires and reducing their impact on the atmosphere.

Canada experiences significant wildfires each year, particularly in its boreal forest regions. The 2023 wildfire season is especially notable, with record-breaking fires that emitted large amounts of carbon monoxide across vast regions. The animation above shows carbon monoxide measured by TROPOMI throughout the summer of 2023. It illustrates how CO is released from various wildfires across the Northern hemisphere and how it then travels around the globe. A prominent example are the Canadian fires in May and June 2023, whose emissions traveled over the Atlantic and reached Southern Scandinavia for example on 25 May 2023 (see image below). During that day aerosol observations at the Birkenes observatory in East Agder showed enhanced levels.

Total column carbon monoxide (in units of mol per square meter) observed by the TROPOMI instrument on the Sentinel-5P platform for 2023-05-25.

A small wildfire near the town of Vestby broke out on the 13 June 2023. While it was very quickly extinguished on 14 June 2023, its impact could still be seen from space. Using this fire as a simple example, the figure below illustrates how we can determine the area that has been burned by a fire. Using 20 m resolution multispectral images from the Sentinel-2 satellite before and after the fire, a metric called “difference in normalized burn ratio (dNBR)” is derived, which is subsequently used for determining the total area that was burned in the fire. In the case of the Vestby fire this was estimated to be approximately 0.1 km², a negligibly small area compared to the large wildfire complexes that are typically burning in the fire season in Siberia or Canada.

Determining burned area from Sentinel-2/MSI data. False-color image before the fire (top left), false color image after the fire (top center), difference in normalized burn ratio (top right and bottom left), binary mask of the burned area determined from the difference in normalized burn ratio (bottom center), and vectorized polygon of the burned area derived from the binary mask (bottom right).

Updated calculations carried out by a team of atmosphere and climate scientists at NILU show that smoke from the forest fires in Canada is still drifting in over Norway.

The figure shows active fires (in red, from MODIS and VIIRS satellite instruments) and gray smoke plumes on June 4th over Canada and the USA. The white areas are regions with cloud-cover. (Image created using NASA Worldview.)

In the updated simulation, the smoke emission from Canada is shown as a cloud moving over a world map. The different colors of the cloud tell the amount of particles the cloud contains. The yellow areas of the cloud signal where there are the most soot particles in the air.

For more info see NILU’s website: https://www.nilu.com/2023/06/smoke-from-canada-still-coming-in-over-norway/

The atmosphere and climate scientists at NILU have used the model FLEXPART in forecast mode to predict how the smoke from the wildfires in Canada will move through the atmosphere.  

As the video below shows, the smoke has moved over Greenland and Iceland since 1 June before it reaches Norway today. The model is confirmed with observations in southern Norway (Birkenes Observatory) with increasing concentrations of aerosols. 

“We may be able to see some haze or smell smoke”, says senior scientist Nikolaos Evangeliou. “However, we do not believe that the number of particles in the air here in Norway will be large enough to be harmful to our health.”  

The concentration of smoke particles in the air in the affected areas of North America can certainly be harmful to health. In addition, smoke and soot particles from forest fires can float through the atmosphere and settle on ice and snow-covered surfaces on, for example, the Greenland ice sheet. There, they can contribute to making the surface darker, so that it absorbs solar radiation to a greater extent and contribute to warming the atmosphere.  

This effect is an important reason why climate and atmospheric scientists monitor particles in the atmosphere at Observatories all over the world, including Birkenes in Agder, Zeppelin on Svalbard and Trollhaugen in Antarctica. 

SPARKS is funded by the Caroline Herschel Framework Partnership Agreement on Copernicus User Uptake. It is a collaboration between the Norwegian Space Agency (NOSA), the Tartu Observatory (TO), and The Climate and Environemtal Research Institute (NILU).