Missing Burns in the High Northern Latitudes: The Case for Regionally Focused Burned Area Products

Abstract

Global estimates of burned areas, enabled by the wide-open access to the standard data products from the Moderate Resolution Imaging Spectroradiometer (MODIS), are heavily relied on by scientists and managers studying issues related to wildfire occurrence and its worldwide consequences. While these datasets, particularly the MODIS MCD64A1 product, have fundamentally improved our understanding of wildfire regimes at the global scale, their performance may be less reliable in certain regions due to a series of region- or ecosystem-specific challenges. Previous studies have indicated that global burned area products tend to underestimate the extent of the burned area within some parts of the boreal domain. Despite this, global products are still being regularly used by research activities and management efforts in the northern regions, likely due to a lack of understanding of the spatial scale of their Arctic-specific limitations, as well as an absence of more reliable alternative products. In this study, we evaluated the performance of two widely used global burned area products, MCD64A1 and FireCCI51, in the circumpolar boreal forests and tundra between 2001 and 2015. Our two-step evaluation shows that MCD64A1 has high commission and omission errors in mapping burned areas in the boreal forests and tundra regions in North America. The omission error overshadows the commission error, leading to MCD64A1 considerably underestimating burned areas in these high northern latitude domains. Based on our estimation, MCD64A1 missed nearly half the total burned areas in the Alaskan and Canadian boreal forests and the tundra during the 15-year period, amounting to an area (74,768 km2) that is equivalent to the land area of the United States state of South Carolina. While the FireCCI51 product performs much better than MCD64A1 in terms of commission error, we found that it also missed about 40% of burned areas in North America north of 60° N between 2001 and 2015. Our intercomparison of MCD64A1 and FireCCI51 with a regionally adapted MODIS-based Arctic Boreal Burned Area (ABBA) shows that the latter outperforms both MCD64A1 and FireCCI51 by a large margin, particularly in terms of omission error, and thus delivers a considerably more accurate and consistent estimate of fire activity in the high northern latitudes. Considering the fact that boreal forests and tundra represent the largest carbon pool on Earth and that wildfire is the dominant disturbance agent in these ecosystems, our study presents a strong case for regional burned area products like ABBA to be included in future Earth system models as the critical input for understanding wildfires’ impacts on global carbon cycling and energy budget.

Assessing the Accuracy of MODIS MCD64A1 C6 and FireCCI51 Burned Area Products in Mediterranean Ecosystems

“…The spatial agreement between the product and reference maps was further evaluated by estimating the proportion of the reference burned areas that was correctly mapped by the MODIS products. This metric can be useful for determining the detection rate (DR) of the products while accounting for the difference among the resolutions of the datasets involved [31,52]. The DR corresponds to the actual MODIS area burned divided by the reference (Sentinel-2) area.…”

“…MODIS-derived BA products have been utilized in several studies across different regions and ecosystems in recent years, with their spatial and temporal accuracy being thoroughly assessed. These studies focus on typical (tropical forests, savannas, grasslands) [6,25,29,30] or less fire-prone (boreal forests or tundra) ecosystems [31] with the time period of investigation commonly spanning, with few exceptions, few seasons as a result of the limited availability of higher-resolution reference datasets, especially when extensive spatial scales are considered.…”

Recent massive expansion of wildfire and its impact on active layer over pan-Arctic permafrost

“…Given that remote sensing datasets tend to underestimate wildfire activity especially in high latitudes [41][42][43], we evaluated the datasets used in this study with other studies on wildfires in high latitude regions. The burned area in 2020 Siberian Arctic (latitudes > 66.5 • N) was estimated between 1.71 and 2.62 Mha [23].…”

Fire-vegetation interactions in Arctic tundra and their spatial variability

“…In terms of wildfire distribution, which is the foundation for assessing and projecting wildfires' ecological and climatic impacts at large spatial scales, we do not yet have a clear picture of the spatio-temporal distribution of tundra wildfires across the circumpolar tundra domain except for the post-2000 era 64 . Even in regions like Alaska, where wildfire history exists since the 1940s and is well-maintained 65 , is shown to have notable omissions when it comes to reporting tundra wildfires 66 . A combination of factors including a lack of reliable long-term tundra wildfire records, tundra's extreme environmental conditions and subsequent lack of access, tundra wildfires' remoteness, and relative infrequency, have led to the fact that wildfires' impacts on tundra ecosystems have remained understudied.…”