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ARCTIC SUMMER FIRES

Posted on: July 30, 2020

Arctic wildfires: How bad are they and what caused them? - BBC News

Arctic wildfires: How bad are they and what caused them? - BBC News

bandicam 2020-07-29 20-05-03-126

bandicam 2020-07-29 20-06-39-823

THIS POST IS A BIBLIOGRAPHY ON ARCTIC WILDFIRES OF JUNE, JULY, AND AUGUST WHEN THE SUN SHINES 24 HOURS A DAY ON THE ARCTIC. THE BIBLIOGRAPHY PROVIDES A CONTEXT FOR THE MEDIA REPORTS ABOUT THESE FIRES IN TERMS OF CLIMATE CHANGE AND THE PRESUMED NEED FOR CLIMATE ACTION IMPLIED BY ARCTIC TUNDRA FIRES. 

 

ARCTIC WILDFIRES: THE RELEVANT BIBLIOGRAPHY

IMAGE FROM HIGUERA ET AL 2008. ANCIENT TUNDRA FIRES

  1. Wein, Ross W. “Frequency and characteristics of arctic tundra fires.” Arctic (1976): 213-222bandicam 2020-07-29 20-19-59-491
  2. Jones, Benjamin M., et al. “Recent Arctic tundra fire initiates widespread thermokarst development.” Scientific reports 5 (2015): 15865. Fire-induced permafrost degradation is well documented in boreal forests, but the role of fires in initiating thermokarst development in Arctic tundra is less well understood. Here we show that Arctic tundra fires may induce widespread thaw subsidence of permafrost terrain in the first seven years following the disturbance. Quantitative analysis of airborne LiDAR data acquired two and seven years post-fire, detected permafrost thaw subsidence across 34% of the burned tundra area studied, compared to less than 1% in similar undisturbed, ice-rich tundra terrain units. The variability in thermokarst development appears to be influenced by the interaction of tundra fire burn severity and near-surface, ground-ice content. Subsidence was greatest in severely burned, ice-rich upland terrain (yedoma), accounting for ~50% of the detected subsidence, despite representing only 30% of the fire disturbed study area. Microtopography increased by 340% in this terrain unit as a result of ice wedge degradation. Increases in the frequency, magnitude and severity of tundra fires will contribute to future thermokarst development and associated landscape change in Arctic tundra regions. [FULL TEXT]
  3. Hu, Feng Sheng, et al. “Arctic tundra fires: natural variability and responses to climate change.” Frontiers in Ecology and the Environment 13.7 (2015): 369-377.  Anthropogenic climate change may result in novel disturbances to Arctic tundra ecosystems. Understanding the natural variability of tundra‐fire regimes and their linkages to climate is essential in evaluating whether tundra burning has increased in recent years. Historical observations and charcoal records from lake sediments reveal a wide range of fire regimes in Arctic tundra, with fire‐return intervals varying from decades to millennia. Analysis of historical data shows strong climate–fire relationships, with threshold effects of summer temperature and precipitation. Projections based on 21st‐century climate scenarios suggest that annual area burned will approximately double in Alaskan tundra by the end of the century. Fires can release ancient carbon from tundra ecosystems and catalyze other biogeochemical and biophysical changes, with local to global consequences. Given the increased likelihood of tundra burning in coming decades, land managers and policy makers need to consider the ecological and socioeconomic impacts of fire in the Far North.
  4. Higuera, Philip E., et al. “Frequent fires in ancient shrub tundra: implications of paleorecords for arctic environmental change.” PloS one 3.3 (2008): e0001744.  Understanding feedbacks between terrestrial and atmospheric systems is vital for predicting the consequences of global change, particularly in the rapidly changing Arctic. Fire is a key process in this context, but the consequences of altered fire regimes in tundra ecosystems are rarely considered, largely because tundra fires occur infrequently on the modern landscape. We present paleoecological data that indicate frequent tundra fires in northcentral Alaska between 14,000 and 10,000 years ago. Charcoal and pollen from lake sediments reveal that ancient birch-dominated shrub tundra burned as often as modern boreal forests in the region, every 144 years on average (+/− 90 s.d.; n = 44). Although paleoclimate interpretations and data from modern tundra fires suggest that increased burning was aided by low effective moisture, vegetation cover clearly played a critical role in facilitating the paleofires by creating an abundance of fine fuels. These records suggest that greater fire activity will likely accompany temperature-related increases in shrub-dominated tundra predicted for the 21st century and beyond. Increased tundra burning will have broad impacts on physical and biological systems as well as on land-atmosphere interactions in the Arctic, including the potential to release stored organic carbon to the atmosphere.
  5. Chen, Yaping, Mark Jason Lara, and Feng Sheng Hu. “A robust visible near-infrared index for fire severity mapping in Arctic tundra ecosystems.” ISPRS Journal of Photogrammetry and Remote Sensing 159 (2020): 101-113 Tundra fires are projected to increase with anthropogenic climate change, yet our ability to assess key wildfire metrics such as fire severity remains limited. The Normalized Burn Ratio (NBR) is the most commonly applied index for fire severity mapping. However, the computation of NBR depends on short-wave infrared (SWIR) data, which are not commonly available from historical and contemporary high-resolution (≤4 m) optical imagery. The increasing availability of visible near-infrared (VNIR) measurements from proximal to spaceborne sensors/platforms has the potential to advance our understanding of the spatiotemporal patterns of fire severity within tundra fires. Here we systematically assess the feasibility of using VNIR data for fire severity mapping in ten Alaskan tundra fires (cumulatively burned ~1700 km2). We compared the accuracy of 10 published VNIR-based fire indices using both uni-temporal (post-fire image) and bi-temporal (pre-fire and post-fire image difference) assessments against ground-based fire severity data (Composite Burn Index, CBI) at 109 tundra sites. The Global Environmental Monitoring Index (GEMI) had the highest correspondence with CBI (R2 = 0.77 uni-temporal; R2 = 0.85 bi-temporal), with similar performance to NBR (R2 = 0.77 uni-temporal; R2 = 0.83 bi-temporal). Tundra vegetation types affected NBR but not GEMI, as SWIR reflectance was influenced to a greater extent in shrub than graminoid tundra. We applied GEMI to contemporary high-resolution (i.e. Quickbird 2) and historical meso-resolution imagery (i.e. Landsat Multispectral Scanner) to demonstrate the capability of GEMI for resolving fine-scale patterns of fire severity and extending fire severity archives. Results suggest that GEMI accurately captured the heterogeneous patterns of tundra fire severity across fire seasons, ecoregions, and vegetation types.
  6. Mack, Michelle C., et al. “Carbon loss from an unprecedented Arctic tundra wildfire.” Nature 475.7357 (2011): 489-492Arctic tundra soils store large amounts of carbon (C) in organic soil layers hundreds to thousands of years old that insulate, and in some cases maintain, permafrost soils1,2. Fire has been largely absent from most of this biome since the early Holocene epoch3, but its frequency and extent are increasing, probably in response to climate warming4. The effect of fires on the C balance of tundra landscapes, however, remains largely unknown. The Anaktuvuk River fire in 2007 burned 1,039 square kilometres of Alaska’s Arctic slope, making it the largest fire on record for the tundra biome and doubling the cumulative area burned since 1950 (ref. 5). Here we report that tundra ecosystems lost 2,016 ± 435 g C m−2 in the fire, an amount two orders of magnitude larger than annual net C exchange in undisturbed tundra6. Sixty per cent of this C loss was from soil organic matter, and radiocarbon dating of residual soil layers revealed that the maximum age of soil C lost was 50 years. Scaled to the entire burned area, the fire released approximately 2.1 teragrams of C to the atmosphere, (=0.0021 gigatonnes) an amount similar in magnitude to the annual net C sink for the entire Arctic tundra biome averaged over the last quarter of the twentieth century7. The magnitude of ecosystem C lost by fire, relative to both ecosystem and biome-scale fluxes, demonstrates that a climate-driven increase in tundra fire disturbance may represent a positive feedback, potentially offsetting Arctic greening8 and influencing the net C balance of the tundra biome.
  7. Rocha, Adrian V., et al. “The footprint of Alaskan tundra fires during the past half-century: implications for surface properties and radiative forcing.” Environmental Research Letters 7.4 (2012): 044039.  Recent large and frequent fires above the Alaskan arctic circle have forced a reassessment of the ecological and climatological importance of fire in arctic tundra ecosystems. Here we provide a general overview of the occurrence, distribution, and ecological and climate implications of Alaskan tundra fires over the past half-century using spatially explicit climate, fire, vegetation and remote sensing datasets for Alaska. Our analyses highlight the importance of vegetation biomass and environmental conditions in regulating tundra burning, and demonstrate that most tundra ecosystems are susceptible to burn, providing the environmental conditions are right. Over the past two decades, fire perimeters above the arctic circle have increased in size and importance, especially on the North Slope, indicating that future wildfire projections should account for fire regime changes in these regions. Remote sensing data and a literature review of thaw depths indicate that tundra fires have both positive and negative implications for climatic feedbacks including a decadal increase in albedo radiative forcing immediately after a fire, a stimulation of surface greenness and a persistent long-term (>10 year) increase in thaw depth. In order to address the future impact of tundra fires on climate, a better understanding of the control of tundra fire occurrence as well as the long-term impacts on ecosystem carbon cycling will be required.
  8. Jones, Benjamin M., et al. “Fire behavior, weather, and burn severity of the 2007 Anaktuvuk River tundra fire, North Slope, Alaska.” Arctic, Antarctic, and Alpine Research 41.3 (2009): 309-316.  In 2007, the Anaktuvuk River Fire (ARF) became the largest recorded tundra fire on the North Slope of Alaska. The ARF burned for nearly three months, consuming more than 100,000 ha. At its peak in early September, the ARF burned at a rate of 7000 ha d−1. The conditions potentially responsible for this large tundra fire include modeled record high summer temperature and record low summer precipitation, a late-season high-pressure system located over the Beaufort Sea, extremely dry soil conditions throughout the summer, and sustained southerly winds during the period of vegetation senescence. Burn severity mapping revealed that more than 80% of the ARF burned at moderate to extreme severity, while the nearby Kuparuk River Fire remained small and burned at predominantly (80%) low severity. While this study provides information that may aid in the prediction of future large tundra fires in northern Alaska, the fact that three other tundra fires that occurred in 2007 combined to burn less than 1000 ha suggests site specific complexities associated with tundra fires on the North Slope, which may hamper the development of tundra fire forecasting models.  [FULL TEXT]
  9. Hu, Feng Sheng, et al. “Arctic tundra fires: natural variability and responses to climate change.” Frontiers in Ecology and the Environment 13.7 (2015): 369-377.  Anthropogenic climate change may result in novel disturbances to Arctic tundra ecosystems. Understanding the natural variability of tundra‐fire regimes and their linkages to climate is essential in evaluating whether tundra burning has increased in recent years. Historical observations and charcoal records from lake sediments reveal a wide range of fire regimes in Arctic tundra, with fire‐return intervals varying from decades to millennia. Analysis of historical data shows strong climate–fire relationships, with threshold effects of summer temperature and precipitation. Projections based on 21st‐century climate scenarios suggest that annual area burned will approximately double in Alaskan tundra by the end of the century. Fires can release ancient carbon from tundra ecosystems and catalyze other biogeochemical and biophysical changes, with local to global consequences. Given the increased likelihood of tundra burning in coming decades, land managers and policy makers need to consider the ecological and socioeconomic impacts of fire in the Far North.

 

 

SUMMARY AND CONCLUSION

 

What we find in the literature for high latitude tundra fires is that the long history of these fires does not imply that they are a creation of anthropogenic global warming and climate change (AGW). Significant works in the literature did investigate a possible link between AGW and the severity and extent of these fires but without firm conclusions. In that regard the only attribution we find is that in the long term, perhaps a hundred years from now, if AGW continues to intensify, tundra fires may become more severe with a possibility of feedbacks from soil carbon. More importantly, the literature does not support claims in the media of the oddity of high Arctic tundra fires in 2020 and of their attribution to AGW. It is also noted that the polar region, where hours of sunshine varies from close to zero in winter to almost 24-hours in summer, undergoes an extreme seasonal temperature range of more than 30C compared with 8C in the tropics and 14C in the temperate zone. Therefore the Arctic should be understood not just as a very cold and icy place but also in terms of its extreme seasons. An additional consideration is the relatively high level of geological activity in that region as described in a related post [LINK] that includes, for example, a “river of molten iron” under Russia [LINK] [LINK]  shown  below. Molten iron river discovered speeding beneath Russia and Canada ...

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