Abstract. Tundra environments are experiencing elevated levels of wildfire, and thefrequency is expected to keep increasing due to rapid climate change in theArctic. Tundra wildfires can release globally significant amounts ofgreenhouse gasses that influence the Earth's radiative balance. Here wedevelop a novel method for estimating carbon loss and the resultingradiative forcings of gaseous and aerosol emissions from the 2015 tundrawildfires in the Yukon–Kuskokwim Delta (YKD), Alaska. We paired burn depthmeasurements using two vegetative reference points that survived the fireevent – Sphagnum fuscum and Dicranum spp. – with measurements of local organic matter and soil carbonproperties to estimate total ecosystem organic matter and carbon loss. Weused remotely sensed data on fire severity from Landsat 8 to scale ourmeasured losses to the entire fire-affected area, with an estimated totalloss of 2.04 Tg of organic matter and 0.91 Tg of carbon and an average lossof 3.76 kg m−2 of organic matter and 1.68 kg m−2 of carbon in the2015 YKD wildfires. To demonstrate the impact of these fires on the Earth'sradiation budget, we developed a simple but comprehensive framework toestimate the radiative forcing from Arctic wildfires. We synthesizedexisting research on the lifetime and radiative forcings of gaseous andaerosol emissions of CO2, N2O, CH4, O3 and itsprecursors, and fire aerosols. The model shows a net positive cumulativemean radiative forcing of 3.67 W m−2 using representative concentration pathway (RCP) 4.5 and 3.37 W m−2using RCP 8.5 at 80 years post-fire, which was dominated by CO2emissions. Our results highlight the climate impact of tundra wildfires,which positively reinforce climate warming and increased fire frequencythrough the radiative forcings of their gaseous emissions.
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Yukon-Kuskokwim River Delta 2015 fire burn depth measurements and unburned soil and vegetation organic matter and carbon content collected in 2019.
Tundra environments in Alaska are experiencing elevated levels of wildfire, and the frequency is expected to keep increasing due to rapid warming of the Arctic. Because of large amounts of carbon stored in permafrost soils, tundra wildfires may release significant amounts of carbon to the atmosphere that ultimately influence the Earth’s radiative balance. Therefore, accounting for the amount of carbon released from tundra wildfires is important for understanding the trajectory of climate change. We collected data in the Yukon-Kuskokwim River Delta during the summer of 2019 for the purpose of determining organic matter and carbon lost during the 2015 fire season. Organic matter and carbon lost from combustion were determined by combining burn depth measurements with organic matter and carbon content measurements from unburned tundra. Burn depth measurements were taken opportunistically across different levels of burn severity. Three vegetative markers, Sphagnum fuscum, Eriophorum, and Dicranum spp., that survived the fire event were used to measure the difference between the pre and post fire soil height in unburned and burned areas respectively, defined here as burn depth. All burn depth measurements are accompanied with coordinate locations so that they can ground truth and be upscaled by remote sensing data of burn severity. Organic matter and carbon content of the dense live vegetation layer and fibric soil layer were measured in the lab from vegetation and soil cores taken from four different sites in unburned tundra areas.
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- Award ID(s):
- 1915307
- NSF-PAR ID:
- 10438456
- Publisher / Repository:
- NSF Arctic Data Center
- Date Published:
- Subject(s) / Keyword(s):
- ["tundra","fire ecology","carbon"]
- Format(s):
- Medium: X Other: text/xml
- Sponsoring Org:
- National Science Foundation
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