An Assessment of the Role of Anthropogenic Climate Change in the Alaska Fire Season of 2015

Partain, James; Alden, Sharon; Strader, Heidi; Bhatt, Uma S.; Bieniek, Peter A.; Brettschneider, Brian; Walsh, John E.; Lader, Rick; Olsson, Peter Q.; Rupp, T. Scott; Thoman, Richard; York, Alison; Ziel, Robert

doi:10.1175/bams-d-16-0149.1

Cited by 53 publications

(45 citation statements)

References 7 publications

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“…The positive trends in annual mean P-ET contrast with the expectation that longer and warmer summers will increase ET sufficiently to favor summer drying, which is indicated by projected decreases of high-latitude soil moisture in major climate change assessments [e.g., Figure 11.14 and Figure 12.23 in [2]). Anticipated increases of high-latitude wildfire activity [3] [4] are consistent with this expectation, highlighting the mixed picture of future surface wetness trends in the Arctic. A more recent evaluation of global climate model projections [5], although global rather than Arctic in scope, highlights the challenge of assessing changes in high-latitude surface wetness.…”

Section: Introductionsupporting

confidence: 64%

Regional Climate Model Simulation of Surface Moisture Flux Variations in Northern Terrestrial Regions

Fischer¹,

Walsh²,

Euskirchen³

et al. 2018

ACS

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The wetness of high-latitude land surfaces is strongly dependent on the difference between precipitation (P) and evapotranspiration (ET). If climate models are to capture the trajectory of surface wetness in high latitudes, they must be able to simulate the seasonality and variations of the surface moisture fluxes, as well as the sensitivities to the variations to the drivers. In this study, a combination of regional climate model output and eddy covariance measurements from flux tower locations in Alaska is used to evaluate model simulations of the surface moisture fluxes and their variations. In particular, we use the model output and the field measurements to test the hypothesis that temperature (T) is the key driver of variations of ET in tundra regions underlain by permafrost, while precipitation plays a greater role in boreal forest areas. Although the model's hydrologic cycle is stronger (larger P, larger ET) relative to the in situ measurements at all the sites, the prominent seasonal cycles of P, T, and ET are captured by the model. The tower measurements from all sites show a short period (one or two months) of negative P-ET during summer, indicative of surface drying, although the model does not show this period of drying at the inland tundra site. At all the tundra sites, both the flux tower data and the model simulations show that daily and warm-season totals of ET are largely temperature-driven. Daily ET shows a weak negative correlation with precipitation in the measurements and in the model results for all the sites. Precipitation is the main driver of year-to-year variations of the seasonally integrated net moisture flux at all the sites, implying that precipitation will be at least as important as temperature in the future trajectory of surface wetness.

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Section: Introductionsupporting

confidence: 64%

Regional Climate Model Simulation of Surface Moisture Flux Variations in Northern Terrestrial Regions

Fischer¹,

Walsh²,

Euskirchen³

et al. 2018

ACS

Self Cite

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“…This implies a large increase in the potential magnitude and frequency of summertime flash floods in Alaska. Also, although we tracked systems producing heavy precipitation, our results raise the question of high latitude dry thunderstorms, that might strongly respond to climate change as well, potentially causing additional wildfire ignitions (Partain et al 2016). This might have potentially large impacts on ecosystems and deserves further work.…”

Section: Resultsmentioning

confidence: 95%

“…Recent research found that mean and maximum temperatures in Alaska could increase as much as 8 • C by 2100, and extreme minimum temperatures could increase by up to 22 • C under a high-end emission scenario (Lader et al 2017;Newman et al 2020). This has dramatic effects such as thawing permafrost, increased risk of wildfires (Partain et al 2016), sea ice loss, increased likelihood of rain-onsnow events (Musselman et al 2018), and more intense precipitation (Bennett and Walsh 2015). Such changes would have major consequences on the local economy, ecosystems, and the life of local populations.…”

Section: Introductionmentioning

confidence: 99%

Kilometer-scale modeling projects a tripling of Alaskan convective storms in future climate

2020

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Convective storms produce heavier downpours and become more intense with climate change. Such changes could be even amplified in high-latitudes since the Arctic is warming faster than any other region in the world and subsequently moistening. However, little attention has been paid to the impact of global warming on intense thunderstorms in high latitude continental regions, where they can produce flash flooding or ignite wildfires. We use a model with kilometer-scale grid spacing to simulate Alaska’s climate under present and end of the century high emission scenario conditions. The current climate simulation is able to capture the frequency and intensity of hourly precipitation compared to rain gauge data. We apply a precipitation tracking algorithm to identify intense, organized convective systems, which are projected to triple in frequency and extend to the northernmost regions of Alaska under future climate conditions. Peak rainfall rates in the core of the storms will intensify by 37% in line with atmospheric moisture increases. These results could have severe impacts on Alaska’s economy and ecology since floods are already the costliest natural disaster in central Alaska and an increasing number of thunderstorms could result in more wildfires ignitions.

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“…The 2015 summer fire season was particularly active, leading to the second largest number of acres burned in Alaska since records began in 1940 (Partain Jr. et al, 2016). The highest density of fires detected from satellite lasted from midJune to mid-July (Fig.…”

Section: Regional Fires Impact Air Composition Over Much Of Central Amentioning

confidence: 99%

The influence of local oil exploration and regional wildfires on summer 2015 aerosol over the North Slope of Alaska

et al. 2018

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Abstract. The Arctic is warming at an alarming rate, yet the processes that contribute to the enhanced warming are not well understood. Arctic aerosols have been targeted in studies for decades due to their consequential impacts on the energy budget, both directly and indirectly through their ability to modulate cloud microphysics. Even with the breadth of knowledge afforded from these previous studies, aerosols and their effects remain poorly quantified, especially in the rapidly changing Arctic. Additionally, many previous studies involved use of ground-based measurements, and due to the frequent stratified nature of the Arctic atmosphere, brings into question the representativeness of these datasets aloft. Here, we report on airborne observations from the US Department of Energy Atmospheric Radiation Measurement (ARM) program's Fifth Airborne Carbon Measurements (ACME-V) field campaign along the North Slope of Alaska during the summer of 2015. Contrary to previous evidence that the Alaskan Arctic summertime air is relatively pristine, we show how local oil extraction activities, 2015's central Alaskan wildfires, and, to a lesser extent, long-range transport introduce aerosols and trace gases higher in concentration than previously reported in Arctic haze measurements to the North Slope. Although these sources were either episodic or localized, they serve as abundant aerosol sources that have the potential to impact a larger spatial scale after emission.

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An Assessment of the Role of Anthropogenic Climate Change in the Alaska Fire Season of 2015

Cited by 53 publications

References 7 publications

Regional Climate Model Simulation of Surface Moisture Flux Variations in Northern Terrestrial Regions

Regional Climate Model Simulation of Surface Moisture Flux Variations in Northern Terrestrial Regions

Kilometer-scale modeling projects a tripling of Alaskan convective storms in future climate

The influence of local oil exploration and regional wildfires on summer 2015 aerosol over the North Slope of Alaska

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