Wildfire smoke reduces lake ecosystem metabolic rates unequally across a trophic gradient

Nature Portfolio (Springer Nature) | May 22nd, 2024

Wildfires increasingly impact western US fluvial networks

Nature Portfolio (Springer Nature) | April 30th, 2021

Wildfires are increasing globally in frequency, severity, and extent, but their impact on fluvial networks, and the resources they provide, remains unclear. We

Wildfires are increasing globally in frequency, severity, and extent, but their impact on fluvial networks, and the resources they provide, remains unclear. We combine remote sensing of burn perimeter and severity, in-situ water quality monitoring, and longitudinal modeling to create the first large-scale, long-term estimates of stream+river length impacted by wildfire for the western US. We find that wildfires directly impact ~6% of the total stream+river length between 1984 and 2014, increasing at a rate of 342 km/year. When longitudinal propagation of water quality impacts is included, we estimate that wildfires affect ~11% of the total stream+river length. Our results indicate that wildfire activity is one of the largest drivers of aquatic impairment, though it is not routinely reported by regulatory agencies, as wildfire impacts on fluvial networks remain unconstrained. We identify key actions to address this knowledge gap and better understand the growing threat to fluvial networks, water security, and public health risks.

Wildfires, Floods, and Climate Variability

University of California, San Diego (UCSD) | May 10th, 2018

The first chapter surveys fire and fuels managers at local, regional, and national levels. Survey results in the form of fire managers’ decision calendars show how clim

The first chapter surveys fire and fuels managers at local, regional, and national levels. Survey results in the form of fire managers’ decision calendars show how climate information needs vary seasonally, over space, and through the organizational network. The study identifies opportunities to use climate information in fire management, including seasonal to inter-annual climate forecasts at all organizational levels, to improve the targeting of fuels treatments and prescribed burns, the positioning and movement of initial attack resources, and staffing and budgeting decisions. The second chapter analyzes National Flood Insurance Program (NFIP) data to quantify the economic impacts of flooding across the western United States from 1978 to 2007. The study compares National Flood Insurance Program data to National Weather Service measures of total damages, and presents a spatial and temporal analysis of daily claims and loss data over this period. The NFIP data reveals that a small number winter-season extreme hydrologic events, covering wide spatial areas, are responsible for a large proportion of total losses. In coastal southern California and across the southwest, El Niño conditions have had a strong effect in producing more frequent and higher magnitudes of insured losses while La Niña conditions significantly reduce both the frequency and magnitude losses. In the Pacific Northwest, the opposite pattern appears, though the effect is somewhat weaker, and less spatially coherent. The third chapter quantifies the economic impacts of flooding due to atmospheric river (AR) events in the western United States from 1978 to 2007, using NFIP claims and loss data. The study confirms that AR-related flood events cause significant economic damages and form the primary source of insurance claims and insured flood losses in the western coastal states. It provides spatial and temporal characterizations of damages as a function of integrated vapor transport (IVT) and antecedent hydrologic conditions. As the magnitude and frequency of wildfire and flood events change in response to anthropogenic climate change, and as economic and demographic contributions to vulnerability increase over time, public policy must adapt to respond. The results in these papers may be used to inform policies to mitigate losses and respond to future disaster scenarios, and may be of interest to policy makers and applied climate researchers alike.

Winter melt trends portend widespread declines in snow water resources

Nature Portfolio (Springer Nature) | April 5th, 2021

In many mountainous regions, winter precipitation accumulates as snow that melts in the spring and summer, which provides water to one billion people globally. Climate wa

In many mountainous regions, winter precipitation accumulates as snow that melts in the spring and summer, which provides water to one billion people globally. Climate warming and earlier snowmelt compromise this natural water storage. Although snowpack trend analyses commonly focus on the snow water equivalent (SWE), we propose that trends in the accumulation season snowmelt serve as a critical indicator of hydrological change. Here we compare long-term changes in the snowmelt and SWE from snow monitoring stations in western North America and find 34% of stations exhibit increasing winter snowmelt trends (P < 0.05), a factor of three larger than the 11% showing SWE declines (P < 0.05). Snowmelt trends are highly sensitive to temperature and an underlying warming signal, whereas SWE trends are more sensitive to precipitation variability. Thus, continental-scale snow water resources are in steeper decline than inferred from SWE trends alone. More winter snowmelt will complicate future water resource planning and management.

Winter wet–dry weather patterns driving atmospheric rivers and Santa Ana winds provide evidence for increasing wildfire hazard in California

Climate Dynamics (Springer) | August 12th, 2022

Floods caused by atmospheric rivers and wildfires fanned by Santa Ana winds are common occurrences in California with devastating societal impacts. In this work

Floods caused by atmospheric rivers and wildfires fanned by Santa Ana winds are common occurrences in California with devastating societal impacts. In this work, we show that winter weather variability in California, including the occurrence of extreme and impactful events, is linked to four atmospheric circulation regimes over the North Pacific Ocean previously named and identified as the “NP4 modes”. These modes come in and out of phase with each other during the season, result- ing in distinct weather patterns that recur throughout the historical record. Some phase combinations favor atmospheric river landfalls and extreme daily or multi-day precipitation, while other phase combinations favor anomalously hot weather and drying Santa Ana wind conditions over Southern California. This historical perspective of atmospheric circulation and impacts over 70 years reveals that weather patterns are changing in a way that enhances wildfire hazard in California, while the frequency of weather patterns linked to historical floods is not diminishing. These changes highlight the rising hazards of cascading weather extremes in California’s present and future.