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Glen MacDonald

Over the past four decades, annual area burned has increased significantly in California and across the western USA. This trend reflects a confluence of intersecting factors that affect wildfire regimes. It is correlated with increasing temperatures and atmospheric vapour pressure deficit. Anthropogenic climate change is the driver behind much of this change, in addition to influencing other climate-related factors, such as compression of the winter wet season. These climatic trends and associated increases in fire activity are projected to continue into the future. Additionally, factors related to the suppression of the Indigenous use of fire, aggressive fire suppression and, in some cases, changes in logging practices...
Categories: Publication; Types: Citation
We used a first-of-its-kind comprehensive scenario approach to evaluate both the vertical and horizontal response of tidal wetlands to projected changes in the rate of sea-level rise (SLR) across 14 estuaries along the Pacific coast of the continental United States. Throughout the U.S. Pacific region, we found that tidal wetlands are highly vulnerable to end-of-century submergence, with resulting extensive loss of habitat. Using higher-range SLR scenarios, all high and middle marsh habitats were lost, with 83% of current tidal wetlands transitioning to unvegetated habitats by 2110. The wetland area lost was greater in California and Oregon (100%) but still severe in Washington, with 68% submerged by the end of the...
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Actionable Science to Understand the Effects of Recent Temperature Increases to Inform Natural Resources Management in the Southwestern United States
In recent decades, average temperatures across the U.S. Southwest have increased substantially and precipitation patterns have increased in variability. The warmer temperatures directly impact water availability within Southwest ecosystems, including earlier snowmelts; reduced snowpacks, soil moisture, and streamflow; and lower humidity. Collectively, this has led to an increase in aridity across this region. This in turn affects terrestrial and aquatic ecosystems, increases wildfire severity, and impacts human activities such as agriculture and municipal water use. These well-documented trends are at the forefront of the concerns of natural resource managers in the Southwest. This project aims to strengthen partnerships...
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Climate Change in the Los Angeles Region: Temperature and Precipitation
The goal of this project was to examine how temperature and precipitation could change by the mid 21st century over the greater Los Angeles region. Major findings for temperature are: (1) large variability in the magnitude exists among downscaled global climate model projections over LA, but all predict warming; (2) warming is smaller over the ocean and coastal zone, but larger in the mountain areas and inland; (3) ensemble mean warming in all parts of the domain is significantly outside the range of historical variability, meaning the change will be detectable. Major findings for precipitation are: (1) large variability in both sign and magnitude exists among downscaled global climate model precipitation projections...
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Effects of Sea-Level Rise and Extreme Storms on California Coastal Habitats: Part 2
In California, the near-shore area where the ocean meets the land is a highly productive yet sensitive region that supports a wealth of wildlife, including several native bird species. These saltmarshes, mudflats, and shallow bays are not only critical for wildlife, but they also provide economic and recreational benefits to local communities. Today, sea-level rise, more frequent and stronger storms, saltwater intrusion, and warming water temperatures are among the threats that are altering these important habitats. Much of the existing research on anticipating the effects of changing conditions on coastal ecosystems relies on global or regional scale data, meaning that the detailed information necessary for local-scale...
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