Gill Net Selectivity for Fifteen Fish Species of the Upper San Francisco Estuary

University of California, Davis (UC Davis) | July 14th, 2022

Gill-net size selectivity for fifteen fish species occurring in the upper San Francisco Estuary was estimated from a data set compiled from multiple studies which togethe

Gill-net size selectivity for fifteen fish species occurring in the upper San Francisco Estuary was estimated from a data set compiled from multiple studies which together contained 7,096 individual fish observations from 882 gill net sets. The gill nets considered in this study closely resembled the American Fisheries Society’s recommended standardized experimental gill nets for sampling inland waters. Relationships between gill-net mesh sizes and the sizes for each fish species retained in them were estimated indirectly using generalized linear modeling and maximum likelihood. Selectivity curves are provided for each species to inform researchers about population characteristics of fishes sampled with similar gill nets.

Gillnet Sampling Methods for Monitoring Status and Trends of Clear Lake Hitch in Clear Lake, Lake County, California

U.S. Geological Survey (USGS) | May 2nd, 2025

The Clear Lake Hitch (Lavinia exilicauda chi) is a minnow endemic to Clear Lake, Lake County, California. This species is listed as a threatened species under the Califor

The Clear Lake Hitch (Lavinia exilicauda chi) is a minnow endemic to Clear Lake, Lake County, California. This species is listed as a threatened species under the California Endangered Species Act and has been petitioned for listing under the United States Endangered Species Act. In 2017, the U.S. Geological Survey, in cooperation with the U.S. Fish and Wildlife Service, initiated a Clear Lake Hitch monitoring program to generate information annually on relative abundance and size structure.

Glaciers in California’s Sierra Nevada are likely disappearing for the first time in the Holocene

American Association for the Advancement of Science (AAAS) | October 1st, 2025

Mountain glaciers are sensitive climate indicators. Glaciers in the western United States are projected to disappear by 2100 CE, but whether they were previously absent i

Mountain glaciers are sensitive climate indicators. Glaciers in the western United States are projected to disappear by 2100 CE, but whether they were previously absent in the current interglacial (past 11,700 years) remains debated. Here, we present evidence that two of the largest glaciers in California’s Sierra Nevada near Yosemite National Park persisted throughout the Holocene. Cosmogenic in situ carbon-14 and beryllium-10 exposure dating in newly exposed proglacial bedrock indicates continuous Holocene cover, likely by ice. At a nearby smaller glacier, bedrock exposure-burial ages suggest glacier expansion at ~7 thousand years ago, earlier than previously recognized. Moraine exposure ages at these sites and the Sierra Nevada’s largest glacier are distributed across the past several thousand years, suggesting that glaciers were near their preindustrial extent for much of the late Holocene. These findings imply that a glacier-free Sierra Nevada is unprecedented since before the Holocene. Future alpine glacial environments in California are thereby likely a no-analog scenario within the current interglacial.

Glenn County | Hamilton City Flood Damage Reduction and Ecosystem Restoration Project

Nature Conservancy | January 14th, 2016

Although not designed explicitly as a groundwater recharge project, the Hamilton City Project is expected to benefit local groundwater supplies. Having an additio

Although not designed explicitly as a groundwater recharge project, the Hamilton City Project is expected to benefit local groundwater supplies. Having an additional 1,450 acres of floodplain reconnected to the Sacramento River during high flow events will allow transitory storage of flood flows and help recharge the groundwater basin.

Global Analysis of Climate Change Projection Effects on Atmospheric Rivers

American Geophysical Union (AGU) | April 19th, 2018

Atmospheric rivers (ARs) are elongated strands of horizontal water vapor transport, accounting for over 90% of the poleward water vapor transport across midlatitudes. The

Atmospheric rivers (ARs) are elongated strands of horizontal water vapor transport, accounting for over 90% of the poleward water vapor transport across midlatitudes. These “rivers in the sky” have important implications for extreme precipitation when they make landfall, particularly along the west coasts of many midlatitude continents (e.g., North America, South America, and West Europe) due to orographic lifting. ARs are important contributors to extreme weather and precipitation events, and while their presence can contribute to beneficial rainfall and snowfall, which can mitigate droughts, they can also lead to flooding and extreme winds. This study takes a uniform, global approach that is used to quantify how ARs change between Coupled Model Intercomparison Project Phase 5 historical simulations and future projections under the Representative Concentration Pathway (RCP) 4.5 and RCP8.5 warming scenarios globally. The projections indicate that while there will be ~10% fewer ARs in the future, the ARs will be ~25% longer, ~25% wider, and exhibit stronger integrated water vapor transports under RCP8.5. These changes result in pronounced increases in the frequency (integrated water vapor transport strength) of AR conditions under RCP8.5: ~50% (25%) globally, ~50% (20%) in the northern midlatitudes, and ~60% (20%) in the southern midlatitudes.

Global and Regional Sea Level Rise Scenarios for the United States

National Oceanic and Atmospheric Administration (NOAA) | January 15th, 2017

The Sea Level Rise and Coastal Flood Hazard Scenarios and Tools Interagency Task Force, jointly convened by the U.S. Global Change Research Program (USGCRP) and the Natio

The Sea Level Rise and Coastal Flood Hazard Scenarios and Tools Interagency Task Force, jointly convened by the U.S. Global Change Research Program (USGCRP) and the National Ocean Council (NOC), began its work in August 2015. The Task Force has focused its efforts on three primary tasks: 1) updating scenarios of global mean sea level (GMSL) rise, 2) integrating the global scenarios with regional factors contributing to sea level change for the entire U.S. coastline, and 3) incorporating these regionally appropriate scenarios within coastal risk management tools and capabilities deployed by individual agencies in support of the needs of specific stakeholder groups and user communities. This technical report focuses on the first two of these tasks and reports on the production of gridded relative sea level (RSL, which includes both ocean-level change and vertical land motion) projections for the United States associated with an updated set of GMSL scenarios. In addition to supporting the longer-term Task Force effort, this new product will be an important input into the USGCRP Sustained Assessment process and upcoming Fourth National Climate Assessment (NCA4) due in 2018. This report also serves as a key technical input into the in-progress USGCRP Climate Science Special Report (CSSR). 

Global and Regional Sea Level Rise Scenarios for the United States

National Oceanic and Atmospheric Administration (NOAA) | January 19th, 2017

The Sea Level Rise and Coastal Flood Hazard Scenarios and Tools Interagency Task Force, jointly convened by the U.S. Global Change Research Program (USGCRP) and t

The Sea Level Rise and Coastal Flood Hazard Scenarios and Tools Interagency Task Force, jointly convened by the U.S. Global Change Research Program (USGCRP) and the National Ocean Council (NOC), began its work in August 2015. The Task Force has focused its efforts on three primary tasks: 1) updating scenarios of global mean sea level (GMSL) rise, 2) integrating the global scenarios with regional factors contributing to sea level change for the entire U.S. coastline, and 3) incorporating these regionally appropriate scenarios within coastal risk management tools and capabilities deployed by individual agencies in support of the needs of specific stakeholder groups and user communities. This technical report focuses on the first two of these tasks and reports on the production of gridded relative sea level (RSL, which includes both ocean-level change and vertical land motion) projections for the United States associated with an updated set of GMSL scenarios. In addition to supporting the longer-term Task Force effort, this new product will be an important input into the USGCRP Sustained Assessment process and upcoming Fourth National Climate Assessment (NCA4) due in 2018. This report also serves as a key technical input into the in-progress USGCRP Climate Science Special Report (CSSR). In order to bound the set of GMSL rise scenarios for year 2100, we assessed the most up-to-date scientific literature on scientifically supported upper-end GMSL projections, including recent observational and modeling literature related to the potential for rapid ice melt in Greenland and Antarctica. The projections and results presented in several peer-reviewed publications provide evidence to support a physically plausible GMSL rise in the range of 2.0 meters (m) to 2.7 m, and recent results regarding Antarctic ice- sheet instability indicate that such outcomes may be more likely than previously thought. To ensure consistency with these recent updates to the peer-reviewed scientific literature, we recommend a revised ‘extreme’ upper-bound scenario for GMSL rise of 2.5 m by the year 2100, which is 0.5 m higher than the upper bound scenario from Parris et al. (2012) employed by the Third NCA (NCA3). In addition, after consideration of tide gauge and altimeter-based estimates of the rates of GMSL change over the past quarter-century and of recent modeling of future low-end projections of GMSL rise, we revise Parris et al. (2012)’s estimate of the lower bound upward by 0.1 m to 0.3 m by the year 2100. This report articulates the linkages between scenario-based and probabilistic projections of future sea levels for coastal-risk planning, management of long-lived critical infrastructure, mission readiness, and other purposes. The probabilistic projections discussed in this report recognize the inherent dependency (conditionality) of future GMSL rise on future greenhouse-gas emissions and associated ocean-atmosphere warming. In recognition of the different time horizons of relevance to different decision contexts, as well as the long-term GMSL rise commitment (lagged GMSL response) from on-going increases in ocean- atmosphere warming, GMSL rise and associated RSL change are quantified from the year 2000 through the year 2200 (on a decadal basis to 2100 and with lower temporal frequency between 2100 and 2200). The 0.3 m-2.5 m GMSL range for 2100 is discretized by 0.5-m increments and aligned with emissions- based, conditional probabilistic storylines and global model projections into six GMSL rise scenarios: aLow, Intermediate-Low, Intermediate, Intermediate-High, High and Extreme, which correspond to GMSL rise of 0.3 m, 0.5 m, 1.0 m, 1.5 m, 2.0 m and 2.5 m, respectively. These GMSL rise scenarios are used to derive regional RSL responses on a 1-degree grid covering the coastlines of the U.S. mainland, Alaska, Hawaii, the Caribbean, and the Pacific island territories, as well as at the precise locations of tide gauges along these coastlines. These scenario-based RSL values fill a major gap in climate information needed to support a wide range of assessment, planning, and decision-making processes. GMSL was adjusted to account for key factors important at regional scales, including: 1) shifts in oceanographic factors such as circulation patterns; 2) changes in the Earth’s gravitational field and rotation, and the flexure of the crust and upper mantle, due to melting of land-based ice; and 3) vertical land movement (VLM; subsidence or uplift) due to glacial isostatic adjustment (GIA, which also changes Earth’s gravitational field and rotation, as well as the overall shape of the ocean basin), sediment compaction, groundwater and fossil fuel withdrawals, and other nonclimatic factors. Key findings include: * Along regions of the Northeast Atlantic (Virginia coast and northward) and the western Gulf of Mexico coasts, RSL rise is projected to be greater than the global average for almost all future GMSL rise scenarios (e.g., 0.3-0.5 m or more RSL rise by the year 2100 than GMSL rise under the Intermediate scenario). * Along much of the Pacific Northwest and Alaska coasts, RSL is projected to be less than the global average under the Low-to-Intermediate scenarios (e.g., 0.1-1 m or less RSL rise by the year 2100 than GMSL rise under the Intermediate scenario). * Along almost all U.S. coasts outside Alaska, RSL is projected to be higher than the global average under the Intermediate-High, High and Extreme scenarios (e.g., 0.3-1 m or more RSL rise by the year 2100 than GMSL rise under the High scenario). Finally, the consequences of rising RSL are presented in terms of how the frequency of moderate-level flooding associated with a NOAA coastal/lakeshore flood warning of a serious risk to life and property may change in the future under the sea level scenarios. The elevation threshold used to classify such events by NOAA on their tide gauges varies along the U.S. coastline, but in general it is about 0.8 m (2.6 feet) above the highest average tide and locally has a 20% annual chance of occurrence. For example, using the flood-frequency definition, we find at most locations examined (90 cities along the U.S. coastline outside of Alaska) that with only about 0.35 m (<14 inches) of local RSL rise, annual frequencies of such disruptive/damaging flooding will increase 25-fold by or about (±5 years) 2080, 2060, 2040 and 2030 under the Low, Intermediate-Low, Intermediate and Intermediate High subset of scenarios, respectively.

Global Application of the Atmospheric River Scale

American Geophysical Union (AGU) | January 18th, 2023

Global aquifers dominated by fossil groundwaters but wells vulnerable to modern contamination

Nature Portfolio (Springer Nature) | July 25th, 2017

The vulnerability of groundwater to contamination is closely related to its age. Groundwaters that infiltrated prior to the Holocene have been documented in many aquifers

The vulnerability of groundwater to contamination is closely related to its age. Groundwaters that infiltrated prior to the Holocene have been documented in many aquifers and are widely assumed to be unaffected by modern contamination. However, the global prevalence of these ‘fossil’ groundwaters and their vulnerability to modern-era pollutants remain unclear. Here we analyse groundwater carbon isotope data (12C, 13C, 14C) from 6,455 wells around the globe. We show that fossil groundwaters comprise a large share (42–85%) of total aquifer storage in the upper 1?km of the crust, and the majority of waters pumped from wells deeper than 250m. However, half of the wells in our study that are dominated by fossil groundwater also contain detectable levels of tritium, indicating the presence of much younger, decadal-age waters and suggesting that contemporary contaminants may be able to reach deep wells that tap fossil aquifers. We conclude that water quality risk should be considered along with sustainable use when managing fossil groundwater resources.

Global assessment and hotspots of lake drought

Nature Portfolio (Springer Nature) | April 23rd, 2025