Drought less predictable under declining future snowpack

Nature Portfolio (Springer Nature) | April 20th, 2020

Mountain snowpack serves as an immense natural water reservoir, and knowledge of snow conditions helps predict seasonal water availability and offers critical ear

Mountain snowpack serves as an immense natural water reservoir, and knowledge of snow conditions helps predict seasonal water availability and offers critical early warning of hydrologic drought. This paradigm faces an impending challenge given consensus that a smaller fraction of future precipitation will fall as snow. Here, we apply downscaled hydrologic simulations from 28 climate model projections to show that by mid-century (2036–2065), 69% of historically snowmelt-dominated areas of the western United States see a decline in the ability of snow to predict seasonal drought, increasing to 83% by late century (2070–2099). Reduced predictability arises when peak snowpack approaches zero or because of decreased warm-season runoff efficiency. Changes in drought prediction skill show significant (P < 0.01) elevation dependence, with lower-elevation coastal areas most impacted by warming. Ancillary predictive information can only partially mitigate snow-based predictability losses to 65% of areas, underscoring the importance of declining future snowpack.

Drought Management and Climate Adaptation among Small, Self-Sufficient Water Systems in California

California Natural Resources Agency (CNRA) | August 27th, 2018

 Examining human impacts, responses, and challenges to extreme climatic events can give insight into needed directions for climate adaptation to reduce future risks. Thi

 Examining human impacts, responses, and challenges to extreme climatic events can give insight into needed directions for climate adaptation to reduce future risks. This study focuses on the 2012-2016 Drought in California, documenting how small self-sufficient drinking water systems were affected and challenged by, and responded to the extreme event. The majority of small, self-sufficient water systems in the state serve rural, low income communities, and many have low technical, managerial, and financial capacity compared to larger systems. This increases the risk that these drinking water systems will be disproportionately impacted by droughts or other disruptions. To assess the impact of drought on small water systems, we employed an iterative approach to gathering perspectives and experiences from drinking water system managers across the state. The goal of employing these iterative methods is to better understand the breadth and scope of impacts, responses, and barriers to dealing with the 2012- 2016 Drought. The first stage of the data collection involved interviewing managers of drinking water systems, which were transcribed and analyzed using semi-grounded theory methods. To cross-check and advance findings from interviews in additional locations, we conducted three small regional workshops and then a larger policy forum. Multiple data collection methods allowed us to gather insights about experiences from nearly 200 water managers. This project uses local knowledge to document the social dimensions within drinking water systems during the 2012-2016 Drought and expresses the value of local knowledge in reflecting on future drinking water system needs in response to extreme events.  We found that drinking water systems, despite size or government project water reliance, experienced a similar set of drought impact, response, and barrier categories (e.g., water quantity and water quality). However, within these categories, the types of impacts, responses, and barriers differed based on both system size and water source portfolio. Common disadvantages that hinder drought resilience, and thus climate adaptation, of small self-sufficient drinking water systems include: staff capacity; financial burden of revenue loss during drought compounded with increased need for staff time for additional reporting; customer awareness and outreach challenges; and consolidation. We found that consolidation is valuable but in many case needs more state support to implement and incentivize. From a long term perspective, the absence of expressed duty and lack of concern for risks of climate change among water managers indicates a major dearth in adaptation planning among these drinking water systems. Documentation of experiences from the 2012-2016 Drought can be used to inform future planning for droughts and more broadly climate change. 

Drought Management and Climate Adaptation of Small, Self-Sufficient Drinking Water Systems in California

California Energy Commission (CEC) | August 15th, 2018

Examining human impacts, responses, and challenges to extreme climatic events can give insight into needed directions for climate adaptation to reduce future risks. This

Examining human impacts, responses, and challenges to extreme climatic events can give insight into needed directions for climate adaptation to reduce future risks. This study focuses on the 2012-2016 Drought in California, documenting how small self-sufficient drinking water systems were affected and challenged by, and responded to the extreme event.

Droughts impede water balance recovery from fires in the Western United States

Nature Portfolio (Springer Nature) | January 2nd, 2024

A steady rise in fires in the Western United States, coincident with intensifying droughts, imparts substantial modifications to the underlying vegetation, hydrology and

A steady rise in fires in the Western United States, coincident with intensifying droughts, imparts substantial modifications to the underlying vegetation, hydrology and overall ecosystem. Drought can compound the ecosystem disturbance caused by fire, although how these compound effects on hydrologic and ecosystem recovery vary among ecosystems is poorly understood. Here we use remote sensing-derived high-resolution evapotranspiration (ET) estimates from before and after 1,514 fires to show that ecoregions dominated by grasslands and shrublands are more susceptible to drought, which amplifies fire-induced ET decline and, subsequently, shifts water flux partitioning. In contrast, severely burned forests recover from fire slowly or incompletely, but are less sensitive to dry extremes. We conclude that moisture limitation caused by droughts influences the dynamics of water balance recovery in post-fire years. This finding explains why moderate to extreme droughts aggravate impacts on the water balance in non-forested vegetation, while moisture accessed by deeper roots in forests helps meet evaporative demands unless severe burns disrupt internal tree structure and deplete fuel load availability. Our results highlight the dominant control of drought on altering the resilience of vegetation to fires, with critical implications for terrestrial ecosystem stability in the face of anthropogenic climate change in the West.

Dynamic flood modeling essential to assess the coastal impacts of climate change

Nature Portfolio (Springer Nature) | March 13th, 2019

Coastal inundation due to sea level rise (SLR) is projected to displace hundreds of millions of people worldwide over the next century, creating significant eco

Coastal inundation due to sea level rise (SLR) is projected to displace hundreds of millions of people worldwide over the next century, creating significant economic, humanitarian, and national-security challenges. However, the majority of previous efforts to characterize potential coastal impacts of climate change have focused primarily on long-term SLR with a static tide level, and have not comprehensively accounted for dynamic physical drivers such as tidal non-linearity, storms, short-term climate variability, erosion response and consequent flooding responses. Here we present a dynamic modeling approach that estimates climate-driven changes in flood-hazard exposure by integrating the effects of SLR, tides, waves, storms, and coastal change (i.e. beach erosion and cliff retreat). We show that for California, USA, the world’s 5th largest economy, over $150 billion of property equating to more than 6% of the state’s GDP and 600,000 people could be impacted by dynamic flooding by 2100; a three- fold increase in exposed population than if only SLR and a static coastline are considered. The potential for underestimating societal exposure to coastal flooding is greater for smaller SLR scenarios, up to a seven-fold increase in exposed population and economic interests when considering storm conditions in addition to SLR. These results highlight the importance of including climate-change driven dynamic coastal processes and impacts in both short-term hazard mitigation and long-term adaptation planning.

Dynamical and Thermodynamical Causes of Large-Scale Changes in the Hydrological Cycle over North America in Response to Global Warming

American Meteorological Society (AMS) | October 15th, 2014

The mechanisms of model-projected atmospheric moisture budget change across North America are exam- ined in simulations conducted with 22 models from phase 5 of t

The mechanisms of model-projected atmospheric moisture budget change across North America are exam- ined in simulations conducted with 22 models from phase 5 of the Coupled Model Intercomparison Project. Modern-day model budgets are validated against the European Centre for Medium-Range Weather Forecasts Interim Re-Analysis. In the winter half year transient eddies converge moisture across the continent while the mean flow wets the west from central California northward and dries the southwest. In the summer half year there is widespread mean flow moisture divergence across the west and convergence over the Great Plains that is offset by transient eddy divergence. In the winter half year the models project drying for the southwest and wetting to the north. Changes in the mean flow moisture convergence are largely responsible across the west but intensified transient eddy moisture convergence wets the northeast. In the summer half year widespread declines in precipitation minus evaporation (P 2 E) are supported by mean flow moisture divergence across the west and transient eddy divergence in the Great Plains. The changes in mean flow convergence are related to increases in specific humidity but also depend on changes in the mean flow including increased low-level divergence in the U.S. Southwest and a zonally varying wave that wets the North American west and east coasts in winter and dries the U.S. Southwest. Increased transient eddy fluxes occur even as low-level eddy activity weakens and arise from strengthened humidity gradients. A full explanation of North American hydroclimate changes will require ex- planation of mean and transient circulation changes and the coupling between the moisture and circulation fields.

Dynamical and thermodynamical modulations on future changes of landfalling atmospheric rivers over western North America

American Geophysical Union (AGU) | September 12th, 2015

This study examines future changes of landfalling atmospheric rivers (ARs) over western North America using outputs from the Coupled Model Intercomparison Project Phase

This study examines future changes of landfalling atmospheric rivers (ARs) over western North America using outputs from the Coupled Model Intercomparison Project Phase 5 (CMIP5). The result reveals a strikingly large increase of AR days by the end of the 21st century in the RCP8.5 scenario, with fractional increases between 50% and 600%, depending on the seasons and landfall locations. These increases are predominantly controlled by the super-Clausius-Clapeyron rate of increase of atmospheric water vapor with warming, while changes of winds that transport moisture in the ARs, or dynamical effect, mostly counter the thermodynamical effect of increasing water vapor, limiting the increase of AR events in the future. The consistent negative effect of wind changes on AR days during spring and fall can be linked to the robust poleward shift of the subtropical jet in the North Pacific basin.

Early warnings and emerging accountability: Total’s responses to global warming, 1971–2021

Global Environmental Change (Elsevier) | November 29th, 2021

Building upon recent work on other major fossil fuel companies, we report new archival research and primary source interviews describing how Total responded to evolving c

Building upon recent work on other major fossil fuel companies, we report new archival research and primary source interviews describing how Total responded to evolving climate science and policy in the last 50 years. We show that Total personnel received warnings of the potential for catastrophic global warming from its products by 1971, became more fully informed of the issue in the 1980s, began promoting doubt regarding the scientific basis for global warming by the late 1980s, and ultimately settled on a position in the late 1990s of publicly accepting climate science while promoting policy delay or policies peripheral to fossil fuel control. Additionally, we find that Exxon, through the International Petroleum Industry Environmental Conservation Association (IPIECA), coordinated an international campaign to dispute climate science and weaken international climate policy, beginning in the 1980s. This represents one of the first longitudinal studies of a major fossil fuel company’s responses to global warming to the present, describing historical stages of awareness, preparation, denial, and delay.

Earth’s clouds are shrinking, boosting global warming

American Association for the Advancement of Science (AAAS) | December 19th, 2024

For more than 20 years, NASA instruments in space have tracked a growing imbalance in Earth’s solar energy budget, with more energy entering than leaving the planet. Mu

For more than 20 years, NASA instruments in space have tracked a growing imbalance in Earth’s solar energy budget, with more energy entering than leaving the planet. Much of that imbalance can be pinned on humanity’s greenhouse gases emissions, which trap heat in the atmosphere. But explaining the rest has been a challenge. The loss of reflective ice, exposing darker ground and water that absorb more heat, isn’t enough to explain the deficit, and the decline in light-reflecting hazes as countries clean up or close polluting industry falls short as well. “Nobody can get a number that’s even close,” says George Tselioudis, a climate scientist at NASA’s Goddard Institute for Space Studies.

Ecological forecasts for marine resource management during climate extremes

Nature Portfolio (Springer Nature) | December 5th, 2023