Summary: Exploring California Climate Change Connections

Background 

On December 2 and 3, 2020, OEHHA convened a virtual workshop to provide a forum for exploring the scientific evidence for the interconnections between climate change and its impacts, and the implications for California. Discussions at the workshop will inform the 2021 edition of the report, Indicators of Climate Change in California. The following were the goals of the workshop:  

• To better understand how the various manifestations of climate change and their impacts interact in ways that create previously unrecognized risks or magnify known risks to humans and the environment.

• To collect scientific information that could inform how climate change indicators can be presented in ways that reflect linkages to fully characterize climate change in California.

• To identify additional climate-related issues to track using indicators.

The workshop consisted of the following sessions that reflect the organization of the indicator report: changes in climate; impacts on physical systems; impacts on human health and well-being; impacts on vegetation; and impacts on fish and wildlife. Speakers from academia, research institutions, government agencies, tribes, and community organizations delivered presentations during the sessions (see Speaker presentations, below). The presentations and panel discussions explored the interrelated nature of climate change and its impacts, and ideas for new indicators.  

For a full list of the video recordings, including opening and concluding remarks, follow this link. Links are also provided in the workshop agenda. You can also view graphical recordings of the workshop by Adi Brown.

Speaker presentations 

Key points from each of the presentations are listed below. A link to the corresponding recording is provided with each keynote or session. 

Opening Keynote 

A "discernible human influence on global climate": Personal reflections on scientific progress since the 1995 IPCC finding
Benjamin D. Santer, Ph.D., Lawrence Livermore National Laboratory 

• Pattern recognition techniques – also known as “climate fingerprint” studies – can help to disentangle human and natural influences on the climate system. 

• Human fingerprints have been identified in dozens of different observed climate records. 

• The main message from climate fingerprinting is that a human-caused global warming signal has emerged from the “noise” of natural climate variability. This warming signal is already causing significant impacts. 

• Climate scientists have a responsibility to speak plainly and clearly about the reality and seriousness of global warming. They must speak science to power.  

Session 1: California’s Changing Climate 

An overview of California’s changing climate
Michael Anderson, Ph.D., P.E., California Department of Water Resources 

• The world is warming with emergent impacts for California.

• Warming in the tropics and polar regions has downstream impacts to California through changes to storm tracks and changes in tropical systems strength, timing, and other characteristics. 

• Atmospheric rivers are central to the hydrologic outcomes for California.  Their evolution with climate change will be critical to understand for successful adaptation strategy development and implementation. 

California weather and climate extremes: connections, consequences, and emerging collaborations
Benjamin Hatchett, Ph.D., Desert Research Institute and Western Regional Climate Center 

• California is susceptible to weather and climate extremes across timescales from seconds to years that impact local, regional, state, and continental space scales.

• Many (most) of these extremes are exacerbated by background warming.

• Drivers of compound and cascading extremes need to be better understood, but we need to accelerate our actions to creatively reduce vulnerabilities immediately. 

Atmospheric rivers
Marty Ralph, Ph.D., Scripps Institution of Oceanography, University of California, San Diego 

• Atmospheric rivers are beneficial for water supply, but can also cause hazardous flooding.  

• Climate change projections suggest that the most extreme atmospheric rivers will become more extreme in the future.  

• Improved forecasts now and in the future enhance resilience and can improve water supply reliability via the Forecast Informed Reservoir Operations (FIRO). 

Large-scale climate patterns and their influence on California
Samantha Stevenson, Ph.D., University of California, Santa Barbara 

• Natural forms of climate variability experience regular fluctuations known as oscillations or “modes.” The El Niño-Southern Oscillation is an example of a large-scale Pacific Ocean climate mode. Many different climate modes influence California – tropical and higher latitude modes (which may include polar regions) – and their importance is variable at different temporal and spatial scales.

• Random variability cannot be neglected. Every El Niño event is different. 

• Climate modes can “load the dice” for extreme events. It is still unclear how these modes will change in the future but their impacts are likely to intensify. 

Session 2: Impacts on California Physical Systems and their Connections 

Changes in ocean conditions along the California coast
Marisol García-Reyes, Ph.D., Farallon Institute  

• Upwelling has been increasing, counteracting temperature trends in ocean temperatures in the central and northern regions, while in southern California temperatures are increasing and upwelling is not changing.

• Marine heatwaves are important disturbances that are increasing in frequency and magnitude.

• Ocean conditions are connected, and co-vary, with terrestrial conditions.

Hydrologic resilience from summertime fog and recharge: a case study for Coho salmon recovery planning
Lorraine E. Flint, Ph.D. and Alicia Torregrosa, US Geological Survey  

• Fog is a critical climate moderating process for coastal California ecosystems and is not well understood, nor is it well represented in future climate projections. Validation of future climate models to accurately project the presence and extent of fog is imperative for conservation planning. 

• Basin recharge provides late season baseflows to California coastal environments and when combined with fog and low cloud cover trends can be used to develop indices that when overlaid on threatened Coho fisheries basins, aid in developing more accurate threat abatement actions and restoration priorities for recovery and sustainability of Coho in a changing climate. 

The implications of climate change for water resources
Alex Hall, Ph.D., University of California, Los Angeles, Center for Climate Science  

In a series of studies over the past few years, we have been examining the implications of a changing climate for precipitation, snowpack, and streamflow in California. The key findings so far are that by the end of the 21st century, under a “business-as-usual” scenario of global greenhouse gas emissions: 

• We lose significant snowpack,  

• Big atmospheric river events get bigger,  

• Flooding increases dramatically, and  

• Dry years get drier. 

Climate change in the Sierra Nevada: Consequences for aquatic ecosystems
Steven Sadro, Ph.D., University of California, Davis 

• Variability in snowpack is buffering many small Sierra lakes from strong long term climate warming trends.

• Snowpack regulates lake thermal responses by determining when lakes begin warming and how long they gain heat during the spring and summer. 

• The effect of climate change on small mountain lakes will be mediated by local scale factors such as elevation, catchment slope and aspect, and lake morphology.  

Session 3: Impacts on Californians’ Health and Well-Being  

Ambient heat exposure, wildfires and health impacts
Rupa Basu, Ph.D., M.P.H., CalEPA Office of Environmental Health Hazard Assessment 

• Heat exposure affects several organs in humans. 

• Populations that are vulnerable to heat have been identified depending on health outcome. 

• Biological mechanisms for heat/adverse health outcomes have been hypothesized. 

Climate change impacts on California farmworkers
Maricela Morales, Central Coast Alliance United for a Sustainable Economy (CAUSE) 

• Farmworkers are devastated by multiple climate crises: wildfire, heat, drought and rains. They are often vulnerable to the adverse health impacts of these extreme events due to a combination of prolonged outdoor exposure, language barriers, and low wages. 

• Centuries of systemic racism and inequities are disasters unto themselves, which climate change further exacerbates. 

• Systemic change is happening. Greater protection for farmworkers was signed into law in 2018 and 2019 as a result of the large wildfires in prior years. Enforcement of these protections is imperative, as are implementation, oversight, and accountability. . 

Climate change, health, and California’s Indian Nations
Shasta Gaughen, Ph.D., Pala Band of Mission Indians  

• California Tribes are disproportionately impacted by climate change. Temperature extremes, wildfire, increased storm and flooding, and drought impact the environment of tribal communities as well as a tribe’s spiritual and cultural health. 

• Tribal health includes physical impacts, physiological impacts, socioeconomic impacts, and spiritual and cultural impacts.  

• Environment and culture are intrinsically connected. Climate impacts on the environment directly affect the cultural identity and well-being of tribes. 

Disproportionate impacts of climate change on communities
Amee Raval, Asian Pacific Environmental Network (APEN) 

• Climate change is a “threat multiplier,” worsening existing inequalities in health, housing, land use and economic opportunities. The cascading disasters of wildfires, heat and the pandemic are combining to make it particularly challenging for communities across the state. 

• APEN’s mapping resilience report offers key definitions and principles for vulnerability and resilience from a community perspective. Among its findings is that, despite the many frameworks that exist, there is none that overlays social vulnerabilities with climate threats. The abundance of available data can be overwhelming to decision-makers, who would benefit from a streamlined actionable framework.  

• Quantitative data and mapping need to be integrated with experiential knowledge and stories, using an inclusive and participatory public process that relies on the expertise of community leaders. 

• APEN’s approach to community resilience is unique: it centers on building power in communities to address underlying systemic inequalities that are oppressing working class communities of color – highlighting the idea of social infrastructure as a climate resilience approach. 

Biodiversity Keynote 

Biodiversity Conservation in a Changing Climate
David Ackerly, Ph.D., University of California, Berkeley 

• Biodiversity responds to climate change on multiple time scales, from ice age cycles to the most recent drought. 

• Biodiversity indicators can include both adaptive responses and evidence of negative impacts, and over time they will also incorporate the beneficial effects of investments in climate change mitigation and adaptation. 

• In the face of climate change, conservation efforts need to focus on conserving large and heterogeneous areas, enhancing connectivity across landscapes, and managing for change. 

Session 4: Impacts on California Vegetation and their Connections 

Climate change effects on California desert vegetation
Anne Kelly, Ph.D., California State University Desert Studies Center 

• Extreme weather will drive desert plant and animal mortality.

• Fewer “good years”, invasive species, and fire will hinder recovery.

• Human threats to desert ecosystems are increasing, including energy development and recreation.

Forest fires in California: The role of climate change and management
Scott Stephens, Ph.D., University of California, Berkeley 

• Climate change is impacting forest fires but there are actions we can take today to conserve our forests. 

• There is hope when it comes to fires in California. 

Impacts of climate change on Tribal agroecosystems and cultural foods and fibers in Karuk Aboriginal Territory
Shawn “Shay” Bourque, Karuk Department of Natural Resources, and Daniel Sarna-Wojcicki, Ph.D., University of California, Berkeley 

• The Karuk Tribe is on the frontlines of climate change, not only in terms of ecological and social vulnerability, but also through their leadership in climate change research, monitoring and adaptation initiatives. 

• Climate change stressors related to drought, higher average temperatures, extreme temperature fluctuations, decreased soil moisture and increases in the size, frequency and severity of wildfires are impacting the physiology and phenology of culturally significant food, fiber and medicinal plant species.  Climate impacts on vegetation communities across Karuk Aboriginal Territory influence the ability of cultural practitioners to harvest and process culturally important plants, and thereby maintain place-based cultural practices and uphold ceremonial responsibilities to manage the landscape through generations. 

• Support and collaboration are needed on climate research, monitoring and adaptation, governance and policy, education and sustainable funding for Tribal programs and infrastructure. 

How does climate change impact California agriculture and vice-versa?
Louise Jackson, Ph.D., University of California, Davis 

• California agriculture has a history of dynamic change and innovation, yet climate change brings major challenges especially for agricultural responses that integrate adaptation and greenhouse gas mitigation. 

• Under warmer temperatures and more variable water supply, increases in agrobiodiversity, water resilience and farmland conservation will be important for agricultural sustainability. 

• Suggestions for indicators of agricultural responses to climate change include time courses of priority issues and multivariate approaches to examine factors associated with distribution of commodities or land use change. 

Session 5: Impacts on California Wildlife and their Connections 

Survival by Degrees: Past and future impacts of climate change on birds
Joanna Wu, M.S., National Audubon Society 

• Climate change has already impacted birds in California and across North America in phenology, morphology, distribution, and population size. 

• We modeled potential future species ranges for 604 North American birds under a business as usual emissions trajectory (30 C average global warming), and under a heavy mitigation trajectory (1.50 C global warming) and found the ranges of two-thirds of species are vulnerable at 30 C. 

• In addition, the contiguous United States faces coincident climate-related threats, such as droughts and increased fire weather, whose effects will be stronger with more warming. 

Stability or Collapse: Climate and Land-use Change Impacts on Birds and Mammals in California's Most Transformed Landscapes
Steve Beissinger, Ph.D., University of California, Berkeley 

• Over the past century bird and small mammal species have responded idiosyncratically across California to climate change as a result of differences in pace, direction and exposure to climate change. 

• Over the past century of drying and warming in the Mojave, the bird community collapsed while the small mammal community showed remarkable stability. 

• Climate and land-use change in California sometimes favor or disfavor the same species, and at other times pull species in opposing directions. 

The impacts of climate-driven and anthropogenic pressures on Pacific Coast marine ecosystems
Steven Bograd, Ph.D., National Oceanic and Atmospheric Administration 

• We have experienced significant climate extremes in the California Current System and surrounding areas over the past several years (Marine Heat Waves, Drought, El Niño). 

• These strong climate perturbations have had significant impacts on the structure and function of the California Current ecosystem, and on the ocean-dependent societies. 

• We are developing frameworks for applying dynamic and ecosystem-based management within a changing climate. 

Climate change impacts on freshwater species
Jeanette Howard, Ph.D., The Nature Conservancy 

• There is not a lot of information on how climate change is impacting freshwater species, in fact there is not a lot of information on California’s freshwater species in general. There is a lack of monitoring in our freshwater systems for species, water availability and water use. 

• The reality of climate change in the freshwater world is that it is not a perpetual land of scarcity – but one of variability. Climate forecasts show increases in scarcity during dry times and increases in winter storms in wet times. There will be more of both – more droughts and more floods. 

• Going out on a limb here - how we manage water resources has a bigger impact on freshwater species than climate change. Our inability to adapt will be far worse than temperature and precipitation changes associated with climate change. 

Closing Keynote 

Climate change: Finding the accelerator pedal
Christopher Field, Ph.D., Stanford Woods Institute for the Environment 

• Stabilizing warming at “well below 2°C above pre-industrial” requires exceedingly optimistic assumptions about global-scale commitments to decarbonization, carbon dioxide removal, and reductions in the emissions of non-CO2 greenhouse gases.  Stabilizing warming at around 2°C above pre-industrial also requires optimistic assumptions, but these are feasible if climate action accelerates rapidly in the next few years.  

• A family of core technologies for rapid decarbonization is affordable now and can shoulder the load for near-term acceleration.  But at the same time, we need increased investments in R&D for key technologies, including long-term storage, grid integration, and direct air capture, so that these technologies are affordable when they are needed.  

• At this point, technology is not the most important limit to progress on solving the climate crisis.  The three most important limits are (1) developing comprehensive national and global-scale plans for climate change adaption, (2) realigning government and economic policy to prioritize climate action, and (3) addressing the critically important issues related to climate justice, including the prospects for those harmed by the economics of decarbonization and the necessity of large-scale international cooperation, especially between rich and poor countries.  

Synthesis 

• Climate change is measurable, manifesting on different space and time scales over air, land, and the oceans. By investigating the regional and seasonal granularity of climate changes and looking across a range of observations, California’s efforts to advance climate science are critical in identifying what is robust and physically interpretable.  

• California is susceptible to weather and climate extremes. These are occurring across time scales – from seconds to years – leading to impacts at local, regional, state and continental scales. What used to be extremes are now the norm. We need to measure and track both variability and the rate or “velocity” of change.  

• Indicators that track change on an annual basis do not provide the temporal resolution for investigating the impacts of the change on physical or biological systems. Seasonal, monthly, or even daily or hourly information are needed, for example to understand how warming spring temperatures are affecting species migration.  

• Climate extremes, including marine heat waves and drought, are having significant impacts on the structure and function of the California Current ecosystem and on ocean-dependent marine and human communities. 

• Over the past century bird and small mammal species have responded idiosyncratically to climate change across California. Biodiversity indicators represent not only negative impacts, but also adaptive responses. Our conservation and management actions should recognize this diversity and not use a “one size fits all” approach. 

• Climate change is a “threat multiplier,” worsening existing inequalities in health and well-being among vulnerable farmworkers, urban-poor and other disadvantaged communities. California tribes are uniquely impacted because their physical, spiritual and cultural health are so intertwined with their environment.  

• Climate change indicators should capture and characterize the resilience of human and ecological communities, and the buffering capacities in certain systems.  

• There's still a lot more that we need to understand about very complex natural systems and even more complex social systems. There was a call to work across disciplines and problem solve and leverage each other's research and advance the science.  

• Climate change is not just a science problem – it's also about human values: the preservation of wilderness, glaciers, plant and animal species, and the rich cultural heritage of Native Americans that are all threatened by climate change, as well as the protection of the health and well-being of all communities. Scientists need to distill complex scientific information into plain English so people can understand why it should matter to them. Stories about shared experiences of climate change in our backyard can be a tool for connecting people with what science knows about climate change. This communication should be directed towards communities we have not been particularly successful in reaching.  

• CalEPA’s climate change indicators are important from a management perspective. In order to respond effectively one needs to understand how climate change and its impacts are evolving.  

• The report can be an effective tool for connecting people with science, presenting evidence that climate change is a crisis, and underscoring the need for urgent action.