California is one of 36 global biodiversity hotspots for conservation, because of both its remarkable biodiversity and the significant threat of losing habitats and wildlife species unique to California. Climate change is one of the biggest threats to conserving the rich biodiversity found in this state; furthermore, current and projected impacts in some locations are further exacerbated by the negative impacts of past land use changes and various infrastructure and associated operations. For additional background information and discussion of climate impacts and vulnerabilities of the Biodiversity and Habitat sector, visit the Background & Climate Impacts information excerpted from the Adaptation Planning Guide and explore the Topic search below.

California ecosystems also provide a means to mitigate climate change via natural sequestration of carbon. In this area, adaptation and mitigation efforts are intertwined, and many activities to build habitat and species resilience will also support the reduction of greenhouse gases. Example adaptation strategies are provided on the Adaptation Strategies page and can be found in many of the resources available by search below.

What Is Biodiversity?

Biodiversity is a measure of the number of different species in an area. Areas with a large mix of species, such as a tropical rainforests or coral reefs, have high biodiversity. Areas with only a few species, such as a large farm field with only a single crop growing, have low biodiversity.

What Is a Biodiversity Hotspot?

A biodiversity hotspot is a small area of Earth’s surface that is home to many endemic plants and animals (species that do not live anywhere else). Biodiversity hotspots cover only about 2 percent of the Earth’s surface, but collectively, these areas are home to about half of all endemic plant species and 35 to 43 percent of all endemic mammals, birds, reptiles, and amphibians.

Defining the Sector

California is one of the world’s biodiversity hotspots and has the greatest number of native and endemic plant species of any US state.4 The state’s unique mix of habitats include the Joshua trees of the high desert, the redwood forests of the Northern California coast, the salt marshes of the San Francisco Bay Area, the annual grasslands ringing the Central Valley, and the bitterbrush sage ecosystems of the Basin and Range region, among many others. For example, the CALVEG vegetation classification system recognizes over 200 different types of ecological groups in the state, not including agriculture, oceanic ecosystems, or urban areas.5 However, climate change threatens California’s habitats and their high level of biodiversity by creating temperature and precipitation changes that may no longer support these ecosystems.

California’s habitats and the biodiversity they support are critical for several reasons. Protecting natural systems is a core value for many Californians, and the health of the natural environment is a major contributor to community well-being. Preserving the state’s biodiversity is often a climate justice issue because these ecosystems are a cultural resource for some communities, including many tribal communities. Many of these ecosystems are iconic symbols of California that attract large numbers of visitors every year, helping to support local economies throughout the state. Productive natural ecosystems provide beneficial services such as sequestering carbon in soil and plant matter, improving water quality, supporting recharge of the state’s groundwater basins, and buffering developed areas from floods and storm surge. These ecosystems are also home to animals that provide important benefits, such as pollinating agricultural crops or controlling the number of pests or disease-carrying organisms.

This sector focuses on terrestrial and freshwater biodiversity and habitat. Saltwater ecosystems, including coastal and open ocean habitats, are discussed in the Ocean and Coast section of this guide. This section includes discussion of forestry ecosystems, although additional discussion of forestry ecosystems and related issues are in the Forests section of this guide. Discussion of the recreation issues associated with natural lands is in the Parks and Recreation section of this guide.

Major Vulnerabilities

Ecosystems are suited to specific temperature and precipitation conditions. Climate change threatens to alter these conditions outside of their optimal range in some places, forcing these natural communities to migrate to maintain their ideal conditions. Depending on future climate conditions, between 21 and 56 percent of California’s natural areas will be marginal or unsuitable for their current ecosystems by 2100.6 Some specific ecosystems may lose much more of their suitable range. For example, up to 69 percent of pinyon-juniper woodland, 81 percent of Pacific Northwest conifer forest, and 97 percent of freshwater marsh area may no longer be suitable for these habitats by the end of the century.7 The Sierra Nevada foothills, the desert areas, and the south coast are expected to be most affected by ecosystem loss due to climate change.8

Even if an ecosystem can remain in its existing area or shift easily to a new area, climate change can still create hazardous conditions for biological communities. Areas that are susceptible to wildland fires, including forests, shrublands, and chaparral areas, are expected to face more frequent and intense fires. Although fire is a regular feature of these ecosystems and many species have adapted to it, changes to the fire regime may exceed optimal conditions for these biological communities. If fires become frequent and/or intense enough to prevent ecosystems from effectively recovering, the existing ecosystem may be replaced by another. Extreme heat and drought conditions may also damage habitat areas and cause an ecosystem transition.

More subtle changes can also harm California’s biodiversity and habitat. For example, many plant and animal species have evolved together to meet each other’s needs, such as plants flowering at the same time that butterflies emerge from their chrysalises. In this instance, the flowers provide food for the butterflies in exchange for pollination. Shifts in temperature and precipitation patterns may alter the timing of these events, potentially throwing their life cycles out of sync. Changes in life cycles or other behaviors caused by climate change can lead to a long-term decline in the species. If the species involved is a keystone species (a species that many others in an ecosystem depend on, and whose removal would cause a significant change to the ecosystem), the overall habitat may decline.

Climate change may threaten the biological integrity of ecosystems by promoting pests and diseases that attack native species. Warmer temperatures during a wider portion of the year can encourage the spread of these organisms and pathogens, especially during wet years. Stresses from other climate-related effects can also make species more susceptible to pest and disease infestations. For example, stresses from the 2012–2017 drought and warm temperatures weakened trees throughout the Sierra Nevada foothills and left them more susceptible to bark beetles. The warm temperatures also created a larger bark beetle population than normal, because cold winters normally control the beetle’s numbers.

Although protecting these ecosystems for their own sake is important enough, it is also important to remember that harm to biodiversity and habitat has a significant effect on California’s human population. Damage to an ecosystem that is a major tourist attraction can lead to a decline in visitors, causing economic harm to nearby communities. Ecosystem services such as flood protection could decrease or disappear if the ecosystems providing these benefits are harmed, exposing people, buildings, and infrastructure to the risk of serious harm. If ecosystems provide important natural resources to communities, including drinking water, damage to the ecosystem can decrease the availability or quality of this resource, in turn affecting all those who depend on it. Ecosystems can also serve as cultural resources for some populations, creating a risk of damage to cultural heritage if the natural communities are damaged.

Appendix C presents examples of ways that communities can support more resilient natural habitats and biodiversity as part of an adaptation planning effort. These strategies are generalized approaches that can be tailored to the specific natural systems in a community.

Levels of Implementation for Ecosystem Adaptation

When developing adaptation strategies related to natural systems, it can be helpful to think of implementing each strategy at four levels. Each successive level requires more human intervention in the natural system and potentially a greater commitment of resources. As climate change–related effects become more harmful and as ecosystems experience more severe impacts, greater implementation levels may be needed. This approach is helpful to explore the full range of potential implementation actions associated with an adaptation strategy, recognizing that some implementation actions may fall into multiple levels.

  • Resistance. Attempt to make the ecosystem more impervious to climate change, so that the overall degree of potential impacts is reduced and current conditions in the biological community are maintained.
  • Resilience. Manage the ecosystem so that it can “absorb” the effects of climate change and more easily recover from damage, accepting that some short-term disturbance of the habitat is likely.
  • Response. Through management efforts, help transition selected elements of the ecosystem to a new condition to avoid or reduce the most harmful effects.
  • Realignment. Accept that substantial ecosystem disturbance is likely and allow the biological community to transition to a “new normal” that includes a substantially altered but healthy natural system.9
Climate hazards Adaptation Strategy Factors to Consider Category Sector overlap Responsible Agencies Funding Examples & Sources
Biodiversity and Habitat Sector
All climate hazards Strategy BH-1: Improve interagency cooperation on ecological conservation efforts. Ecological communities very often cross jurisdictional boundaries, and many protected natural areas are under state or federal jurisdiction. Protecting and improving habitat resiliency for the parts of an ecosystem only within one community will likely not achieve the hoped-for degree of adaptation benefits. Instead, communities should coordinate with each other, with appropriate state and federal agencies, and with other relevant stakeholders on biodiversity and habitat protection to develop and implement a comprehensive resilience strategy. These efforts should take advantage of the resources and opportunities available to each stakeholder, including regulatory authority, access to funding sources, and staff time and institutional knowledge. Depending on the agencies involved, building cooperation and developing a comprehensive adaptation approach for ecological conservation can vary widely in the level of complexity. Any existing agreements or memoranda of understanding (MOUs) between agencies can be a good place to start. When deciding which agencies should be involved, consider those that own or regulate both current and future suitable land for local biological communities, as well as agencies that have regulatory authority over wildlife (such as the California Department of Fish and Wildlife, or the US Fish and Wildlife Service) even if they do not have land use control in the area. Education, Outreach, Coordination Forests Ocean and Coast Land Use and Community Development Water Parks and Recreation Cities and Counties Council or Association of Governments State and federal agencies Community-based organizations General Fund Habitat Conservation Fund grant Department of Fish and Wildlife grants Department of Water Resources grant Wildlife Conservation Board grant ESA Nontraditional Section 6 grant National Fish and Wildlife Foundation grants Other grant programs Integrated Regional Conservation and Development (ICARD) program, and RePlan System
All climate hazards Strategy BH-2: Restore and conserve land identified as newly suitable for habitats and species of concern, as well as corridors between current habitat and future newly suitable lands. One of the primary climate vulnerabilities for biodiversity and habitats in California is the anticipated shifts in the areas that are suitable for these ecological communities. To protect these habitats, jurisdictions should conserve as natural lands the areas that become newly suitable for shifting ecosystems. They should also conserve the corridors between the current and future suitable areas, so that the ecosystem has the space to migrate naturally. These actions enhance the overall connectivity of California’s natural systems, removing barriers to species movement and helping to limit habitat fragmentation. As a part of this strategy, identify land in the newly suitable area that may be degraded, but is appropriate for ecological restoration. Sync the timeline for restoration so that communities can complete these activities in time for the area to act as a suitable “receiving site” for migrating biological communities. Ensure that the land being protected is suitable in the long term for the habitats and species of concern. Be aware that, in mountainous terrain, climate conditions can vary widely over a relatively short horizontal distance, and so ecosystems may be able to migrate to newly suitable land that is only a short distance away. However, in flatter areas and other locations that have similar climate conditions over a large region, habitats may need to migrate a greater distance to stay viable. Multijurisdictional and interagency cooperation is critical to the success of this strategy. Consider how to adapt or expand existing habitat protection efforts, such as conservation easements, to meet the needs of this strategy. Ensure that riparian corridors and other water bodies are protected, as well as terrestrial habitats. Once habitats begin to migrate, monitor the state of the migration, and be prepared to protect additional lands as needed to ensure continued protection of the area’s biodiversity. Plans, Regulations, and Policy Development Evaluation Forests Ocean and Coast Land Use and Community Development Water Parks and Recreation Agriculture Cities and Counties Council or Association of Governments State and federal agencies General Fund Habitat Conservation Fund grant Department of Fish and Wildlife grants Department of Water Resources grant Wildlife Conservation Board gran ESA Nontraditional Section 6 grant National Fish and Wildlife Foundation grants Other grant programs Integrated Regional Conservation and Development (ICARD) program, and RePlan System
All climate hazards Strategy BH-3: Restore degraded ecosystems to enhance the natural adaptive capacity of biological communities. Healthy ecosystems are better able to resist the pressures of climate change and other stressors than damaged ones. Even if an ecosystem type is generally resilient to climate change, it may face higher-than-expected harm if it has been damaged. Restoring these degraded ecosystems back to their natural state helps to better prepare them for climate change. Such ecosystems often have higher biodiversity, improving overall ecosystem health and reducing the odds that invasive or other non-native species will replace them. Restoring degraded ecosystems also allows them to support other biodiversity and habitat-related adaptation efforts, or to provide additional ecosystem services that benefit surrounding communities. Ensure that degraded ecosystems are restored to a “climate-smart” condition that allows for a healthy and functioning biological community both now and in the future, rather than a “business as usual” ecosystem that may have been appropriate in past years but is not adapted to expected future conditions. The species and specific breeds or strains of organisms re-introduced to degraded areas should be appropriate for the current ecosystem and demonstrate a moderate or high level of climate change resilience, to the extent possible. Communities should also practice climate-smart restoration should also be practiced in non-organic restoration activities, such as corrections to the area’s hydrology. Conduct regular monitoring of the site once the primary restoration is complete, especially as climate stressors appear or become greater, and adjust future restoration and management practices as needed. Plans, Regulations, and Policy Development Programmatic Evaluation Forests Ocean and Coast Land Use and Community Development Water Parks and Recreation Agriculture Cities and Counties Council or Association of Governments State and federal agencies General Fund Habitat Conservation Fund grant Department of Fish and Wildlife grants Department of Water Resources grant Wildlife Conservation Board grant ESA Nontraditional Section 6 grant National Fish and Wildlife Foundation grants Other grant programs Integrated Regional Conservation and Development (ICARD) program, and RePlan System Save the Bay Restored Wetlands
All climate hazards Strategy BH-4: Educate community members about the climate risks to habitats and biodiversity, and the need to safeguard these natural systems. Protecting nature is an important value for many Californians, but it is still helpful to reinforce the importance of natural systems, particularly as climate change stressors require a greater allocation of government resources toward conservation activities. In partnership with community-based organizations and landowners, jurisdictions should educate community members of all ages about why it is necessary to safeguard species and natural resources in their area. These educational and outreach efforts can often be integrated into existing programs, which can make them easier to implement. Consider what types of education programs could be most effective in the community. This can include interpretive signage and in-person educational events at natural sites, online resources and information on social media, outreach to community groups and stakeholders, volunteer opportunities, more intensive efforts such as after-school and summer camp programs, and any other strategies that may be relevant. Multiple forms of outreach could likely be helpful. Ensure that educational programs are widely accessible to the community, including persons with different income levels and access to resources, who speak different languages, and who have differing levels of ability. Ensure that educational efforts reflect the most recent and best available science, which may require revisions to outreach approaches as scientific understanding evolves. Communities should also ensure that educational efforts are universally accessible, including to people with access and functional needs. Education, Outreach, Coordination Programmatic Public Health Parks and Recreation Cities and counties Community-based organizations General Fund EPA Environmental Education grants Other grant programs
All climate hazards Strategy BH-5: Promote diverse economic opportunities that are responsive to changes in available natural resources. The economies of communities often rely at least in part on local natural ecosystems as a source of economically important resources, a site for cultural and recreational activities, and as a scenic benefit, among others. Damage to these ecosystems may lead to economic harm for the community, causing a host of indirect effects. Communities should expand their economic activities to use resources that are less vulnerable to climate change, and resources that may shift into the area as ecosystems migrate. This economic diversification can also help to buffer the community against other types of economic hardships. Economic development plan or program that can serve as an overarching implementation mechanism for this strategy. In some cases, adapting to future ecosystem conditions may be a relatively easy process for businesses, requiring little government involvement other than education and outreach. In other cases, communities may need to extensively alter their land use plans and zoning codes to allow for new types of activities, or activities in new locations. If changes to the natural environment are likely to lead to economic opportunities requiring different job skills than those currently held by community members, jurisdictions and their economic partners should enact appropriate job training programs and other workforce development efforts. Such programs should emphasize empowering and retraining economically disadvantaged persons and those whose jobs face the greatest risk from climate change. Education, Outreach, Coordination Programmatic Evaluation Plans, Regulations, and Policy Development Land Use and Community Development Parks and Recreation Forests Ocean and Coast Cities and counties Community-based organizations General Fund Workforce development grants Other grant programs
All climate hazards Strategy BH-6: Use nature-based solutions to improve resilience while promoting biodiversity. Many infrastructure and other capital projects to improve community resilience involve “hard” structures, which are often made out of materials such as concrete and metal and are very clearly built by people. While sometimes effective, these artificial structures can interrupt natural activities and may be actively harmful to the ecosystem. Nature-based solutions, sometimes called “green infrastructure,” rely on natural materials and systems to increase resilience. These strategies can offer the same or greater adaptation benefits to the community at large while also providing habitat to local flora and fauna. Nature-based solutions can be implemented at multiple scales. For example, a rain garden or bioswale near a parking lot can provide protection against floods, as can a restored wetland or dune system. If constructing multiple small-scale green infrastructure projects, consider connecting them to create a habitat corridor, further enhancing local biodiversity and the health of regional ecosystems. Be aware of the types of ecosystems that are naturally present in the community and would best support endemic species and consider developing nature-based solutions to restore and enhance degraded habitats. As with all other types of adaptation infrastructure, nature-based solutions should be designed to protect against hazards caused by both current and future climate conditions. Consider using habitat types that are still viable in the future climate of the area. Plans, Regulations, and Policy Development Capital Improvement & Infrastructure Projects Land Use and Community Development Parks and Recreation Forests Ocean and Coast Water Cities and counties Council or Association of Governments General Fund Habitat Conservation Fund grant Department of Fish and Wildlife grants Department of Water Resources grant Wildlife Conservation Board grant National Fish and Wildlife Foundation grants Other grant programs Guidance for Considering the Use of Living Shorelines, Living Shorelines: From Barriers to Opportunities

Featured State Resources

All Resources for Biodiversity And Habitat