COASTAL HAZARDS

Introduction

Topic: Challenge of sea-level rise and extreme events affecting California's coast.Presenter: Gary Griggs, Distinguished Professor of Earth Sciences, University of California, Santa Cruz.

Coastal Populations

  • A significant portion of the global population resides in coastal cities, making them vulnerable to the impacts of rising sea levels and extreme weather events.

  • The implications for towns, cities, and megacities affected by sea-level rise are profound, affecting infrastructure, economic stability, and public health. In particular, cities with high population density face challenges including increased flooding and diminished freshwater resources.

Evidence of Rising Sea Levels

  • Global sea-level rise has become an ongoing threat to coastal communities, changing the dynamics of coastal ecosystems.

  • Observations, such as increasing wave sizes along coastlines (notably observed at locations like West Cliff), exacerbate coastal erosion and flooding, threatening infrastructure and natural habitats.

Sea Level Dynamics

  • Causes: Earth warming, driven by anthropogenic greenhouse gas emissions, and the melting of polar ice caps contribute significantly to rising sea levels.

  • Historical data indicates that melting from Greenland contributes approximately 24 feet to sea-level rise, while mountain glaciers provide around 2 feet, with Antarctica contributing approximately 190 feet—highlighting the critical need for addressing climate change.

Satellite Altimetry and Measurement

  • Satellite measurements, particularly from tools like the Jason satellites launched since 1992, are pivotal in providing scientific data on sea-level rise and its acceleration. Recent annual measurements point to a concerning acceleration trend in sea-level rise that underscores the urgency for timely response strategies.

Climate Change Denial and Misinformation

  • Despite the overwhelming scientific consensus, misinformation regarding the pace and impact of sea-level rise continues to circulate in public discourse.

  • Misleading comparisons between actual rising rates and misleading claims made by political figures illustrate the need for accurate data dissemination and public education regarding the urgency of climate issues.

Coastal Environment Adjustments

  • Natural coastal environments demonstrate resilience and adaptability to historical sea-level fluctuations; for instance, ecosystems such as mangroves, seagrass, and coral reefs play critical roles in coastal stabilization and biodiversity.

  • However, human-made structures and urban areas are often ill-equipped to adapt efficiently, which leads to significant economic losses and social disruption.

Population Exposure

  • Approximately 150 million people globally live within 3 feet of high tide, and in the U.S., about 13 million reside within 6 feet, leading to heightened risks in coastal cities like San Francisco and Oakland from extreme weather events such as hurricane storm surges.

  • These exposures not only threaten lives but also jeopardize local economies heavily reliant on tourism and marine resources.

California's Coastal Issues

  • Key issues faced by California’s coastline include increased erosion rates and coastal retreat affecting cliffs and bluffs, leading to a loss of habitat and property.

  • The risk of temporary flooding escalating into permanent inundation in low-lying areas has raised alarms among local communities and governments, necessitating proactive planning and response measures.

Sea-Level Rise Projections

  • Studies project long-term global sea-level rise trends as well as short-term increases related to significant climate phenomena like El Niño events, predicting potential short-term rises of around 30 cm or ~12 inches.

  • Understanding the importance of these short-term extreme events is crucial, as they can exacerbate existing coastal challenges and put additional stress on already vulnerable regions.

Observations and Data

  • Recent observations of tide levels during extreme weather events provide a wealth of data essential for understanding wave impacts and improving sea-level forecasts, which can inform better mitigation strategies.

Response Options

  • Responses to climate challenges can be categorized into three overarching strategies:

    • Mitigation: Efforts to reduce greenhouse gas emissions through sustainable practices and renewable energy sources.

    • Adaptation: Implementing responsive strategies, such as designing climate-resilient infrastructure and relocating vulnerable communities.

    • Denial: Addressing issues related to climate denialism that obstruct social and governmental progress in combating sea-level rise effectively.

Addressing Coastal Erosion

  • Solutions for coastal erosion, such as beach nourishment, seawall construction, and building living shorelines (nature-based solutions), require careful consideration regarding their environmental impacts and sustainability over time.

  • The costs associated with beach nourishment often raise questions about long-term viability, especially given the projected increases in sea level.

The Future of Coastal Management

  • Current approaches to coastal management must evolve to respond to the realities imposed by rising seas and climate change.

  • Emphasis should be placed on implementing both hard (such as seawalls) and soft (vegetation-based) solutions as part of comprehensive, long-term strategies focused on sustainability and resilience.

Conclusion

  • The inevitability of managing or adapting to rising sea levels necessitates urgent global attention and action.

  • Acknowledging that natural processes will often outweigh engineered solutions necessitates a transformative shift towards proactive climate change actions paired with informed public discourse and engagement in the climate crisis response.