Sea level rise

What Is Sea Level Rise?

Sea level rise refers to the increase in the average global sea level over time, a critical component within the broader field of environmental economics. This phenomenon is primarily driven by two factors related to global warming: the thermal expansion of seawater as it warms, and the added water from melting glaciers and ice sheets¹⁸, ¹⁹. The ongoing increase in sea level presents a significant environmental risk with profound economic impact, affecting coastal communities, infrastructure, and financial markets worldwide. Understanding sea level rise is essential for assessing physical risk and informing long-term strategic decisions across various sectors.

History and Origin

The scientific observation and understanding of global sea level rise have evolved significantly, particularly with advancements in satellite altimetry. While tide gauge records have provided historical data for over a century, continuous satellite measurements began in 1993, offering a more precise and comprehensive view of global sea level changes¹⁷. Since 1880, the global mean sea level has risen approximately 8–9 inches (21–24 centimeters). Th¹⁶e rate of sea level rise has not been constant; it has accelerated over time, more than doubling from an average of 1.4 millimeters per year throughout most of the 20th century to 3.6 millimeters per year from 2006–2015. Rece¹⁵nt data indicates this acceleration is continuing, with 2023 setting a new record high for global average sea level. The ¹⁴Intergovernmental Panel on Climate Change (IPCC), a leading international body for assessing climate change, consolidates scientific findings on this topic in its comprehensive assessment reports, with the Sixth Assessment Report (AR6) providing updated projections and insights into the physical science basis of climate change, including detailed analysis of sea level rise.

¹², ¹³Key Takeaways

• Sea level rise is driven by thermal expansion of warming oceans and melting land-based ice (glaciers and ice sheets).
• Global mean sea level has been rising at an accelerating rate, with significant increases observed since the late 20th century.
• The phenomenon poses substantial risks to coastal communities, infrastructure, and ecosystems, leading to increased flooding and erosion.
• Financial implications include impacts on real estate, insurance, trade, and the potential for large-scale displacement and economic disruption.
• Addressing sea level rise requires adaptation strategies and investment in resilient infrastructure, alongside global efforts to mitigate greenhouse gas emissions.

Interpreting Sea Level Rise

Interpreting sea level rise involves understanding both global averages and regional variations. While satellite data provides a global mean sea level, local sea level changes can differ significantly due to factors such as land subsidence or uplift, ocean currents, and Earth's gravitational changes. For ¹¹instance, some U.S. coastlines experience rates of sea level rise greater than the global average. For ¹⁰financial professionals and policymakers, interpreting sea level rise data is crucial for asset valuation and long-term planning, especially for investments in real estate and urban development in coastal zones. Projections from scientific bodies like the IPCC and NOAA are regularly updated, providing scenarios for future sea level rise under different emissions pathways, which are vital for risk assessment.

⁸, ⁹Hypothetical Example

Consider a hypothetical coastal city, "Oceantown," that relies heavily on its beachfront properties and port for its economy. Current data indicates a historical sea level rise of 0.12 inches per year, but projections suggest an accelerating rate, potentially reaching 1 foot of rise by 2050. Property developers in Oceantown, engaged in coastal development, would need to integrate these projections into their feasibility studies and designs. For example, a new condominium project might need to raise its ground floor elevation or incorporate enhanced flood barriers. An existing residential area might face increased "nuisance flooding" during high tides, affecting property values and requiring homeowners to consider floodproofing measures or even relocation. Local government might assess the viability of maintaining current infrastructure investment in seawalls versus managed retreat strategies, weighing the long-term economic costs against potential future damages.

Practical Applications

The implications of sea level rise extend across numerous financial and economic sectors:

• Real Estate and Property Insurance: Rising sea levels directly impact the value and insurability of real estate in coastal areas. Insurance premiums are likely to increase, and some properties may become uninsurable, leading to declines in asset valuation and potential shifts in population.
• ⁷Infrastructure Planning: Governments and private entities must consider sea level rise in planning and funding [infrastructure investment], such as transportation networks, wastewater treatment plants, and energy facilities in low-lying areas. This involves assessing [physical risk] and allocating capital for adaptation measures or relocation.
• Supply Chain and Trade: Port cities are critical hubs for global trade. Increased flooding and storm surges due to sea level rise can lead to [supply chain disruption], impacting import/export activities and global commerce.
• Government Finance: Coastal municipalities and states may face significant fiscal burdens due to the need for costly protective measures, emergency response, and potential loss of tax revenue from devalued properties. This can affect the creditworthiness of [government bonds].
• Investment and Capital Markets: Investors are increasingly incorporating [transition risk] and physical climate risks, including sea level rise, into their investment analysis. This influences capital allocation towards more resilient assets and regions, or away from vulnerable ones. The World Bank Group, for instance, actively supports developing countries in building resilience to climate change impacts, including sea level rise, by integrating climate risks into development work and providing financing for adaptation strategies. This⁵, ⁶ often involves substantial [adaptation finance] to help communities prepare for future changes.

Limitations and Criticisms

While the scientific consensus on sea level rise is robust, its projection and precise local impacts carry inherent uncertainties. Critics and stakeholders sometimes highlight the challenges in accurately forecasting future rates, especially concerning the unpredictable dynamics of large ice sheet melt. These uncertainties can complicate long-term [financial planning] and investment decisions, leading to debates over the appropriate scale and urgency of responses. For example, the wide range in projections for future sea level rise, dependent on various greenhouse gas emissions scenarios, can make precise [asset valuation] difficult for properties with very long lifespans.

Ano⁴ther limitation lies in the economic models used to estimate the total [economic impact]. These models often struggle to fully account for complex social and ecological feedback loops, the costs of large-scale displacement, or the cascading effects of [supply chain disruption] on broader economies. There can also be critiques regarding the equitable distribution of costs and benefits of adaptation measures. For instance, rising [insurance premiums] may disproportionately affect lower-income communities in vulnerable areas, raising questions about social equity and potential market failures in addressing [environmental risk]. Effective response requires robust data and continuous assessment to refine predictions and strategies.

Sea Level Rise vs. Coastal Erosion

While often discussed together and certainly linked, sea level rise and coastal erosion are distinct phenomena.

The confusion between the two often arises because coastal erosion is a direct and visible consequence of rising waters. However, sea level rise is the overarching phenomenon that sets the stage for intensified erosion, rather than being the erosion itself.

FAQs

How much has sea level risen globally?

Global mean sea level has risen approximately 8–9 inches (21–24 centimeters) since 1880, with about one-third of that rise occurring in the last 25 years. This ong³oing increase has significant implications for [coastal development] and related investments.

What are the main causes of sea level rise?

The two primary causes are the thermal expansion of ocean water as it warms from increased global temperatures, and the melting of land-based ice, such as glaciers and ice sheets. Both are¹, ² consequences of [climate change] driven by human activities.

How does sea level rise affect financial markets?

Sea level rise can impact financial markets by increasing [physical risk] to coastal assets like [real estate], leading to higher [insurance premiums], affecting municipal bond ratings due to infrastructure costs, and potentially disrupting global supply chains through impacts on ports and trade. This necessitates shifts in [financial planning] and investment strategies.

Can sea level rise be stopped?

While past emissions mean some continued sea level rise is inevitable, the rate and ultimate extent of future rise can be significantly reduced by drastically cutting greenhouse gas emissions. Global efforts in [mitigation finance] and [adaptation finance] are crucial to limit future impacts and build resilience.