Coastal Hazards & Climate Change

Sea level rise, tropical cyclones, storm surge, coastal erosion, and adaptation strategies for resilient coastlines

Overview

Coastal zones face intensifying hazards driven by climate change: accelerating sea level rise, more intense tropical cyclones, increased flooding, shoreline erosion, and saltwater intrusion. The Intergovernmental Panel on Climate Change (IPCC) projects global mean sea level rise of 0.28–1.01 m by 2100, depending on emissions scenario (SSP). Low-lying deltas (Bangladesh, Mekong, Nile) and small island states are particularly vulnerable. Adaptation strategies include nature-based solutions (mangrove restoration, living shorelines), engineered defenses (seawalls, storm surge barriers), managed retreat, and early warning systems.

3.7 mm/yr
Current SLR rate (accelerating)
~1 m
Projected SLR by 2100 (high emission)
~1B
People at risk from coastal flooding
$1T+
Annual coastal flood damages by 2050

Key Hazards

Sea Level Rise

Thermal expansion of ocean water and ice sheet/glacier melt drive global SLR. Regional rates vary due to ocean dynamics, land subsidence, and gravitational effects of ice mass loss. Bangladesh faces compound risks where SLR combines with monsoon flooding and land subsidence.

Tropical Cyclones

Warming SSTs are projected to increase the proportion of intense (Category 4–5) cyclones. The Bay of Bengal and western Pacific are particularly at risk. Cyclone Amphan (2020) caused $13 billion in damages across Bangladesh and India.

Storm Surge

Wind-driven water piles against the coast during cyclones, amplified by low pressure. Shallow continental shelves (Bangladesh, Gulf of Mexico) are susceptible to extreme surges. ADCIRC and SLOSH models forecast surge for emergency management.

η_surge ≈ (τ_w × L) / (ρ × g × D) + η_IB

Coastal Erosion

Sea level rise, wave energy, and reduced sediment supply accelerate shoreline retreat. Bruun Rule provides a first-order estimate: 1 cm SLR ≈ 1 m of shoreline retreat on sandy coasts. Remote sensing (Landsat time series) quantifies decadal change.

Saltwater Intrusion

Rising sea levels push the freshwater-saltwater interface landward in coastal aquifers and river systems, threatening drinking water supplies and agriculture. The Ghyben-Herzberg relation estimates the depth of the interface.

Adaptation Strategies

Nature-based solutions (mangroves attenuate 66% of wave energy), hard engineering (seawalls, levees), early warning systems, building codes, land-use planning, and managed retreat form an integrated adaptation portfolio.

Interactive Visualizations

Global Mean Sea Level Rise Projections (IPCC SSP Scenarios)

Tropical Cyclone Intensity Distribution — Historical vs. Projected

Coastal Vulnerability Index Components

Key References

  1. IPCC (2021). AR6 Climate Change 2021: The Physical Science Basis. Chapter 9: Ocean, Cryosphere and Sea Level Change.
  2. Nicholls, R.J. & Cazenave, A. (2010). Sea-level rise and its impact on coastal zones. Science, 328(5985), 1517–1520.
  3. Knutson, T.R. et al. (2020). Tropical cyclones and climate change assessment. Bull. Amer. Meteorol. Soc., 101(3), E303–E322.
  4. Oppenheimer, M. et al. (2019). Sea Level Rise and Implications for Low-Lying Islands, Coasts and Communities. IPCC SROCC.
  5. Mentaschi, L. et al. (2018). Global long-term observations of coastal erosion and accretion. Scientific Reports, 8, 12876.