UNDERSTAND THE WHY BEHIND THE WATER

Sea level rise isn't random - it's driven by real, measurable changes in our planet. Dive into the science behind rising seas, from melting glaciers to thermal expansion, and see how human activity accelerates it all. The better we understand the causes, the better prepared we are to respond.

How Sea Level Rise Works

Melting Glaciers & Ice Sheets

Polar ice is melting faster than ever due to global warming.
Glaciers in Greenland and Antarctica are adding massive volumes of water to the ocean.

Thermal Expansion

As ocean temperatures rise, water expands.
This accounts for about one-third of observed sea level rise.

Loss of Natural Barriers

Wetlands and mangroves that normally absorb water are disappearing.
Urban development is speeding up this loss.

Land Subsidence

Natural geologic processes and human activities like pumping water out of aquifers can cause land to sink, leading to increased flooding in coastal areas.

Effects of Sea Level Rise

Increased Coastal Flooding

Even minor storms can cause major floods in low-lying areas.
Places like Mission Bay High School already experience flooding during heavy rains.

Erosion of Shorelines

Rising seas wear away beaches, cliffs, and dunes.
San Diego’s coastline is particularly at risk.

Saltwater Intrusion

Saltwater moves into freshwater supplies, damaging ecosystems and water systems.

Habitat Loss

Coastal habitats like wetlands and marshes are vanishing.
Local wildlife is being displaced or dying off.

What’s Causing the Ocean to Rise

Global Warming and Thermal Expansion

As Earth warms, the ocean absorbs most of that excess heat
Warm water expands, taking up more space — a process called thermal expansion
This is responsible for nearly half of observed global sea level rise
(Source: NOAA)

Melting Glaciers and Ice Sheets

Glaciers and ice sheets in places like Greenland and Antarctica are melting faster than ever
The meltwater flows directly into the oceans, increasing sea levels
Greenland is losing hundreds of billions of tons of ice every year
(Source: NASA, IPCC)

Loss of Natural Water Storage

When glaciers and snowpacks melt, long-term water storage on land decreases
That water shifts to the ocean, contributing to rising seas
Groundwater pumping and land use changes also redirect water toward the coast
(Source: USGS)

Why It Matters to Coastal Cities Like San Diego

Higher seas mean higher tides — even on sunny days
Storm surges and king tides cause more flooding than in the past
Erosion threatens homes, roads, and beaches along the coast
Wetlands, estuaries, and freshwater systems are being damaged by saltwater intrusion
Communities near Mission Bay and low-lying areas already see flooding during heavy rains and high tides

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