Rising Sea Levels — Reading Comprehension

Sea level is the average height of the ocean's surface, measured around the world. Over the past 140 years, global sea level has risen about 8 to 9 inches (20 to 23 centimeters), and the pace is getting faster. This change is a clear sign of how Earth's systems are affected by climate. Rising sea levels threaten millions of people, especially those living near coasts, on islands, or in low-lying cities. Scientists study this problem to understand its causes, impacts, and what can be done.

Why Are Sea Levels Rising?
There are two main reasons for rising sea levels. The first is thermal expansion. As the planet warms, ocean water absorbs heat and expands, which means the same amount of water takes up more space. This process has contributed to about half of the observed rise. The second cause is the melting of land ice, like glaciers and ice sheets in places such as Greenland and Antarctica. When this ice melts, the water flows into the ocean, increasing its volume. Scientists use satellites and tide gauges to measure these changes, confirming that the rate of sea level rise is now much faster than it was a century ago.

Impacts on Coastal Areas
Rising sea levels do not affect every place equally. Some regions, like the U.S. Gulf Coast and Southeast Asia, see water rise faster because of local factors. For example, land subsidence—where land sinks due to natural or human causes—can make the problem worse. Ocean currents and wind patterns also influence local sea levels. As seas rise, coastal flooding happens more often, especially during storms or king tides. Saltwater can move into freshwater aquifers, threatening drinking water and crops. Coastal erosion increases, and valuable land is lost. Vulnerable places include low-lying islands like the Maldives and Tuvalu, coastal cities such as Miami and New Orleans, and river deltas in Bangladesh and Vietnam. Already, some communities are relocating as their homes become unsafe.

Looking to the Future
Future sea level rise depends on how much greenhouse gas humans release and how fast ice sheets melt. Projections suggest global sea level could rise by 1 to 8 feet (0.3 to 2.5 meters) by 2100. Even small increases can make storm surges worse and cause more frequent flooding. Scientists use computer models to predict these changes and help governments plan. Adapting to sea level rise may involve building sea walls, restoring wetlands, or moving entire neighborhoods. Understanding the connections between climate, the ocean, and human activities is key to making smart choices for the future.

Rising sea levels highlight how Earth's systems interact and why monitoring environmental changes is essential for protecting people and ecosystems.

Interesting Fact:
About two-thirds of the world's largest cities are located near coasts, putting hundreds of millions of people at risk from rising seas.

How much has global sea level risen since 1880?

What are the two main causes of rising sea levels mentioned in the passage?

Which tool do scientists use to measure changes in sea level?

What does 'thermal expansion' mean as used in the passage?

What is meant by 'land subsidence'?

Why do some areas experience faster sea level rise than others?

If greenhouse gas emissions continue to rise, what could happen by 2100?

Which of the following is NOT listed as a consequence of rising sea levels in the passage?

True or False: Sea level rise affects every coastal area in the same way.

True or False: Most of the world’s largest cities are located near coasts.