The Link to Climate ChangeGlobal Sea Level Rise Is Linked to Climate Change
For over 100 years, humans have burned coal, gas, and oil to produce energy. Burning these fossil fuels releases greenhouse gases into the air. Greenhouse gases warm the Earth, like a blanket wrapped around the globe. Adding more greenhouse gases thickens the blanket and the Earth becomes warmer.
Around 90% of this added heat is being absorbed by the ocean, warming it up. When water warms, it expands and takes up more space. This causes the water to rise along the coastline. Currently, about one third (around 33%) of global sea level rise is because of ocean warming.
The other two thirds (around 66%) of global sea level rise is because of melting land ice. As Earth heats up, it melts the land ice, including the Greenland and Antarctic Ice Sheets and other mountain glaciers. The water then flows into the ocean which raises sea levels.
How Do We Know Sea Level Rise Is Increasing?How Do We Know Sea Levels Are Rising Faster Than They Were Before?
For decades, sea levels have been measured across the world with tide gauges and satellite altimeters. These measurements are combined to calculate the average ocean height across the world, the global sea level, each month or year. Comparing these values over time shows the amount and rate of change of global sea level.
The global sea level has been rising since the 19th century, when modern records began. And, it has been rising faster in recent years. It took 90 years (1902 – 1992) for the global sea level to rise around 10 cm. In just the last 30 years (1993 - 2023), that same amount of rise, around 10 cm, happened again.
When we plot global sea level it is not a straight line, but rather it goes up and down slightly. These movements, known as variability, show natural changes that happen due to a number of different factors. Things like tides can change sea levels over hours or days. Large climate events, like El Niño, can cause changes in sea levels over months or years. However, even though we see wiggles up and down in the global sea level, these natural changes are not large enough to offset the overall rise in global sea level we are seeing from climate change.
Dive Deeper: Learn more about global sea level rise and why it is happening.