Sea level projections refer to estimates of future sea level rise based on models and scenarios that take into account a range of factors that contribute to sea level change. These projections are important for planning and decision-making in coastal communities and for identifying areas that are most vulnerable to the impacts of sea level rise.

Sea level projections are typically based on a combination of observations of past sea level trends and computer models that simulate the behavior of the Earth’s climate system. These models take into account a range of factors that contribute to sea level rise, including thermal expansion of the ocean, melting of glaciers and ice caps, and melting of the Greenland and Antarctic ice sheets.

Sea level projections are typically presented in ranges, reflecting the uncertainty in the underlying models and assumptions. The Intergovernmental Panel on Climate Change (IPCC), which is the leading international body for assessing the science related to climate change, has published a range of sea level projections for different scenarios of future greenhouse gas emissions.

For example, under a low emissions scenario in which global temperatures are limited to 2 degrees Celsius above preindustrial levels, the IPCC projects that global sea level will rise by between 0.26 and 0.55 meters (0.85 to 1.8 feet) by the end of the 21st century. However, under a high emissions scenario in which greenhouse gas emissions continue to increase rapidly, the IPCC projects that global sea level could rise by between 0.61 and 1.1 meters (2 to 3.6 feet) by the end of the century.

It’s important to note that sea level projections are subject to uncertainty and that the actual amount of sea level rise could be higher or lower than projected. Factors such as changes in ocean circulation and melting of ice sheets that are not well understood or included in models could cause sea level rise to be higher than projected.

Sea level projections are an important tool for planning and decision-making in coastal communities. By understanding the range of possible sea level scenarios, policymakers and communities can develop adaptation strategies to protect critical infrastructure and vulnerable populations, and to mitigate the impacts of sea level rise on natural systems and ecosystems.

Sea level projections are based on a variety of factors that are used to estimate how much sea level is likely to rise in the future. These factors include:

  • Thermal expansion: As the ocean absorbs more heat due to global warming, the water expands and causes sea level to rise.
  • Melting of glaciers and ice caps: Glaciers and ice caps are melting at an accelerating rate due to rising temperatures, which is contributing to sea level rise.
  • Melting of the Greenland ice sheet: The Greenland ice sheet is currently losing mass at an accelerating rate due to rising temperatures, which is contributing to sea level rise.
  • Melting of the Antarctic ice sheet: The Antarctic ice sheet is currently losing mass, primarily due to melting at the base of ice shelves, which is contributing to sea level rise.
  • Changes in land use: Land use changes, such as urbanization and deforestation, can alter water runoff and affect sea level by changing the amount of water that enters the ocean.

Sea level projections can vary widely depending on the assumptions and scenarios used in the models. Some models may include more conservative assumptions about future emissions, while others may include more extreme assumptions. In addition, some models may not account for certain feedback loops or tipping points, such as the possibility of rapid ice sheet collapse, which could lead to even higher levels of sea level rise.

Despite the uncertainty in sea level projections, it is clear that sea level is rising and that the rate of sea level rise is increasing. This presents significant challenges for coastal communities, which are already experiencing increased flooding and erosion due to sea level rise. It is important for policymakers and communities to use sea level projections as a tool for planning and decision-making, and to take proactive measures to adapt to and mitigate the impacts of sea level rise.