SLR Causes

Our climate is warming. Mean global temperatures have risen by 2 degrees Fahrenheit since the 1880s and the past five years have been the hottest on record. A hotter climate brings more severe storms, more droughts, more wildfires and higher sea levels.

The primary cause of sea level rise to date has been thermal expansion (as the ocean heats up its expands), but there are other factors at play too.

Key Drivers of Sea-Level Rise

Scientists anticipate that sea levels will rise at an increasing rate in coming decades, as the amount of heat-trapping gases, principally carbon dioxide, in our atmosphere continue to rise and global warming intensifies. Concentrations of CO2 are already 45% higher than pre-industrial levels and rising fast.

The path for sea-level rise in the short term (through to 2050) is more certain than further out. That’s because the ocean and land ice respond slowly to warming so the short-term outlook is largely determined by past emissions. Beyond 2050, the jury is out. The outlook will depend critically on how humans adapt their carbon behavior and the rate of ice melt from the great polar ice sheets covering Greenland and Antarctica.

It is important to stress that the world’s seas are not rising at the same rate. It is relative sea level – the local difference in elevation between the sea surface and land surface – that will determine the risk that communities face from local flooding.

For a scientific read on sea-level rise, please see this document.

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