In some places sea level naturally changes by up to 16.3 metres on a daily basis because of tides [8,11]. It can also fluctuate due to volcanic eruptions and cyclical climate patterns, such as El Nino . However, overlaid on these normal patterns, climate change is causing the average sea level to increase permanently . Over the last 25 years, it has increased by about 7cm .
Moreover, the rate of sea level rise is accelerating, from 2.5mm per year in the 1990s to 3.4mm per year now . With 4°C of temperature rise by 2100 (which is expected if emissions continue to increase ), sea levels are predicted to rise by 1 meter . If we were to hit 5°C, it could even be 2 meters . Due to a time lag in ice melt, this could lead to 7.5m of average sea level rise by 2200 .
2m of sea level rise could cause loss of 1.79 million square km of land, and displacement of perhaps 187 million people . Sea level rise increases the frequency and strength of storm surges, rather than just gradual flooding .
Modelling future sea level rise is really tricky because we lack understanding of parts of the natural system: snowfall, ice melt, the temperature of the ice itself, and how fast ice slides over rock . Plus, scientists also have to take guesses at how much greenhouse gas will be released in coming years .
So, we need be cautious and be prepared for rapid sea level rise by protecting our cities and farmland [1, 9].
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