Global mean sea level
How much could sea level increase until 2100?
To answer this question for the global mean sea level (GMSL), we extrapolate the current sea level rise to 2100, assuming a linear and an accelerated future rise. This allows to estimate if and to what extent the actual sea level rise is consistent with the sea level projections of IPCC [2019].
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- If GMSL continues to rise like in the last 100 years, it would increase about 20 cm by 2100 based on the linear extrapolation.
- Assuming a quadratic extrapolation, it could incease about 36 cm by 2100.
- According to IPCC [2019], GMSL in 2100 is projected to be 43 cm (29-59 cm) under RCP2.6 and 84 cm (61-110 cm) under RCP8.5.
- Compared to the projections of GMSL in 2100 [IPCC, 2019], the linear extrapolation of the last 100-year sea level rise of GMSL is below the projected range of RCP2.6.
- The quadratic extrapolation of the last 100-year sea level rise of GMSL is within the lower half of the projected range of RCP2.6. Note: A high uncertainty range of the quadratic fit (large green area) indicates that it is currently not the best fit.

- According to the quadratic fit, there is a positive acceleration of sea level rise in the last 100 years.
- The last 23 consecutive overlapping 100-year periods show accelerating rates of sea level rise.
- In the last 22 consecutive overlapping 100-year periods, each acceleration was higher than in the previous period. *Note: Due to changing availablities of GMSL data, inhomogeneities in the arithmetic mean can not be excluded.