The graph below is derived from coastal tide and satellite data. It shows how much sea level changed from about 1870 to 2018. Items with pluses (+) are factors that cause global mean sea level to increase, while minuses (-) are variables that cause sea levels to decrease. These items are displayed at the time they were affecting sea level. According to the graph, melting ice sheets and glaciers combined with thermal expansion as factors increasing sea level rise. What additional variable may have caused the rate of sea level rise between 2000 and 2020?

- More global dams
- Refreezing Arctic
- Ocean circulation
- Cooler Antarctic