The average global temperature has been increasing since 1970.** Warmer temperatures cause glaciers and ice sheets to melt faster. As they melt, more water reaches the ocean, which causes the sea level to rise. Researchers working for the Australian Commonwealth Scientific and Industrial Research Organization (CSIRO) collected sea level data using coastal tide gauges from 1880 to 2018. Since 1993, the sea level has risen faster than it did from 1901 to 1990.
In 1880, the Sea level change is 0 because this is the starting measurement used to calculate future change. There is a continual ocean level increase shown by the jagged black line. From 1901 to 1990, the yearly increase was 1.1 to 1.9 mm. From 1993 to 2010, the yearly increase was 2.8 to 3.1 mm. Perhaps the yearly increase from 1993 to 2010 is not significantly different than the yearly increase before 1990. Debating whether 1.9 is different from 2.8 misses the main point of the graph. Sea level rise is accelerating rather than holding steady or going down. Because of global warming, sea levels are higher than they have been for at least 140 years, which is significant and undeniable.
Yearly sea level increase from 1993 to 2010 almost doubled what it was from 1901 to 1990. In 2010, around 40% of the population of the United States lived in counties that lie directly on the coast.*** Rising sea level leads to more frequent flooding, shoreline erosion and ability for storms to move farther inland. If actions are not taken soon to combat global temperature increase, all of these harmful effects could leave millions of people homeless, jobless and forced to move inland.
*NASA. (access 2019, March 18). Sea Level, Vital Signs of the Planet. Retrieved from https://climate.nasa.gov/vital-signs/sea-level/
**Hansen et al., 2010 Reviews of Geophysics
***NOAA. (access 2019, March 21). What percent of the American population lives near the coast? Retrieved from https://oceanservice.noaa.gov/facts/population.html