The global average sea level has risen about 20 centimeters since 1880. This steady climb accelerated dramatically after the 1970s, reaching a rate of 4.62 millimeters per year during the decade from 2013 to 2022.
Thermal expansion accounts for about 42 percent of the rise between 1993 and 2018 while melting ice sheets and glaciers contributed another 44 percent during that same period. Ocean heat content increased by 1.2 degrees Fahrenheit since 1950 contributing more than half of all observed sea level rise.
Under the highest emission scenario SSP5-8.5 sea levels could rise by up to 1.9 meters by 2100. Low-emission pathways might limit growth to between 0.3 and 0.6 meters.
The Bramble Cay melomys became the first known mammal species to go extinct due to rising seas when its habitat was inundated in 2016. It was officially declared extinct in 2019 after living on Bramble Cay islet until it disappeared under water.
Scientists estimate 150 million people will be underwater during high tides by 2050 based on current population distributions. Another 300 million face annual flooding risks with these numbers potentially growing to 410 million and 640 million respectively if emissions remain high by 2100.