Under the conditions of global warming sea levels globally are expected to rise considerably this century. The sea levels will rise largely due to expanding water due to elevated ocean temperatures and from melting ice, especially ice sheets. Now a recent study published in the journal Nature and conducted by a number of climate organizations globally indicated bad news on the rising seas front.
The organizations involved in the study were the National Center for Atmospheric Research and Climate Central, both in the U.S., and the Centre for Australian Weather and Climate Research. The study results indicate that even massive reductions by nations globally will not stop rising sea levels around the world. However, the study did indicate that the level of rise can be reduced and slowed due to emission reductions.
Currently nations have targeted 2 degrees Celsius as the maximum warming allowable since the Industrial Revolution to mitigate the effects of climate change. The world is gradually approaching this figure, a figure which many see as an inevitable tipping point, especially as nations continue to bicker instead of producing major emission agreements.
Due to the warming world, approximately 2.3 millimeters of sea level rise per year has occurred in recent years. However, this rise is minimal compared to figures the organizations have detailed in their study for the years 2100 through 2300. If limited changes are made to global emissions, the study indicated a likely rise of 3.91 degrees Celsius by the year 2100. Under such conditions, they indicate we could expect to see an increase of at least 32.3 centimeters (12.7 inches) by 2100. By 2300, the world would have seas that have risen by 139.4 centimeters (52.9 inches).
As for greatly reducing emissions, the world would still experience rising seas but not at the speed or to the degree indicated above. Life along coastlines would be altered but not destroyed, unlike the worst case scenarios of many climate studies. The greatest emission reductions according to the study would effectively bring the temperature down to 0.83 degrees Celsius by 2100. This would still result in a sea level rise of 14.3 centimeters (5.6 inches) by 2100. However, temperatures would decline further by 2300 and be at 0.55 degrees Celsius. This decrease limit’s the rise by 2300 to only an estimated 24.2 centimeters (9.5 inches).
The published study indicated: “Though sea-level rise cannot be stopped for at least the next several hundred years, with aggressive mitigation it can be slowed down, and this would buy time for adaptation measures to be adopted.”
The reason for the continued sea rise even with cooling temperatures is due to the expansion of water at warmer temperatures. Even if emissions are reduced significantly, this would not automatically alleviate ocean warmth. Oceans take a considerable amount of time to warm up and they need a considerable amount of time to cool as well. The surface of the oceans, however, would likely cool in these scenarios but deeper ocean waters which have warmed and continue to warm today will take significantly longer to cool. These deeper warm pockets of water will also be circulated by currents around the globe further solidifying rising seas globally.