A “powerful” computer model has predicted that sharply reducing global greenhouse gas emissions would stave off rising sea levels by the end of the 21st century, significantly reducing a looming threat to coastal cities the world over.
Thermal expansion of the world’s ocean waters, caused by increasing global temperatures, will account for about 33% of the projected rise in sea levels over the course of the next 60 years as a result of climate change. As sea levels continue to rise, coastal regions around the world face a real possibility of being swamped by the end of the century.
It has largely been an open question in climate change research whether there is still time to take action to stall or delay the harsh consequences foreseen as a result of factors like global warming. As reported on in a news release yesterday from the National Center for Atmospheric Research (NCAR), a recent study offered some cautiously optimistic results that suggest cutting back on greenhouse gas emissions could significantly reduce average global sea level rise by 2080.
Funded by the U.S. Department of Energy and the National Science Foundation, the study was conducted by NCAR researchers Aixue Hu and Susan Bates.
In a statement for NCAR’s AtmosNews, Hu said that, according to their study, “mitigating greenhouse gases will reduce sea level rise later this century, with some regions seeing especially significant benefits.
The study itself involved two separate computer simulations of a climate model of ocean-atmosphere interactions (air, wind and currents) based on publicly available data. The first simulation, called “business as usual”, ran a scenario in which human greenhouse gas emissions continued to increase at their current rate. In this scenario, global temperatures would be approximately 3 degrees Celsius higher by 2080 than they were late last century. In the second simulation, researchers attempted to model a “moderate mitigation” scenario, in which humans would actively cut back on greenhouse gas emissions. From this scenario, it was found that this projected global temperature increase could be kept to just 1.8 degrees Celsius.
From a moderate mitigation of human emissions where average global temperature increases no more than 1.8 degrees Celsisus, average global sea level rise would be reduced by up to 26% by 2061-2080. For certain coastal regions, projected sea level rise could be reduced by up to 50%. Coastal cities around the world, including New York, Boston, London, and Mumbai, would benefit the most, where sea level rise could be reduced by around 6-10 cm by late century.
However, other coastal cities in Asia, Australia, and South America, where ocean-atmospheric interactions are less affected by global warming, would face more or less the same threat of rising sea levels as they do today. Researchers predict that sea levels in the North Atlantic Ocean stand to be influenced the most by reductions in greenhouse gas emissions, whereas sea levels across the Pacific Ocean will be more stubborn to change due.
The NCAR study was published late last week in Nature Communications. Though its results hold promise, its authors emphasize that they do not tell the whole story. About 66% of the projected global sea level rise will be due to melting glaciers and ice sheets, which were not modelled in this study.
Climate researchers are currently working to incorporate these factors into their climate models, and future studies will be necessary in order to test whether reducing human emissions can slow both rising seas and melting ice before it’s too late.