“Every delay in peaking emissions by five years between 2020 and 2035 could mean additional 20 cm of sea-level rise in the end—which is the same amount the world’s coasts have experienced since the beginning of the pre-industrial era,” asserts Matthias Mengel from the Potsdam Institute for Climate Impact Research (PIK).
This means that even if the global warming is controlled to less than 2 degrees Celsius, under the Paris climate agreement, it is still necessary and very critical to significantly reduce global carbon footprint as fast as it can be in order to avoid further sea-level rise. This is the message conveyed in a study led by Mengel and published in the journal Nature Communications.
For the first time, an analysis of the sea-level legacy until 2300 under the full implementation of the Paris Agreement was conducted. It concludes that even when Paris Climate Change Agreement is fully adopted, a global sea-level rise of between 0.7 to 1.2 meters is expected to occur by 2300.
The study accounted for the limiting levels of greenhouse gas emissions set by the Paris Agreement beyond 2050, which comprise of various reduction rates and emission peak years. Using these set of cases under Paris Agreement with a model that simulates climate and sea-level, the researchers conducted the analysis.
Considering that these restrictions on emissions are ideally met, then the future sea levels will solely depend on the greenhouse-gas emissions levels before 2050. Mengel and his co-researchers learned that for every five-year long delay in lowering global carbon dioxide emissions will most probably result in 20-centimeter higher median sea-level rise for 2300.
“Man-made climate change has already pre-programmed a certain amount of sea-level rise for the coming centuries, so for some, it might seem that our present actions might not make such a big difference—but our study illustrates how wrong this perception is,” explains Mengel.
The model used in the study represents melting of glaciers and warming of oceans individually enabling to reflect their different responses to earth warming. The researchers have identified that in particular, an Antarctic ice sheet seems to be very sensitive to this warming.
“Indeed, the uncertainty of future sea-level rise is at present dominated by the response of Antarctica. With present knowledge of ice sheet instability, large ice loss from Antarctica seems possible even under modest warming in line with the Paris agreement. Even a sea-level rise of up to three meters until 2300 cannot be ruled out completely, as we are not yet fully certain how the Antarctic ice sheet will respond to global warming.”, says Mengel.
“The Paris Agreement calls for emissions to peak as soon as possible. This might sound like a hollow phrase to some, but our results show that there are quantifiable consequences of delaying action. So even within the Paris Agreement range, swift climate mitigation is crucial to limit additional risks. For millions of people around the world living in coastal areas, every centimeter can make a huge difference—to limit sea-level rise risks immediate CO2 reduction is key,” adds co-author Carl-Friedrich Schleussner from PIK and Climate Analytics, a non-profit research and policy institute in Berlin.