Climate Change agreement, Paris
Scientists and policy makers say the agreement entering into force is just the first step of a much longer and complicated process of transitioning away from fossil fuelsReuters

Global warming levels are so sensitive that in the next century, even if the Paris Climate Agreement is met, just a half degree rise in temperatures worldwide would mean the displacement of over five million people.

In 2015, the whole world got together and signed the Paris Agreement, or the Paris Climate Accord promising to keep the rise in temperatures and control global warming by "keeping a global temperature rise this century well below 2 degrees Celsius above pre-industrial levels and to pursue efforts to limit the temperature increase even further to 1.5 degrees Celsius".

A recent peer review published by Princeton University has found that the 2 degree mark is "inadequate", reports The researchers have concluded that the mark should be set lower – to 1.5 degrees instead. This half a degree rise will make a big difference in future, they found.

By 2150, this seemingly small difference between 1.5 to 2.0 degrees C would lead to the displacement of five million more people, including 60,000 living in islands across the world.

To get an idea of what this would mean, or translate to in the real world, the researchers made use of a global network of tide gauges to build localized sea level projections that studies the differences in the frequency of "extreme sea-level events". These extreme events are defined as the height of a storm surge plus height of a high tide. Projections were created for three scenarios – global temperature rise of 1.5, 2.0 and 2.5 degrees C.

Rising sea level, which is directly related to the rising global surface temperature, is already increasing the frequency of extreme sea-level events and by the end of this century, coastal flooding will be the most expensive impact of climate change, the study found.

The kicker is that even if global temperatures are stabilized and kept under control, seas will continue to rise for hundreds of years. This is because of the extended residence time that carbon dioxide has in the atmosphere, the thermal inertia of oceans, and the slow response of ice sheets.