Climate Central, an American organization conducting scientific research on climate change, published the study MAPPING CHOICES – CARBON, CLIMATE AND RISING SEAS: OUR GLOBAL LEGACY in November 2015.
This study estimates the longterm sea level rise based on different scales of future climate warming. To show what is at stake, Climate Central also developed a tool to show the rise of the seas visually in the biggest cities that will suffer from the rising seas what is very impressive to look at. These results are based on median sea level rise projections. They are also based on global elevation data with a tendency to understate exposure. The results of this study show the longterm effects of the climate warming that will occur in the next centuries. But due to the dependency of the coming sea level rise to the amout of emitted carbon emissions released this centuries, humanity decides until 2100 how much sea level rise post-2100 societies will suffer from. The study says that it is easier to estimate how much ice will melt instead of determining when it will melt.
These are the most important findings of the study:
- Carbon emissions causing 4 degrees Celsius of warming (7.2 degrees Fahrenheit) – a business-as-usual scenario – could lock in enough eventuall sea level rise to submerge land currently home to 470 to 760 million people globally.
- Carbon cuts resulting in the proposed international target of 2 degree C warming (3.6 degree F) would reduce the rise of locked in so that it would threaten areas now occupied by as few as 130 million people.
- Among all nations, this reports finds that China has the most to lose from buisness as usual, with 145 million citizens today on implicated land. China also has the most to gain from limiting warming to 2 degree C, which would cut the total to 64 million.
- Twelve other nations have more than 10 million people living on implicated land under 4 degree C warming – India, Bangladesh, Vietnam, Indonesia, Japan, the United States, Philippines, Egypt, Brazil, Myanmar and the Netherlands.
- Four separate models underlie the global sea level projections employed here: one for the expansion of ocean water as it warms, one for melting glaciers, and one each for the decay of Greenland and Antarctic ice sheets.
- Some research has suggested that the West Antarctic Ice Sheet has already begun an unstoppable collapse, which would lead to roughly 3.3 meters of sea level rise by itself, but the evidence is far from conclusive.
- Global coast, nations and cities at risk: This analysis finds that carbon emissions causing 4 degrees C of warming could lock in a median of 8.9m of long-term global sea level rise, enough to submerge land home (in 2010) to 627 million people globally. Carbon cuts resulting in the proposed international target of 2 degree C warming could reduce these numbers to medians of 4.7 m in sea level rise and 280 million people.
- Warming (C) / Locked-in sea level rise (meters) / 2010 global population at risk
- 1.5 C / 2.9m (1.6 – 4.2m) / 137 (51-291 millions)
- 2 C / 4.7m (3.0 – 6.3m) / 280 (130-458 millions)
- 3 C / 6.4m (4.7 – 8.2m) / 432 (255-597 millions)
- 4 C / 8.9m (6.9 – 10.8m) / 627 (470-760 millions)