Greenpeace figuresPosted: November 3, 2015
- 23% of the worlds’ population lives in the near coastal zone with population densities about three times higher than the global average.
- Of the 39 big metropolitan areas with a population over 5 million, sixty percent are located within 100km of the coast.
- These include twelve of the biggest 16 with populations exceeding 10 million although the great majority of people live in smaller settlements in the coastal zone.
- Over the 20th century as a whole, sea levels rose by an average of around 1.7mm a year with evidence that in recent years the rate of rise has increased.
- Latest satellite data put the rise at around 3mm a year.
- The most recent IPCC assessment based on the most gloomy scenario puts predictions of 21st century sea level rise at between 26 and 59cm (10-23 inches).
- With a fossil fuel intensive future, a global average sea level rise of 26-59cm (10-23 inches) is expected over the next hundred years, thanks to the greenhouse gases we have emitted to date and likely future emissions.
- Even with more optimistic projections based on greenhouse gas emissions being controlled, sea level could rise by between 10-24cm (4-9 inches). Over several centuries, therefore, sea level could rise by several metres.
- One area of critical concern are the ice sheets of Greenland and Antarctica which if fully melted would raise sea level by 64m.
- Greenland ice sheets – if global temperatures rise by somewhere between 1.9 and 4.6 degrees and they have already risen by an estimated 0.8 degrees. Complete melting would lead to a sea level rise of around 6-7m.
- Antarctica ice sheets
- Potentially, according the IPCC, the West Antarctic ice sheet (WAIS) alone could contribute an additional six metres (20 feet) to sea level rise over several thousand years, although more recent estimates suggest a lower figure of 3.3 metres may be more plausible.
- While melting of the Greenland ice sheet and the Western Antarctic ice sheet could ultimately raise sea levels by anything up to 13 metres or so (43 foot) if we do not drastically curb our greenhouse gas emissions, even the small fraction of this predicted by 2100 would be an economic and humanitarian disaster.
- If current warming trends are allowed to continue, London, Bangkok and New York, Shanghai and Mumbai will be among a number of cities which will eventually end up below sea level.
- A recent study estimated the costs of adapting to even a one metre sea level rise in the US would amount to US$156 billion
- More recent estimates of the impact of a 66 cm sea level rise by 2100 suggest costs could be in the region of US$ 236 billion, with nearly 9000 square kilometers of land having to be abandoned and 13,000 km of coastal defences needing to be constructed. Needless to say many poorer countries do not have these resources.
- Rising oceans will contaminate both surface and underground fresh water supplies