365 Days of Climate Awareness 227 – The Maldives and Sea Level Rise

The Maldives is microtidal, with a spring tide range of less than 1 m/3.2 ft. Annual sea level can vary by up to 1 m due to natural variations like the Indian Ocean Dipole. So mean sea level is a noisy signal but according to tidal gauge and satellite data has risen by nearly 50 cm in the last 35 years. IPCC models show sea level continuing to rise by another 50-100 cm by 2100, which will make the Maldives partially or totally uninhabitable.

IPCC Shared Socioeconomic Pathways (SSPs) with their predicted population and economic trends.

The Intergovernmental Panel on Climate Change  (IPCC) has published a set of Shared Socioeconomic Pathways (SSPs) which it uses as the backdrop for its various climate change model scenarios, ranging from less severe impacts to more severe. Briefly:

• SSP1: sustainability – the green road, low challenges to mitigation & adaptation
• SSP2: medium road, moderate challenges to mitigation & adaptation
• SSP3: regional rivalry - rocky road, high challenges to mitigation & adaptation
• SSP4: inequality, low challenges to mitigation, high challenges to adaptation
• SSP5: fossil-fueled development, high challenges to mitigation, low challenges to adaptation

Two scenarios, 1 and 5, lead to predicted sea level rise of 0.43 m/1.4 ft and 0.86 m/2.8 ft by 2100. The lower scenario would result in roughly 77% of the Maldives being flooded; the high scenario would inundate more than 90%. NASA estimates that by 2050—less than thirty years from now—more than 80% of the islands could be uninhabitable.

Predicted sea level rise at Malé, by 2050, for several SSPs (NASA).

Predicted future sea level rise curves for Malé (NASA), SSPs 1 & 5 (the second number refers to the scenario's associated radiative forcing: +1.9 W/m² and +8.5 W/m², respectively.

An attempt is underway to mitigate this, by raising one of the islands, Hulhumalé, an extra meter above its neighbors. As in the case of Kiribati, this is a race against time with no certain finish line. Citizens use their own improvised methods, such as building tiny breakwaters with concrete blocks, to reduce erosion.

Hulhumalé

Makeshift concrete block seawalls.

Fresh water has also become more of a problem in the era of rising seas. In 2004 only 11% of the Maldives islands had potable freshwater, but the Indian Ocean tsunami of that year contaminated the remaining aquifers. Now residents rely on collected rainwater. Water from the shallow aquifers there are is not used for eating or drinking.

Tomorrow: introduction to Africa.

Be brave, and be well.