Impacts and risks of accelerating sea level rise on low lying islands, coasts and communities

doi:10.12006/j.issn.1673-1719.2019.225

Abstract

Abstract:

The IPCC special report on the ocean and cryosphere in a changing climate (SROCC) presents an assessment of past and future contributions of climate change to global, regional and extreme sea level changes, the associated risk to low-lying islands, and response options and pathways to resilience as reported in the sea level chapter. The special report covers the field from observational changes, improved physical insights and projections to impacts and risk, and response options. The results indicate that, in the context of global warming, the global mean sea level (GMSL) is rising (virtually certain) and accelerating (high confidence), and the height of extreme sea level (ESL) is increasing significantly, attributed to the contribution of land glaciers and ice sheets that has exceeded the effect of the ocean thermal expansion since 2006. Meanwhile, the rate of ocean warming has more than doubled since 1993, strong tropical cyclones and storm surges have increased and the return period of ESL has greatly decreased. By 2100, GMSL will rise by about 0.43 m (low greenhouse gas emission scenario, RCP2.6) and 0.84 m (high emission scenario, RCP8.5) (medium confidence), and the currently rare ESL, e.g., today’s hundred-year event at many coastal locations, will become annually or more frequently, which will even happen by the mid-century for many low-lying coastal areas. The results also indicate that, rising GMSL, frequent ESL and anthropogenic drivers such as reclamation and subsidence, increase the exposure and vulnerability of coastal social-ecological systems. The sea level related hazards (such as submergence of land, enhanced coastal erosion, more frequent or intense flooding, salinization of soils, groundwater and surface waters, loss of and change of coastal ecosystems) will increase (high confidence). At the century scale and without adaptation, the vast majority of low-lying islands, coasts and communities, e.g., resources-rich coastal cities, urban atoll islands, tropical agriculture deltas, and Arctic communities, face substantial risk from these coastal hazards (high confidence).

Key words: Sea level rise, Low lying, Coasts, Impacts, Risk

CAI Rong-Shuo,TAN Hong-Jian. Impacts and risks of accelerating sea level rise on low lying islands, coasts and communities[J]. Climate Change Research, 2020, 16(2): 163-171.

Figures/Tables 3

Fig. 1 Comparison of observed and simulated global mean sea level change since 1901 (a) and since 1993 (b) [1]

Fig. 2 The relation between expected extreme sea level events and return period at a set of characteristic tide gauge locations (see upper left for their locations), referenced to 1986-2005 mean sea level and 2081-2100 conditions for three different RCP (2.6, 4.5, 8.5) scenarios [1]

Fig. 3 Additional risk related to sea level rise for low-lying coastal areas by the end of the 21st century[1] (left describes GMSL rise observations for the recent past (1986-2005) and projections under RCP2.6 and RCP8.5 by 2100 relative to the recent past (1986-2005). Right describes risk to local geographies, e.g., megacities, urban atoll islands, tropical agricultural deltas, and Arctic communities under two adaptation scenarios (“No-to-moderate adaptation” and “High adaptation”))

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