Lasting Coastal Hazards from Past Greenhouse Gas Emissions COMMENTARY Tony E
COMMENTARY Lasting coastal hazards from past greenhouse gas emissions COMMENTARY Tony E. Wonga,1 The emission of greenhouse gases into Earth’satmo- 100% sphereisaby-productofmodernmarvelssuchasthe Extremely likely by 2073−2138 production of vast amounts of energy, heating and 80% cooling inhospitable environments to be amenable to human existence, and traveling great distances 60% Likely by 2064−2105 faster than our saddle-sore ancestors ever dreamed possible. However, these luxuries come at a price: 40% climate changes in the form of severe droughts, ex- Probability treme precipitation and temperatures, increased fre- 20% quency of flooding in coastal cities, global warming, RCP2.6 and sea-level rise (1, 2). Rising seas pose a severe risk RCP8.5 0% to coastal areas across the globe, with billions of 2020 2040 2060 2080 2100 2120 2140 US dollars in assets at risk and about 10% of the ’ Year when 50-cm sea-level rise world s population living within 10 m of sea level threshold is exceeded (3–5). The price of our emissions is not felt immedi- ately throughout the entire climate system, however, Fig. 1. Cumulative probability of exceeding 50 cm of sea-level rise by year (relative to the global mean sea because processes such as ice sheet melt and the level from 1986 to 2005). The yellow box denotes the expansion of warming ocean water act over the range of years after which exceedance is likely [≥66% course of centuries. Thus, even if all greenhouse probability (12)], where the left boundary follows a gas emissions immediately ceased, our past emis- business-as-usual emissions scenario (RCP8.5, red line) sions have already “locked in” some amount of con- and the right boundary follows a low-emissions scenario (RCP2.6, blue line).
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