(a) (b)
Figure 6C.15: Examples of accommodation and protection measures.
(a) Sea wall protecting road in the atoll of South Tarawa, Kiribati. The elevated building in background is also a protection measure.
(b) The Thames Barrier. Built 25 years ago, the barrier and associated defences require significant upgrading to protect the City of
London from higher sea levels and storm surges, at a probable cost of billions of pounds
85,86
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Photos: (a) John Hay; (b) The Environment Agency
Need for mitigation Ice Sheets, as experienced during the last interglacial
period. Such a sea-level rise would put huge pressures
The rate and magnitude of sea-level rise, particularly on society and could result in many millions of environ-
later in the 21st century and beyond, depends on future mental refugees
1,87,88
.
emissions of greenhouse gases. Indeed, 21st century
greenhouse gas emissions could commit the world to If we are to avoid these large rises in sea level, a significant
a sea-level rise of several metres over hundreds of years reduction in greenhouse gas emissions is essential. Achiev-
as a result of ongoing ocean thermal expansion and ing the necessary reduction in emissions will be challeng-
contributions from the Greenland and West Antarctic ing and requires urgent and sustained commitment.
176 GLOBAL OUTLOOK FOR ICE AND SNOW