In Dead Water: Merging of climate change with - UNEP

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SEA LEVEL RISE A significant sea level rise is one of the major anticipated consequences of climate change (IPCC, 2007; UNEP 2007). Global warming from increasing greenhouse gas concentrations is a significant driver of both contributions to sea-level rise. From 1955 to 1995, ocean thermal expansion is estimated to have contributed about 0.4 mm per year to sea level rise, less than 25 per cent of the observed rise over the same period. For the 1993 to 2003 decade, for which the best data are available, thermal expansion is estimated to be significantly larger, at about 1.6 mm per year for the upper 750 m of the ocean alone, about 50 per cent of the observed sea level rise of 3.1 mm per year. Scientists estimate the melting of glaciers and ice caps (exclud- ing the glaciers covering Greenland and Antarctica) contributed to sea level rise by about 0.3 mm per year from 1961 to 1990 increasing to about 0.8 mm per year from 2001–2004. CM Even for today’s socio-economic conditions, both regionally MY and globally, large numbers of people and significant economic activity are exposed to an increase and acceleration of sea level CY rise. The densely populated megadeltas such as those of Gan- CMY ges-Brahmaputra, Mekong and Nile are especially vulnerable to sea level rise. Some 75 per cent of the population affected live K on the Asian megadeltas and deltas, with a large proportion of the remainder living on deltas in Africa. Globally, at least 150 million people live within 1 metre of high tide level, and 250 million live within 5 metres of high tide (UNEP, 2007). Figure 14. The projected and observed sea level rise. Observed sea level rise is currently larger than that projected by current climate models. The bar to the left also shows the contribution of different factors to sea level rise, the two most important being a) thermal expansion of ocean waters as they warm, and b) increase in the ocean mass, principally from land-based sources of ice (glaciers and ice caps, and the ice sheets of Greenland and Antarctica). C M Y Greenland Ice Sheet 0.2 ± 0.1 mm/yr Antarctic Ice Sheet 0.2 ± 0.4 mm/yr Glaciers and ice caps 0.8 ± 0.2 mm/yr Ocean thermal expansion 1.6 ± 0.5 mm/yr 6c_sealevelcontributions.pdf 2007-04-26 15:12:09 Estimated contributions to sea-level rise ±0.7 2.83 mm/yr 3.1 Satellite and tide gauge observations 3.1 ± 0.7 mm/yr Observed sea-level rise ±0.7 mm/yr
Figure 15. How sea level rise will happen. Expansion of the ocean and melting of land ice are two of the largest contributing factors to sea level rise. 33
Page 1 and 2: RAPID RESPONSE ASSESSMENT IN DEAD W
Page 3 and 4: Christian Nellemann Stefan Hain Jac
Page 5: PREFACE The world’s oceans are al
Page 8 and 9: covered and possible loss of cold-w
Page 10: Over-harvesting and bottom trawling
Page 13 and 14: CONTENTS 0 0 PREFACE SUMMARY WHY OC
Page 16 and 17: THE SEA - ONE OF THE LARGEST FOOD F
Page 18 and 19: SEAMOUNTS AND CONTINENTAL SHELVES -
Page 20 and 21: These unique features make seamount
Page 22 and 23: CORAL REEFS Coral reefs are marine
Page 25 and 26: More and more coral reefs are being
Page 27 and 28: CLIMATE CHANGE IN THE SEA The Fourt
Page 29 and 30: global bleaching event was recorded
Page 31: Number of events per year 450 400 3
Page 35 and 36: OCEAN ACIDIFICATION The oceans act
Page 37 and 38: Figure 18. As carbon concentrations
Page 39 and 40: SLOWING DOWN OF THERMOHALINE CIRCUL
Page 41 and 42: opean Seas) - of which UNEP is a pa
Page 43 and 44: Figure 23. Infrastructure developme
Page 45 and 46: Figure 24. Sewage treatment is low
Page 47: Among the most destructive fishing
Page 51 and 52: It is important, however, to realiz
Page 53 and 54: Figure 27. The locations of major p
Page 55 and 56: UNEP-WCMC & UNEP/GRID-Arendal Figur
Page 57 and 58: Overharvest from fisheries Coastal
Page 59 and 60: CONTRIBUTORS AND REVIEWERS Christia
Page 61 and 62: current status and prospects of ant
Page 64: UNEP/GRID-Arendal Teaterplassen 3 N

In Dead Water: Merging of climate change with - UNEP

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