The Honorable Tom Roper
Oceans cover about 70 per cent of the Earth's surface, abut most of the world's nations and surround thousands of inhabited islands. The IPCC's 2001 assessment suggests that approximately a fifth of the world's population lives within 30 km of the sea and nearly double that within 100 km. The proportion is growing, particularly with rapid urbanization.
Oceans pose a number of threats to coastal environments and communities, the most significant of which has been storms. In mid- to high latitudes, the strongest storms are often in winter; in low to mid-latitudes, the strongest storms are typically in summer. Both can result in high winds, creating damaging storm surges, causing coastal erosion and high amounts of precipitation. This is particularly true for tropical cyclones, which draw their power from warm ocean waters and intensify into hurricanes, creating winds and rains that destroy coastal settlements and forests, inundate agriculture, and cause serious flooding and mudslides. Although improved warning of such events has led to reduced death rates, evacuations and damage typically create significant disruption.
While there is considerable debate about the extent of climate change impacts on coasts, the differences are about degree, not direction. Warmer ocean waters, melting glaciers and perhaps ice sheets are raising sea level above its long-term level - and prospects are for up to 1 m rise during the 21st century. Rachel Warren of the UK's Tyndall Centre and James Hansen of NASA point to potentially much greater rises with ice melt in Antarctica and Greenland.
The 2001 IPCC Report states that many coastal systems would experience:
• increased levels of inundation and storm flooding;
• accelerated coastal erosion;
• seawater intrusion into fresh groundwater;
• encroachment of tidal waters into estuaries and river systems;
• elevated sea surface and ground temperatures;
• threats to coral and mangroves.
It is also predicted that the number of extreme events will increase. There may or may not be more hurricanes and typhoons, but it is expected that they will become more powerful and, consequently, more destructive. Ecosystem resilience will be reduced by a combination of human and climate impacts.
Millions more are likely to be flooded regularly, particularly in the mega-deltas of Asia and Africa and in the especially vulnerable small islands, as described in repeated IPCC assessments. In Nigeria, for instance, 25 million people live along the coastal zone. A sea level rise of 0.5 m would displace 1.5 million people and result in the loss of 200,000 jobs in Alexandria, Egypt, alone.
While the atolls in small island developing states such as the Maldives, Marshalls, Tuvalu and Kiribati are the most vulnerable, and even may vanish as geographical areas and nations, almost all small island developing states have most of their social and economic activity and capital investment less than 2 m above sea level. As a result of the 2004 Indian Ocean tsunami, the Maldives suffered the effects of a century of sea level rise in an afternoon, with 10 per cent of the habitable land lost and the ongoing salinization of scarce fresh water supplies and food gardens.
Part 3 describes three vulnerable coastal situations in the US that are typical of situations worldwide. These examples show the need and potential for taking action to protect lives and properties in many areas vulnerable to sea level rise. In Chapter 7, Professor Michael Kearney details the potential for significant impacts on Chesapeake Bay, the largest estuary in the US and typical of large estuaries worldwide. In Chapter 8, Dr Virginia Burkett outlines the situation along the Gulf Coast and Mississippi River delta, which is typical of many low-lying coastal areas that are protected by barrier islands and wetlands. In Chapter 9, Professor Malcolm Bowman describes the situation facing the New York metropolitan area, which has major development right up to the coastal edge and is extremely vulnerable to powerful storms, the effects of which will be exacerbated by sea level rise and climate change. In Chapter 10, Dr Bruce Douglas and Professor Stephen Leatherman depict the worsening situation facing many of the world's coastlines from rising sea levels, intensifying storms, coastal erosion and intense development, and then outline the near-term steps needed to address these concerns. In the final chapter in this section, Admiral Loy, former Commandant of the US Coast Guard, presents the urgently needed actions required to protect the lives of people living in coastal areas.
Although there have always been risks for coastal residents, they are worsening, creating situations for which neither coastal ecosystems nor communities are prepared. Attention must be devoted to prepare for what seem to be inevitable challenges and changes while simultaneously taking action, as we are doing in the Global Sustainable Energy Islands Initiative, to reduce greenhouse gas emissions and slow and then stop the intensifying pace of climate change. It is too late to stop serious deleterious impacts to our coastlines. Hopefully, there is still time to prevent catastrophic change.
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