|
|||||||||||||||||||||||||||||||||||||||||||||
|
|||||||||||||||||||||||||||||||||||||||||||||
 |
|
 |
 |
 |
|
|
Sea Level Rapid increase in greenhouse gases and consequent climate warming is expected to cause a global rise in sea level in the 21st century, resulting from thermal expansion of the volume of the world's oceans, and the addition of meltwater from glaciers and polar ice caps. Scientists agree that with global warming, the melting of mountain glaciers will certainly increase. Melting of the marginal areas of the Greenland Ice Sheet will likely occur under global warming conditions, and this will be accompanied by the drawing down of the inland ice and increased calving of icebergs. Modeling studies predict a sea-level rise of about 50 cm by 2100, based on increasing greenhouse gas concentrations (i.e., concentrations of atmospheric carbon dioxide, methane, nitrous oxide, and certain other gases). However, it should be noted that because of the thermal inertia of the oceans, the global mean temperature would continue to increase beyond 2100, and sea level would continue to rise at a similar rate in future centuries even if greenhouse gas concentrations were stabilised by that time. Changes in climate will affect coastal systems through sea level rise and an increase in storm-surge hazards and possible changes in the frequency and/or intensity of extreme events. For example, an estimated 46 million people per year are at risk of flooding from storm surges. Climate change will exacerbate these problems, leading to potential impacts on ecosystems and human coastal infrastructure. Small island developing states are three times as vulnerable as developed countries to sea level rise. Island nations and continental beaches and cities would be endangered. Agricultural lands could be displaced, just as patterns of arid, semiarid, and wet lands might become modified. It is essential that society plan for such potential changes so that, if they do occur, appropriate adjustments can be made to accommodate them. WMO and the United Nations Environment Programme (UNEP), through the Intergovernmental Panel on Climate Change (IPCC) are addressing the potential problems of sea level rise. |