We have heard a million times that if we don’t stop emitting greenhouse gases, our inexcusable actions will result in a warmer earth, and the warming of the planet will cause icecaps and mountain glaciers to melt and sea level to rise. Island nations will be drowned, coastlines around the world will go underwater, Florida will cease to exist, and the World Trade Center Memorial could someday be a sight seen only by scuba enthusiasts. The United Nations Intergovernmental Panel on Climate Change says very clearly in the Summary for Policymakers “Global average sea level rose at an average rate of 1.8 [1.3 to 2.3] mm per year over 1961 to 2003. The rate was faster over 1993 to 2003: about 3.1 [2.4 to 3.8] mm per year. Whether the faster rate for 1993 to 2003 reflects decadal variability or an increase in the longer-term trend is unclear. There is high confidence that the rate of observed sea level rise increased from the 19th to the 20th century.” The IPCC crew reminds us that “Global average sea level in the last interglacial period (about 125,000 years ago) was likely 4 to 6 m higher than during the 20th century, mainly due to the retreat of polar ice.” It seems that sea levels fell and rose many times in the past and long before humans had any chance interfere with the natural order of things. There is no reason whatsoever to expect sea level to remain constant – it never has and it never will.
We have covered this sea-level rise issue many times in the past at World Climate Report and we fully agree that sea level is rising – sea level has been somewhat steadily rising for the past 10,000 years. During the last glacial advance, a large amount of fresh water was tied up in ice, and as the glaciation ended, that water returned to the oceans. Furthermore, as the earth warmed up following the last glacial advance, thermal expansion of the ocean water occurred, and sea level rose even more. There is little doubt that the sea-level rise will continue into the future, but the rate of rise is the focus of an interesting paper published recently in Global and Planetary Change by a team of scientists from France and Spain.
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