What is the greenhouse effect? The sun puts off radiation energy. There are two different types of the greenhouse effect: natural and enhanced. Natural Greenhouse Effect The atmosphere is made up of nitrogen oxygen water vapor carbon dioxide other minor gases This absorbs a portion of thermal radiation that warms the earth. This is considered “natural” because these gases were present before human intervention. Enhanced Greenhouse Effect Human beings have effectively polluted the atmosphere with carbon dioxide through the burning of fossil fuels. This adds another blanket to the atmosphere trapping more thermal radiation leading to higher temperatures.
How does this effect sea levels? Thermal expansion Cold water is more dense than warm. Like a swimming pool, the warm water on the top takes time to mix with the cold water at the bottom. With this, even if greenhouse gases were stabilized by the year 2030, oceans would continue to rise at a rate of about 30 cm per year until oceanic temperature is stabilized. Melting of glaciers & ice sheets Warmer oceans and higher temperatures have led to the melting of glaciers and ice sheets. Over the past five years, studies have found that melting Antarctic ice caps contribute at least 15% to the current global sea level rise of 2mm a year. Many more icebergs falling into the sea will cause two things to happen - the sea- level will rise and the injection of freshwater could disrupt the ocean currents, including the Gulf Stream.
Is the MOSE Worth It? The facts… The MOSE solution will cost an estimated US $2.6 billion. The gates will be activated if sea levels exceed 87 cm over the average sea level. The gates will, in theory, cut the lagoon off from high water events, protecting the city.
Is the MOSE Worth It? Questionable setbacks… If sea levels continue to rise, the gates will become obsolete. Water runoff due to rain and other drainage will be trapped in the isolated lagoon creating rising levels of their own. Long term isolation of the lagoon will disrupt the vital exchange of water between lagoon, gulf, and sea. Many high water events that cause flooding in the city of Venice never reach the 87 cm mark.