To: weatherguru who wrote (83 ) 10/20/2015 3:47:20 PM From: TideGlider 2 RecommendationsRecommended By
Read Replies (3) | Respond to Seems totally unlikely that my property in Jersey will ever be beach front.Climate Sanity Mass and volume units for water and ice One gigatonne is one billion metric tonnes ( 1 Gt = 1 x 109 tonnes)One metric tonne is 1000 kilograms (1 tonne = 1000 kg) One metric tonne of water has a volume of one cubic meter (1 tonne water = 1 m³) One gagatonne of water has a volume of one billion cubic meters, or one cubic kilomter.(1 Gt water = 1 km³)Of course, one gigatonne of ice has a greater volume than one gigatonne of water. But it will still have a volume of 1 km³ when it melts. How much does one Gigatonne of melted ice (1 km³ of water) raise the oceans? The oceans occupy 361 million square kilometers ( 361 x 106 km²) of the Earth’s surface. If one cubic kilometer of water (i.e., one gigatonne of water) is spread evenly over the entire 361 million square kilomters, the thickness of the new layer of water will be given by: 1 km³ / 361 x 106 km² = 2.78 x 10-6 meters = 2.78 microns. Or, in terms of gigatonnes: 1 Gt x (1 km³/Gt) / 361 x 106 km² = 2.78 x 10-6 meters = 2.78 microns / Gt That is, one cubic kilometer of water (i.e., one gigatonne of water) will add less than 3 millionths of a meter to the oceans! The number of gigatonnes of water that must be added to the oceans to raise the sea level 1 millimeter is given by: 1 mm / (2.78 microns / Gt) = 10-3 m / (2.78 x 10-6 m / Gt) = 360 Gt Similarly, 360 km³ of water will raise the oceans 1 mm. ******************************************************************************************* How many gigatonnes of ice must melt to raise the oceans one inch? 1 inch = 25.4 mm = 2.54 x 10-2 metersThe number of gigatonnes of water that must be added to the oceans to raise the sea level 1 inch is given by: 1 inch x ( 2.54 x 10-2 m / inch) / (2.78 x 10-6 m / Gt) = 9137 Gt Similarly, 9137 km³ of water will raise the oceans 1 inch. ******************************************************************************************* How many gigatonnes of ice must melt each year to raise the oceans one foot per decade? 1 foot = 305 mm = 3.05 x 10-1 metersThe number of gigatonnes of water that must be added to the oceans to raise the sea level 1 foot per decade is the same as the number of gigatonnes required to raise the oceans 30.5 mm/yr, and is given by: 360 Gt/mm x 30.5 mm/yr = 10,980 Gt/yr Similarly, 10,980 km³ of water per year will raise the oceans 1 foot per decade.
