tankers deadheading to their home ports filled with sea water for ballast is a waste of an opportunity. The tanker capacity over a year is about the same as the amount of water Saudi Arabia is desalinating and was pumping from its aquifers for irrigation and general use. A recent study by Yadu Pohkrel estimated that pumping of aquifers has been a significant contributor to sea level rise recently. Irrigatiion with runoff that would othewise contribute to sea level rise would be a double barreled attack on the problem and the lowest hanging fruit looks to me to be tankers. Kent Otho Doering said: Dear Sirs: There are other cases for a carbon tax.  Germany has a 5%net carbon tax which actually stimulates a broad synergy of clean tech solutions which do work to stimulate clean tech and carbon reduction as described here in the article. However, Germany has long had another financial instrument in place which is also a part of forward financing its clean tech production set up, production and installation of those fossil fuel saving technologies That same instrument financed German unification under Otto von Bismark, accellerated late 19th century industrialisation, and its war efforts and rebuilding in the 20th century. I am writing about Germany's long established, parallel public banking system. Back in the mid-19th century, in the late 1860s, German Chancellor Otto von Bismarck copied the U.S. parallel public banking system from the U.S. devised to finance the Northern States war efforts during the civil