Joe, my friend when we talk decades, or when we talk centuries as in the case of temperature rises, the real answer is no one knows, and guesses about the future are almost always wrong. BTW, the string would not lift off the earth by 3.83 inches. Can you figure out why? - Millet

Forgot to factor out the "2". It would be half that. Barbara

It would only take about 60 billion metric tons of lead to raise the concentration to 50 ppb (assuming your volume). I do not believe that would even dissolve all of the lead that man has put into the ocean given the amount in batteries and lead sinkers that have been lost. In all honesty, I am sure I have lost near 100 pounds of lead as sinkers considering I have lost many in the 1/4 to 1 pound size. Many of the channel marker batteries were just dumped in the water for years. That is not to mention the natural sources of lead in the oceans and rivers.

Temperature is not the driving force here--it is the atmospheric CO2 concentration. When CO2 dissolves in seawater it becomes Carbonic Acid (H2CO3) that enters into the equillibrium between Carbonate and Bicarbonate and drives the equillibrium toward Bicarbonate and reduces the concentation of Carbonate. Lead concentration in seawater is controlled due to the low product solubility constant of lead carbonate and the high concentration of carbonate in seawater-- as carbonate concentration goes down lead concentration goes up.