Meanwhile the carbon dioxide content of the oceans will have doubled. This raises an incidental question about the welfare of sea organisms. We know that an increase in carbon dioxide concentration increases the acidity of water, and that many marine animals are extremely sensitive to changes in acidity. However, if the carbon dioxide content of the air were to increase sevenfold, the acidity (pH) of sea water would not rise more than .5 above its present value. Thus changes in carbon dioxide concentration, which have such a profound effect on climate, will probably not disturb future marine life. Perhaps only man will be uncomfortable.
We shall be able to test the carbon dioxide theory against other theories of climatic change quite conclusively during the next half-century. Since we now can measure the sun's energy output independent of the distorting influence of the atmosphere, we shall see whether the earth's temperature trend correlates with measured fluctuations in solar radiation. If volcanic dust is the more important factor, then we may observe the earth's temperature following fluctuations in the number of large volcanic eruptions. But if carbon dioxide is the most important factor, long-term temperature records will rise continuously as long as man consumes the earth's reserves of fossil fuels.