The science academies of 70 nations addressed the opening of the climate talks in Bonn today concerning the seriousness of emission cuts required to keep ocean acidity under control. From the statement:
Ocean acidification is irreversible on timescales of at least tens of thousands of years; At current emission rates models suggest that all coral reefs and polar ecosystems will be severely affected by 2050 or potentially even earlier;
Carbonate saturation, or the basics chemistry allowing primary productivity to survive as at it lowest level in 800,000 years. If current trends continue ocean acidity will be higher than at any time in the last 10 million years. (By current trends, they mean those trends established over the last 30 or more years. since the turn of the century, trends have been accelerating beyond those of the last 30 years.) The statement says: "The current rate of change is much more rapid than at any time in the last 65 million years."
Ocean acidity changes are happening now across the globe and have already begun to affect coral growth. In the Antarctic and parts of the North Sea, it has already begun to affect primary productivity and mass extinctions are projected between 2030 and 2050. (See here and here)
Even with stabilization of atmospheric CO2 at 450 ppm, ocean acidification will have profound impacts on many marine systems. Large and rapid reductions of global CO2 emissions are needed globally by at least 50% below 1990 levels by 2050. The highest emission reductions proposed to date are by the European Union at 30% below 1990 levels by 2020. The U.S was (last month) proposing 20% below 2005 levels, which is about 7% below 1990 levels. Now the U.S proposal is down to 17% or below 2005.
Cuts under Kyoto look like they will now be realized in the European Union, but almost nowhere else. Worldwide, CO2 keeps rising at an accelerating rate.
Most developed countries today, including the U.S. are proposing cuts of 50% to 80% by 2050, or what it’s worth.