On April 8, 2010, Presidents Obama and Medvedev signed the New START nuclear weapons reduction agreement, committing the United States and Russia to reduce their nuclear arsenals to levels of less than 10 percent of the maximum during the height of the Cold War in the 1980s. An important factor in the end of the arms race between the United States and the Soviet Union was the realization that the climatic consequences, and indirect effects of the collapse of society, would be so severe that the ensuing nuclear winter would produce famine for billions of people far from the target zones. But has the world now eliminated the possibility of nuclear winter? We will present new climate model simulations that show that the resulting arsenals, with 1,550 weapons on each side, if used, can still produce nuclear winter and massive ozone depletion and that much larger reductions are still needed to prevent this possibility and to continue to serve as an example to the rest of the world to stop nuclear proliferation. New studies suggest that a nuclear conflict using even a small number of weapons would have a devastating local effect and global climatic consequences, with catastrophic effects on stratospheric ozone, precipitation, agriculture, and water supplies. Clear policy implications follow from these results that the world will not be safe from catastrophic climate change due to nuclear war until almost all current nuclear weapons are eliminated.