Final answer:
The claim that the U.S. immediately proposed legislation to ban all CFCs after discovering their effects on the ozone layer is false. Early actions were taken, but comprehensive international efforts like the Montreal Protocol emerged later in 1987, gradually phasing out harmful substances.
Step-by-step explanation:
The statement that political leaders in the United States immediately proposed legislation to ban the production of all CFCs as soon as the theoretical basis for ozone destruction by CFCs was worked out is False. While it is true that scientists calculated that CFCs (chlorofluorocarbons) could reach the stratosphere and destroy ozone in 1973, it was not until a significant reduction in the ozone layer was confirmed over Antarctica that more concrete international actions were taken. The United States and some Scandinavian countries did ban CFCs in spray cans in 1978, but a global agreement, the Montreal Protocol on Substances that Deplete the Ozone Layer, was not ratified until 1987. This agreement gradually phased out the production and emission of numerous ozone-depleting substances, including CFCs, and implemented a timeline for complete phase-out, taking special consideration for developing countries.
Furthermore, it is essential to note that the Montreal Protocol has been successful but with variability in recovery, as illustrated by the variations in the size and duration of the Antarctic ozone hole across the years. Additionally, global cooperation and continued reduction of CFCs and other controlled substances are still required for the complete restoration of the ozone layer, with hopes that it will return to normal by around 2065.