The first green revolution occurred between 1950 and 1970; the second green revolution has been taking place since 1967. Some scientists are warning that the the green revolution is unlikely to continue to expand in the future. Which of the following best explains their reasoning?The first green revolution occurred between 1950 and 1970; the second green revolution has been taking place since 1967. Some scientists are warning that the the green revolution is unlikely to continue to expand in the future. Which of the following best explains their reasoning?