It is necessary to assess this issue by the approach of utilitarianism. If people want to pursue the maximum happiness, they must reduce the pain they cause. And geo engineering is a really good way to reduce environmental problems. Thus, having a great climate condition is definitely able to maximize the happiness.
However, if we solve this issue by the measure of Kantian theory of ethics, there will be another sight of view. Because Kant's emphasis of human beings(humanity), the environment seems not so crucial for people. Thus, the geo engineering is not so necessary.