Results of recent investigations of the greenhouse effect are reviewed. The temperature rise due to doubling of CO2 is estimated to be 3.0±1.5°C. Other trace gases also contribute to the warming significantly. Climatic records of the past century are not inconsistent with the warming hypothesis. Environmental effects of the warming are also discussed. The possible drought in the United States is suggested, which could affect the Japanese life seriously. The possible disappearance of upwelling regions in the world oceans is also pointed out. However, the most serious problem is melting of polar ice, particularly the catastrophic disintegration of the West Antiarctica, which could lead to the submergence of the world coastal regions. It is emphasized that introduction of nuclear energy could avoid this disaster, and hence nuclear energy has a global significance.
