Global warming by carbon dioxide is insisted by the IPCC. But according to observations in Hawaii, the variations of the temperature are ahead and the variations of the carbon dioxide follow. The insistence that increase in carbon dioxide concentration in air promotes global warming is wrong. On the contrary, Little Ice Age like Maunder minimum of 17 century is approaching shown by decrease of sunspots. The decrease of sunspots means the decrease of solar magnetic field that protects galaxy cosmic rays. The increase in the galactic cosmic rays in the air generates clouds and reflects sunlight to cool the earth. Currently the sunspots are decreasing (Minimum period). The temperature will be lowered similarly to the Maunder minimum in the 17th century (little ice age). Agriculture will be damaged and a certain scientist estimates two milliard people will be starved to death. Even world war three may occur. Proposed is to construct plant factories using LED lights or high pressure sodium lamps to reduce victims. The electric power necessary is to be created by space-based solar power generation as remaining underground fuels are to be lost within approximately 100 years. Plant Factories in large scale to produce even crops are possible if sufficient electric power for lamps are supplied. Basic technological problems of Space-Based solar power Generation are already solved. The power should be sent by microwave to penetrate clouds and rain.