Thirty years ago, experts were still confused about the issue of global warming or cooling. They could not tell whether the future world was an ice bank or a greenhouse. In 1975, the first sophisticated computer models It shows that if the carbon dioxide in the atmosphere doubles, the global temperature will rise by about three degrees. However, at that time, scientists and the general public were still calm. For some time, some researchers even thought that excess carbon dioxide in the atmosphere With fertile farmland around the world, farmers will usher in a prosperous age. From this text, can we launch? ['Scientific research depends on data to avoid speculation.', 'Not all scientific research is instructive to agriculture.', 'The severity of global warming was unexpected.', "Experts' judgment on climate warming is different from now."]