Why is it getting colder and hotter?

Because with the development of industry and the increase of automobile usage, more and more carbon dioxide is discharged into the atmosphere. Carbon dioxide has the property of heat preservation, so the earth is getting hotter and hotter because the heat on the earth cannot be dissipated into the universe. But this is only the initial stage. In the future, with the increase of carbon dioxide in the atmosphere, the heat of the sun may also be separated from the atmosphere, so the earth may become colder and colder. So now there are many science fiction films that show the earth hundreds of years later, endless ice and snow. It should be noted that although most people agree with the greenhouse effect, so far no country or institution can prove that global warming must be the cause of carbon dioxide, which is only speculation. It is for this reason that the United States suddenly announced its withdrawal from the Kyoto Protocol some time ago. )

Some scientists believe that global warming is only a natural law, because looking at the changes of the earth's temperature for thousands of years, the earth has not always kept the same temperature, but has always changed from hot to cold, then from cold to hot, and so on. According to some previous laws, the earth is now in a period from cold to hot. It is also possible that after reaching a certain temperature, the earth will slowly cool down. Of course, each cycle takes a long time, and the temperature difference between hot and cold is not very large.