Atmospheric carbon dioxide produces a so-called "greenhouse effect" by trapping heat near Earth's surface. What human activities might tend to increase the greenhouse effect?
The widespread, large scale, worlddwide burning of enormous quantities of fossil fuels for their energy, such as coal, oil, and natural gas, could do that, if it ever began and became popular. Oh, wait ! That"s what we've been doing, for a couple of centuries now !
Human Activities like increased pollution , unsustainable use of resources , combustion of fossil fuels and setting up big factories tends to increase the greenhouse effect.