Of course, those who do not believe that CO2 is bad could explain to people whether smog in cities is bad or not. After all, all that smog is coming from motor vehicles, factory exhausts, HVAC systems, etc. I wonder if those who think that global warming is a joke would agree that living in polluted cities is good. Well, it is easier to say that global warming is a hoax than to accept that reducing energy consumption and waste is necessary. I wonder if those who are trying to debunk global warming ever got money from oil companies.

"One of the biggest opponents of action on global warming has been the fossil fuels energy industry, and particularly the oil industry, such as ExxonMobil, which regularly publishes papers minimizing the threat of global warming. In 1998, the company started providing financial support to organizations and individuals who disagreed with the scientific consensus that human activities were contributing to climate change. One of the groups that received funds from the company was the Competitive Enterprise Institute. ExxonMobil also helped create the "Global Climate Science Team" whose members were active climate contrarians. According to a study by the Union of Concerned Scientists, between 1998 and 2005, ExxonMobil dispersed roughly $16 million to organizations that were challenging the scientific consensus view. After heavy criticism from the press and environmental groups in late 2006 and early 2007, ExxonMobil began distancing itself from these organizations.
In 2005, the oil giant opposed a shareholders' resolution to explain the science behind its denial of global warming."

What a coincidence what Exxon (the biggest cotributor to the Bush election campaigns, and biggest profiteer in Iraq) wqould fork out money to oppose global warming.