Cheaper to accept that it does exist
Claims that human activity has influenced the climate to our disadvantage: rising sea-levels, increased tornados, more severe droughts, more fierce fire-seasons: what if they are right?
The cost: some increased taxes; a preference for renewable energy sources such as wind, solar, tidal, and geothermic; a decrease in the import of and reliance upon Middle-Eastern volatile sources of energy; cleaner air as a result of diminished coal usage; huge costs as a result of coastal flooding in San Francisco, Los Angeles, New York, et alia, at billions; riotous migrations of starving people from new deserts to populated lands; significant and largely unpredictable species changes in the face of new global geotherms.
What if they are wrong: then we do not have to do anything particular, save for crossing our fingers and wishing our kids "good luck." Climate fluctuations occur and are aberrations anyway. Why spend money against that which might not occur, but may be required to spend billions to correct that which would cost millions.
I would argue that proposition one: that global warming exists, is a cheaper proposition than that global warming does not.
Are you willing to take that bet?
It is easier to solve problems in retrospect. Looking at it backwards may help.