It would probably be better in the long run if we all drove less and walked more, then built a 1,000 mile aqueduct from the ocean to (and I can't believe I'm typing this) replenish the Great Salt Lake.
One might argue that would accelerate the collapse of the Great Salt Lake because the vast majority of diverted water is used for agriculture and increasing everyone's caloric requirements would result in more agriculture.
75% of U.S. adults are considered overweight, I would think that walking would first help this problem, as well as be a catalyst to other beneficial habits, including eating less meat and more vegetables, which would further reduce the amount of CO2 released from agriculture, as well as slim people's waistlines.
I'm not saying we shouldn't be working on climate change, but the solution for this problem must be much sooner and more local than a giant worldwide effort.