The global (or U.S.) economy does not have to suffer; in fact, I think recent events indicate that our dependence on foreign oil and the tightness of energy supplies is far more important to economic health. There are measures that can certainly be taken that can reduce our dependence on foreign oil, increase the "robustness" and flexibility of the economy's energy sector without inducing an economic crisis or downturn.
And if we don't do something (or somethings) serious about energy, economic malaise might be wished for as a best-case scenario.
I'm with you there. That speaks to my priorities.
For me it's security first, economy second, environment a distant third because let's face it: a bomb means immediate damage and mayhem. A depression, well, we know full well what a depression can entail. But gradual rising of the seas over 100 years? Okay, so the landscape slowly changes. Some land is covered by water as other land is uncovered by thawing ice. So? By that time, most edifices built along the coastline will be old and crumbling anyway. So move inland. Like I said, we've got decades and decades to do it in.
Look at it this way: if the warming were real but had NOTHING TO DO with human activity, what attitude would we take? Cope, that's what. Deal with it. Adapt. So if there is ever any question of choosing between the economy and the environment, bye-bye New Jersey, hello warm Minnesota. That's my stance.