There is no free lunch. The gulf stream is not free energy. In the first place, it would cost a great deal to harvest the energy. In the second, every erg withdrawn from the gulf stream off Florida is not available further downstream, e.g., in Northern Europe. Result: colder Europe and political opposition.
RRRRIGHT. AND all the windmills in Calif are causing the droughts in the midwest too. Silting of turbine blades probably the biggest problem - as in Bay of Fundy.
Read the link. Plant cost would be less than that for coal or nuclear. The kinetic energy of ocean currents is free.
Your speculation on downstream climate effects is not informed by the math. It would take sapping hundreds of gigawatts of power to even begin to make a climate effect. In any event, Iceland and the British Isles don't vote in USA elections.
It would be an underwater waterwheel, not a stinking emergency brake.
Agreed...TANSTAAFL....tapping the GS in any appreciable amount would probably affect many other aspects (as in what would the West-East airliners do then?) Spend all of their time dodging the tapping apparatii? Or, worse yet, the 'tapping apparatii' causes a decrease in West-East wind flow at ground level. That would mean the next big Nino, Nano, Nono (whatever is now fashionable) sea circle jerk would stay on the west coast obliterating LA, SF and Seattle...wait a minute....where IS the down side in this?????