Yes, carbon offsets are a good approach to addressing global warming, especially in the United States. This is because greenhouse gases have proven to be the largest cause of global warming. These greenhouse gas emissions (particularly carbon dioxide) must be compensated for if we are ever going to stop the increase of the earth's temperature.
Carbon dioxide needs to stop being emitted into the atmsophere, at the very least at the levels we've been doing it. Carbon offsets are an attempt at a band-aide, but a crisis like this requires far more than a band-aid, it requires systemic change that unfortunately may be very painful, at least in the short run.