Conference registration offers these round-trip options:
Carbon offset (air/auto travel within the U.S.):
Contribute $5 towards offsetting your footprint
Carbon offset (air travel from Canada or Central America):
Contribute $10 towards offsetting your footprint
Carbon offset (air travel from South America):
Contribute $15 towards offsetting your footprint
Carbon offset (air travel from U.K., Europe):
Contribute $20 towards offsetting your footprint
Carbon offset (air travel from Africa):
Contribute $25 towards offsetting your footprint
Carbon offset (air travel from Australia or Asia):
Contribute $30 towards offsetting your footprint