More defense of emission offsets

My colleague Elizabeth Brown has this to say about Blankley's column on environmental indulgences:

I don’t know who Tony Blankley is but he doesn’t know much about economics.  Buying carbon emission offsets makes lots of economic sense and moral sense.  It is basically applying the same idea that has been proven successful at reducing overall pollution in other areas.  For example, cap and trade has been hugely successful at reducing SO2 emissions (the ones that cause acid rain).  In addition, see this article about how cap and trade for greenhouse gases makes sense, particularly if the money could be used to invest in developing nations like China>.  As the article below points out, carbon emission offsets provide a better and more efficient solution to a problem.  What is morally reprehensible about that?  The comparison to indulgences is a terribly flawed one.