How To Gauge Humanitarian Gains?

Larison challenges Kristof's rosy view of intervention in Libya:

Saying that the war has averted a humanitarian catastrophe is an extremely useful claim, and there’s no obvious way to disprove it. Outside governments intervened, and a humanitarian catastrophe hasn’t happened, and supporters of the war take it for granted that one would have happened otherwise.... The more serious problem for humanitarian interventionists is that their interventions can make things drastically worse.

They can create humanitarian catastrophes where they wouldn’t have existed otherwise. The growing humanitarian crisis in Misurata isn’t the fault of the intervening governments, but to the extent that intervening governments prolong the civil war they are contributing to the conditions that will create humanitarian crises around the country. If Libyan civilians begin dying “on a huge scale” partly because outside governments chose to prolong the conflict, bolstered the losing side in a civil war, and made it more difficult for the civilian population to receive food, water, and medicine, what war does Kristof think Libya will look like then?

Douthat jumps on Dennis Ross' bold claim that 100,000 Libyans were spared slaughter due to UN intervention.