With the policy summary of the IPCC WGII report out, this is a good time to concentrate on policy. Any effort to lower emissions has to put a price on carbon and other greenhouse sources. As I think extensive discussion has shown, a carbon tax is the best way to price emissions, and to price the destruction of carbon sinks.
One advantage of carbon taxes (and auctioned permits as well -- close enough to a carbon tax for practical purposes) not often noted is that it they produce revenue that can be directed back to consumers. This is an important contrast to the Kyoto system, where large numbers of permits were given away to big polluters. As with any method of raising the price of carbon, ultimately the cost was passed on to consumers. But with the permit giveaways, the consumer did not recover any of those costs.
On a small scale, this is merely painful and unfair. But suppose this was done with a large-scale rise in emission prices -- one that increased the prices of consumer goods by 25 or 50 percent? Not only would this cause direct suffering, the odds are pretty good that reduced consumer demand would cause at least a recession, with a real risk of world-wide depression. You need to return some the costs to consumers, not only on moral grounds but on Keynesian ones -- to avoid a precipitous drop in overall demand.
I will add that when you talk about a drop in consumption for poor people, you are talking not just suffering but death. Even in the rich nations, there people poor enough that cutting their real income by a third or half will kill some of them. Cut the income of people in poor nations already living on a few dollars a day, and you are talking slaughter.