Considering Geo-Engineering

at the NYT, via Mark Thoma, first, laying out the problems:

Carbon dioxide levels in the atmosphere are pushing 400 parts per million (p.p.m.) — up from the natural pre-industrial level of 280 p.p.m. Emissions for last year were the highest ever. Rather than drift along until a calamity galvanizes the world, and especially the United States, into precipitous action, the time to act is now.
The biology of the planet indicates we are already in a danger zone. The goal of limiting temperature increase to 2 degrees Celsius, as discussed at the Copenhagen and Cancun climate summits, is actually disastrous.
As we push the planet’s average temperature increase beyond 0.75°C, coral reefs (upon which 5 percent of humanity depends) are in increasing trouble. The balance of the coniferous forests of western North America has been tipped in favor of wood-boring bark beetles; in many places 70 percent of the trees are dead. The Amazon — which suffered the two greatest droughts in recorded history in 2005 and 2010 — teeters close to tipping into dieback, in which the southern and eastern parts of the forest die and turn into savannah vegetation. Estimates of sea-level rise continue to climb.
Even more disturbing, scientists have determined that, if we want to stop at a 2°C increase, global emissions have to peak in 2016. That seems impossible given current trends. Yet most people seem oblivious to the danger because of the lag time between reaching a greenhouse gas concentration level and the heat increase it will cause.

Then there is the consideration of geo-engineering.  Here the recommendations are reforestation and carbon sequestering in the soil.  Pumping sulfates into the atmosphere is mentioned, but the potential problems may outweigh the benefits.  This is interesting, but scary stuff.  Doing large-scale projects with unknown side effects could be disastrous, but potential activities will have to be considered.