Your question is threefold: (1) if 350ppm is technically feasible, (2) if it is politically feasible, and (3) if can be done on time.

Comments: (1) Yes, it is technically feasible. The simplest way (although an utopia) is to shut down any source of greenhouse gases, as to allow the biosphere (soil, atmosphere, oceans) to naturally capture the "excedent" and to help nature by capturing/sequestering carbon using technology (an example at http://sequestration.mit.edu/). Such option is not feasible in the short term because the huge disruption caused to the society and the economy; the substitutes are not there in place in order to just shut down the current emissions sources. This is more a gradual change because the amount of investment needed.

But overall yes, it is technically feasible to reduce or eliminate emissions, and to capture carbon at its emitting source, be it at an electricity generation plant or at the exhaust tailpipe of a vehicle. Other technical option is not to have an emission in first place (i.e. electric or hydrogen powered vehicles).

(2) About the political feasibility, maybe. In my opinion, the political feasibility comes from putting the money where the mouth is, with no or low regrets, and with public support from doing so. In other words, convincing national constituencies, public companies and mainly multinational corporations about the need to invest in products, technologies and services that have significantly less emissions compared to the currently available options. Some examples: -tranportation: we are taking about the feasibility of having economic incentives from governments for the wide use of electric or hydrogen-powered vehicles. Both are technically feasible. The support for such type of vehicles is something that countries could agree on this on a planetary scale. Getting rid of fossil-fuel based vehicles would eliminate about 14% of global GHG emissions; that is appealling, technically and, if people do not loose jobs in the process, politically feasible. - electricity generation: we are taking about the feasibility of changing the energy consumption matrix of the countries as to rely more on non-emitting or low-emitting technologies for electricity generation; that would mean to significantly increase the amount of electricity generated by photovoltaic, solar thermal, wind, biomass, wave technologies. Because of geographical considerations, not every country could do so. Not all countries have wind, solar or wave potential in an amount as to eliminate fossil fuel electricity plants. But those who have, could reach an agreement. Cooperation, lowered impact and health issues are assets that make such agreement a politically feasible one.

(3) on time? We are not sure what the tipping point of the climate system is (at what concentration of CO2 there will be a no-return change) and when we may reach it. The safest way is to try to avoid it and it means keeping the CO2 concentration at a level where we currently know does not affect the global climate system. That is where the 350ppm comes from.

The more delay we have on reducing or eliminating CO2 emissions, the faster we may reach the tipping point. The timing is what has been missing on the "politically feasible" side.