If true, great!
There are a few wrinkles to sort out before we start uncorking champagne bottles though:
1) Stockpile drawdowns.
2) Syngas production and natural gas imports. These will help solve the air pollution problem, but not the CO2 problem. Ironically, with a steeper drawdown of SO2 emissions, warming will accelerate. (The "Faustian Bargain" Hansen has been hammering on for a couple of decades.) As a silver lining, perhaps a strong regional temperature response will invoke more serious action from the Chinese.
3) Sustained, multiple years of decline. India needs to be on board for the cuts to be meaningful, and so far, Modi's comments haven't exactly inspired confidence.
Again: Cumulative emissions are what matters. There's a reason RCP 2.6 has to go carbon negative to stay below 2C. Removing the screening effect of aerosols means we will need to get CO2 back under 405-415 ppm to have a decent chance of staying under 2C. Risk increases exponentially from here, and the further we penetrate above the cap, the harder and riskier it becomes due to carbon cycle feedbacks.