The world needs to act fast: if humans continue to emit greenhouse gases at current rates, the remaining carbon budget to reduce risk of exceeding the 2°C target will be exhausted in around 20 years. Emissions should peak by 2020 and approach zero by around 2050 if the world is serious about reducing risk. As a simple rule of thumb, this means halving global emissions every decade, which can act as a golden rule. This golden rule is a road-map to prosperity. A fossil-fuel free society is economically attractive: renewable energy sources increasingly compete with fossil fuels, even when these are priced at historic lows. Moreover, the estimated costs of inaction range from 2–10% of GDP by 2100 by some estimates, to a final invoice equivalent to a 23% collapse in global productivity.
via https://medium.com/world-economic-forum/we-have-the-tools-to-fight-climate-change-its-time-to-start-using-them-e73d7c4c61e9