In advance of next week's United Nations climate meeting in Paris, Allen Fawcett et al. highlight the Intended Nationally Determined Contributions (INDCs), in which various countries have put forward their commitments toward emissions reductions. The INDCs will be discussed at the Paris meeting. During past international climate negotiations, one general approach had been to provide some global, overarching rules to limit greenhouse gas emissions (GHG) and to then oblige all countries to exercise them. But, such "top down" approaches have shortcomings. The INDCs are more a "bottom up" approach, in which each country determines what types of commitments they are going to make to limit GHG emissions through 2025 or 2030. To date, over 150 countries, representing over 90% of global emissions have submitted their INDCs. In this Policy Forum, Fawcett and colleagues discuss how the INDCs might set the stage to reduce the likelihood of 4?C climate warming and improve our chances of limiting warming to 2?C. Similar estimates of the impacts of INDCs have recently been undertaken, but this paper focuses on uncertainty in the climate change system from an overall risk management perspective. Fawcett and colleagues use scenarios produced by a global integrated assessment model (GCAM) to model the INDCs and forecast future emissions trajectories. They found that the INDCs are a stepping stone towards both reducing the probability of the worst levels of temperature change until 2100 and increasing the probability of limiting global warming to 2?C. However, these outcomes will depend on the level of effort beyond 2030.
Source: American Association for the Advancement of Science