The analyses on the economic costs for achieving the nationally determined contributions and the expected global emission pathways

The Paris Agreement for a post-2020 international framework for tackling climate change was adopted in December 2015. The agreement requires that each country prepares and communicates nationally determined contributions (NDCs) every 5 years, including greenhouse gas (GHG) emission reduction targets. Most countries submitted NDCs before the Paris Agreement. According to our analyses using a global energy and GHG emission reduction assessment model, the emission reduction costs of the NDCs vary widely among countries; and those differences will induce carbon leakage, thus the expected global emission reduction is smaller than that predicted by simply aggregating the emission reductions of all the countries. Moreover, the emissions are larger than those required for the pathways leading to a high probability of temperature stabilization at below 2 degrees C above pre-industrial levels. To fill the gap, a rigorous review process employing robust indicators measuring emission reduction efforts is crucial. However, the development and deployment of innovative technologies with cheaper costs is even more significant.