As Reuters comment:
The 2030 target should be fairly easy to meet. By then, the most manufacturing-intensive phase of China’s development will be complete and hundreds of millions more people will have been lifted into the middle class. Emissions are likely to stabilise by that date even without the joint statement.
For China, climate action remains subordinate to the primary goals of economic development and political and social stability. The joint statement enshrines China’s right to tackle climate change in its own way and at its own pace.