## 1 Introduction  
China faces a challenging dilemma characterized by the need for rapid economic development, which inherently leads to increased energy consumption. However, the combustion of fossil fuels exacerbates the greenhouse effect, presenting a conflict between economic growth and the imperative for energy conservation and emission reduction. Achieving a harmonious and sustainable balance between the economy and the environment is an urgent issue for the Chinese government and industrial sectors. In response to this challenge, China introduced the \"dual carbon\" strategy in 2020. This strategic initiative sets forth ambitious goals, aiming to peak carbon dioxide emissions by 2030, also known as \"carbon peaking\", and achieve carbon neutrality by 2060, termed \"carbon neutrality\" [1]. These targets, although commendable, pose significant challenges to socioeconomic development. To meet these goals, innovative energy organizational paradigms have emerged, driven by the promotion of renewable energy applications and other low-carbon technologies [2; 3; 4]. A notable solution is the regional integrated energy system (RIES), which efficiently combines renewable and fossil energy sources [5], also known as an integrated energy system [6]. In contrast to a single-category energy supply, the RIES represents a multi-energy supply framework that integrates renewable and fossil energy sources. This framework not only enhances the flexibility and reliability of the energy supply [7] but also, more importantly, effectively reduces greenhouse gas emissions by incorporating low-carbontechnologies, such as renewable energy. The RIES, thus, provides robust support for achieving carbon reduction strategy goals. Currently, the RIES is experiencing robust development in China, gaining widespread attention from both industry and academia. It has emerged as a crucial energy supply model for realizing the objectives outlined in the \"dual carbon\" strategy [8]. However, it is essential to highlight that with the introduction of the \"dual carbon\" strategic goals, the construction plan of the energy system inevitably sets forth constrained targets for carbon emission reduction. The successful achievement of the carbon-peaking target, particularly the more-recent goal, holds paramount importance for carbon neutrality and the realization of long-term emission reduction targets. In this context, the construction planning and optimized operation of the regional integrated energy system (RIES) face new challenges under the current circumstances. Analyzing the carbon emission behavior of the RIES from the perspective of the carbon-peaking development strategy is crucial to plan the construction of the RIES while adhering to the requirements of the carbon-peaking implementation pathway. This analysis is of utmost importance for the successful attainment of the expected goals of carbon peaking. Specifically, this study reveals Shanghai's RIES carbon emissions under carbon-peaking targets, offering insights for energy system development. Using an extended STIRPAT model, Shanghai could peak emissions by 2025-2035, depending on development paths. CP-RIES, powered by renewables, can autonomously meet targets, while FP-RIES, reliant on fossil fuels, struggles, especially in high-load modes. Market-based policies, like carbon trading and green certificate trading, optimize the load allocation, reducing emissions. Carbon trading is more effective but costly. The key factors include trading prices and renewable quotas, with carbon price having the most significant impact. Although focused on Shanghai, these findings support broader low-carbon transitions, showcasing the impacts of diverse technologies and policies. The main contributions of this paper can be summarized as follows:  
1. The introduction of factors such as the population size, per capita GDP, urbanization rate, industrial structure, energy structure, and energy intensity, considering the existence of the environmental Kuznets curve.